

<!--XBRL Document Created with Wdesk from Workiva-->
<!-- -->
<link:linkbase xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd" xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
  <link:roleRef roleURI="http://www.oesx.com/role/AccountsReceivable" xlink:href="oesx-20170331.xsd#AccountsReceivable" xlink:type="simple" />
  <link:roleRef roleURI="http://www.oesx.com/role/AccountsReceivableAndAllowanceForDoubtfulAccountsDetails" xlink:href="oesx-20170331.xsd#AccountsReceivableAndAllowanceForDoubtfulAccountsDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.oesx.com/role/AccountsReceivableNarrativeDetails" xlink:href="oesx-20170331.xsd#AccountsReceivableNarrativeDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.oesx.com/role/AccountsReceivableTables" xlink:href="oesx-20170331.xsd#AccountsReceivableTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.oesx.com/role/AccruedExpensesAndOther" xlink:href="oesx-20170331.xsd#AccruedExpensesAndOther" xlink:type="simple" />
  <link:roleRef roleURI="http://www.oesx.com/role/AccruedExpensesAndOtherAccruedExpensesAndOtherDetails" xlink:href="oesx-20170331.xsd#AccruedExpensesAndOtherAccruedExpensesAndOtherDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.oesx.com/role/AccruedExpensesAndOtherNarrativeDetails" xlink:href="oesx-20170331.xsd#AccruedExpensesAndOtherNarrativeDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.oesx.com/role/AccruedExpensesAndOtherTables" xlink:href="oesx-20170331.xsd#AccruedExpensesAndOtherTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.oesx.com/role/AccruedExpensesAndOtherWarrantyAccrualDetails" xlink:href="oesx-20170331.xsd#AccruedExpensesAndOtherWarrantyAccrualDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.oesx.com/role/Acquisition" xlink:href="oesx-20170331.xsd#Acquisition" xlink:type="simple" />
  <link:roleRef roleURI="http://www.oesx.com/role/AcquisitionDetails" xlink:href="oesx-20170331.xsd#AcquisitionDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.oesx.com/role/CommitmentsAndContingencies" xlink:href="oesx-20170331.xsd#CommitmentsAndContingencies" xlink:type="simple" />
  <link:roleRef roleURI="http://www.oesx.com/role/CommitmentsAndContingenciesNarrativeDetails" xlink:href="oesx-20170331.xsd#CommitmentsAndContingenciesNarrativeDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.oesx.com/role/CommitmentsAndContingenciesScheduleOfAnnualCommitmentsUnderNonCancelableOperatingAgreementsDetails" xlink:href="oesx-20170331.xsd#CommitmentsAndContingenciesScheduleOfAnnualCommitmentsUnderNonCancelableOperatingAgreementsDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.oesx.com/role/CommitmentsAndContingenciesTables" xlink:href="oesx-20170331.xsd#CommitmentsAndContingenciesTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.oesx.com/role/ConsolidatedBalanceSheets" xlink:href="oesx-20170331.xsd#ConsolidatedBalanceSheets" xlink:type="simple" />
  <link:roleRef roleURI="http://www.oesx.com/role/ConsolidatedBalanceSheetsParenthetical" xlink:href="oesx-20170331.xsd#ConsolidatedBalanceSheetsParenthetical" xlink:type="simple" />
  <link:roleRef roleURI="http://www.oesx.com/role/ConsolidatedStatementsOfCashFlows" xlink:href="oesx-20170331.xsd#ConsolidatedStatementsOfCashFlows" xlink:type="simple" />
  <link:roleRef roleURI="http://www.oesx.com/role/ConsolidatedStatementsOfOperationsAndComprehensiveIncome" xlink:href="oesx-20170331.xsd#ConsolidatedStatementsOfOperationsAndComprehensiveIncome" xlink:type="simple" />
  <link:roleRef roleURI="http://www.oesx.com/role/DescriptionOfBusiness" xlink:href="oesx-20170331.xsd#DescriptionOfBusiness" xlink:type="simple" />
  <link:roleRef roleURI="http://www.oesx.com/role/DocumentAndEntityInformation" xlink:href="oesx-20170331.xsd#DocumentAndEntityInformation" xlink:type="simple" />
  <link:roleRef roleURI="http://www.oesx.com/role/FinancingReceivables" xlink:href="oesx-20170331.xsd#FinancingReceivables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.oesx.com/role/FinancingReceivablesAgingAnalysisDetails" xlink:href="oesx-20170331.xsd#FinancingReceivablesAgingAnalysisDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.oesx.com/role/FinancingReceivablesAllowanceForDoubtfulAccountsDetails" xlink:href="oesx-20170331.xsd#FinancingReceivablesAllowanceForDoubtfulAccountsDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.oesx.com/role/FinancingReceivablesTables" xlink:href="oesx-20170331.xsd#FinancingReceivablesTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.oesx.com/role/GoodwillAndOtherIntangibleAssets" xlink:href="oesx-20170331.xsd#GoodwillAndOtherIntangibleAssets" xlink:type="simple" />
  <link:roleRef roleURI="http://www.oesx.com/role/GoodwillAndOtherIntangibleAssetsAmortizationExpenseDetails" xlink:href="oesx-20170331.xsd#GoodwillAndOtherIntangibleAssetsAmortizationExpenseDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.oesx.com/role/GoodwillAndOtherIntangibleAssetsChangeInCarryingValueOfGoodwillDetails" xlink:href="oesx-20170331.xsd#GoodwillAndOtherIntangibleAssetsChangeInCarryingValueOfGoodwillDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.oesx.com/role/GoodwillAndOtherIntangibleAssetsFutureAmortizationByFiscalYearDetails" xlink:href="oesx-20170331.xsd#GoodwillAndOtherIntangibleAssetsFutureAmortizationByFiscalYearDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.oesx.com/role/GoodwillAndOtherIntangibleAssetsNarrativeDetails" xlink:href="oesx-20170331.xsd#GoodwillAndOtherIntangibleAssetsNarrativeDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.oesx.com/role/GoodwillAndOtherIntangibleAssetsOtherIntangibleAssetsDetails" xlink:href="oesx-20170331.xsd#GoodwillAndOtherIntangibleAssetsOtherIntangibleAssetsDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.oesx.com/role/GoodwillAndOtherIntangibleAssetsTables" xlink:href="oesx-20170331.xsd#GoodwillAndOtherIntangibleAssetsTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.oesx.com/role/GoodwillAndOtherIntangibleAssetsUsefulLivesDetails" xlink:href="oesx-20170331.xsd#GoodwillAndOtherIntangibleAssetsUsefulLivesDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.oesx.com/role/IncomeTaxes" xlink:href="oesx-20170331.xsd#IncomeTaxes" xlink:type="simple" />
  <link:roleRef roleURI="http://www.oesx.com/role/IncomeTaxesNarrativeDetails" xlink:href="oesx-20170331.xsd#IncomeTaxesNarrativeDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.oesx.com/role/IncomeTaxesReconciliationOfTaxRatesDetails" xlink:href="oesx-20170331.xsd#IncomeTaxesReconciliationOfTaxRatesDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.oesx.com/role/IncomeTaxesScheduleOfComponentsOfIncomeTaxExpenseOrBenefitDetails" xlink:href="oesx-20170331.xsd#IncomeTaxesScheduleOfComponentsOfIncomeTaxExpenseOrBenefitDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.oesx.com/role/IncomeTaxesScheduleOfDeferredTaxAssetsAndLiabilitiesDetails" xlink:href="oesx-20170331.xsd#IncomeTaxesScheduleOfDeferredTaxAssetsAndLiabilitiesDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.oesx.com/role/IncomeTaxesTables" xlink:href="oesx-20170331.xsd#IncomeTaxesTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.oesx.com/role/IncomeTaxesUnrecognizedTaxBenefitActivityDetails" xlink:href="oesx-20170331.xsd#IncomeTaxesUnrecognizedTaxBenefitActivityDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.oesx.com/role/Inventories" xlink:href="oesx-20170331.xsd#Inventories" xlink:type="simple" />
  <link:roleRef roleURI="http://www.oesx.com/role/InventoriesDetails" xlink:href="oesx-20170331.xsd#InventoriesDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.oesx.com/role/InventoriesTables" xlink:href="oesx-20170331.xsd#InventoriesTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.oesx.com/role/LongTermDebt" xlink:href="oesx-20170331.xsd#LongTermDebt" xlink:type="simple" />
  <link:roleRef roleURI="http://www.oesx.com/role/LongTermDebtAggregateMaturitiesDetails" xlink:href="oesx-20170331.xsd#LongTermDebtAggregateMaturitiesDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.oesx.com/role/LongTermDebtAllOtherDebtDetails" xlink:href="oesx-20170331.xsd#LongTermDebtAllOtherDebtDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.oesx.com/role/LongTermDebtRevolvingCreditFacilityDetails" xlink:href="oesx-20170331.xsd#LongTermDebtRevolvingCreditFacilityDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.oesx.com/role/LongTermDebtSummaryOfDebtDetails" xlink:href="oesx-20170331.xsd#LongTermDebtSummaryOfDebtDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.oesx.com/role/LongTermDebtTables" xlink:href="oesx-20170331.xsd#LongTermDebtTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.oesx.com/role/NetIncomeLossPerCommonShare" xlink:href="oesx-20170331.xsd#NetIncomeLossPerCommonShare" xlink:type="simple" />
  <link:roleRef roleURI="http://www.oesx.com/role/NetIncomeLossPerCommonShareDilutiveSecuritiesDetails" xlink:href="oesx-20170331.xsd#NetIncomeLossPerCommonShareDilutiveSecuritiesDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.oesx.com/role/NetIncomeLossPerCommonShareEarningsPerShareDetails" xlink:href="oesx-20170331.xsd#NetIncomeLossPerCommonShareEarningsPerShareDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.oesx.com/role/NetIncomeLossPerCommonShareTables" xlink:href="oesx-20170331.xsd#NetIncomeLossPerCommonShareTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.oesx.com/role/OtherLongTermAssets" xlink:href="oesx-20170331.xsd#OtherLongTermAssets" xlink:type="simple" />
  <link:roleRef roleURI="http://www.oesx.com/role/OtherLongTermAssetsNarrativeDetails" xlink:href="oesx-20170331.xsd#OtherLongTermAssetsNarrativeDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.oesx.com/role/OtherLongTermAssetsSummaryOfOtherLongTermAssetsDetails" xlink:href="oesx-20170331.xsd#OtherLongTermAssetsSummaryOfOtherLongTermAssetsDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.oesx.com/role/OtherLongTermAssetsTables" xlink:href="oesx-20170331.xsd#OtherLongTermAssetsTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.oesx.com/role/PrepaidExpensesAndOtherCurrentAssets" xlink:href="oesx-20170331.xsd#PrepaidExpensesAndOtherCurrentAssets" xlink:type="simple" />
  <link:roleRef roleURI="http://www.oesx.com/role/PrepaidExpensesAndOtherCurrentAssetsDetails" xlink:href="oesx-20170331.xsd#PrepaidExpensesAndOtherCurrentAssetsDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.oesx.com/role/PrepaidExpensesAndOtherCurrentAssetsTables" xlink:href="oesx-20170331.xsd#PrepaidExpensesAndOtherCurrentAssetsTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.oesx.com/role/PropertyAndEquipment" xlink:href="oesx-20170331.xsd#PropertyAndEquipment" xlink:type="simple" />
  <link:roleRef roleURI="http://www.oesx.com/role/PropertyAndEquipmentEquipmentUnderCapitalLeasesDetails" xlink:href="oesx-20170331.xsd#PropertyAndEquipmentEquipmentUnderCapitalLeasesDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.oesx.com/role/PropertyAndEquipmentNarrativeDetails" xlink:href="oesx-20170331.xsd#PropertyAndEquipmentNarrativeDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.oesx.com/role/PropertyAndEquipmentSummaryOfPropertyAndEquipmentDetails" xlink:href="oesx-20170331.xsd#PropertyAndEquipmentSummaryOfPropertyAndEquipmentDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.oesx.com/role/PropertyAndEquipmentTables" xlink:href="oesx-20170331.xsd#PropertyAndEquipmentTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.oesx.com/role/PropertyAndEquipmentUsefulLivesDetails" xlink:href="oesx-20170331.xsd#PropertyAndEquipmentUsefulLivesDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.oesx.com/role/QuarterlyFinancialDataDetails" xlink:href="oesx-20170331.xsd#QuarterlyFinancialDataDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.oesx.com/role/QuarterlyFinancialDataUnaudited" xlink:href="oesx-20170331.xsd#QuarterlyFinancialDataUnaudited" xlink:type="simple" />
  <link:roleRef roleURI="http://www.oesx.com/role/QuarterlyFinancialDataUnauditedTables" xlink:href="oesx-20170331.xsd#QuarterlyFinancialDataUnauditedTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.oesx.com/role/RelatedPartyTransactions" xlink:href="oesx-20170331.xsd#RelatedPartyTransactions" xlink:type="simple" />
  <link:roleRef roleURI="http://www.oesx.com/role/RelatedPartyTransactionsDetails" xlink:href="oesx-20170331.xsd#RelatedPartyTransactionsDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.oesx.com/role/ScheduleIiValuationAndQualifyingAccounts" xlink:href="oesx-20170331.xsd#ScheduleIiValuationAndQualifyingAccounts" xlink:type="simple" />
  <link:roleRef roleURI="http://www.oesx.com/role/ScheduleIiValuationAndQualifyingAccountsDetails" xlink:href="oesx-20170331.xsd#ScheduleIiValuationAndQualifyingAccountsDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.oesx.com/role/SegmentData" xlink:href="oesx-20170331.xsd#SegmentData" xlink:type="simple" />
  <link:roleRef roleURI="http://www.oesx.com/role/SegmentDataReconciliationOfSegmentAssetsAndLiabilitiesDetails" xlink:href="oesx-20170331.xsd#SegmentDataReconciliationOfSegmentAssetsAndLiabilitiesDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.oesx.com/role/SegmentDataReconciliationOfSegmentOperationsDetails" xlink:href="oesx-20170331.xsd#SegmentDataReconciliationOfSegmentOperationsDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.oesx.com/role/SegmentDataTables" xlink:href="oesx-20170331.xsd#SegmentDataTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.oesx.com/role/ShareholdersEquity" xlink:href="oesx-20170331.xsd#ShareholdersEquity" xlink:type="simple" />
  <link:roleRef roleURI="http://www.oesx.com/role/ShareholdersEquityNarrativeDetails" xlink:href="oesx-20170331.xsd#ShareholdersEquityNarrativeDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.oesx.com/role/ShareholdersEquityScheduleOfEsppActivityDetails" xlink:href="oesx-20170331.xsd#ShareholdersEquityScheduleOfEsppActivityDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.oesx.com/role/ShareholdersEquityTables" xlink:href="oesx-20170331.xsd#ShareholdersEquityTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.oesx.com/role/StatementsOfShareholdersEquity" xlink:href="oesx-20170331.xsd#StatementsOfShareholdersEquity" xlink:type="simple" />
  <link:roleRef roleURI="http://www.oesx.com/role/StockOptionsRestrictedSharesAndWarrants" xlink:href="oesx-20170331.xsd#StockOptionsRestrictedSharesAndWarrants" xlink:type="simple" />
  <link:roleRef roleURI="http://www.oesx.com/role/StockOptionsRestrictedSharesAndWarrantsNarrativeDetails" xlink:href="oesx-20170331.xsd#StockOptionsRestrictedSharesAndWarrantsNarrativeDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.oesx.com/role/StockOptionsRestrictedSharesAndWarrantsScheduleOfRestrictedSharesDetails" xlink:href="oesx-20170331.xsd#StockOptionsRestrictedSharesAndWarrantsScheduleOfRestrictedSharesDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.oesx.com/role/StockOptionsRestrictedSharesAndWarrantsScheduleOfSharesAvailableForGrantDetails" xlink:href="oesx-20170331.xsd#StockOptionsRestrictedSharesAndWarrantsScheduleOfSharesAvailableForGrantDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.oesx.com/role/StockOptionsRestrictedSharesAndWarrantsStockBasedCompensationDetails" xlink:href="oesx-20170331.xsd#StockOptionsRestrictedSharesAndWarrantsStockBasedCompensationDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.oesx.com/role/StockOptionsRestrictedSharesAndWarrantsSummaryOfExercisePriceRangeDetails" xlink:href="oesx-20170331.xsd#StockOptionsRestrictedSharesAndWarrantsSummaryOfExercisePriceRangeDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.oesx.com/role/StockOptionsRestrictedSharesAndWarrantsSummaryOfOutstandingStockOptionsDetails" xlink:href="oesx-20170331.xsd#StockOptionsRestrictedSharesAndWarrantsSummaryOfOutstandingStockOptionsDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.oesx.com/role/StockOptionsRestrictedSharesAndWarrantsSummaryOfUnrecognizedCompensationCostDetails" xlink:href="oesx-20170331.xsd#StockOptionsRestrictedSharesAndWarrantsSummaryOfUnrecognizedCompensationCostDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.oesx.com/role/StockOptionsRestrictedSharesAndWarrantsTables" xlink:href="oesx-20170331.xsd#StockOptionsRestrictedSharesAndWarrantsTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.oesx.com/role/SubsequentEvents" xlink:href="oesx-20170331.xsd#SubsequentEvents" xlink:type="simple" />
  <link:roleRef roleURI="http://www.oesx.com/role/SubsequentEventsDetails" xlink:href="oesx-20170331.xsd#SubsequentEventsDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.oesx.com/role/SummaryOfSignificantAccountingPolicies" xlink:href="oesx-20170331.xsd#SummaryOfSignificantAccountingPolicies" xlink:type="simple" />
  <link:roleRef roleURI="http://www.oesx.com/role/SummaryOfSignificantAccountingPoliciesConcentrationRiskDetails" xlink:href="oesx-20170331.xsd#SummaryOfSignificantAccountingPoliciesConcentrationRiskDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.oesx.com/role/SummaryOfSignificantAccountingPoliciesIncentiveCompensationDetails" xlink:href="oesx-20170331.xsd#SummaryOfSignificantAccountingPoliciesIncentiveCompensationDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.oesx.com/role/SummaryOfSignificantAccountingPoliciesNarrativeDetails" xlink:href="oesx-20170331.xsd#SummaryOfSignificantAccountingPoliciesNarrativeDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.oesx.com/role/SummaryOfSignificantAccountingPoliciesPolicies" xlink:href="oesx-20170331.xsd#SummaryOfSignificantAccountingPoliciesPolicies" xlink:type="simple" />
  <link:roleRef roleURI="http://www.xbrl.org/2009/role/negatedLabel" xlink:href="http://www.xbrl.org/lrr/role/negated-2009-12-16.xsd#negatedLabel" xlink:type="simple" />
  <link:roleRef roleURI="http://www.xbrl.org/2009/role/negatedNetLabel" xlink:href="http://www.xbrl.org/lrr/role/negated-2009-12-16.xsd#negatedNetLabel" xlink:type="simple" />
  <link:roleRef roleURI="http://www.xbrl.org/2009/role/negatedPeriodEndLabel" xlink:href="http://www.xbrl.org/lrr/role/negated-2009-12-16.xsd#negatedPeriodEndLabel" xlink:type="simple" />
  <link:roleRef roleURI="http://www.xbrl.org/2009/role/negatedPeriodStartLabel" xlink:href="http://www.xbrl.org/lrr/role/negated-2009-12-16.xsd#negatedPeriodStartLabel" xlink:type="simple" />
  <link:roleRef roleURI="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:href="http://www.xbrl.org/lrr/role/negated-2009-12-16.xsd#negatedTerseLabel" xlink:type="simple" />
  <link:roleRef roleURI="http://www.xbrl.org/2009/role/negatedTotalLabel" xlink:href="http://www.xbrl.org/lrr/role/negated-2009-12-16.xsd#negatedTotalLabel" xlink:type="simple" />
  <link:roleRef roleURI="http://www.xbrl.org/2009/role/netLabel" xlink:href="http://www.xbrl.org/lrr/role/net-2009-12-16.xsd#netLabel" xlink:type="simple" />
  <link:presentationLink xlink:role="http://www.oesx.com/role/AccountsReceivable" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ReceivablesAbstract" xlink:label="loc_us-gaap_ReceivablesAbstract_DD5A5E8719AFF141DAC00DBF9B3303C6" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LoansNotesTradeAndOtherReceivablesDisclosureTextBlock" xlink:label="loc_us-gaap_LoansNotesTradeAndOtherReceivablesDisclosureTextBlock_75DA9DAEDD81E1677B980DBF9B33A0AC" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ReceivablesAbstract_DD5A5E8719AFF141DAC00DBF9B3303C6" xlink:to="loc_us-gaap_LoansNotesTradeAndOtherReceivablesDisclosureTextBlock_75DA9DAEDD81E1677B980DBF9B33A0AC" xlink:type="arc" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.oesx.com/role/AccountsReceivableAndAllowanceForDoubtfulAccountsDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ReceivablesAbstract" xlink:label="loc_us-gaap_ReceivablesAbstract_585331389F2FD42CFA9AF8E57E8FBE26" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AccountsReceivableGrossCurrent" xlink:label="loc_us-gaap_AccountsReceivableGrossCurrent_9DF2A97437749F8FA55CF8E57E90D8BB" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ReceivablesAbstract_585331389F2FD42CFA9AF8E57E8FBE26" xlink:to="loc_us-gaap_AccountsReceivableGrossCurrent_9DF2A97437749F8FA55CF8E57E90D8BB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent" xlink:label="loc_us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent_A6130439E055C9EB9CA3F8E57E90B1AD" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2009/role/negatedLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ReceivablesAbstract_585331389F2FD42CFA9AF8E57E8FBE26" xlink:to="loc_us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent_A6130439E055C9EB9CA3F8E57E90B1AD" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AccountsReceivableNetCurrent" xlink:label="loc_us-gaap_AccountsReceivableNetCurrent_6BEB4EF7F80C3FA9ECC3F8E57E903185" xlink:type="locator" />
    <link:presentationArc order="3" preferredLabel="http://www.xbrl.org/2003/role/totalLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ReceivablesAbstract_585331389F2FD42CFA9AF8E57E8FBE26" xlink:to="loc_us-gaap_AccountsReceivableNetCurrent_6BEB4EF7F80C3FA9ECC3F8E57E903185" xlink:type="arc" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.oesx.com/role/AccountsReceivableNarrativeDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ReceivablesAbstract" xlink:label="loc_us-gaap_ReceivablesAbstract_0925D3DC9066DCE8D17EF84D913C8859" xlink:type="locator" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_AccountsReceivablesDueMinimumPeriod" xlink:label="loc_oesx_AccountsReceivablesDueMinimumPeriod_867AA08BB1E9560CC4C9F857733C6856" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ReceivablesAbstract_0925D3DC9066DCE8D17EF84D913C8859" xlink:to="loc_oesx_AccountsReceivablesDueMinimumPeriod_867AA08BB1E9560CC4C9F857733C6856" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_AccountsReceivablesDueMaximumPeriod" xlink:label="loc_oesx_AccountsReceivablesDueMaximumPeriod_329412B5C83382F37145F857735C949A" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ReceivablesAbstract_0925D3DC9066DCE8D17EF84D913C8859" xlink:to="loc_oesx_AccountsReceivablesDueMaximumPeriod_329412B5C83382F37145F857735C949A" xlink:type="arc" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.oesx.com/role/AccountsReceivableTables" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ReceivablesAbstract" xlink:label="loc_us-gaap_ReceivablesAbstract_4763AB28953983ABD4F5F84D912F92CF" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTextBlock" xlink:label="loc_us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTextBlock_BAF29C1FF50A31F403A2F8523835C8E6" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ReceivablesAbstract_4763AB28953983ABD4F5F84D912F92CF" xlink:to="loc_us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTextBlock_BAF29C1FF50A31F403A2F8523835C8E6" xlink:type="arc" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.oesx.com/role/AccruedExpensesAndOther" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_OtherLiabilitiesDisclosureAbstract" xlink:label="loc_us-gaap_OtherLiabilitiesDisclosureAbstract_89367F8E99EDABAD4DFB0DE1F127B8DE" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AccountsPayableAccruedLiabilitiesAndOtherLiabilitiesDisclosureCurrentTextBlock" xlink:label="loc_us-gaap_AccountsPayableAccruedLiabilitiesAndOtherLiabilitiesDisclosureCurrentTextBlock_115485185144388327D20DE1F12DAD09" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_OtherLiabilitiesDisclosureAbstract_89367F8E99EDABAD4DFB0DE1F127B8DE" xlink:to="loc_us-gaap_AccountsPayableAccruedLiabilitiesAndOtherLiabilitiesDisclosureCurrentTextBlock_115485185144388327D20DE1F12DAD09" xlink:type="arc" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.oesx.com/role/AccruedExpensesAndOtherAccruedExpensesAndOtherDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_OtherLiabilitiesDisclosureAbstract" xlink:label="loc_us-gaap_OtherLiabilitiesDisclosureAbstract_1FCC8EFF7880A6AFBF260DE1F11C37E6" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_EmployeeRelatedLiabilitiesCurrent" xlink:label="loc_us-gaap_EmployeeRelatedLiabilitiesCurrent_923EAFE487147AF31E810DE1F11CC19F" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_OtherLiabilitiesDisclosureAbstract_1FCC8EFF7880A6AFBF260DE1F11C37E6" xlink:to="loc_us-gaap_EmployeeRelatedLiabilitiesCurrent_923EAFE487147AF31E810DE1F11CC19F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SalesAndExciseTaxPayableCurrent" xlink:label="loc_us-gaap_SalesAndExciseTaxPayableCurrent_5E6EF7054F1AE29A24010DE1F11C2518" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_OtherLiabilitiesDisclosureAbstract_1FCC8EFF7880A6AFBF260DE1F11C37E6" xlink:to="loc_us-gaap_SalesAndExciseTaxPayableCurrent_5E6EF7054F1AE29A24010DE1F11C2518" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_AccruedContractCostsCurrent" xlink:label="loc_oesx_AccruedContractCostsCurrent_1BD1ACE6D4370C2215D80DE1F11C883C" xlink:type="locator" />
    <link:presentationArc order="3" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_OtherLiabilitiesDisclosureAbstract_1FCC8EFF7880A6AFBF260DE1F11C37E6" xlink:to="loc_oesx_AccruedContractCostsCurrent_1BD1ACE6D4370C2215D80DE1F11C883C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AccruedProfessionalFeesCurrent" xlink:label="loc_us-gaap_AccruedProfessionalFeesCurrent_1F4C244E9FBBE580D8110DE1F11C7C4F" xlink:type="locator" />
    <link:presentationArc order="4" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_OtherLiabilitiesDisclosureAbstract_1FCC8EFF7880A6AFBF260DE1F11C37E6" xlink:to="loc_us-gaap_AccruedProfessionalFeesCurrent_1F4C244E9FBBE580D8110DE1F11C7C4F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ProductWarrantyAccrualClassifiedCurrent" xlink:label="loc_us-gaap_ProductWarrantyAccrualClassifiedCurrent_C9DFC6BE8EE686246E520DE1F11C06B0" xlink:type="locator" />
    <link:presentationArc order="5" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_OtherLiabilitiesDisclosureAbstract_1FCC8EFF7880A6AFBF260DE1F11C37E6" xlink:to="loc_us-gaap_ProductWarrantyAccrualClassifiedCurrent_C9DFC6BE8EE686246E520DE1F11C06B0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_OtherAccruedLiabilitiesCurrent" xlink:label="loc_us-gaap_OtherAccruedLiabilitiesCurrent_65DE8410D857AB5706BF0DE1F11C95D9" xlink:type="locator" />
    <link:presentationArc order="6" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_OtherLiabilitiesDisclosureAbstract_1FCC8EFF7880A6AFBF260DE1F11C37E6" xlink:to="loc_us-gaap_OtherAccruedLiabilitiesCurrent_65DE8410D857AB5706BF0DE1F11C95D9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AccruedLiabilitiesCurrent" xlink:label="loc_us-gaap_AccruedLiabilitiesCurrent_91896FA8E6C9F05819A60DE1F11CDC38" xlink:type="locator" />
    <link:presentationArc order="7" preferredLabel="http://www.xbrl.org/2003/role/totalLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_OtherLiabilitiesDisclosureAbstract_1FCC8EFF7880A6AFBF260DE1F11C37E6" xlink:to="loc_us-gaap_AccruedLiabilitiesCurrent_91896FA8E6C9F05819A60DE1F11CDC38" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LossContingencyAccrualAtCarryingValue" xlink:label="loc_us-gaap_LossContingencyAccrualAtCarryingValue_A3C1867B71AC4532EFA40DE1F11D59D8" xlink:type="locator" />
    <link:presentationArc order="8" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_OtherLiabilitiesDisclosureAbstract_1FCC8EFF7880A6AFBF260DE1F11C37E6" xlink:to="loc_us-gaap_LossContingencyAccrualAtCarryingValue_A3C1867B71AC4532EFA40DE1F11D59D8" xlink:type="arc" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.oesx.com/role/AccruedExpensesAndOtherNarrativeDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_OtherLiabilitiesDisclosureAbstract" xlink:label="loc_us-gaap_OtherLiabilitiesDisclosureAbstract_CAFDAE2E7CE84753DBFD643CABACF491" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable" xlink:label="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_A7816BCDC73CF21B578C643CABAC6D88" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_OtherLiabilitiesDisclosureAbstract_CAFDAE2E7CE84753DBFD643CABACF491" xlink:to="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_A7816BCDC73CF21B578C643CABAC6D88" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RangeAxis" xlink:label="loc_us-gaap_RangeAxis_7CBE93D4504DA406BB53643CABAC6301" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_A7816BCDC73CF21B578C643CABAC6D88" xlink:to="loc_us-gaap_RangeAxis_7CBE93D4504DA406BB53643CABAC6301" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember_39CF051071AF4D83F5F3643CABAC55C3" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_RangeAxis_7CBE93D4504DA406BB53643CABAC6301" xlink:to="loc_us-gaap_RangeMember_39CF051071AF4D83F5F3643CABAC55C3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_MinimumMember" xlink:label="loc_us-gaap_MinimumMember_9BF64D9EF8C8FB219A9A643CABAF3490" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_RangeMember_39CF051071AF4D83F5F3643CABAC55C3" xlink:to="loc_us-gaap_MinimumMember_9BF64D9EF8C8FB219A9A643CABAF3490" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_MaximumMember" xlink:label="loc_us-gaap_MaximumMember_1D9B69D192519488BB6F643CABAFA02F" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_RangeMember_39CF051071AF4D83F5F3643CABAC55C3" xlink:to="loc_us-gaap_MaximumMember_1D9B69D192519488BB6F643CABAFA02F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SegmentReportingInformationLineItems" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_7CD1DD4768D9F2C399DE643CABAF52F6" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_A7816BCDC73CF21B578C643CABAC6D88" xlink:to="loc_us-gaap_SegmentReportingInformationLineItems_7CD1DD4768D9F2C399DE643CABAF52F6" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_LimitedProductWarrantyTerm" xlink:label="loc_oesx_LimitedProductWarrantyTerm_90CCC67EAA3EB280D543643CABAF45E8" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_7CD1DD4768D9F2C399DE643CABAF52F6" xlink:to="loc_oesx_LimitedProductWarrantyTerm_90CCC67EAA3EB280D543643CABAF45E8" xlink:type="arc" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.oesx.com/role/AccruedExpensesAndOtherTables" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_OtherLiabilitiesDisclosureAbstract" xlink:label="loc_us-gaap_OtherLiabilitiesDisclosureAbstract_BB8168EA18FC96BE0B200DE1F12529F4" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScheduleOfAccruedLiabilitiesTableTextBlock" xlink:label="loc_us-gaap_ScheduleOfAccruedLiabilitiesTableTextBlock_530F5871B487F41CA94F0DE1F125AFED" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_OtherLiabilitiesDisclosureAbstract_BB8168EA18FC96BE0B200DE1F12529F4" xlink:to="loc_us-gaap_ScheduleOfAccruedLiabilitiesTableTextBlock_530F5871B487F41CA94F0DE1F125AFED" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScheduleOfProductWarrantyLiabilityTableTextBlock" xlink:label="loc_us-gaap_ScheduleOfProductWarrantyLiabilityTableTextBlock_0174A00B541601A807CF0DE1F12589C8" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_OtherLiabilitiesDisclosureAbstract_BB8168EA18FC96BE0B200DE1F12529F4" xlink:to="loc_us-gaap_ScheduleOfProductWarrantyLiabilityTableTextBlock_0174A00B541601A807CF0DE1F12589C8" xlink:type="arc" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.oesx.com/role/AccruedExpensesAndOtherWarrantyAccrualDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_OtherLiabilitiesDisclosureAbstract" xlink:label="loc_us-gaap_OtherLiabilitiesDisclosureAbstract_E19ED6ABB1D24E8E0EF0844B46DC6436" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_MovementInStandardProductWarrantyAccrualRollForward" xlink:label="loc_us-gaap_MovementInStandardProductWarrantyAccrualRollForward_18C8E56C33EE8E9A5EAE844B46DCB6D3" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_OtherLiabilitiesDisclosureAbstract_E19ED6ABB1D24E8E0EF0844B46DC6436" xlink:to="loc_us-gaap_MovementInStandardProductWarrantyAccrualRollForward_18C8E56C33EE8E9A5EAE844B46DCB6D3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ProductWarrantyAccrual" xlink:label="loc_us-gaap_ProductWarrantyAccrual_62B1A39E24F2142A7B74844B46DCA724" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/periodStartLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_MovementInStandardProductWarrantyAccrualRollForward_18C8E56C33EE8E9A5EAE844B46DCB6D3" xlink:to="loc_us-gaap_ProductWarrantyAccrual_62B1A39E24F2142A7B74844B46DCA724" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ProductWarrantyAccrualPreexistingIncreaseDecrease" xlink:label="loc_us-gaap_ProductWarrantyAccrualPreexistingIncreaseDecrease_E8332408802C9B98BED984AD3F0C9C68" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_MovementInStandardProductWarrantyAccrualRollForward_18C8E56C33EE8E9A5EAE844B46DCB6D3" xlink:to="loc_us-gaap_ProductWarrantyAccrualPreexistingIncreaseDecrease_E8332408802C9B98BED984AD3F0C9C68" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ProductWarrantyAccrualPayments" xlink:label="loc_us-gaap_ProductWarrantyAccrualPayments_81A9827BA85C26BAFAEC844B46DC1758" xlink:type="locator" />
    <link:presentationArc order="3" preferredLabel="http://www.xbrl.org/2009/role/negatedLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_MovementInStandardProductWarrantyAccrualRollForward_18C8E56C33EE8E9A5EAE844B46DCB6D3" xlink:to="loc_us-gaap_ProductWarrantyAccrualPayments_81A9827BA85C26BAFAEC844B46DC1758" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ProductWarrantyAccrual" xlink:label="loc_us-gaap_ProductWarrantyAccrual_FCA3A5CC93B00711E070844B46DCB039" xlink:type="locator" />
    <link:presentationArc order="4" preferredLabel="http://www.xbrl.org/2003/role/periodEndLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_MovementInStandardProductWarrantyAccrualRollForward_18C8E56C33EE8E9A5EAE844B46DCB6D3" xlink:to="loc_us-gaap_ProductWarrantyAccrual_FCA3A5CC93B00711E070844B46DCB039" xlink:type="arc" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.oesx.com/role/Acquisition" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_BusinessCombinationsAbstract" xlink:label="loc_us-gaap_BusinessCombinationsAbstract_194C0E79582AA9852A584108827F7928" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_BusinessCombinationDisclosureTextBlock" xlink:label="loc_us-gaap_BusinessCombinationDisclosureTextBlock_5C2C99987113D2398E734108827F8EC5" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_BusinessCombinationsAbstract_194C0E79582AA9852A584108827F7928" xlink:to="loc_us-gaap_BusinessCombinationDisclosureTextBlock_5C2C99987113D2398E734108827F8EC5" xlink:type="arc" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.oesx.com/role/AcquisitionDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_BusinessCombinationsAbstract" xlink:label="loc_us-gaap_BusinessCombinationsAbstract_FC987792164764174FA65FA93FB2095E" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_709312EBEDC1589EEFCE5FA93FB2D8F6" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_BusinessCombinationsAbstract_FC987792164764174FA65FA93FB2095E" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_709312EBEDC1589EEFCE5FA93FB2D8F6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_BusinessAcquisitionAxis" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_6A7D313273D1384DBE425FA93FB3157C" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_709312EBEDC1589EEFCE5FA93FB2D8F6" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_6A7D313273D1384DBE425FA93FB3157C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_B43BAF37AC43A8C94A9D5FA93FB332CA" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_6A7D313273D1384DBE425FA93FB3157C" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_B43BAF37AC43A8C94A9D5FA93FB332CA" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_HarrisMember" xlink:label="loc_oesx_HarrisMember_F580D966BCD97367BAD35FA93FB3E039" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_B43BAF37AC43A8C94A9D5FA93FB332CA" xlink:to="loc_oesx_HarrisMember_F580D966BCD97367BAD35FA93FB3E039" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_BusinessAcquisitionLineItems" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_BA2921016293E64CB3875FA93FB3D060" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_709312EBEDC1589EEFCE5FA93FB2D8F6" xlink:to="loc_us-gaap_BusinessAcquisitionLineItems_BA2921016293E64CB3875FA93FB3D060" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_BusinessCombinationConsiderationTransferredInitialPurchaseAgreementAmount" xlink:label="loc_oesx_BusinessCombinationConsiderationTransferredInitialPurchaseAgreementAmount_A94194686B584D3FFDCF5FA93FB3C32F" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_BA2921016293E64CB3875FA93FB3D060" xlink:to="loc_oesx_BusinessCombinationConsiderationTransferredInitialPurchaseAgreementAmount_A94194686B584D3FFDCF5FA93FB3C32F" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_BusinessCombinationConsiderationTransferredInitialPurchaseAgreementContingentAdjustmentAmount" xlink:label="loc_oesx_BusinessCombinationConsiderationTransferredInitialPurchaseAgreementContingentAdjustmentAmount_DB06F84C077C2F3EB8405FA93FB35D2E" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_BA2921016293E64CB3875FA93FB3D060" xlink:to="loc_oesx_BusinessCombinationConsiderationTransferredInitialPurchaseAgreementContingentAdjustmentAmount_DB06F84C077C2F3EB8405FA93FB35D2E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_BusinessCombinationContingentConsiderationLiability" xlink:label="loc_us-gaap_BusinessCombinationContingentConsiderationLiability_A544E7DBE3ACEAC629645FA93FB37660" xlink:type="locator" />
    <link:presentationArc order="3" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_BA2921016293E64CB3875FA93FB3D060" xlink:to="loc_us-gaap_BusinessCombinationContingentConsiderationLiability_A544E7DBE3ACEAC629645FA93FB37660" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_BusinessCombinationFixedFutureConsiderationAmount" xlink:label="loc_oesx_BusinessCombinationFixedFutureConsiderationAmount_4B5584B841344DA2A1B15FA93FB47DBD" xlink:type="locator" />
    <link:presentationArc order="4" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_BA2921016293E64CB3875FA93FB3D060" xlink:to="loc_oesx_BusinessCombinationFixedFutureConsiderationAmount_4B5584B841344DA2A1B15FA93FB47DBD" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_BusinessAcquisitionEquityInterestIssuedOrIssuableValueAssigned" xlink:label="loc_us-gaap_BusinessAcquisitionEquityInterestIssuedOrIssuableValueAssigned_AAEC9E0D08545F0231CA5FA93FB49046" xlink:type="locator" />
    <link:presentationArc order="5" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_BA2921016293E64CB3875FA93FB3D060" xlink:to="loc_us-gaap_BusinessAcquisitionEquityInterestIssuedOrIssuableValueAssigned_AAEC9E0D08545F0231CA5FA93FB49046" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_BusinessAcquisitionEquityInterestsIssuedOrIssuableNumberOfSharesIssued" xlink:label="loc_us-gaap_BusinessAcquisitionEquityInterestsIssuedOrIssuableNumberOfSharesIssued_CC15D2CA0612451E9D295FA93FB473F1" xlink:type="locator" />
    <link:presentationArc order="6" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_BA2921016293E64CB3875FA93FB3D060" xlink:to="loc_us-gaap_BusinessAcquisitionEquityInterestsIssuedOrIssuableNumberOfSharesIssued_CC15D2CA0612451E9D295FA93FB473F1" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_BusinessCombinationFixedFutureConsiderationSharesPricePerShare" xlink:label="loc_oesx_BusinessCombinationFixedFutureConsiderationSharesPricePerShare_144762175146F3549CAB5FA93FB423DC" xlink:type="locator" />
    <link:presentationArc order="7" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_BA2921016293E64CB3875FA93FB3D060" xlink:to="loc_oesx_BusinessCombinationFixedFutureConsiderationSharesPricePerShare_144762175146F3549CAB5FA93FB423DC" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_BusinessCombinationFixedFutureConsiderationCash" xlink:label="loc_oesx_BusinessCombinationFixedFutureConsiderationCash_7C428782A2DB2731F6255FA93FB4552A" xlink:type="locator" />
    <link:presentationArc order="8" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_BA2921016293E64CB3875FA93FB3D060" xlink:to="loc_oesx_BusinessCombinationFixedFutureConsiderationCash_7C428782A2DB2731F6255FA93FB4552A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PaymentsToAcquireBusinessesGross" xlink:label="loc_us-gaap_PaymentsToAcquireBusinessesGross_9C54CA8990518D2EE0305FA93FB465C3" xlink:type="locator" />
    <link:presentationArc order="9" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_BA2921016293E64CB3875FA93FB3D060" xlink:to="loc_us-gaap_PaymentsToAcquireBusinessesGross_9C54CA8990518D2EE0305FA93FB465C3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1" xlink:label="loc_us-gaap_BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1_796A51F64345AD3614375FA93FB43A5C" xlink:type="locator" />
    <link:presentationArc order="10" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_BA2921016293E64CB3875FA93FB3D060" xlink:to="loc_us-gaap_BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1_796A51F64345AD3614375FA93FB43A5C" xlink:type="arc" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.oesx.com/role/CommitmentsAndContingencies" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CommitmentsAndContingenciesDisclosureAbstract" xlink:label="loc_us-gaap_CommitmentsAndContingenciesDisclosureAbstract_60BD7E4F6A24F10C17D50DBF9A6AB87A" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CommitmentsAndContingenciesDisclosureTextBlock" xlink:label="loc_us-gaap_CommitmentsAndContingenciesDisclosureTextBlock_82B62B8D8C9258637D0B0DBF9A6A7564" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_CommitmentsAndContingenciesDisclosureAbstract_60BD7E4F6A24F10C17D50DBF9A6AB87A" xlink:to="loc_us-gaap_CommitmentsAndContingenciesDisclosureTextBlock_82B62B8D8C9258637D0B0DBF9A6A7564" xlink:type="arc" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.oesx.com/role/CommitmentsAndContingenciesNarrativeDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CommitmentsAndContingenciesDisclosureAbstract" xlink:label="loc_us-gaap_CommitmentsAndContingenciesDisclosureAbstract_A4C2F6B7E5734ECE280064872C7DDE88" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LongTermPurchaseCommitmentTable" xlink:label="loc_us-gaap_LongTermPurchaseCommitmentTable_B3DEB4A51E0B25D7211264872C7D1C40" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_CommitmentsAndContingenciesDisclosureAbstract_A4C2F6B7E5734ECE280064872C7DDE88" xlink:to="loc_us-gaap_LongTermPurchaseCommitmentTable_B3DEB4A51E0B25D7211264872C7D1C40" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SaleLeasebackTransactionDescriptionAxis" xlink:label="loc_us-gaap_SaleLeasebackTransactionDescriptionAxis_53BD8A96D141C3F3AB9064872C7D4F88" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LongTermPurchaseCommitmentTable_B3DEB4A51E0B25D7211264872C7D1C40" xlink:to="loc_us-gaap_SaleLeasebackTransactionDescriptionAxis_53BD8A96D141C3F3AB9064872C7D4F88" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SaleLeasebackTransactionNameDomain" xlink:label="loc_us-gaap_SaleLeasebackTransactionNameDomain_EC85674B54CC5E38DEB864872C7DA992" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_SaleLeasebackTransactionDescriptionAxis_53BD8A96D141C3F3AB9064872C7D4F88" xlink:to="loc_us-gaap_SaleLeasebackTransactionNameDomain_EC85674B54CC5E38DEB864872C7DA992" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_AgreementwithTramontinaU.S.CookwareInc.Member" xlink:label="loc_oesx_AgreementwithTramontinaU.S.CookwareInc.Member_490B6A0DD3B16252274E64872C7DEDCA" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_SaleLeasebackTransactionNameDomain_EC85674B54CC5E38DEB864872C7DA992" xlink:to="loc_oesx_AgreementwithTramontinaU.S.CookwareInc.Member_490B6A0DD3B16252274E64872C7DEDCA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_IncomeStatementLocationAxis" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_7E231045DAE4ED93F73464872C7D0FA6" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LongTermPurchaseCommitmentTable_B3DEB4A51E0B25D7211264872C7D1C40" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_7E231045DAE4ED93F73464872C7D0FA6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_240F079B3FF13AA4CA5F64872C7D17D5" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_7E231045DAE4ED93F73464872C7D0FA6" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_240F079B3FF13AA4CA5F64872C7D17D5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_GeneralAndAdministrativeExpenseMember" xlink:label="loc_us-gaap_GeneralAndAdministrativeExpenseMember_7F4F5F441DF94B6AA19264872C7D512D" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_240F079B3FF13AA4CA5F64872C7D17D5" xlink:to="loc_us-gaap_GeneralAndAdministrativeExpenseMember_7F4F5F441DF94B6AA19264872C7D512D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LongTermPurchaseCommitmentByCategoryOfItemPurchasedAxis" xlink:label="loc_us-gaap_LongTermPurchaseCommitmentByCategoryOfItemPurchasedAxis_A44A88A218679F92D95564872C7DA5E3" xlink:type="locator" />
    <link:presentationArc order="3" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LongTermPurchaseCommitmentTable_B3DEB4A51E0B25D7211264872C7D1C40" xlink:to="loc_us-gaap_LongTermPurchaseCommitmentByCategoryOfItemPurchasedAxis_A44A88A218679F92D95564872C7DA5E3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LongTermPurchaseCommitmentCategoryOfItemPurchasedDomain" xlink:label="loc_us-gaap_LongTermPurchaseCommitmentCategoryOfItemPurchasedDomain_0104BC921D8091F25B4564872C7D7BE3" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LongTermPurchaseCommitmentByCategoryOfItemPurchasedAxis_A44A88A218679F92D95564872C7DA5E3" xlink:to="loc_us-gaap_LongTermPurchaseCommitmentCategoryOfItemPurchasedDomain_0104BC921D8091F25B4564872C7D7BE3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_InventoriesMember" xlink:label="loc_us-gaap_InventoriesMember_5FDE09F009DDBE24734664872C7D0526" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LongTermPurchaseCommitmentCategoryOfItemPurchasedDomain_0104BC921D8091F25B4564872C7D7BE3" xlink:to="loc_us-gaap_InventoriesMember_5FDE09F009DDBE24734664872C7D0526" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_IncomeTaxAuthorityAxis" xlink:label="loc_us-gaap_IncomeTaxAuthorityAxis_7CB618792F372CE0DEB264872C7D875B" xlink:type="locator" />
    <link:presentationArc order="4" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LongTermPurchaseCommitmentTable_B3DEB4A51E0B25D7211264872C7D1C40" xlink:to="loc_us-gaap_IncomeTaxAuthorityAxis_7CB618792F372CE0DEB264872C7D875B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_IncomeTaxAuthorityDomain" xlink:label="loc_us-gaap_IncomeTaxAuthorityDomain_589B9D36BC81CCA66ACE64872C7DABF0" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncomeTaxAuthorityAxis_7CB618792F372CE0DEB264872C7D875B" xlink:to="loc_us-gaap_IncomeTaxAuthorityDomain_589B9D36BC81CCA66ACE64872C7DABF0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StateAndLocalJurisdictionMember" xlink:label="loc_us-gaap_StateAndLocalJurisdictionMember_39AD097BAB444C97BDEE64872C7E09BE" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncomeTaxAuthorityDomain_589B9D36BC81CCA66ACE64872C7DABF0" xlink:to="loc_us-gaap_StateAndLocalJurisdictionMember_39AD097BAB444C97BDEE64872C7E09BE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_IncomeTaxAuthorityNameAxis" xlink:label="loc_us-gaap_IncomeTaxAuthorityNameAxis_9404977649DD0EE04FE264872C7EF1AF" xlink:type="locator" />
    <link:presentationArc order="5" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LongTermPurchaseCommitmentTable_B3DEB4A51E0B25D7211264872C7D1C40" xlink:to="loc_us-gaap_IncomeTaxAuthorityNameAxis_9404977649DD0EE04FE264872C7EF1AF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_IncomeTaxAuthorityNameDomain" xlink:label="loc_us-gaap_IncomeTaxAuthorityNameDomain_5AD4F4ADF09B51ACD7B064872C7EA81C" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncomeTaxAuthorityNameAxis_9404977649DD0EE04FE264872C7EF1AF" xlink:to="loc_us-gaap_IncomeTaxAuthorityNameDomain_5AD4F4ADF09B51ACD7B064872C7EA81C" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_WisconsinDepartmentOfRevenueMember" xlink:label="loc_oesx_WisconsinDepartmentOfRevenueMember_002D82DB7FD0656C6F3D64872C7E3559" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncomeTaxAuthorityNameDomain_5AD4F4ADF09B51ACD7B064872C7EA81C" xlink:to="loc_oesx_WisconsinDepartmentOfRevenueMember_002D82DB7FD0656C6F3D64872C7E3559" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LongTermPurchaseCommitmentLineItems" xlink:label="loc_us-gaap_LongTermPurchaseCommitmentLineItems_A05A9FDD41C51C2D779964872C7EBFD4" xlink:type="locator" />
    <link:presentationArc order="6" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LongTermPurchaseCommitmentTable_B3DEB4A51E0B25D7211264872C7D1C40" xlink:to="loc_us-gaap_LongTermPurchaseCommitmentLineItems_A05A9FDD41C51C2D779964872C7EBFD4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_OperatingLeasesRentExpenseNet" xlink:label="loc_us-gaap_OperatingLeasesRentExpenseNet_644BC9A4B50EC6B371E864872C7E5E5E" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LongTermPurchaseCommitmentLineItems_A05A9FDD41C51C2D779964872C7EBFD4" xlink:to="loc_us-gaap_OperatingLeasesRentExpenseNet_644BC9A4B50EC6B371E864872C7E5E5E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LessorLeasingArrangementsOperatingLeasesTermOfContract" xlink:label="loc_us-gaap_LessorLeasingArrangementsOperatingLeasesTermOfContract_4A0AF3E79960B71FADD164872C7E34DE" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LongTermPurchaseCommitmentLineItems_A05A9FDD41C51C2D779964872C7EBFD4" xlink:to="loc_us-gaap_LessorLeasingArrangementsOperatingLeasesTermOfContract_4A0AF3E79960B71FADD164872C7E34DE" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_LessorLeasingArrangementsOperatingLeasesNumberofExtensionOptions" xlink:label="loc_oesx_LessorLeasingArrangementsOperatingLeasesNumberofExtensionOptions_09C06FB1E51DFE2D622164872C7EBFF6" xlink:type="locator" />
    <link:presentationArc order="3" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LongTermPurchaseCommitmentLineItems_A05A9FDD41C51C2D779964872C7EBFD4" xlink:to="loc_oesx_LessorLeasingArrangementsOperatingLeasesNumberofExtensionOptions_09C06FB1E51DFE2D622164872C7EBFF6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LessorLeasingArrangementsOperatingLeasesRenewalTerm" xlink:label="loc_us-gaap_LessorLeasingArrangementsOperatingLeasesRenewalTerm_D1FF73D0801DCC9BCA9264872C7E6858" xlink:type="locator" />
    <link:presentationArc order="4" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LongTermPurchaseCommitmentLineItems_A05A9FDD41C51C2D779964872C7EBFD4" xlink:to="loc_us-gaap_LessorLeasingArrangementsOperatingLeasesRenewalTerm_D1FF73D0801DCC9BCA9264872C7E6858" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_OperatingLeasesMonthlyRentalPaymentsReceivable" xlink:label="loc_oesx_OperatingLeasesMonthlyRentalPaymentsReceivable_FB20C86107428432B6DC64872C7E9B71" xlink:type="locator" />
    <link:presentationArc order="5" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LongTermPurchaseCommitmentLineItems_A05A9FDD41C51C2D779964872C7EBFD4" xlink:to="loc_oesx_OperatingLeasesMonthlyRentalPaymentsReceivable_FB20C86107428432B6DC64872C7E9B71" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SaleLeasebackTransactionNetProceedsInvestingActivities" xlink:label="loc_us-gaap_SaleLeasebackTransactionNetProceedsInvestingActivities_482FE5F6AE7CB7785A4A64872C7E0730" xlink:type="locator" />
    <link:presentationArc order="6" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LongTermPurchaseCommitmentLineItems_A05A9FDD41C51C2D779964872C7EBFD4" xlink:to="loc_us-gaap_SaleLeasebackTransactionNetProceedsInvestingActivities_482FE5F6AE7CB7785A4A64872C7E0730" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_SaleLeasebackTransactionAreaofLeasedProperty" xlink:label="loc_oesx_SaleLeasebackTransactionAreaofLeasedProperty_DAA9B0BDC8DA36E0D5DF64872C7EF153" xlink:type="locator" />
    <link:presentationArc order="7" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LongTermPurchaseCommitmentLineItems_A05A9FDD41C51C2D779964872C7EBFD4" xlink:to="loc_oesx_SaleLeasebackTransactionAreaofLeasedProperty_DAA9B0BDC8DA36E0D5DF64872C7EF153" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_SaleLeasebackTransactionLeaseTerm" xlink:label="loc_oesx_SaleLeasebackTransactionLeaseTerm_B331694901AF1E5C33A064872C7EE6C6" xlink:type="locator" />
    <link:presentationArc order="8" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LongTermPurchaseCommitmentLineItems_A05A9FDD41C51C2D779964872C7EBFD4" xlink:to="loc_oesx_SaleLeasebackTransactionLeaseTerm_B331694901AF1E5C33A064872C7EE6C6" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_SaleLeasebackTransactionRentExpensePerSquareFoot" xlink:label="loc_oesx_SaleLeasebackTransactionRentExpensePerSquareFoot_3AF750D5D7BD07B002E864872C7E72DB" xlink:type="locator" />
    <link:presentationArc order="9" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LongTermPurchaseCommitmentLineItems_A05A9FDD41C51C2D779964872C7EBFD4" xlink:to="loc_oesx_SaleLeasebackTransactionRentExpensePerSquareFoot_3AF750D5D7BD07B002E864872C7E72DB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SaleLeasebackTransactionMonthlyRentalPayments" xlink:label="loc_us-gaap_SaleLeasebackTransactionMonthlyRentalPayments_767D0DE7C9DC38A78FA064872C7E7016" xlink:type="locator" />
    <link:presentationArc order="10" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LongTermPurchaseCommitmentLineItems_A05A9FDD41C51C2D779964872C7EBFD4" xlink:to="loc_us-gaap_SaleLeasebackTransactionMonthlyRentalPayments_767D0DE7C9DC38A78FA064872C7E7016" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PurchaseObligationDueInNextTwelveMonths" xlink:label="loc_us-gaap_PurchaseObligationDueInNextTwelveMonths_35CBD049998945E1799664872C7E24BD" xlink:type="locator" />
    <link:presentationArc order="11" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LongTermPurchaseCommitmentLineItems_A05A9FDD41C51C2D779964872C7EBFD4" xlink:to="loc_us-gaap_PurchaseObligationDueInNextTwelveMonths_35CBD049998945E1799664872C7E24BD" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DefinedContributionPlanEmployerDiscretionaryContributionAmount" xlink:label="loc_us-gaap_DefinedContributionPlanEmployerDiscretionaryContributionAmount_1611976B52AB45D0F28764872C7E4900" xlink:type="locator" />
    <link:presentationArc order="12" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LongTermPurchaseCommitmentLineItems_A05A9FDD41C51C2D779964872C7EBFD4" xlink:to="loc_us-gaap_DefinedContributionPlanEmployerDiscretionaryContributionAmount_1611976B52AB45D0F28764872C7E4900" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LossContingencyClaimsDismissedNumber" xlink:label="loc_us-gaap_LossContingencyClaimsDismissedNumber_7AC76E4B426E6EA78F2A64872C7F3163" xlink:type="locator" />
    <link:presentationArc order="13" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LongTermPurchaseCommitmentLineItems_A05A9FDD41C51C2D779964872C7EBFD4" xlink:to="loc_us-gaap_LossContingencyClaimsDismissedNumber_7AC76E4B426E6EA78F2A64872C7F3163" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_IncomeTaxExaminationLiabilityRefundAdjustmentFromSettlementWithTaxingAuthority" xlink:label="loc_us-gaap_IncomeTaxExaminationLiabilityRefundAdjustmentFromSettlementWithTaxingAuthority_0DBA56C260AD5133E44264872C7FD2FE" xlink:type="locator" />
    <link:presentationArc order="14" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LongTermPurchaseCommitmentLineItems_A05A9FDD41C51C2D779964872C7EBFD4" xlink:to="loc_us-gaap_IncomeTaxExaminationLiabilityRefundAdjustmentFromSettlementWithTaxingAuthority_0DBA56C260AD5133E44264872C7FD2FE" xlink:type="arc" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.oesx.com/role/CommitmentsAndContingenciesScheduleOfAnnualCommitmentsUnderNonCancelableOperatingAgreementsDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CommitmentsAndContingenciesDisclosureAbstract" xlink:label="loc_us-gaap_CommitmentsAndContingenciesDisclosureAbstract_DA21B667FC22F4F778224108823AEF40" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_OperatingLeasesFutureMinimumPaymentsDueCurrent" xlink:label="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsDueCurrent_06A049F8C6E35E3FD5184108823A0039" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_CommitmentsAndContingenciesDisclosureAbstract_DA21B667FC22F4F778224108823AEF40" xlink:to="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsDueCurrent_06A049F8C6E35E3FD5184108823A0039" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_OperatingLeasesFutureMinimumPaymentsDueInTwoYears" xlink:label="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsDueInTwoYears_E22169632AA99DD257F74108823AEA55" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_CommitmentsAndContingenciesDisclosureAbstract_DA21B667FC22F4F778224108823AEF40" xlink:to="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsDueInTwoYears_E22169632AA99DD257F74108823AEA55" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_OperatingLeasesFutureMinimumPaymentsDueInThreeYears" xlink:label="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsDueInThreeYears_FE705D0DD905142DB2C04108823A6F49" xlink:type="locator" />
    <link:presentationArc order="3" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_CommitmentsAndContingenciesDisclosureAbstract_DA21B667FC22F4F778224108823AEF40" xlink:to="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsDueInThreeYears_FE705D0DD905142DB2C04108823A6F49" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_OperatingLeasesFutureMinimumPaymentsDue" xlink:label="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsDue_B6E53AFDD1718E05B4AE4108823AB6EF" xlink:type="locator" />
    <link:presentationArc order="4" preferredLabel="http://www.xbrl.org/2003/role/totalLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_CommitmentsAndContingenciesDisclosureAbstract_DA21B667FC22F4F778224108823AEF40" xlink:to="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsDue_B6E53AFDD1718E05B4AE4108823AB6EF" xlink:type="arc" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.oesx.com/role/CommitmentsAndContingenciesTables" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CommitmentsAndContingenciesDisclosureAbstract" xlink:label="loc_us-gaap_CommitmentsAndContingenciesDisclosureAbstract_4F24C73F6C7BFB35FDCF66E04C114D25" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScheduleOfFutureMinimumRentalPaymentsForOperatingLeasesTableTextBlock" xlink:label="loc_us-gaap_ScheduleOfFutureMinimumRentalPaymentsForOperatingLeasesTableTextBlock_2A937693BB5E6BD9860266E04C110B85" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_CommitmentsAndContingenciesDisclosureAbstract_4F24C73F6C7BFB35FDCF66E04C114D25" xlink:to="loc_us-gaap_ScheduleOfFutureMinimumRentalPaymentsForOperatingLeasesTableTextBlock_2A937693BB5E6BD9860266E04C110B85" xlink:type="arc" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.oesx.com/role/ConsolidatedBalanceSheets" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StatementOfFinancialPositionAbstract" xlink:label="loc_us-gaap_StatementOfFinancialPositionAbstract_7C171B4F8315FA5384384068B8015F70" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AssetsAbstract" xlink:label="loc_us-gaap_AssetsAbstract_27E89EA52FF4EBE6E8314068B803AF4F" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_StatementOfFinancialPositionAbstract_7C171B4F8315FA5384384068B8015F70" xlink:to="loc_us-gaap_AssetsAbstract_27E89EA52FF4EBE6E8314068B803AF4F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue" xlink:label="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_097FC8CCAA69C32CA0204068B806381D" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AssetsAbstract_27E89EA52FF4EBE6E8314068B803AF4F" xlink:to="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_097FC8CCAA69C32CA0204068B806381D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AccountsReceivableNetCurrent" xlink:label="loc_us-gaap_AccountsReceivableNetCurrent_044C532D1BF15055B4BA4068B8066DD9" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AssetsAbstract_27E89EA52FF4EBE6E8314068B803AF4F" xlink:to="loc_us-gaap_AccountsReceivableNetCurrent_044C532D1BF15055B4BA4068B8066DD9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_InventoryNet" xlink:label="loc_us-gaap_InventoryNet_3164D91ECEC405C8461A4068B80608E5" xlink:type="locator" />
    <link:presentationArc order="3" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AssetsAbstract_27E89EA52FF4EBE6E8314068B803AF4F" xlink:to="loc_us-gaap_InventoryNet_3164D91ECEC405C8461A4068B80608E5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DeferredCostsCurrent" xlink:label="loc_us-gaap_DeferredCostsCurrent_169A37EDB87F7251ED954068B806B26F" xlink:type="locator" />
    <link:presentationArc order="4" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AssetsAbstract_27E89EA52FF4EBE6E8314068B803AF4F" xlink:to="loc_us-gaap_DeferredCostsCurrent_169A37EDB87F7251ED954068B806B26F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PrepaidExpenseAndOtherAssetsCurrent" xlink:label="loc_us-gaap_PrepaidExpenseAndOtherAssetsCurrent_6CF69F06D4B4C0DCFCBA4068B8067DE1" xlink:type="locator" />
    <link:presentationArc order="5" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AssetsAbstract_27E89EA52FF4EBE6E8314068B803AF4F" xlink:to="loc_us-gaap_PrepaidExpenseAndOtherAssetsCurrent_6CF69F06D4B4C0DCFCBA4068B8067DE1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AssetsCurrent" xlink:label="loc_us-gaap_AssetsCurrent_2AF9C95688E8F2FFFC824068B8067FD1" xlink:type="locator" />
    <link:presentationArc order="6" preferredLabel="http://www.xbrl.org/2003/role/totalLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AssetsAbstract_27E89EA52FF4EBE6E8314068B803AF4F" xlink:to="loc_us-gaap_AssetsCurrent_2AF9C95688E8F2FFFC824068B8067FD1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PropertyPlantAndEquipmentNet" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNet_B5940027EE4BB29F451B4068B806A5EF" xlink:type="locator" />
    <link:presentationArc order="7" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AssetsAbstract_27E89EA52FF4EBE6E8314068B803AF4F" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentNet_B5940027EE4BB29F451B4068B806A5EF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_IntangibleAssetsNetExcludingGoodwill" xlink:label="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_8696927C4F1C097170E54068B8078F48" xlink:type="locator" />
    <link:presentationArc order="8" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AssetsAbstract_27E89EA52FF4EBE6E8314068B803AF4F" xlink:to="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_8696927C4F1C097170E54068B8078F48" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AccountsReceivableNetNoncurrent" xlink:label="loc_us-gaap_AccountsReceivableNetNoncurrent_4B9178D079E044A7DB194068B8072563" xlink:type="locator" />
    <link:presentationArc order="9" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AssetsAbstract_27E89EA52FF4EBE6E8314068B803AF4F" xlink:to="loc_us-gaap_AccountsReceivableNetNoncurrent_4B9178D079E044A7DB194068B8072563" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_OtherAssetsNoncurrent" xlink:label="loc_us-gaap_OtherAssetsNoncurrent_DA93063FAD887CB6426C4068B8070E5F" xlink:type="locator" />
    <link:presentationArc order="10" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AssetsAbstract_27E89EA52FF4EBE6E8314068B803AF4F" xlink:to="loc_us-gaap_OtherAssetsNoncurrent_DA93063FAD887CB6426C4068B8070E5F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_Assets" xlink:label="loc_us-gaap_Assets_120D43215F16139CDC1C4068B80782E7" xlink:type="locator" />
    <link:presentationArc order="11" preferredLabel="http://www.xbrl.org/2003/role/totalLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AssetsAbstract_27E89EA52FF4EBE6E8314068B803AF4F" xlink:to="loc_us-gaap_Assets_120D43215F16139CDC1C4068B80782E7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LiabilitiesAndStockholdersEquityAbstract" xlink:label="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_BD424FAC090169B2A4784068B80772A6" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_StatementOfFinancialPositionAbstract_7C171B4F8315FA5384384068B8015F70" xlink:to="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_BD424FAC090169B2A4784068B80772A6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AccountsPayableCurrent" xlink:label="loc_us-gaap_AccountsPayableCurrent_0A9D4E9A8128FE1DBAAF4068B807F7FA" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_BD424FAC090169B2A4784068B80772A6" xlink:to="loc_us-gaap_AccountsPayableCurrent_0A9D4E9A8128FE1DBAAF4068B807F7FA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AccruedLiabilitiesCurrent" xlink:label="loc_us-gaap_AccruedLiabilitiesCurrent_6A7A1FCA377BDEE89D7A4068B80837CD" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_BD424FAC090169B2A4784068B80772A6" xlink:to="loc_us-gaap_AccruedLiabilitiesCurrent_6A7A1FCA377BDEE89D7A4068B80837CD" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DeferredRevenueCurrent" xlink:label="loc_us-gaap_DeferredRevenueCurrent_83B955CB668E0F2EDC724068B808EC47" xlink:type="locator" />
    <link:presentationArc order="3" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_BD424FAC090169B2A4784068B80772A6" xlink:to="loc_us-gaap_DeferredRevenueCurrent_83B955CB668E0F2EDC724068B808EC47" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LongTermDebtCurrent" xlink:label="loc_us-gaap_LongTermDebtCurrent_32E849316A00C27494E44068B80874A7" xlink:type="locator" />
    <link:presentationArc order="4" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_BD424FAC090169B2A4784068B80772A6" xlink:to="loc_us-gaap_LongTermDebtCurrent_32E849316A00C27494E44068B80874A7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LiabilitiesCurrent" xlink:label="loc_us-gaap_LiabilitiesCurrent_8FB986D92DD1A990F5C04068B808C258" xlink:type="locator" />
    <link:presentationArc order="5" preferredLabel="http://www.xbrl.org/2003/role/totalLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_BD424FAC090169B2A4784068B80772A6" xlink:to="loc_us-gaap_LiabilitiesCurrent_8FB986D92DD1A990F5C04068B808C258" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LongTermLineOfCredit" xlink:label="loc_us-gaap_LongTermLineOfCredit_F7F679888422CE8FD0654068B808083B" xlink:type="locator" />
    <link:presentationArc order="6" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_BD424FAC090169B2A4784068B80772A6" xlink:to="loc_us-gaap_LongTermLineOfCredit_F7F679888422CE8FD0654068B808083B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_OtherLongTermDebtNoncurrent" xlink:label="loc_us-gaap_OtherLongTermDebtNoncurrent_983415CB9E12AC6769E44068B80872EE" xlink:type="locator" />
    <link:presentationArc order="7" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_BD424FAC090169B2A4784068B80772A6" xlink:to="loc_us-gaap_OtherLongTermDebtNoncurrent_983415CB9E12AC6769E44068B80872EE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DeferredRevenueNoncurrent" xlink:label="loc_us-gaap_DeferredRevenueNoncurrent_D965D5BB1EA349DE2AE24068B808947E" xlink:type="locator" />
    <link:presentationArc order="8" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_BD424FAC090169B2A4784068B80772A6" xlink:to="loc_us-gaap_DeferredRevenueNoncurrent_D965D5BB1EA349DE2AE24068B808947E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_OtherLiabilitiesNoncurrent" xlink:label="loc_us-gaap_OtherLiabilitiesNoncurrent_621F32016A21D185D3434068B808464C" xlink:type="locator" />
    <link:presentationArc order="9" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_BD424FAC090169B2A4784068B80772A6" xlink:to="loc_us-gaap_OtherLiabilitiesNoncurrent_621F32016A21D185D3434068B808464C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_Liabilities" xlink:label="loc_us-gaap_Liabilities_6C48093BF56A094AA1914068B808E2AE" xlink:type="locator" />
    <link:presentationArc order="10" preferredLabel="http://www.xbrl.org/2003/role/totalLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_BD424FAC090169B2A4784068B80772A6" xlink:to="loc_us-gaap_Liabilities_6C48093BF56A094AA1914068B808E2AE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CommitmentsAndContingencies" xlink:label="loc_us-gaap_CommitmentsAndContingencies_801691F1CD1DC6BDB2D94068B8097242" xlink:type="locator" />
    <link:presentationArc order="11" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_BD424FAC090169B2A4784068B80772A6" xlink:to="loc_us-gaap_CommitmentsAndContingencies_801691F1CD1DC6BDB2D94068B8097242" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StockholdersEquityAbstract" xlink:label="loc_us-gaap_StockholdersEquityAbstract_243CE14A65348D1855384068B8098897" xlink:type="locator" />
    <link:presentationArc order="12" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_BD424FAC090169B2A4784068B80772A6" xlink:to="loc_us-gaap_StockholdersEquityAbstract_243CE14A65348D1855384068B8098897" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PreferredStockValue" xlink:label="loc_us-gaap_PreferredStockValue_D1274E74745A98FDC9DE4068B8097AF2" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_StockholdersEquityAbstract_243CE14A65348D1855384068B8098897" xlink:to="loc_us-gaap_PreferredStockValue_D1274E74745A98FDC9DE4068B8097AF2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CommonStockValue" xlink:label="loc_us-gaap_CommonStockValue_5E4B5023107E3E62855A4068B809BCA2" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_StockholdersEquityAbstract_243CE14A65348D1855384068B8098897" xlink:to="loc_us-gaap_CommonStockValue_5E4B5023107E3E62855A4068B809BCA2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AdditionalPaidInCapital" xlink:label="loc_us-gaap_AdditionalPaidInCapital_0DF0978A34EF302A1D814068B80940E7" xlink:type="locator" />
    <link:presentationArc order="3" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_StockholdersEquityAbstract_243CE14A65348D1855384068B8098897" xlink:to="loc_us-gaap_AdditionalPaidInCapital_0DF0978A34EF302A1D814068B80940E7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_TreasuryStockValue" xlink:label="loc_us-gaap_TreasuryStockValue_3587301EAA5F0445BC664068B8090505" xlink:type="locator" />
    <link:presentationArc order="4" preferredLabel="http://www.xbrl.org/2009/role/negatedLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_StockholdersEquityAbstract_243CE14A65348D1855384068B8098897" xlink:to="loc_us-gaap_TreasuryStockValue_3587301EAA5F0445BC664068B8090505" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ReceivableFromShareholdersOrAffiliatesForIssuanceOfCapitalStock" xlink:label="loc_us-gaap_ReceivableFromShareholdersOrAffiliatesForIssuanceOfCapitalStock_2CA8013E5F7F761895CA4068B8094B43" xlink:type="locator" />
    <link:presentationArc order="5" preferredLabel="http://www.xbrl.org/2009/role/negatedLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_StockholdersEquityAbstract_243CE14A65348D1855384068B8098897" xlink:to="loc_us-gaap_ReceivableFromShareholdersOrAffiliatesForIssuanceOfCapitalStock_2CA8013E5F7F761895CA4068B8094B43" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RetainedEarningsAccumulatedDeficit" xlink:label="loc_us-gaap_RetainedEarningsAccumulatedDeficit_47C435BF067F534C773D4068B8096963" xlink:type="locator" />
    <link:presentationArc order="6" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_StockholdersEquityAbstract_243CE14A65348D1855384068B8098897" xlink:to="loc_us-gaap_RetainedEarningsAccumulatedDeficit_47C435BF067F534C773D4068B8096963" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StockholdersEquity" xlink:label="loc_us-gaap_StockholdersEquity_624D7CFF72A5B7D1E5D54068B809F57C" xlink:type="locator" />
    <link:presentationArc order="7" preferredLabel="http://www.xbrl.org/2003/role/totalLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_StockholdersEquityAbstract_243CE14A65348D1855384068B8098897" xlink:to="loc_us-gaap_StockholdersEquity_624D7CFF72A5B7D1E5D54068B809F57C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LiabilitiesAndStockholdersEquity" xlink:label="loc_us-gaap_LiabilitiesAndStockholdersEquity_2C96B2BA5EE70E43F10E4068B80A2EA7" xlink:type="locator" />
    <link:presentationArc order="13" preferredLabel="http://www.xbrl.org/2003/role/totalLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_BD424FAC090169B2A4784068B80772A6" xlink:to="loc_us-gaap_LiabilitiesAndStockholdersEquity_2C96B2BA5EE70E43F10E4068B80A2EA7" xlink:type="arc" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.oesx.com/role/ConsolidatedBalanceSheetsParenthetical" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StatementOfFinancialPositionAbstract" xlink:label="loc_us-gaap_StatementOfFinancialPositionAbstract_5E21E70E6EE8BD00637A66E049AED946" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PreferredStockParOrStatedValuePerShare" xlink:label="loc_us-gaap_PreferredStockParOrStatedValuePerShare_4CBBE0FFF686EE57D38566E049AE781B" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_StatementOfFinancialPositionAbstract_5E21E70E6EE8BD00637A66E049AED946" xlink:to="loc_us-gaap_PreferredStockParOrStatedValuePerShare_4CBBE0FFF686EE57D38566E049AE781B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PreferredStockSharesAuthorized" xlink:label="loc_us-gaap_PreferredStockSharesAuthorized_791F723AE1BF29D3C6D566E049BEF41C" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_StatementOfFinancialPositionAbstract_5E21E70E6EE8BD00637A66E049AED946" xlink:to="loc_us-gaap_PreferredStockSharesAuthorized_791F723AE1BF29D3C6D566E049BEF41C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PreferredStockSharesIssued" xlink:label="loc_us-gaap_PreferredStockSharesIssued_27DD330FE7FAF68D8CC966E049BE2C3E" xlink:type="locator" />
    <link:presentationArc order="3" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_StatementOfFinancialPositionAbstract_5E21E70E6EE8BD00637A66E049AED946" xlink:to="loc_us-gaap_PreferredStockSharesIssued_27DD330FE7FAF68D8CC966E049BE2C3E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PreferredStockSharesOutstanding" xlink:label="loc_us-gaap_PreferredStockSharesOutstanding_86ED3AB26E6B7AB4097B66E049BEF6BE" xlink:type="locator" />
    <link:presentationArc order="4" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_StatementOfFinancialPositionAbstract_5E21E70E6EE8BD00637A66E049AED946" xlink:to="loc_us-gaap_PreferredStockSharesOutstanding_86ED3AB26E6B7AB4097B66E049BEF6BE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CommonStockNoParValue" xlink:label="loc_us-gaap_CommonStockNoParValue_8210935DAB8C24D3438D66E049BE8F4C" xlink:type="locator" />
    <link:presentationArc order="5" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_StatementOfFinancialPositionAbstract_5E21E70E6EE8BD00637A66E049AED946" xlink:to="loc_us-gaap_CommonStockNoParValue_8210935DAB8C24D3438D66E049BE8F4C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CommonStockSharesAuthorized" xlink:label="loc_us-gaap_CommonStockSharesAuthorized_7C5269E8894056B36B7066E049BE2B40" xlink:type="locator" />
    <link:presentationArc order="6" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_StatementOfFinancialPositionAbstract_5E21E70E6EE8BD00637A66E049AED946" xlink:to="loc_us-gaap_CommonStockSharesAuthorized_7C5269E8894056B36B7066E049BE2B40" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CommonStockSharesIssued" xlink:label="loc_us-gaap_CommonStockSharesIssued_A8B0F06C4482A8D0347D66E049BE6C68" xlink:type="locator" />
    <link:presentationArc order="7" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_StatementOfFinancialPositionAbstract_5E21E70E6EE8BD00637A66E049AED946" xlink:to="loc_us-gaap_CommonStockSharesIssued_A8B0F06C4482A8D0347D66E049BE6C68" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SharesOutstanding" xlink:label="loc_us-gaap_SharesOutstanding_38CF69C89B5C5224D40B66E049BE0AFB" xlink:type="locator" />
    <link:presentationArc order="8" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_StatementOfFinancialPositionAbstract_5E21E70E6EE8BD00637A66E049AED946" xlink:to="loc_us-gaap_SharesOutstanding_38CF69C89B5C5224D40B66E049BE0AFB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_TreasuryStockShares" xlink:label="loc_us-gaap_TreasuryStockShares_F881471815EEE188234266E049BE4AEF" xlink:type="locator" />
    <link:presentationArc order="9" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_StatementOfFinancialPositionAbstract_5E21E70E6EE8BD00637A66E049AED946" xlink:to="loc_us-gaap_TreasuryStockShares_F881471815EEE188234266E049BE4AEF" xlink:type="arc" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.oesx.com/role/ConsolidatedStatementsOfCashFlows" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StatementOfCashFlowsAbstract" xlink:label="loc_us-gaap_StatementOfCashFlowsAbstract_B3B8E7AC30319DE5B61A5FEF2EA02797" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract" xlink:label="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_DB87BDEF828CCE192BD45FEF2EA0C9C1" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_StatementOfCashFlowsAbstract_B3B8E7AC30319DE5B61A5FEF2EA02797" xlink:to="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_DB87BDEF828CCE192BD45FEF2EA0C9C1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_NetIncomeLoss" xlink:label="loc_us-gaap_NetIncomeLoss_0002E1D61B23FA8A599F5FEF2EA1FCFF" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_DB87BDEF828CCE192BD45FEF2EA0C9C1" xlink:to="loc_us-gaap_NetIncomeLoss_0002E1D61B23FA8A599F5FEF2EA1FCFF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AdjustmentsNoncashItemsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract" xlink:label="loc_us-gaap_AdjustmentsNoncashItemsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_C05C85517A530477D0225FEF2EA11AB5" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_DB87BDEF828CCE192BD45FEF2EA0C9C1" xlink:to="loc_us-gaap_AdjustmentsNoncashItemsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_C05C85517A530477D0225FEF2EA11AB5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_Depreciation" xlink:label="loc_us-gaap_Depreciation_A2EA4017E080A28EE1685FEF2EA1C904" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AdjustmentsNoncashItemsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_C05C85517A530477D0225FEF2EA11AB5" xlink:to="loc_us-gaap_Depreciation_A2EA4017E080A28EE1685FEF2EA1C904" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AdjustmentForAmortization" xlink:label="loc_us-gaap_AdjustmentForAmortization_16BA658DC75DBE24187A5FEF2EA17EDD" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AdjustmentsNoncashItemsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_C05C85517A530477D0225FEF2EA11AB5" xlink:to="loc_us-gaap_AdjustmentForAmortization_16BA658DC75DBE24187A5FEF2EA17EDD" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensation" xlink:label="loc_us-gaap_ShareBasedCompensation_5A142595813872D7AC805FEF2EA14DD8" xlink:type="locator" />
    <link:presentationArc order="3" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AdjustmentsNoncashItemsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_C05C85517A530477D0225FEF2EA11AB5" xlink:to="loc_us-gaap_ShareBasedCompensation_5A142595813872D7AC805FEF2EA14DD8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AssetImpairmentCharges" xlink:label="loc_us-gaap_AssetImpairmentCharges_4640681302048200D84C5FEF2EA1DD30" xlink:type="locator" />
    <link:presentationArc order="4" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AdjustmentsNoncashItemsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_C05C85517A530477D0225FEF2EA11AB5" xlink:to="loc_us-gaap_AssetImpairmentCharges_4640681302048200D84C5FEF2EA1DD30" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_GainLossOnSaleOfPropertyPlantEquipment" xlink:label="loc_us-gaap_GainLossOnSaleOfPropertyPlantEquipment_79675B4BC6B025C9CB9F5FEF2EA2F3CE" xlink:type="locator" />
    <link:presentationArc order="5" preferredLabel="http://www.xbrl.org/2009/role/negatedLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AdjustmentsNoncashItemsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_C05C85517A530477D0225FEF2EA11AB5" xlink:to="loc_us-gaap_GainLossOnSaleOfPropertyPlantEquipment_79675B4BC6B025C9CB9F5FEF2EA2F3CE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_InventoryWriteDown" xlink:label="loc_us-gaap_InventoryWriteDown_8C68905D108A6D906EA75FEF2EA26BCE" xlink:type="locator" />
    <link:presentationArc order="6" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AdjustmentsNoncashItemsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_C05C85517A530477D0225FEF2EA11AB5" xlink:to="loc_us-gaap_InventoryWriteDown_8C68905D108A6D906EA75FEF2EA26BCE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ProvisionForDoubtfulAccounts" xlink:label="loc_us-gaap_ProvisionForDoubtfulAccounts_149079F19235B4D8256A5FEF2EA21469" xlink:type="locator" />
    <link:presentationArc order="7" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AdjustmentsNoncashItemsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_C05C85517A530477D0225FEF2EA11AB5" xlink:to="loc_us-gaap_ProvisionForDoubtfulAccounts_149079F19235B4D8256A5FEF2EA21469" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_OtherNoncashIncomeExpense" xlink:label="loc_us-gaap_OtherNoncashIncomeExpense_7A6284B79D663FBBB4415FEF2EA710AA" xlink:type="locator" />
    <link:presentationArc order="8" preferredLabel="http://www.xbrl.org/2009/role/negatedLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AdjustmentsNoncashItemsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_C05C85517A530477D0225FEF2EA11AB5" xlink:to="loc_us-gaap_OtherNoncashIncomeExpense_7A6284B79D663FBBB4415FEF2EA710AA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_IncreaseDecreaseInOperatingCapitalAbstract" xlink:label="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_EB4E174A3113CB61524C5FEF2EA71C10" xlink:type="locator" />
    <link:presentationArc order="9" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AdjustmentsNoncashItemsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_C05C85517A530477D0225FEF2EA11AB5" xlink:to="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_EB4E174A3113CB61524C5FEF2EA71C10" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_IncreaseDecreaseInAccountsReceivable" xlink:label="loc_us-gaap_IncreaseDecreaseInAccountsReceivable_84CB01F87B7667721EB95FEF2EA71D47" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2009/role/negatedLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_EB4E174A3113CB61524C5FEF2EA71C10" xlink:to="loc_us-gaap_IncreaseDecreaseInAccountsReceivable_84CB01F87B7667721EB95FEF2EA71D47" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_IncreaseDecreaseInInventories" xlink:label="loc_us-gaap_IncreaseDecreaseInInventories_158B1E80C27527D38E615FEF2EA82470" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2009/role/negatedLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_EB4E174A3113CB61524C5FEF2EA71C10" xlink:to="loc_us-gaap_IncreaseDecreaseInInventories_158B1E80C27527D38E615FEF2EA82470" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_IncreaseDecreaseInDeferredCharges" xlink:label="loc_us-gaap_IncreaseDecreaseInDeferredCharges_CE1D77A1ACD34B53EC5A5FEF2EA81ED0" xlink:type="locator" />
    <link:presentationArc order="3" preferredLabel="http://www.xbrl.org/2009/role/negatedLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_EB4E174A3113CB61524C5FEF2EA71C10" xlink:to="loc_us-gaap_IncreaseDecreaseInDeferredCharges_CE1D77A1ACD34B53EC5A5FEF2EA81ED0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets" xlink:label="loc_us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets_237880E8D241C198A5F15FEF2EA99DC0" xlink:type="locator" />
    <link:presentationArc order="4" preferredLabel="http://www.xbrl.org/2009/role/negatedLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_EB4E174A3113CB61524C5FEF2EA71C10" xlink:to="loc_us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets_237880E8D241C198A5F15FEF2EA99DC0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_IncreaseDecreaseInAccountsPayable" xlink:label="loc_us-gaap_IncreaseDecreaseInAccountsPayable_1703C4B04C34D35A8A865FEF2EA95FE1" xlink:type="locator" />
    <link:presentationArc order="5" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_EB4E174A3113CB61524C5FEF2EA71C10" xlink:to="loc_us-gaap_IncreaseDecreaseInAccountsPayable_1703C4B04C34D35A8A865FEF2EA95FE1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_IncreaseDecreaseInAccruedLiabilities" xlink:label="loc_us-gaap_IncreaseDecreaseInAccruedLiabilities_2EAB0B64E5AD5D1492015FEF2EA963C0" xlink:type="locator" />
    <link:presentationArc order="6" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_EB4E174A3113CB61524C5FEF2EA71C10" xlink:to="loc_us-gaap_IncreaseDecreaseInAccruedLiabilities_2EAB0B64E5AD5D1492015FEF2EA963C0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_IncreaseDecreaseInDeferredRevenue" xlink:label="loc_us-gaap_IncreaseDecreaseInDeferredRevenue_9BC9B13B3B81A6DEB5E75FEF2EA9B65B" xlink:type="locator" />
    <link:presentationArc order="7" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_EB4E174A3113CB61524C5FEF2EA71C10" xlink:to="loc_us-gaap_IncreaseDecreaseInDeferredRevenue_9BC9B13B3B81A6DEB5E75FEF2EA9B65B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivities" xlink:label="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_F7DB8400296DF74297805FEF2EA925B9" xlink:type="locator" />
    <link:presentationArc order="3" preferredLabel="http://www.xbrl.org/2003/role/totalLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_DB87BDEF828CCE192BD45FEF2EA0C9C1" xlink:to="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_F7DB8400296DF74297805FEF2EA925B9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract" xlink:label="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_0C28AEF8B95355C011305FEF2EAAF2C6" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_StatementOfCashFlowsAbstract_B3B8E7AC30319DE5B61A5FEF2EA02797" xlink:to="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_0C28AEF8B95355C011305FEF2EAAF2C6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PaymentsToAcquirePropertyPlantAndEquipment" xlink:label="loc_us-gaap_PaymentsToAcquirePropertyPlantAndEquipment_8510DBAB082C960033F75FEF2EAAA5AF" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2009/role/negatedLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_0C28AEF8B95355C011305FEF2EAAF2C6" xlink:to="loc_us-gaap_PaymentsToAcquirePropertyPlantAndEquipment_8510DBAB082C960033F75FEF2EAAA5AF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PaymentsToAcquireShortTermInvestments" xlink:label="loc_us-gaap_PaymentsToAcquireShortTermInvestments_920DE15F66DC2AA2B4E55FEF2EABB961" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2009/role/negatedLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_0C28AEF8B95355C011305FEF2EAAF2C6" xlink:to="loc_us-gaap_PaymentsToAcquireShortTermInvestments_920DE15F66DC2AA2B4E55FEF2EABB961" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ProceedsFromSaleOfShortTermInvestments" xlink:label="loc_us-gaap_ProceedsFromSaleOfShortTermInvestments_87A7A1145CF6B1545E455FEF2EABF994" xlink:type="locator" />
    <link:presentationArc order="3" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_0C28AEF8B95355C011305FEF2EAAF2C6" xlink:to="loc_us-gaap_ProceedsFromSaleOfShortTermInvestments_87A7A1145CF6B1545E455FEF2EABF994" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PaymentsToAcquireIntangibleAssets" xlink:label="loc_us-gaap_PaymentsToAcquireIntangibleAssets_E41D769F9117C89E87D85FEF2EAB1F5B" xlink:type="locator" />
    <link:presentationArc order="4" preferredLabel="http://www.xbrl.org/2009/role/negatedLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_0C28AEF8B95355C011305FEF2EAAF2C6" xlink:to="loc_us-gaap_PaymentsToAcquireIntangibleAssets_E41D769F9117C89E87D85FEF2EAB1F5B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ProceedsFromSaleOfPropertyPlantAndEquipment" xlink:label="loc_us-gaap_ProceedsFromSaleOfPropertyPlantAndEquipment_94DC21931C29C6DD99275FEF2EABF174" xlink:type="locator" />
    <link:presentationArc order="5" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_0C28AEF8B95355C011305FEF2EAAF2C6" xlink:to="loc_us-gaap_ProceedsFromSaleOfPropertyPlantAndEquipment_94DC21931C29C6DD99275FEF2EABF174" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivities" xlink:label="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_81E79E994C6504420E805FEF2EAB812C" xlink:type="locator" />
    <link:presentationArc order="6" preferredLabel="http://www.xbrl.org/2003/role/totalLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_0C28AEF8B95355C011305FEF2EAAF2C6" xlink:to="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_81E79E994C6504420E805FEF2EAB812C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract" xlink:label="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_6F283F0A6A25FC00EE465FEF2EABD65A" xlink:type="locator" />
    <link:presentationArc order="3" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_StatementOfCashFlowsAbstract_B3B8E7AC30319DE5B61A5FEF2EA02797" xlink:to="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_6F283F0A6A25FC00EE465FEF2EABD65A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RepaymentsOfLongTermDebt" xlink:label="loc_us-gaap_RepaymentsOfLongTermDebt_ECC2D046C1074F314A6F5FEF2EACB880" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2009/role/negatedLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_6F283F0A6A25FC00EE465FEF2EABD65A" xlink:to="loc_us-gaap_RepaymentsOfLongTermDebt_ECC2D046C1074F314A6F5FEF2EACB880" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ProceedsFromLongTermLinesOfCredit" xlink:label="loc_us-gaap_ProceedsFromLongTermLinesOfCredit_6CA1B74E502EBEB970F45FEF2EAC1B46" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_6F283F0A6A25FC00EE465FEF2EABD65A" xlink:to="loc_us-gaap_ProceedsFromLongTermLinesOfCredit_6CA1B74E502EBEB970F45FEF2EAC1B46" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RepaymentsOfLongTermLinesOfCredit" xlink:label="loc_us-gaap_RepaymentsOfLongTermLinesOfCredit_474B5D3E3E22435CA6875FEF2EADEBF2" xlink:type="locator" />
    <link:presentationArc order="3" preferredLabel="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_6F283F0A6A25FC00EE465FEF2EABD65A" xlink:to="loc_us-gaap_RepaymentsOfLongTermLinesOfCredit_474B5D3E3E22435CA6875FEF2EADEBF2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ProceedsFromIssuanceOfDebt" xlink:label="loc_us-gaap_ProceedsFromIssuanceOfDebt_C7EAAB601E643048BFA25FEF2EAD0545" xlink:type="locator" />
    <link:presentationArc order="4" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_6F283F0A6A25FC00EE465FEF2EABD65A" xlink:to="loc_us-gaap_ProceedsFromIssuanceOfDebt_C7EAAB601E643048BFA25FEF2EAD0545" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ProceedsFromRelatedPartyDebt" xlink:label="loc_us-gaap_ProceedsFromRelatedPartyDebt_BA8650A1D7A42016E8355FEF2EAD28D9" xlink:type="locator" />
    <link:presentationArc order="5" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_6F283F0A6A25FC00EE465FEF2EABD65A" xlink:to="loc_us-gaap_ProceedsFromRelatedPartyDebt_BA8650A1D7A42016E8355FEF2EAD28D9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ProceedsFromIssuanceOfCommonStock" xlink:label="loc_us-gaap_ProceedsFromIssuanceOfCommonStock_E3F2690B7F55F8D900535FEF2EAD4043" xlink:type="locator" />
    <link:presentationArc order="6" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_6F283F0A6A25FC00EE465FEF2EABD65A" xlink:to="loc_us-gaap_ProceedsFromIssuanceOfCommonStock_E3F2690B7F55F8D900535FEF2EAD4043" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation" xlink:label="loc_us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation_8982199BCC89240FB6BC5FEF2EB255F1" xlink:type="locator" />
    <link:presentationArc order="7" preferredLabel="http://www.xbrl.org/2009/role/negatedLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_6F283F0A6A25FC00EE465FEF2EABD65A" xlink:to="loc_us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation_8982199BCC89240FB6BC5FEF2EB255F1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PaymentsOfFinancingCosts" xlink:label="loc_us-gaap_PaymentsOfFinancingCosts_58A030060F30512416B25FEF2EB2CCB0" xlink:type="locator" />
    <link:presentationArc order="8" preferredLabel="http://www.xbrl.org/2009/role/negatedLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_6F283F0A6A25FC00EE465FEF2EABD65A" xlink:to="loc_us-gaap_PaymentsOfFinancingCosts_58A030060F30512416B25FEF2EB2CCB0" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_ProceedsfromExerciseofWarrantsandStockOptions" xlink:label="loc_oesx_ProceedsfromExerciseofWarrantsandStockOptions_F4A3DBC2D50E02146E555FEF2EB27343" xlink:type="locator" />
    <link:presentationArc order="9" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_6F283F0A6A25FC00EE465FEF2EABD65A" xlink:to="loc_oesx_ProceedsfromExerciseofWarrantsandStockOptions_F4A3DBC2D50E02146E555FEF2EB27343" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivities" xlink:label="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_2DCB7E6040B1D8B28EFD5FEF2EB364B4" xlink:type="locator" />
    <link:presentationArc order="10" preferredLabel="http://www.xbrl.org/2003/role/totalLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_6F283F0A6A25FC00EE465FEF2EABD65A" xlink:to="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_2DCB7E6040B1D8B28EFD5FEF2EB364B4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease" xlink:label="loc_us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease_092FE79C02B68731AA655FEF2EB34F52" xlink:type="locator" />
    <link:presentationArc order="4" preferredLabel="http://www.xbrl.org/2003/role/totalLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_StatementOfCashFlowsAbstract_B3B8E7AC30319DE5B61A5FEF2EA02797" xlink:to="loc_us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease_092FE79C02B68731AA655FEF2EB34F52" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue" xlink:label="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_4852E3DD3221A2CEE46B5FEF2EB47190" xlink:type="locator" />
    <link:presentationArc order="5" preferredLabel="http://www.xbrl.org/2003/role/periodStartLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_StatementOfCashFlowsAbstract_B3B8E7AC30319DE5B61A5FEF2EA02797" xlink:to="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_4852E3DD3221A2CEE46B5FEF2EB47190" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue" xlink:label="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_D5176A70817E98DB96665FEF2EB42AE3" xlink:type="locator" />
    <link:presentationArc order="6" preferredLabel="http://www.xbrl.org/2003/role/periodEndLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_StatementOfCashFlowsAbstract_B3B8E7AC30319DE5B61A5FEF2EA02797" xlink:to="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_D5176A70817E98DB96665FEF2EB42AE3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SupplementalCashFlowInformationAbstract" xlink:label="loc_us-gaap_SupplementalCashFlowInformationAbstract_C9D24F22F5437720125A5FEF2EB47A51" xlink:type="locator" />
    <link:presentationArc order="7" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_StatementOfCashFlowsAbstract_B3B8E7AC30319DE5B61A5FEF2EA02797" xlink:to="loc_us-gaap_SupplementalCashFlowInformationAbstract_C9D24F22F5437720125A5FEF2EB47A51" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_InterestPaid" xlink:label="loc_us-gaap_InterestPaid_8B766F7C34E4729085275FEF2EB40BCF" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_SupplementalCashFlowInformationAbstract_C9D24F22F5437720125A5FEF2EB47A51" xlink:to="loc_us-gaap_InterestPaid_8B766F7C34E4729085275FEF2EB40BCF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_IncomeTaxesPaidNet" xlink:label="loc_us-gaap_IncomeTaxesPaidNet_867391498D24554D68AB6001D1CE6AA0" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_SupplementalCashFlowInformationAbstract_C9D24F22F5437720125A5FEF2EB47A51" xlink:to="loc_us-gaap_IncomeTaxesPaidNet_867391498D24554D68AB6001D1CE6AA0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CashFlowNoncashInvestingAndFinancingActivitiesDisclosureAbstract" xlink:label="loc_us-gaap_CashFlowNoncashInvestingAndFinancingActivitiesDisclosureAbstract_3120B229F0B2DCB967C15FEF2EB5A9C7" xlink:type="locator" />
    <link:presentationArc order="8" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_StatementOfCashFlowsAbstract_B3B8E7AC30319DE5B61A5FEF2EA02797" xlink:to="loc_us-gaap_CashFlowNoncashInvestingAndFinancingActivitiesDisclosureAbstract_3120B229F0B2DCB967C15FEF2EB5A9C7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CapitalLeaseObligationsIncurred" xlink:label="loc_us-gaap_CapitalLeaseObligationsIncurred_ED16C6ED3D904BD4413C5FEF2EB51C17" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_CashFlowNoncashInvestingAndFinancingActivitiesDisclosureAbstract_3120B229F0B2DCB967C15FEF2EB5A9C7" xlink:to="loc_us-gaap_CapitalLeaseObligationsIncurred_ED16C6ED3D904BD4413C5FEF2EB51C17" xlink:type="arc" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.oesx.com/role/ConsolidatedStatementsOfOperationsAndComprehensiveIncome" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_IncomeStatementAbstract" xlink:label="loc_us-gaap_IncomeStatementAbstract_17176A71B946D7DDB9DF9D5B30DBD7E5" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SalesRevenueGoodsNet" xlink:label="loc_us-gaap_SalesRevenueGoodsNet_423BB3E30E71D7D522239D5B30DB670F" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncomeStatementAbstract_17176A71B946D7DDB9DF9D5B30DBD7E5" xlink:to="loc_us-gaap_SalesRevenueGoodsNet_423BB3E30E71D7D522239D5B30DB670F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SalesRevenueServicesNet" xlink:label="loc_us-gaap_SalesRevenueServicesNet_4AF506B241164D2D6A969D5B30DB1BE8" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncomeStatementAbstract_17176A71B946D7DDB9DF9D5B30DBD7E5" xlink:to="loc_us-gaap_SalesRevenueServicesNet_4AF506B241164D2D6A969D5B30DB1BE8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_Revenues" xlink:label="loc_us-gaap_Revenues_AB51D2DBB9F18BA55BEC9D5B30DB07ED" xlink:type="locator" />
    <link:presentationArc order="3" preferredLabel="http://www.xbrl.org/2003/role/totalLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncomeStatementAbstract_17176A71B946D7DDB9DF9D5B30DBD7E5" xlink:to="loc_us-gaap_Revenues_AB51D2DBB9F18BA55BEC9D5B30DB07ED" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CostOfGoodsSold" xlink:label="loc_us-gaap_CostOfGoodsSold_C0BFB6AA972E4D279A1C9D5B30DB7F08" xlink:type="locator" />
    <link:presentationArc order="4" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncomeStatementAbstract_17176A71B946D7DDB9DF9D5B30DBD7E5" xlink:to="loc_us-gaap_CostOfGoodsSold_C0BFB6AA972E4D279A1C9D5B30DB7F08" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CostOfServices" xlink:label="loc_us-gaap_CostOfServices_4A862A47980F3F753CAB9D5B30DB48DF" xlink:type="locator" />
    <link:presentationArc order="5" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncomeStatementAbstract_17176A71B946D7DDB9DF9D5B30DBD7E5" xlink:to="loc_us-gaap_CostOfServices_4A862A47980F3F753CAB9D5B30DB48DF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CostOfRevenue" xlink:label="loc_us-gaap_CostOfRevenue_CCC5AF487FD352EE14809D5B30DB0C25" xlink:type="locator" />
    <link:presentationArc order="6" preferredLabel="http://www.xbrl.org/2003/role/totalLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncomeStatementAbstract_17176A71B946D7DDB9DF9D5B30DBD7E5" xlink:to="loc_us-gaap_CostOfRevenue_CCC5AF487FD352EE14809D5B30DB0C25" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_GrossProfit" xlink:label="loc_us-gaap_GrossProfit_56237F1E4FA5C4DB5FDD9D5B30DCB160" xlink:type="locator" />
    <link:presentationArc order="7" preferredLabel="http://www.xbrl.org/2003/role/totalLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncomeStatementAbstract_17176A71B946D7DDB9DF9D5B30DBD7E5" xlink:to="loc_us-gaap_GrossProfit_56237F1E4FA5C4DB5FDD9D5B30DCB160" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_OperatingExpensesAbstract" xlink:label="loc_us-gaap_OperatingExpensesAbstract_B69DA67E556A48373E069D5B30DCA7DF" xlink:type="locator" />
    <link:presentationArc order="8" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncomeStatementAbstract_17176A71B946D7DDB9DF9D5B30DBD7E5" xlink:to="loc_us-gaap_OperatingExpensesAbstract_B69DA67E556A48373E069D5B30DCA7DF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_GeneralAndAdministrativeExpense" xlink:label="loc_us-gaap_GeneralAndAdministrativeExpense_60F4BD96C8C669F8577D9D5B30DC2C41" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_OperatingExpensesAbstract_B69DA67E556A48373E069D5B30DCA7DF" xlink:to="loc_us-gaap_GeneralAndAdministrativeExpense_60F4BD96C8C669F8577D9D5B30DC2C41" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_GoodwillImpairmentLossAndImpairmentOfRealEstate" xlink:label="loc_oesx_GoodwillImpairmentLossAndImpairmentOfRealEstate_F25194E5AFC9141BA9479D5B30DCCD1C" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_OperatingExpensesAbstract_B69DA67E556A48373E069D5B30DCA7DF" xlink:to="loc_oesx_GoodwillImpairmentLossAndImpairmentOfRealEstate_F25194E5AFC9141BA9479D5B30DCCD1C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_BusinessCombinationAcquisitionRelatedCosts" xlink:label="loc_us-gaap_BusinessCombinationAcquisitionRelatedCosts_4551120DEC7612AF15249D5B30DCF571" xlink:type="locator" />
    <link:presentationArc order="3" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_OperatingExpensesAbstract_B69DA67E556A48373E069D5B30DCA7DF" xlink:to="loc_us-gaap_BusinessCombinationAcquisitionRelatedCosts_4551120DEC7612AF15249D5B30DCF571" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SellingAndMarketingExpense" xlink:label="loc_us-gaap_SellingAndMarketingExpense_811A5813D172C0EED4119D5B30DCDD8A" xlink:type="locator" />
    <link:presentationArc order="4" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_OperatingExpensesAbstract_B69DA67E556A48373E069D5B30DCA7DF" xlink:to="loc_us-gaap_SellingAndMarketingExpense_811A5813D172C0EED4119D5B30DCDD8A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ResearchAndDevelopmentExpense" xlink:label="loc_us-gaap_ResearchAndDevelopmentExpense_77B0E638154DA26DFAE99D5B30DC248A" xlink:type="locator" />
    <link:presentationArc order="5" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_OperatingExpensesAbstract_B69DA67E556A48373E069D5B30DCA7DF" xlink:to="loc_us-gaap_ResearchAndDevelopmentExpense_77B0E638154DA26DFAE99D5B30DC248A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_OperatingExpenses" xlink:label="loc_us-gaap_OperatingExpenses_1AB27F1F2B3686E5F4CC9D5B30DCFF06" xlink:type="locator" />
    <link:presentationArc order="6" preferredLabel="http://www.xbrl.org/2003/role/totalLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_OperatingExpensesAbstract_B69DA67E556A48373E069D5B30DCA7DF" xlink:to="loc_us-gaap_OperatingExpenses_1AB27F1F2B3686E5F4CC9D5B30DCFF06" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_OperatingIncomeLoss" xlink:label="loc_us-gaap_OperatingIncomeLoss_A2B062BC2BE5598774759D5B30DC098B" xlink:type="locator" />
    <link:presentationArc order="9" preferredLabel="http://www.xbrl.org/2003/role/totalLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncomeStatementAbstract_17176A71B946D7DDB9DF9D5B30DBD7E5" xlink:to="loc_us-gaap_OperatingIncomeLoss_A2B062BC2BE5598774759D5B30DC098B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_NonoperatingIncomeExpenseAbstract" xlink:label="loc_us-gaap_NonoperatingIncomeExpenseAbstract_BD1C1AA6A3E9F79119369D5B30DD61D5" xlink:type="locator" />
    <link:presentationArc order="10" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncomeStatementAbstract_17176A71B946D7DDB9DF9D5B30DBD7E5" xlink:to="loc_us-gaap_NonoperatingIncomeExpenseAbstract_BD1C1AA6A3E9F79119369D5B30DD61D5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_OtherNonoperatingIncome" xlink:label="loc_us-gaap_OtherNonoperatingIncome_043AE917515EB6789CDC9D5B30DD913D" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_NonoperatingIncomeExpenseAbstract_BD1C1AA6A3E9F79119369D5B30DD61D5" xlink:to="loc_us-gaap_OtherNonoperatingIncome_043AE917515EB6789CDC9D5B30DD913D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_InterestExpense" xlink:label="loc_us-gaap_InterestExpense_6AD69BC7E1405CA11E7A9D5B30DDC308" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2009/role/negatedLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_NonoperatingIncomeExpenseAbstract_BD1C1AA6A3E9F79119369D5B30DD61D5" xlink:to="loc_us-gaap_InterestExpense_6AD69BC7E1405CA11E7A9D5B30DDC308" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_InvestmentIncomeInterest" xlink:label="loc_us-gaap_InvestmentIncomeInterest_460536705844AA6189C29D5B30DD16E2" xlink:type="locator" />
    <link:presentationArc order="3" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_NonoperatingIncomeExpenseAbstract_BD1C1AA6A3E9F79119369D5B30DD61D5" xlink:to="loc_us-gaap_InvestmentIncomeInterest_460536705844AA6189C29D5B30DD16E2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_NonoperatingIncomeExpense" xlink:label="loc_us-gaap_NonoperatingIncomeExpense_89CE3315BB0F9AAC76599D5B30DD5730" xlink:type="locator" />
    <link:presentationArc order="4" preferredLabel="http://www.xbrl.org/2003/role/totalLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_NonoperatingIncomeExpenseAbstract_BD1C1AA6A3E9F79119369D5B30DD61D5" xlink:to="loc_us-gaap_NonoperatingIncomeExpense_89CE3315BB0F9AAC76599D5B30DD5730" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments_437947A75AF3AC39093C9D5B30DD79A2" xlink:type="locator" />
    <link:presentationArc order="11" preferredLabel="http://www.xbrl.org/2003/role/totalLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncomeStatementAbstract_17176A71B946D7DDB9DF9D5B30DBD7E5" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments_437947A75AF3AC39093C9D5B30DD79A2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_IncomeTaxExpenseBenefit" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_6C267370AC2BC1711F689D5B30DD1163" xlink:type="locator" />
    <link:presentationArc order="12" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncomeStatementAbstract_17176A71B946D7DDB9DF9D5B30DBD7E5" xlink:to="loc_us-gaap_IncomeTaxExpenseBenefit_6C267370AC2BC1711F689D5B30DD1163" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_NetIncomeLoss" xlink:label="loc_us-gaap_NetIncomeLoss_54A062E714B563D0D1809D5B30DD1493" xlink:type="locator" />
    <link:presentationArc order="13" preferredLabel="http://www.xbrl.org/2003/role/totalLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncomeStatementAbstract_17176A71B946D7DDB9DF9D5B30DBD7E5" xlink:to="loc_us-gaap_NetIncomeLoss_54A062E714B563D0D1809D5B30DD1493" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_EarningsPerShareBasic" xlink:label="loc_us-gaap_EarningsPerShareBasic_53EA2AA97F60519ADD6A9D5B30DD6CE0" xlink:type="locator" />
    <link:presentationArc order="14" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncomeStatementAbstract_17176A71B946D7DDB9DF9D5B30DBD7E5" xlink:to="loc_us-gaap_EarningsPerShareBasic_53EA2AA97F60519ADD6A9D5B30DD6CE0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingBasic" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_6559E604C15CEF350CC29D5B30DD0240" xlink:type="locator" />
    <link:presentationArc order="15" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncomeStatementAbstract_17176A71B946D7DDB9DF9D5B30DBD7E5" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_6559E604C15CEF350CC29D5B30DD0240" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_EarningsPerShareDiluted" xlink:label="loc_us-gaap_EarningsPerShareDiluted_B3618D110C25D10721319D5B30DDC246" xlink:type="locator" />
    <link:presentationArc order="16" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncomeStatementAbstract_17176A71B946D7DDB9DF9D5B30DBD7E5" xlink:to="loc_us-gaap_EarningsPerShareDiluted_B3618D110C25D10721319D5B30DDC246" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding" xlink:label="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_4844AB8224E94A7A139A9D5B30DD0735" xlink:type="locator" />
    <link:presentationArc order="17" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncomeStatementAbstract_17176A71B946D7DDB9DF9D5B30DBD7E5" xlink:to="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_4844AB8224E94A7A139A9D5B30DD0735" xlink:type="arc" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.oesx.com/role/DescriptionOfBusiness" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_OrganizationConsolidationAndPresentationOfFinancialStatementsAbstract" xlink:label="loc_us-gaap_OrganizationConsolidationAndPresentationOfFinancialStatementsAbstract_8EF6EEB8AF1AA663A55166E04C500C4B" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_OrganizationConsolidationAndPresentationOfFinancialStatementsDisclosureTextBlock" xlink:label="loc_us-gaap_OrganizationConsolidationAndPresentationOfFinancialStatementsDisclosureTextBlock_15B3EE5E6809C19E2E6066E04C504610" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_OrganizationConsolidationAndPresentationOfFinancialStatementsAbstract_8EF6EEB8AF1AA663A55166E04C500C4B" xlink:to="loc_us-gaap_OrganizationConsolidationAndPresentationOfFinancialStatementsDisclosureTextBlock_15B3EE5E6809C19E2E6066E04C504610" xlink:type="arc" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.oesx.com/role/DocumentAndEntityInformation" xlink:type="extended">
    <link:loc xlink:href="oesx-20170331.xsd#oesx_DocumentAndEntityInformationAbstract" xlink:label="loc_oesx_DocumentAndEntityInformationAbstract_D032994B6ECF15072EDE66E048C30C1A" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.sec.gov/dei/2014/dei-2014-01-31.xsd#dei_EntityRegistrantName" xlink:label="loc_dei_EntityRegistrantName_FE12C5DE9E3404328FD566E048C3029A" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_oesx_DocumentAndEntityInformationAbstract_D032994B6ECF15072EDE66E048C30C1A" xlink:to="loc_dei_EntityRegistrantName_FE12C5DE9E3404328FD566E048C3029A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.sec.gov/dei/2014/dei-2014-01-31.xsd#dei_EntityCentralIndexKey" xlink:label="loc_dei_EntityCentralIndexKey_5D327CE70E326431487766E048C47739" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_oesx_DocumentAndEntityInformationAbstract_D032994B6ECF15072EDE66E048C30C1A" xlink:to="loc_dei_EntityCentralIndexKey_5D327CE70E326431487766E048C47739" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.sec.gov/dei/2014/dei-2014-01-31.xsd#dei_DocumentType" xlink:label="loc_dei_DocumentType_D99FEEF0074AF8CBBFB566E048C4BC59" xlink:type="locator" />
    <link:presentationArc order="3" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_oesx_DocumentAndEntityInformationAbstract_D032994B6ECF15072EDE66E048C30C1A" xlink:to="loc_dei_DocumentType_D99FEEF0074AF8CBBFB566E048C4BC59" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.sec.gov/dei/2014/dei-2014-01-31.xsd#dei_DocumentPeriodEndDate" xlink:label="loc_dei_DocumentPeriodEndDate_4D5F1489406287EB166066E048C4D37F" xlink:type="locator" />
    <link:presentationArc order="4" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_oesx_DocumentAndEntityInformationAbstract_D032994B6ECF15072EDE66E048C30C1A" xlink:to="loc_dei_DocumentPeriodEndDate_4D5F1489406287EB166066E048C4D37F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.sec.gov/dei/2014/dei-2014-01-31.xsd#dei_AmendmentFlag" xlink:label="loc_dei_AmendmentFlag_48D94841CA08D393430866E048C4FBE8" xlink:type="locator" />
    <link:presentationArc order="5" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_oesx_DocumentAndEntityInformationAbstract_D032994B6ECF15072EDE66E048C30C1A" xlink:to="loc_dei_AmendmentFlag_48D94841CA08D393430866E048C4FBE8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.sec.gov/dei/2014/dei-2014-01-31.xsd#dei_DocumentFiscalYearFocus" xlink:label="loc_dei_DocumentFiscalYearFocus_0FCE6D868332ABF832AA66E048C4D6BC" xlink:type="locator" />
    <link:presentationArc order="6" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_oesx_DocumentAndEntityInformationAbstract_D032994B6ECF15072EDE66E048C30C1A" xlink:to="loc_dei_DocumentFiscalYearFocus_0FCE6D868332ABF832AA66E048C4D6BC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.sec.gov/dei/2014/dei-2014-01-31.xsd#dei_DocumentFiscalPeriodFocus" xlink:label="loc_dei_DocumentFiscalPeriodFocus_4F1EF8EA7244BFE8EA3466E048C59C3F" xlink:type="locator" />
    <link:presentationArc order="7" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_oesx_DocumentAndEntityInformationAbstract_D032994B6ECF15072EDE66E048C30C1A" xlink:to="loc_dei_DocumentFiscalPeriodFocus_4F1EF8EA7244BFE8EA3466E048C59C3F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.sec.gov/dei/2014/dei-2014-01-31.xsd#dei_CurrentFiscalYearEndDate" xlink:label="loc_dei_CurrentFiscalYearEndDate_757DA64A8008C491A5B666E048C500B8" xlink:type="locator" />
    <link:presentationArc order="8" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_oesx_DocumentAndEntityInformationAbstract_D032994B6ECF15072EDE66E048C30C1A" xlink:to="loc_dei_CurrentFiscalYearEndDate_757DA64A8008C491A5B666E048C500B8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.sec.gov/dei/2014/dei-2014-01-31.xsd#dei_EntityWellKnownSeasonedIssuer" xlink:label="loc_dei_EntityWellKnownSeasonedIssuer_3657A80EC37AEF80CA0966E048C59491" xlink:type="locator" />
    <link:presentationArc order="9" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_oesx_DocumentAndEntityInformationAbstract_D032994B6ECF15072EDE66E048C30C1A" xlink:to="loc_dei_EntityWellKnownSeasonedIssuer_3657A80EC37AEF80CA0966E048C59491" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.sec.gov/dei/2014/dei-2014-01-31.xsd#dei_EntityVoluntaryFilers" xlink:label="loc_dei_EntityVoluntaryFilers_29270F6E7CEC02EE7AB466E048C50A93" xlink:type="locator" />
    <link:presentationArc order="10" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_oesx_DocumentAndEntityInformationAbstract_D032994B6ECF15072EDE66E048C30C1A" xlink:to="loc_dei_EntityVoluntaryFilers_29270F6E7CEC02EE7AB466E048C50A93" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.sec.gov/dei/2014/dei-2014-01-31.xsd#dei_EntityCurrentReportingStatus" xlink:label="loc_dei_EntityCurrentReportingStatus_8E32AA8B8F5A9999222F66E048C6A403" xlink:type="locator" />
    <link:presentationArc order="11" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_oesx_DocumentAndEntityInformationAbstract_D032994B6ECF15072EDE66E048C30C1A" xlink:to="loc_dei_EntityCurrentReportingStatus_8E32AA8B8F5A9999222F66E048C6A403" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.sec.gov/dei/2014/dei-2014-01-31.xsd#dei_EntityFilerCategory" xlink:label="loc_dei_EntityFilerCategory_7D7EB0CEF52639F3591D66E048C672F3" xlink:type="locator" />
    <link:presentationArc order="12" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_oesx_DocumentAndEntityInformationAbstract_D032994B6ECF15072EDE66E048C30C1A" xlink:to="loc_dei_EntityFilerCategory_7D7EB0CEF52639F3591D66E048C672F3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.sec.gov/dei/2014/dei-2014-01-31.xsd#dei_EntityPublicFloat" xlink:label="loc_dei_EntityPublicFloat_C14C4E159233F05B354966E048C6CA9F" xlink:type="locator" />
    <link:presentationArc order="13" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_oesx_DocumentAndEntityInformationAbstract_D032994B6ECF15072EDE66E048C30C1A" xlink:to="loc_dei_EntityPublicFloat_C14C4E159233F05B354966E048C6CA9F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.sec.gov/dei/2014/dei-2014-01-31.xsd#dei_EntityCommonStockSharesOutstanding" xlink:label="loc_dei_EntityCommonStockSharesOutstanding_AED1C66ED88F6112FEAC66E048C68B3E" xlink:type="locator" />
    <link:presentationArc order="14" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_oesx_DocumentAndEntityInformationAbstract_D032994B6ECF15072EDE66E048C30C1A" xlink:to="loc_dei_EntityCommonStockSharesOutstanding_AED1C66ED88F6112FEAC66E048C68B3E" xlink:type="arc" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.oesx.com/role/FinancingReceivables" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ReceivablesAbstract" xlink:label="loc_us-gaap_ReceivablesAbstract_14B9A7A9443A8F247D020DBF9B22A2C1" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FinancingReceivablesTextBlock" xlink:label="loc_us-gaap_FinancingReceivablesTextBlock_160AC76CB5C8BF136DA10DBF9B22DFB4" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ReceivablesAbstract_14B9A7A9443A8F247D020DBF9B22A2C1" xlink:to="loc_us-gaap_FinancingReceivablesTextBlock_160AC76CB5C8BF136DA10DBF9B22DFB4" xlink:type="arc" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.oesx.com/role/FinancingReceivablesAgingAnalysisDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ReceivablesAbstract" xlink:label="loc_us-gaap_ReceivablesAbstract_A70EC21C5A6B4187CDF960C3D178B239" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScheduleOfFinancingReceivableRecordedInvestmentCreditQualityIndicatorTable" xlink:label="loc_us-gaap_ScheduleOfFinancingReceivableRecordedInvestmentCreditQualityIndicatorTable_0D59A8587C18A3EDBDAC60C3D1782E8F" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ReceivablesAbstract_A70EC21C5A6B4187CDF960C3D178B239" xlink:to="loc_us-gaap_ScheduleOfFinancingReceivableRecordedInvestmentCreditQualityIndicatorTable_0D59A8587C18A3EDBDAC60C3D1782E8F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FinancingReceivablePortfolioSegmentAxis" xlink:label="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_91D01054450ECB4145C560D608176BEB" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfFinancingReceivableRecordedInvestmentCreditQualityIndicatorTable_0D59A8587C18A3EDBDAC60C3D1782E8F" xlink:to="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_91D01054450ECB4145C560D608176BEB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FinancingReceivablePortfolioSegmentDomain" xlink:label="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_076FE6C8B3C18EA0E8DA60D608207A22" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_91D01054450ECB4145C560D608176BEB" xlink:to="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_076FE6C8B3C18EA0E8DA60D608207A22" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FinanceLeasesPortfolioSegmentMember" xlink:label="loc_us-gaap_FinanceLeasesPortfolioSegmentMember_E8F118A5C5A1365538BA60D63C1715BB" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_076FE6C8B3C18EA0E8DA60D608207A22" xlink:to="loc_us-gaap_FinanceLeasesPortfolioSegmentMember_E8F118A5C5A1365538BA60D63C1715BB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FinancingReceivablesPeriodPastDueAxis" xlink:label="loc_us-gaap_FinancingReceivablesPeriodPastDueAxis_931A46296FBE3F3840AD60D3059B3960" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfFinancingReceivableRecordedInvestmentCreditQualityIndicatorTable_0D59A8587C18A3EDBDAC60C3D1782E8F" xlink:to="loc_us-gaap_FinancingReceivablesPeriodPastDueAxis_931A46296FBE3F3840AD60D3059B3960" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FinancingReceivablesPeriodPastDueDomain" xlink:label="loc_us-gaap_FinancingReceivablesPeriodPastDueDomain_0C97DEDF5DF2FB7099BB60D33D1F04E4" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_FinancingReceivablesPeriodPastDueAxis_931A46296FBE3F3840AD60D3059B3960" xlink:to="loc_us-gaap_FinancingReceivablesPeriodPastDueDomain_0C97DEDF5DF2FB7099BB60D33D1F04E4" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_NotPastDueMember" xlink:label="loc_oesx_NotPastDueMember_9A82C13EBEEA57D0F00F60C3D17942E4" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_FinancingReceivablesPeriodPastDueDomain_0C97DEDF5DF2FB7099BB60D33D1F04E4" xlink:to="loc_oesx_NotPastDueMember_9A82C13EBEEA57D0F00F60C3D17942E4" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_OneToNinetyDaysMember" xlink:label="loc_oesx_OneToNinetyDaysMember_398C10F1D2BA04FF369D60C3D1793D6E" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_FinancingReceivablesPeriodPastDueDomain_0C97DEDF5DF2FB7099BB60D33D1F04E4" xlink:to="loc_oesx_OneToNinetyDaysMember_398C10F1D2BA04FF369D60C3D1793D6E" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_GreaterThanNinetyDaysMember" xlink:label="loc_oesx_GreaterThanNinetyDaysMember_C8DDE1784B8102C3CC7060C3D1791C10" xlink:type="locator" />
    <link:presentationArc order="3" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_FinancingReceivablesPeriodPastDueDomain_0C97DEDF5DF2FB7099BB60D33D1F04E4" xlink:to="loc_oesx_GreaterThanNinetyDaysMember_C8DDE1784B8102C3CC7060C3D1791C10" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_PastDueLeaseNetMember" xlink:label="loc_oesx_PastDueLeaseNetMember_648B81167C6133BC71DF60C3D1798ECB" xlink:type="locator" />
    <link:presentationArc order="4" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_FinancingReceivablesPeriodPastDueDomain_0C97DEDF5DF2FB7099BB60D33D1F04E4" xlink:to="loc_oesx_PastDueLeaseNetMember_648B81167C6133BC71DF60C3D1798ECB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AccountsNotesAndLoansReceivableLineItems" xlink:label="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_DFFC697DCD85E5A2020960C3D179891B" xlink:type="locator" />
    <link:presentationArc order="3" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfFinancingReceivableRecordedInvestmentCreditQualityIndicatorTable_0D59A8587C18A3EDBDAC60C3D1782E8F" xlink:to="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_DFFC697DCD85E5A2020960C3D179891B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AccountsNotesAndLoansReceivableClassifiedAbstract" xlink:label="loc_us-gaap_AccountsNotesAndLoansReceivableClassifiedAbstract_AD93B4F9EC710F0FA2FE60C3D1792D62" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_DFFC697DCD85E5A2020960C3D179891B" xlink:to="loc_us-gaap_AccountsNotesAndLoansReceivableClassifiedAbstract_AD93B4F9EC710F0FA2FE60C3D1792D62" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AccountsNotesAndLoansReceivableNetCurrent" xlink:label="loc_us-gaap_AccountsNotesAndLoansReceivableNetCurrent_CAAF270E8C520F6EEE0F60C3D179C666" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableClassifiedAbstract_AD93B4F9EC710F0FA2FE60C3D1792D62" xlink:to="loc_us-gaap_AccountsNotesAndLoansReceivableNetCurrent_CAAF270E8C520F6EEE0F60C3D179C666" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LongTermAccountsNotesAndLoansReceivableNetNoncurrent" xlink:label="loc_us-gaap_LongTermAccountsNotesAndLoansReceivableNetNoncurrent_38B190C672B5DE4046BA60C3D17A4387" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableClassifiedAbstract_AD93B4F9EC710F0FA2FE60C3D1792D62" xlink:to="loc_us-gaap_LongTermAccountsNotesAndLoansReceivableNetNoncurrent_38B190C672B5DE4046BA60C3D17A4387" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AccountsReceivableGrossCurrent" xlink:label="loc_us-gaap_AccountsReceivableGrossCurrent_A835A90523E302992C0260C3D17A8CA1" xlink:type="locator" />
    <link:presentationArc order="3" preferredLabel="http://www.xbrl.org/2003/role/totalLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableClassifiedAbstract_AD93B4F9EC710F0FA2FE60C3D1792D62" xlink:to="loc_us-gaap_AccountsReceivableGrossCurrent_A835A90523E302992C0260C3D17A8CA1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent" xlink:label="loc_us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent_BA8756C1666D1470005260C3D17A74B2" xlink:type="locator" />
    <link:presentationArc order="4" preferredLabel="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableClassifiedAbstract_AD93B4F9EC710F0FA2FE60C3D1792D62" xlink:to="loc_us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent_BA8756C1666D1470005260C3D17A74B2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AccountsReceivableNetCurrent" xlink:label="loc_us-gaap_AccountsReceivableNetCurrent_04B7BA5963400818434060C3D17A3570" xlink:type="locator" />
    <link:presentationArc order="5" preferredLabel="http://www.xbrl.org/2003/role/totalLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableClassifiedAbstract_AD93B4F9EC710F0FA2FE60C3D1792D62" xlink:to="loc_us-gaap_AccountsReceivableNetCurrent_04B7BA5963400818434060C3D17A3570" xlink:type="arc" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.oesx.com/role/FinancingReceivablesAllowanceForDoubtfulAccountsDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ReceivablesAbstract" xlink:label="loc_us-gaap_ReceivablesAbstract_4B5B6A82B6C713802CAE60ED122A4656" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScheduleOfFinancingReceivableAllowanceForCreditLossesTable" xlink:label="loc_us-gaap_ScheduleOfFinancingReceivableAllowanceForCreditLossesTable_55DC28BCD432771FA6E760ED122A1F70" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ReceivablesAbstract_4B5B6A82B6C713802CAE60ED122A4656" xlink:to="loc_us-gaap_ScheduleOfFinancingReceivableAllowanceForCreditLossesTable_55DC28BCD432771FA6E760ED122A1F70" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FinancingReceivablePortfolioSegmentAxis" xlink:label="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_89F8562432B8F6F3008E60ED122A3051" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfFinancingReceivableAllowanceForCreditLossesTable_55DC28BCD432771FA6E760ED122A1F70" xlink:to="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_89F8562432B8F6F3008E60ED122A3051" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FinancingReceivablePortfolioSegmentDomain" xlink:label="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_B9AC88402BF49745801860ED122A4275" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_89F8562432B8F6F3008E60ED122A3051" xlink:to="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_B9AC88402BF49745801860ED122A4275" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FinanceLeasesPortfolioSegmentMember" xlink:label="loc_us-gaap_FinanceLeasesPortfolioSegmentMember_858C1502EAA56265004960ED122A46E0" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_B9AC88402BF49745801860ED122A4275" xlink:to="loc_us-gaap_FinanceLeasesPortfolioSegmentMember_858C1502EAA56265004960ED122A46E0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FinancingReceivableAllowanceForCreditLossesLineItems" xlink:label="loc_us-gaap_FinancingReceivableAllowanceForCreditLossesLineItems_E509064FDC0B9EC5E32660ED122A9E4B" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfFinancingReceivableAllowanceForCreditLossesTable_55DC28BCD432771FA6E760ED122A1F70" xlink:to="loc_us-gaap_FinancingReceivableAllowanceForCreditLossesLineItems_E509064FDC0B9EC5E32660ED122A9E4B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AllowanceForDoubtfulAccountsReceivableRollforward" xlink:label="loc_us-gaap_AllowanceForDoubtfulAccountsReceivableRollforward_AFF415D4CA66037A99AB60ED122AE299" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_FinancingReceivableAllowanceForCreditLossesLineItems_E509064FDC0B9EC5E32660ED122A9E4B" xlink:to="loc_us-gaap_AllowanceForDoubtfulAccountsReceivableRollforward_AFF415D4CA66037A99AB60ED122AE299" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AllowanceForDoubtfulAccountsReceivable" xlink:label="loc_us-gaap_AllowanceForDoubtfulAccountsReceivable_E608F4D2F99B317CA07460ED122A88C6" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/periodStartLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AllowanceForDoubtfulAccountsReceivableRollforward_AFF415D4CA66037A99AB60ED122AE299" xlink:to="loc_us-gaap_AllowanceForDoubtfulAccountsReceivable_E608F4D2F99B317CA07460ED122A88C6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ProvisionForDoubtfulAccounts" xlink:label="loc_us-gaap_ProvisionForDoubtfulAccounts_CA0D278C6D5D6B1FE89F60ED122A9D27" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AllowanceForDoubtfulAccountsReceivableRollforward_AFF415D4CA66037A99AB60ED122AE299" xlink:to="loc_us-gaap_ProvisionForDoubtfulAccounts_CA0D278C6D5D6B1FE89F60ED122A9D27" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AllowanceForDoubtfulAccountsReceivableWriteOffs" xlink:label="loc_us-gaap_AllowanceForDoubtfulAccountsReceivableWriteOffs_3554AFD3C9A4757B6DD760ED122AF35A" xlink:type="locator" />
    <link:presentationArc order="3" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AllowanceForDoubtfulAccountsReceivableRollforward_AFF415D4CA66037A99AB60ED122AE299" xlink:to="loc_us-gaap_AllowanceForDoubtfulAccountsReceivableWriteOffs_3554AFD3C9A4757B6DD760ED122AF35A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AllowanceForDoubtfulAccountsReceivable" xlink:label="loc_us-gaap_AllowanceForDoubtfulAccountsReceivable_819B6D4A12CDE8C54C8460ED122BCB94" xlink:type="locator" />
    <link:presentationArc order="4" preferredLabel="http://www.xbrl.org/2003/role/periodEndLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AllowanceForDoubtfulAccountsReceivableRollforward_AFF415D4CA66037A99AB60ED122AE299" xlink:to="loc_us-gaap_AllowanceForDoubtfulAccountsReceivable_819B6D4A12CDE8C54C8460ED122BCB94" xlink:type="arc" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.oesx.com/role/FinancingReceivablesTables" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ReceivablesAbstract" xlink:label="loc_us-gaap_ReceivablesAbstract_A595B59D787B7DD84174F859FEE27517" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FinancingReceivableCreditQualityIndicatorsTableTextBlock" xlink:label="loc_us-gaap_FinancingReceivableCreditQualityIndicatorsTableTextBlock_548D8CB84D35F3117FB2F85D46472FD8" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ReceivablesAbstract_A595B59D787B7DD84174F859FEE27517" xlink:to="loc_us-gaap_FinancingReceivableCreditQualityIndicatorsTableTextBlock_548D8CB84D35F3117FB2F85D46472FD8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AllowanceForCreditLossesOnFinancingReceivablesTableTextBlock" xlink:label="loc_us-gaap_AllowanceForCreditLossesOnFinancingReceivablesTableTextBlock_9BCEE1CDCD822523C9C1F85D464E8BE4" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ReceivablesAbstract_A595B59D787B7DD84174F859FEE27517" xlink:to="loc_us-gaap_AllowanceForCreditLossesOnFinancingReceivablesTableTextBlock_9BCEE1CDCD822523C9C1F85D464E8BE4" xlink:type="arc" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.oesx.com/role/GoodwillAndOtherIntangibleAssets" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_GoodwillAndIntangibleAssetsDisclosureAbstract" xlink:label="loc_us-gaap_GoodwillAndIntangibleAssetsDisclosureAbstract_D0ED5F4876621BC475980DBF99E208C8" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_GoodwillAndIntangibleAssetsDisclosureTextBlock" xlink:label="loc_us-gaap_GoodwillAndIntangibleAssetsDisclosureTextBlock_BC9BA1810C69E02B4DD30DBF99E2E102" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_GoodwillAndIntangibleAssetsDisclosureAbstract_D0ED5F4876621BC475980DBF99E208C8" xlink:to="loc_us-gaap_GoodwillAndIntangibleAssetsDisclosureTextBlock_BC9BA1810C69E02B4DD30DBF99E2E102" xlink:type="arc" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.oesx.com/role/GoodwillAndOtherIntangibleAssetsAmortizationExpenseDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_GoodwillAndIntangibleAssetsDisclosureAbstract" xlink:label="loc_us-gaap_GoodwillAndIntangibleAssetsDisclosureAbstract_9B1F4C37685F8007BC535ACDE2AD644A" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable" xlink:label="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_0C76E1BF035C1127A5B25ACDE2ADE97D" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_GoodwillAndIntangibleAssetsDisclosureAbstract_9B1F4C37685F8007BC535ACDE2AD644A" xlink:to="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_0C76E1BF035C1127A5B25ACDE2ADE97D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_IncomeStatementLocationAxis" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_E11365BB594FA31086F05ACDE2AE34F7" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_0C76E1BF035C1127A5B25ACDE2ADE97D" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_E11365BB594FA31086F05ACDE2AE34F7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_7D7079AB2F6FD81936405ACDE2AE8D37" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_E11365BB594FA31086F05ACDE2AE34F7" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_7D7079AB2F6FD81936405ACDE2AE8D37" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CostOfSalesMember" xlink:label="loc_us-gaap_CostOfSalesMember_23E6C8BF3303832584365ACDE2AE4DA3" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_7D7079AB2F6FD81936405ACDE2AE8D37" xlink:to="loc_us-gaap_CostOfSalesMember_23E6C8BF3303832584365ACDE2AE4DA3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_OperatingExpenseMember" xlink:label="loc_us-gaap_OperatingExpenseMember_493CA8EC3A59CD9682C35ACDE2AE3312" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_7D7079AB2F6FD81936405ACDE2AE8D37" xlink:to="loc_us-gaap_OperatingExpenseMember_493CA8EC3A59CD9682C35ACDE2AE3312" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_A30486DD976E8B8E06BA5ACDE2AE4C72" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_0C76E1BF035C1127A5B25ACDE2ADE97D" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_A30486DD976E8B8E06BA5ACDE2AE4C72" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_F1BDDCA458C950218FFB5ACDE2AED6A0" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_A30486DD976E8B8E06BA5ACDE2AE4C72" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_F1BDDCA458C950218FFB5ACDE2AED6A0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CustomerRelationshipsMember" xlink:label="loc_us-gaap_CustomerRelationshipsMember_237B13B496A1EAFF0C235ACDE2AE7C29" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_F1BDDCA458C950218FFB5ACDE2AED6A0" xlink:to="loc_us-gaap_CustomerRelationshipsMember_237B13B496A1EAFF0C235ACDE2AE7C29" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DevelopedTechnologyRightsMember" xlink:label="loc_us-gaap_DevelopedTechnologyRightsMember_F46CBDD3FFE32100CB905ACDE2AF1244" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_F1BDDCA458C950218FFB5ACDE2AED6A0" xlink:to="loc_us-gaap_DevelopedTechnologyRightsMember_F46CBDD3FFE32100CB905ACDE2AF1244" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_NoncompeteAgreementsMember" xlink:label="loc_us-gaap_NoncompeteAgreementsMember_B22FB30FF1A8DBEEF7EC5ACDE2AFC104" xlink:type="locator" />
    <link:presentationArc order="3" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_F1BDDCA458C950218FFB5ACDE2AED6A0" xlink:to="loc_us-gaap_NoncompeteAgreementsMember_B22FB30FF1A8DBEEF7EC5ACDE2AFC104" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PatentsMember" xlink:label="loc_us-gaap_PatentsMember_04E61A721EF89105379C5ACDE2AE654B" xlink:type="locator" />
    <link:presentationArc order="4" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_F1BDDCA458C950218FFB5ACDE2AED6A0" xlink:to="loc_us-gaap_PatentsMember_04E61A721EF89105379C5ACDE2AE654B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsLineItems" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_14D3538E3588602127C55ACDE2AFC9E8" xlink:type="locator" />
    <link:presentationArc order="3" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_0C76E1BF035C1127A5B25ACDE2ADE97D" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_14D3538E3588602127C55ACDE2AFC9E8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AmortizationOfIntangibleAssets" xlink:label="loc_us-gaap_AmortizationOfIntangibleAssets_A5756AE916013E99E5F95ACDE2AF381C" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_14D3538E3588602127C55ACDE2AFC9E8" xlink:to="loc_us-gaap_AmortizationOfIntangibleAssets_A5756AE916013E99E5F95ACDE2AF381C" xlink:type="arc" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.oesx.com/role/GoodwillAndOtherIntangibleAssetsChangeInCarryingValueOfGoodwillDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_GoodwillAndIntangibleAssetsDisclosureAbstract" xlink:label="loc_us-gaap_GoodwillAndIntangibleAssetsDisclosureAbstract_B919C1D23A4F8A957170FCFF03A5D645" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_GoodwillRollForward" xlink:label="loc_us-gaap_GoodwillRollForward_5C8933445028A60EA2FAFCFF7AFDDB6E" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_GoodwillAndIntangibleAssetsDisclosureAbstract_B919C1D23A4F8A957170FCFF03A5D645" xlink:to="loc_us-gaap_GoodwillRollForward_5C8933445028A60EA2FAFCFF7AFDDB6E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_Goodwill" xlink:label="loc_us-gaap_Goodwill_26891A649C70D20843D8FCFF7B0C9182" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/periodStartLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_GoodwillRollForward_5C8933445028A60EA2FAFCFF7AFDDB6E" xlink:to="loc_us-gaap_Goodwill_26891A649C70D20843D8FCFF7B0C9182" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_GoodwillImpairmentLoss" xlink:label="loc_us-gaap_GoodwillImpairmentLoss_4B5056D4E03056AD9276FCFF7B0C313C" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_GoodwillRollForward_5C8933445028A60EA2FAFCFF7AFDDB6E" xlink:to="loc_us-gaap_GoodwillImpairmentLoss_4B5056D4E03056AD9276FCFF7B0C313C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_Goodwill" xlink:label="loc_us-gaap_Goodwill_8399F9496E9FCEEDB117FCFF7B0D30B9" xlink:type="locator" />
    <link:presentationArc order="3" preferredLabel="http://www.xbrl.org/2003/role/periodEndLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_GoodwillRollForward_5C8933445028A60EA2FAFCFF7AFDDB6E" xlink:to="loc_us-gaap_Goodwill_8399F9496E9FCEEDB117FCFF7B0D30B9" xlink:type="arc" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.oesx.com/role/GoodwillAndOtherIntangibleAssetsFutureAmortizationByFiscalYearDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_GoodwillAndIntangibleAssetsDisclosureAbstract" xlink:label="loc_us-gaap_GoodwillAndIntangibleAssetsDisclosureAbstract_A8563A054DB41142DFB6FCF3F19BA8FD" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsFutureAmortizationExpenseAbstract" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsFutureAmortizationExpenseAbstract_CF6793ABDF6DC7AF9A46FCF89060D823" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_GoodwillAndIntangibleAssetsDisclosureAbstract_A8563A054DB41142DFB6FCF3F19BA8FD" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsFutureAmortizationExpenseAbstract_CF6793ABDF6DC7AF9A46FCF89060D823" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths_82C86E7349B254227DAFFCF890601024" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsFutureAmortizationExpenseAbstract_CF6793ABDF6DC7AF9A46FCF89060D823" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths_82C86E7349B254227DAFFCF890601024" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo_8F242FC4C52C193CD387FCF890612F9F" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsFutureAmortizationExpenseAbstract_CF6793ABDF6DC7AF9A46FCF89060D823" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo_8F242FC4C52C193CD387FCF890612F9F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree_EC918E2CF40BDA246FA9FCF89061CA5B" xlink:type="locator" />
    <link:presentationArc order="3" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsFutureAmortizationExpenseAbstract_CF6793ABDF6DC7AF9A46FCF89060D823" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree_EC918E2CF40BDA246FA9FCF89061CA5B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour_F743D8EECD9E74C729A6FCF8906181C5" xlink:type="locator" />
    <link:presentationArc order="4" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsFutureAmortizationExpenseAbstract_CF6793ABDF6DC7AF9A46FCF89060D823" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour_F743D8EECD9E74C729A6FCF8906181C5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFive" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFive_A3A34C189C46A3030F6BFCF89061DAC7" xlink:type="locator" />
    <link:presentationArc order="5" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsFutureAmortizationExpenseAbstract_CF6793ABDF6DC7AF9A46FCF89060D823" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFive_A3A34C189C46A3030F6BFCF89061DAC7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseAfterYearFive" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseAfterYearFive_4331A11051AE538DE6F0FCF890611B20" xlink:type="locator" />
    <link:presentationArc order="6" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsFutureAmortizationExpenseAbstract_CF6793ABDF6DC7AF9A46FCF89060D823" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseAfterYearFive_4331A11051AE538DE6F0FCF890611B20" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsNet" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsNet_21EEF1A22E96E56A9EAFFCF890619AEF" xlink:type="locator" />
    <link:presentationArc order="7" preferredLabel="http://www.xbrl.org/2003/role/totalLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsFutureAmortizationExpenseAbstract_CF6793ABDF6DC7AF9A46FCF89060D823" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsNet_21EEF1A22E96E56A9EAFFCF890619AEF" xlink:type="arc" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.oesx.com/role/GoodwillAndOtherIntangibleAssetsNarrativeDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_GoodwillAndIntangibleAssetsDisclosureAbstract" xlink:label="loc_us-gaap_GoodwillAndIntangibleAssetsDisclosureAbstract_5F312C45285C2DDD693964B047BA42E2" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable" xlink:label="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_579C9C115E5697C82BCC64B047BA0DBE" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_GoodwillAndIntangibleAssetsDisclosureAbstract_5F312C45285C2DDD693964B047BA42E2" xlink:to="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_579C9C115E5697C82BCC64B047BA0DBE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_0D2831F25E55A3D0912C64B047BAF872" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_579C9C115E5697C82BCC64B047BA0DBE" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_0D2831F25E55A3D0912C64B047BAF872" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaap_SegmentDomain_E8A3B0AB78F77073085764B047BAB1DC" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_0D2831F25E55A3D0912C64B047BAF872" xlink:to="loc_us-gaap_SegmentDomain_E8A3B0AB78F77073085764B047BAB1DC" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_U.S.MarketsMember" xlink:label="loc_oesx_U.S.MarketsMember_5ECD7A04FFEEA885EE4264B047BA74AC" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_SegmentDomain_E8A3B0AB78F77073085764B047BAB1DC" xlink:to="loc_oesx_U.S.MarketsMember_5ECD7A04FFEEA885EE4264B047BA74AC" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_EngineeredSystemsMember" xlink:label="loc_oesx_EngineeredSystemsMember_F8F9E241D2C351AD997A64B047BACE14" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_SegmentDomain_E8A3B0AB78F77073085764B047BAB1DC" xlink:to="loc_oesx_EngineeredSystemsMember_F8F9E241D2C351AD997A64B047BACE14" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ConsolidationItemsAxis" xlink:label="loc_us-gaap_ConsolidationItemsAxis_404DD6F4E086B39710B464B047BA72A3" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_579C9C115E5697C82BCC64B047BA0DBE" xlink:to="loc_us-gaap_ConsolidationItemsAxis_404DD6F4E086B39710B464B047BA72A3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ConsolidationItemsDomain" xlink:label="loc_us-gaap_ConsolidationItemsDomain_79BC451A2796FA59C9A464B047BA499F" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ConsolidationItemsAxis_404DD6F4E086B39710B464B047BA72A3" xlink:to="loc_us-gaap_ConsolidationItemsDomain_79BC451A2796FA59C9A464B047BA499F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_OperatingSegmentsMember" xlink:label="loc_us-gaap_OperatingSegmentsMember_CEFD78ABD2B082E269BE64B047BA4812" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ConsolidationItemsDomain_79BC451A2796FA59C9A464B047BA499F" xlink:to="loc_us-gaap_OperatingSegmentsMember_CEFD78ABD2B082E269BE64B047BA4812" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_19B62A628A35F8C2FAAD64B047BA3A85" xlink:type="locator" />
    <link:presentationArc order="3" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_579C9C115E5697C82BCC64B047BA0DBE" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_19B62A628A35F8C2FAAD64B047BA3A85" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_A5C992F530C22F20528A64B047BA615B" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_19B62A628A35F8C2FAAD64B047BA3A85" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_A5C992F530C22F20528A64B047BA615B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_TrademarksAndTradeNamesMember" xlink:label="loc_us-gaap_TrademarksAndTradeNamesMember_B93C4C78FEA44A43CF3F64B047BB93AF" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_A5C992F530C22F20528A64B047BA615B" xlink:to="loc_us-gaap_TrademarksAndTradeNamesMember_B93C4C78FEA44A43CF3F64B047BB93AF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_52F0AB35549CE9E5C94B64B047BB5E88" xlink:type="locator" />
    <link:presentationArc order="4" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_579C9C115E5697C82BCC64B047BA0DBE" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_52F0AB35549CE9E5C94B64B047BB5E88" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_4CB1152114A3083BA0B064B047BB76BA" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_52F0AB35549CE9E5C94B64B047BB5E88" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_4CB1152114A3083BA0B064B047BB76BA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PatentsMember" xlink:label="loc_us-gaap_PatentsMember_9CFDC0273BCB838A629464B047BB2F50" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_4CB1152114A3083BA0B064B047BB76BA" xlink:to="loc_us-gaap_PatentsMember_9CFDC0273BCB838A629464B047BB2F50" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SegmentReportingInformationLineItems" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_2461DC8A33BED628340264B047BB45A6" xlink:type="locator" />
    <link:presentationArc order="5" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_579C9C115E5697C82BCC64B047BA0DBE" xlink:to="loc_us-gaap_SegmentReportingInformationLineItems_2461DC8A33BED628340264B047BB45A6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_Goodwill" xlink:label="loc_us-gaap_Goodwill_E518AE62A9B4166208C664B047BBC268" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_2461DC8A33BED628340264B047BB45A6" xlink:to="loc_us-gaap_Goodwill_E518AE62A9B4166208C664B047BBC268" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_GoodwillImpairmentLoss" xlink:label="loc_us-gaap_GoodwillImpairmentLoss_F28421F6FB054BF3AE6764B047BB3DAF" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_2461DC8A33BED628340264B047BB45A6" xlink:to="loc_us-gaap_GoodwillImpairmentLoss_F28421F6FB054BF3AE6764B047BB3DAF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ImpairmentOfIntangibleAssetsExcludingGoodwill" xlink:label="loc_us-gaap_ImpairmentOfIntangibleAssetsExcludingGoodwill_0013B4CE8F70450D5E6D64B047BBD4E5" xlink:type="locator" />
    <link:presentationArc order="3" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_2461DC8A33BED628340264B047BB45A6" xlink:to="loc_us-gaap_ImpairmentOfIntangibleAssetsExcludingGoodwill_0013B4CE8F70450D5E6D64B047BBD4E5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetUsefulLife" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetUsefulLife_4644BBE6D4DB9597C3BE64B047BB31C8" xlink:type="locator" />
    <link:presentationArc order="4" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_2461DC8A33BED628340264B047BB45A6" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetUsefulLife_4644BBE6D4DB9597C3BE64B047BB31C8" xlink:type="arc" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.oesx.com/role/GoodwillAndOtherIntangibleAssetsOtherIntangibleAssetsDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_GoodwillAndIntangibleAssetsDisclosureAbstract" xlink:label="loc_us-gaap_GoodwillAndIntangibleAssetsDisclosureAbstract_AE932E6B19CDA7207766460DF1FF3406" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable" xlink:label="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_EC4AB49109A20BF3E612460DF1FF7C5E" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_GoodwillAndIntangibleAssetsDisclosureAbstract_AE932E6B19CDA7207766460DF1FF3406" xlink:to="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_EC4AB49109A20BF3E612460DF1FF7C5E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_1790E479A1815EC361B3460DF1FF5CA9" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_EC4AB49109A20BF3E612460DF1FF7C5E" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_1790E479A1815EC361B3460DF1FF5CA9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_DF0A8B1FC7B0C89B9CA1460DF1FFD43D" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_1790E479A1815EC361B3460DF1FF5CA9" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_DF0A8B1FC7B0C89B9CA1460DF1FFD43D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PatentsMember" xlink:label="loc_us-gaap_PatentsMember_F6BED4672864562EE6E7460DF1FF173E" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_DF0A8B1FC7B0C89B9CA1460DF1FFD43D" xlink:to="loc_us-gaap_PatentsMember_F6BED4672864562EE6E7460DF1FF173E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LicensingAgreementsMember" xlink:label="loc_us-gaap_LicensingAgreementsMember_88EA73812F990836EA9D460DF1FFDC2A" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_DF0A8B1FC7B0C89B9CA1460DF1FFD43D" xlink:to="loc_us-gaap_LicensingAgreementsMember_88EA73812F990836EA9D460DF1FFDC2A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_TrademarksAndTradeNamesMember" xlink:label="loc_us-gaap_TrademarksAndTradeNamesMember_6EED9245145538382B31460DF1FFCD63" xlink:type="locator" />
    <link:presentationArc order="3" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_DF0A8B1FC7B0C89B9CA1460DF1FFD43D" xlink:to="loc_us-gaap_TrademarksAndTradeNamesMember_6EED9245145538382B31460DF1FFCD63" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CustomerRelationshipsMember" xlink:label="loc_us-gaap_CustomerRelationshipsMember_417DB84DCC15061F37AB460DF1FF91B7" xlink:type="locator" />
    <link:presentationArc order="4" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_DF0A8B1FC7B0C89B9CA1460DF1FFD43D" xlink:to="loc_us-gaap_CustomerRelationshipsMember_417DB84DCC15061F37AB460DF1FF91B7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DevelopedTechnologyRightsMember" xlink:label="loc_us-gaap_DevelopedTechnologyRightsMember_BA6F71058CDFD8253BD5460DF1FFE344" xlink:type="locator" />
    <link:presentationArc order="5" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_DF0A8B1FC7B0C89B9CA1460DF1FFD43D" xlink:to="loc_us-gaap_DevelopedTechnologyRightsMember_BA6F71058CDFD8253BD5460DF1FFE344" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_NoncompeteAgreementsMember" xlink:label="loc_us-gaap_NoncompeteAgreementsMember_1C4D1C12E3B58A991783460DF1FF3918" xlink:type="locator" />
    <link:presentationArc order="6" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_DF0A8B1FC7B0C89B9CA1460DF1FFD43D" xlink:to="loc_us-gaap_NoncompeteAgreementsMember_1C4D1C12E3B58A991783460DF1FF3918" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsLineItems" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_4431CBC9FF14438F035A460DF200F265" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_EC4AB49109A20BF3E612460DF1FF7C5E" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_4431CBC9FF14438F035A460DF200F265" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_FiniteLivedandIndefiniteLivedIntangibleAssetsGross" xlink:label="loc_oesx_FiniteLivedandIndefiniteLivedIntangibleAssetsGross_F2BB57EADD4D73D2CFF1460DF2000A5B" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_4431CBC9FF14438F035A460DF200F265" xlink:to="loc_oesx_FiniteLivedandIndefiniteLivedIntangibleAssetsGross_F2BB57EADD4D73D2CFF1460DF2000A5B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_70817224A7245B9B83D2460DF2000442" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_4431CBC9FF14438F035A460DF200F265" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_70817224A7245B9B83D2460DF2000442" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_IntangibleAssetsNetExcludingGoodwill" xlink:label="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_631926CC716DB65F8178460DF20038E9" xlink:type="locator" />
    <link:presentationArc order="3" preferredLabel="http://www.xbrl.org/2003/role/totalLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_4431CBC9FF14438F035A460DF200F265" xlink:to="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_631926CC716DB65F8178460DF20038E9" xlink:type="arc" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.oesx.com/role/GoodwillAndOtherIntangibleAssetsTables" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_GoodwillAndIntangibleAssetsDisclosureAbstract" xlink:label="loc_us-gaap_GoodwillAndIntangibleAssetsDisclosureAbstract_2526C94A3F05BC13D15A410882B1FA96" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScheduleOfGoodwillTextBlock" xlink:label="loc_us-gaap_ScheduleOfGoodwillTextBlock_EF5EFE3A4470A3CDDB5E410882B1F8E0" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_GoodwillAndIntangibleAssetsDisclosureAbstract_2526C94A3F05BC13D15A410882B1FA96" xlink:to="loc_us-gaap_ScheduleOfGoodwillTextBlock_EF5EFE3A4470A3CDDB5E410882B1F8E0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScheduleOfIntangibleAssetsAndGoodwillTableTextBlock" xlink:label="loc_us-gaap_ScheduleOfIntangibleAssetsAndGoodwillTableTextBlock_944F95BA08FF8AB02C33410882B13FEC" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_GoodwillAndIntangibleAssetsDisclosureAbstract_2526C94A3F05BC13D15A410882B1FA96" xlink:to="loc_us-gaap_ScheduleOfIntangibleAssetsAndGoodwillTableTextBlock_944F95BA08FF8AB02C33410882B13FEC" xlink:type="arc" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.oesx.com/role/GoodwillAndOtherIntangibleAssetsUsefulLivesDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_GoodwillAndIntangibleAssetsDisclosureAbstract" xlink:label="loc_us-gaap_GoodwillAndIntangibleAssetsDisclosureAbstract_031A678F92F16672D8720DBF99B2A87D" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable" xlink:label="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_DF541B36775BAE30AEA00DBF99B269F1" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_GoodwillAndIntangibleAssetsDisclosureAbstract_031A678F92F16672D8720DBF99B2A87D" xlink:to="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_DF541B36775BAE30AEA00DBF99B269F1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_655633BDAE2ED2996D610DBF99B33595" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_DF541B36775BAE30AEA00DBF99B269F1" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_655633BDAE2ED2996D610DBF99B33595" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_9F7E044073D93F4EDFA70DBF99B35B3D" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_655633BDAE2ED2996D610DBF99B33595" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_9F7E044073D93F4EDFA70DBF99B35B3D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PatentsMember" xlink:label="loc_us-gaap_PatentsMember_470F8D627BD2189812D30DBF99B36784" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_9F7E044073D93F4EDFA70DBF99B35B3D" xlink:to="loc_us-gaap_PatentsMember_470F8D627BD2189812D30DBF99B36784" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LicensingAgreementsMember" xlink:label="loc_us-gaap_LicensingAgreementsMember_0E774D895572C1B0E6860DBF99B35FD9" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_9F7E044073D93F4EDFA70DBF99B35B3D" xlink:to="loc_us-gaap_LicensingAgreementsMember_0E774D895572C1B0E6860DBF99B35FD9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CustomerRelationshipsMember" xlink:label="loc_us-gaap_CustomerRelationshipsMember_EAD568B3D669224A66D10DBF99B32306" xlink:type="locator" />
    <link:presentationArc order="3" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_9F7E044073D93F4EDFA70DBF99B35B3D" xlink:to="loc_us-gaap_CustomerRelationshipsMember_EAD568B3D669224A66D10DBF99B32306" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DevelopedTechnologyRightsMember" xlink:label="loc_us-gaap_DevelopedTechnologyRightsMember_559914080494846D67580DBF99B34024" xlink:type="locator" />
    <link:presentationArc order="4" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_9F7E044073D93F4EDFA70DBF99B35B3D" xlink:to="loc_us-gaap_DevelopedTechnologyRightsMember_559914080494846D67580DBF99B34024" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_NoncompeteAgreementsMember" xlink:label="loc_us-gaap_NoncompeteAgreementsMember_B78EDEF6F7FBF29BECA80DBF99B3ACC3" xlink:type="locator" />
    <link:presentationArc order="5" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_9F7E044073D93F4EDFA70DBF99B35B3D" xlink:to="loc_us-gaap_NoncompeteAgreementsMember_B78EDEF6F7FBF29BECA80DBF99B3ACC3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RangeAxis" xlink:label="loc_us-gaap_RangeAxis_B167868563ED6CD43DF90DBF99B3383D" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_DF541B36775BAE30AEA00DBF99B269F1" xlink:to="loc_us-gaap_RangeAxis_B167868563ED6CD43DF90DBF99B3383D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember_4E9AB24D66145F2F94770DBF99B472B9" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_RangeAxis_B167868563ED6CD43DF90DBF99B3383D" xlink:to="loc_us-gaap_RangeMember_4E9AB24D66145F2F94770DBF99B472B9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_MinimumMember" xlink:label="loc_us-gaap_MinimumMember_024EEB1878E7439518AA0DBF99B49CB2" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_RangeMember_4E9AB24D66145F2F94770DBF99B472B9" xlink:to="loc_us-gaap_MinimumMember_024EEB1878E7439518AA0DBF99B49CB2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_MaximumMember" xlink:label="loc_us-gaap_MaximumMember_211FBCE643D26A49EF860DBF99B41849" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_RangeMember_4E9AB24D66145F2F94770DBF99B472B9" xlink:to="loc_us-gaap_MaximumMember_211FBCE643D26A49EF860DBF99B41849" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsLineItems" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_57BB336BE1F3975D9C460DBF99B47BA8" xlink:type="locator" />
    <link:presentationArc order="3" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_DF541B36775BAE30AEA00DBF99B269F1" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_57BB336BE1F3975D9C460DBF99B47BA8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetUsefulLife" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetUsefulLife_0525880C1E4058FC52620DBF99B9889F" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_57BB336BE1F3975D9C460DBF99B47BA8" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetUsefulLife_0525880C1E4058FC52620DBF99B9889F" xlink:type="arc" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.oesx.com/role/IncomeTaxes" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_IncomeTaxDisclosureAbstract" xlink:label="loc_us-gaap_IncomeTaxDisclosureAbstract_E609CC3148A18761E4510DBF9A52B07A" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_IncomeTaxDisclosureTextBlock" xlink:label="loc_us-gaap_IncomeTaxDisclosureTextBlock_7F584ADFE145363AD5640DBF9A52087E" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncomeTaxDisclosureAbstract_E609CC3148A18761E4510DBF9A52B07A" xlink:to="loc_us-gaap_IncomeTaxDisclosureTextBlock_7F584ADFE145363AD5640DBF9A52087E" xlink:type="arc" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.oesx.com/role/IncomeTaxesNarrativeDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_IncomeTaxDisclosureAbstract" xlink:label="loc_us-gaap_IncomeTaxDisclosureAbstract_C3DB9F418FFB762F724E64872C8812E6" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_OperatingLossCarryforwardsTable" xlink:label="loc_us-gaap_OperatingLossCarryforwardsTable_FBBED9960B5DBA24C41664872C882C67" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncomeTaxDisclosureAbstract_C3DB9F418FFB762F724E64872C8812E6" xlink:to="loc_us-gaap_OperatingLossCarryforwardsTable_FBBED9960B5DBA24C41664872C882C67" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_IncomeTaxAuthorityAxis" xlink:label="loc_us-gaap_IncomeTaxAuthorityAxis_80F20E666412EBC1ED4C64872C88948C" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_OperatingLossCarryforwardsTable_FBBED9960B5DBA24C41664872C882C67" xlink:to="loc_us-gaap_IncomeTaxAuthorityAxis_80F20E666412EBC1ED4C64872C88948C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_IncomeTaxAuthorityDomain" xlink:label="loc_us-gaap_IncomeTaxAuthorityDomain_D4940D33962B06A4B97264872C880A4D" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncomeTaxAuthorityAxis_80F20E666412EBC1ED4C64872C88948C" xlink:to="loc_us-gaap_IncomeTaxAuthorityDomain_D4940D33962B06A4B97264872C880A4D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DomesticCountryMember" xlink:label="loc_us-gaap_DomesticCountryMember_8DEBC65EB0C5FBDB2D6D64872C88A1D3" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncomeTaxAuthorityDomain_D4940D33962B06A4B97264872C880A4D" xlink:to="loc_us-gaap_DomesticCountryMember_8DEBC65EB0C5FBDB2D6D64872C88A1D3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StateAndLocalJurisdictionMember" xlink:label="loc_us-gaap_StateAndLocalJurisdictionMember_FD0036E2CDA5D6A0385364872C88F201" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncomeTaxAuthorityDomain_D4940D33962B06A4B97264872C880A4D" xlink:to="loc_us-gaap_StateAndLocalJurisdictionMember_FD0036E2CDA5D6A0385364872C88F201" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RangeAxis" xlink:label="loc_us-gaap_RangeAxis_66991750857D6FBA86BD64872C8867F3" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_OperatingLossCarryforwardsTable_FBBED9960B5DBA24C41664872C882C67" xlink:to="loc_us-gaap_RangeAxis_66991750857D6FBA86BD64872C8867F3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember_1BE8E10FDD8EE0A7445B64872C88D121" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_RangeAxis_66991750857D6FBA86BD64872C8867F3" xlink:to="loc_us-gaap_RangeMember_1BE8E10FDD8EE0A7445B64872C88D121" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_MinimumMember" xlink:label="loc_us-gaap_MinimumMember_C57F85DAB4058BF42B4964872C88F872" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_RangeMember_1BE8E10FDD8EE0A7445B64872C88D121" xlink:to="loc_us-gaap_MinimumMember_C57F85DAB4058BF42B4964872C88F872" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_MaximumMember" xlink:label="loc_us-gaap_MaximumMember_7CAE1628481AE052F4C764872C88898A" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_RangeMember_1BE8E10FDD8EE0A7445B64872C88D121" xlink:to="loc_us-gaap_MaximumMember_7CAE1628481AE052F4C764872C88898A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_IncomeTaxAuthorityNameAxis" xlink:label="loc_us-gaap_IncomeTaxAuthorityNameAxis_80E21198555397F5189864872C8832A1" xlink:type="locator" />
    <link:presentationArc order="3" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_OperatingLossCarryforwardsTable_FBBED9960B5DBA24C41664872C882C67" xlink:to="loc_us-gaap_IncomeTaxAuthorityNameAxis_80E21198555397F5189864872C8832A1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_IncomeTaxAuthorityNameDomain" xlink:label="loc_us-gaap_IncomeTaxAuthorityNameDomain_475CEAEC2D469268B34664872C8862FA" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncomeTaxAuthorityNameAxis_80E21198555397F5189864872C8832A1" xlink:to="loc_us-gaap_IncomeTaxAuthorityNameDomain_475CEAEC2D469268B34664872C8862FA" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_WisconsinDepartmentOfRevenueMember" xlink:label="loc_oesx_WisconsinDepartmentOfRevenueMember_6E6D3CF74DF8C4E2336764872C891388" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncomeTaxAuthorityNameDomain_475CEAEC2D469268B34664872C8862FA" xlink:to="loc_oesx_WisconsinDepartmentOfRevenueMember_6E6D3CF74DF8C4E2336764872C891388" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_OperatingLossCarryforwardsLineItems" xlink:label="loc_us-gaap_OperatingLossCarryforwardsLineItems_5DC1C0C35594272965E064872C89AD83" xlink:type="locator" />
    <link:presentationArc order="4" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_OperatingLossCarryforwardsTable_FBBED9960B5DBA24C41664872C882C67" xlink:to="loc_us-gaap_OperatingLossCarryforwardsLineItems_5DC1C0C35594272965E064872C89AD83" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ExcessTaxBenefitFromShareBasedCompensationFinancingActivities" xlink:label="loc_us-gaap_ExcessTaxBenefitFromShareBasedCompensationFinancingActivities_8DCB4EC70B0CB047F3E464872C89A875" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_5DC1C0C35594272965E064872C89AD83" xlink:to="loc_us-gaap_ExcessTaxBenefitFromShareBasedCompensationFinancingActivities_8DCB4EC70B0CB047F3E464872C89A875" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_OperatingLossCarryforwards" xlink:label="loc_us-gaap_OperatingLossCarryforwards_93A8FDDF64434FC59BD364872C89D39A" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_5DC1C0C35594272965E064872C89AD83" xlink:to="loc_us-gaap_OperatingLossCarryforwards_93A8FDDF64434FC59BD364872C89D39A" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_OperatingLossCarryforwardsAssociatedWithExerciseOfNonQualifiedStockOptions" xlink:label="loc_oesx_OperatingLossCarryforwardsAssociatedWithExerciseOfNonQualifiedStockOptions_CB5B857D74C9049A34EE64872C894287" xlink:type="locator" />
    <link:presentationArc order="3" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_5DC1C0C35594272965E064872C89AD83" xlink:to="loc_oesx_OperatingLossCarryforwardsAssociatedWithExerciseOfNonQualifiedStockOptions_CB5B857D74C9049A34EE64872C894287" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_TaxCreditCarryforwardAmount" xlink:label="loc_us-gaap_TaxCreditCarryforwardAmount_608E3AE0EADADA3D5B7764872C894A37" xlink:type="locator" />
    <link:presentationArc order="4" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_5DC1C0C35594272965E064872C89AD83" xlink:to="loc_us-gaap_TaxCreditCarryforwardAmount_608E3AE0EADADA3D5B7764872C894A37" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DeferredTaxAssetsValuationAllowance" xlink:label="loc_us-gaap_DeferredTaxAssetsValuationAllowance_86128D74458EEBF93A8664872C894D80" xlink:type="locator" />
    <link:presentationArc order="5" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_5DC1C0C35594272965E064872C89AD83" xlink:to="loc_us-gaap_DeferredTaxAssetsValuationAllowance_86128D74458EEBF93A8664872C894D80" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ValuationAllowanceDeferredTaxAssetChangeInAmount" xlink:label="loc_us-gaap_ValuationAllowanceDeferredTaxAssetChangeInAmount_A1506FAE6FC54BC2908264872C8984F4" xlink:type="locator" />
    <link:presentationArc order="6" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_5DC1C0C35594272965E064872C89AD83" xlink:to="loc_us-gaap_ValuationAllowanceDeferredTaxAssetChangeInAmount_A1506FAE6FC54BC2908264872C8984F4" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_PeriodOfTimeStateIncomeTaxReturnsSubjectToExamination" xlink:label="loc_oesx_PeriodOfTimeStateIncomeTaxReturnsSubjectToExamination_EA5C4967036CA026C72E64872C8990C1" xlink:type="locator" />
    <link:presentationArc order="7" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_5DC1C0C35594272965E064872C89AD83" xlink:to="loc_oesx_PeriodOfTimeStateIncomeTaxReturnsSubjectToExamination_EA5C4967036CA026C72E64872C8990C1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_IncomeTaxExaminationLiabilityRefundAdjustmentFromSettlementWithTaxingAuthority" xlink:label="loc_us-gaap_IncomeTaxExaminationLiabilityRefundAdjustmentFromSettlementWithTaxingAuthority_D6E65E1AF0689F3F2E8064872C895131" xlink:type="locator" />
    <link:presentationArc order="8" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_5DC1C0C35594272965E064872C89AD83" xlink:to="loc_us-gaap_IncomeTaxExaminationLiabilityRefundAdjustmentFromSettlementWithTaxingAuthority_D6E65E1AF0689F3F2E8064872C895131" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_UnrecognizedTaxBenefits" xlink:label="loc_us-gaap_UnrecognizedTaxBenefits_8094054F1A082B926DD164872C89D044" xlink:type="locator" />
    <link:presentationArc order="9" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_5DC1C0C35594272965E064872C89AD83" xlink:to="loc_us-gaap_UnrecognizedTaxBenefits_8094054F1A082B926DD164872C89D044" xlink:type="arc" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.oesx.com/role/IncomeTaxesReconciliationOfTaxRatesDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_IncomeTaxDisclosureAbstract" xlink:label="loc_us-gaap_IncomeTaxDisclosureAbstract_201620C365D921031FBE0DE88BE1186D" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate" xlink:label="loc_us-gaap_EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate_EC7C6D8676A9F7C5CC600DE88BE15CFA" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncomeTaxDisclosureAbstract_201620C365D921031FBE0DE88BE1186D" xlink:to="loc_us-gaap_EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate_EC7C6D8676A9F7C5CC600DE88BE15CFA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes" xlink:label="loc_us-gaap_EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes_D92FF9C8DA996F2DA5EB0DE88BE1A8D0" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncomeTaxDisclosureAbstract_201620C365D921031FBE0DE88BE1186D" xlink:to="loc_us-gaap_EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes_D92FF9C8DA996F2DA5EB0DE88BE1A8D0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationTaxCreditsResearch" xlink:label="loc_us-gaap_EffectiveIncomeTaxRateReconciliationTaxCreditsResearch_0C7C399088979151E6F60DE88BE1AAE5" xlink:type="locator" />
    <link:presentationArc order="3" preferredLabel="http://www.xbrl.org/2009/role/negatedLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncomeTaxDisclosureAbstract_201620C365D921031FBE0DE88BE1186D" xlink:to="loc_us-gaap_EffectiveIncomeTaxRateReconciliationTaxCreditsResearch_0C7C399088979151E6F60DE88BE1AAE5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationTaxCreditsOther" xlink:label="loc_us-gaap_EffectiveIncomeTaxRateReconciliationTaxCreditsOther_2F617DA95065CFD647700DE88BE1F476" xlink:type="locator" />
    <link:presentationArc order="4" preferredLabel="http://www.xbrl.org/2009/role/negatedLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncomeTaxDisclosureAbstract_201620C365D921031FBE0DE88BE1186D" xlink:to="loc_us-gaap_EffectiveIncomeTaxRateReconciliationTaxCreditsOther_2F617DA95065CFD647700DE88BE1F476" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationChangeInDeferredTaxAssetsValuationAllowance" xlink:label="loc_us-gaap_EffectiveIncomeTaxRateReconciliationChangeInDeferredTaxAssetsValuationAllowance_BA007C36782AC96251910DE88BE1224A" xlink:type="locator" />
    <link:presentationArc order="5" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncomeTaxDisclosureAbstract_201620C365D921031FBE0DE88BE1186D" xlink:to="loc_us-gaap_EffectiveIncomeTaxRateReconciliationChangeInDeferredTaxAssetsValuationAllowance_BA007C36782AC96251910DE88BE1224A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationNondeductibleExpense" xlink:label="loc_us-gaap_EffectiveIncomeTaxRateReconciliationNondeductibleExpense_9429F5A49C5EAA27CFDC0DE88BE28B5D" xlink:type="locator" />
    <link:presentationArc order="6" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncomeTaxDisclosureAbstract_201620C365D921031FBE0DE88BE1186D" xlink:to="loc_us-gaap_EffectiveIncomeTaxRateReconciliationNondeductibleExpense_9429F5A49C5EAA27CFDC0DE88BE28B5D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationTaxContingencies" xlink:label="loc_us-gaap_EffectiveIncomeTaxRateReconciliationTaxContingencies_CDF5D58307DF0649BBEE0DE88BE2E5DD" xlink:type="locator" />
    <link:presentationArc order="7" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncomeTaxDisclosureAbstract_201620C365D921031FBE0DE88BE1186D" xlink:to="loc_us-gaap_EffectiveIncomeTaxRateReconciliationTaxContingencies_CDF5D58307DF0649BBEE0DE88BE2E5DD" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationPriorYearIncomeTaxes" xlink:label="loc_us-gaap_EffectiveIncomeTaxRateReconciliationPriorYearIncomeTaxes_168FC25596F57C8F58020DF7EF0F447B" xlink:type="locator" />
    <link:presentationArc order="8" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncomeTaxDisclosureAbstract_201620C365D921031FBE0DE88BE1186D" xlink:to="loc_us-gaap_EffectiveIncomeTaxRateReconciliationPriorYearIncomeTaxes_168FC25596F57C8F58020DF7EF0F447B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationOtherAdjustments" xlink:label="loc_us-gaap_EffectiveIncomeTaxRateReconciliationOtherAdjustments_043013C712EE1DD18FBC0DE88BE20AF9" xlink:type="locator" />
    <link:presentationArc order="9" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncomeTaxDisclosureAbstract_201620C365D921031FBE0DE88BE1186D" xlink:to="loc_us-gaap_EffectiveIncomeTaxRateReconciliationOtherAdjustments_043013C712EE1DD18FBC0DE88BE20AF9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_EffectiveIncomeTaxRateContinuingOperations" xlink:label="loc_us-gaap_EffectiveIncomeTaxRateContinuingOperations_14F10FD3F50E7D8C48990DE88BE2985F" xlink:type="locator" />
    <link:presentationArc order="10" preferredLabel="http://www.xbrl.org/2003/role/totalLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncomeTaxDisclosureAbstract_201620C365D921031FBE0DE88BE1186D" xlink:to="loc_us-gaap_EffectiveIncomeTaxRateContinuingOperations_14F10FD3F50E7D8C48990DE88BE2985F" xlink:type="arc" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.oesx.com/role/IncomeTaxesScheduleOfComponentsOfIncomeTaxExpenseOrBenefitDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_IncomeTaxDisclosureAbstract" xlink:label="loc_us-gaap_IncomeTaxDisclosureAbstract_466FA6604582F9BE9F5B0DE88BE6319A" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CurrentIncomeTaxExpenseBenefit" xlink:label="loc_us-gaap_CurrentIncomeTaxExpenseBenefit_919144B570D81CFA58BE0DE88BE67185" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncomeTaxDisclosureAbstract_466FA6604582F9BE9F5B0DE88BE6319A" xlink:to="loc_us-gaap_CurrentIncomeTaxExpenseBenefit_919144B570D81CFA58BE0DE88BE67185" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DeferredIncomeTaxExpenseBenefit" xlink:label="loc_us-gaap_DeferredIncomeTaxExpenseBenefit_7CD687B27A2E8651ED8D0DE88BE77B86" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncomeTaxDisclosureAbstract_466FA6604582F9BE9F5B0DE88BE6319A" xlink:to="loc_us-gaap_DeferredIncomeTaxExpenseBenefit_7CD687B27A2E8651ED8D0DE88BE77B86" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FederalIncomeTaxExpenseBenefitContinuingOperations" xlink:label="loc_us-gaap_FederalIncomeTaxExpenseBenefitContinuingOperations_4AE65FC60EA6F1D46C1A0DE88BE7C3E5" xlink:type="locator" />
    <link:presentationArc order="3" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncomeTaxDisclosureAbstract_466FA6604582F9BE9F5B0DE88BE6319A" xlink:to="loc_us-gaap_FederalIncomeTaxExpenseBenefitContinuingOperations_4AE65FC60EA6F1D46C1A0DE88BE7C3E5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StateAndLocalIncomeTaxExpenseBenefitContinuingOperations" xlink:label="loc_us-gaap_StateAndLocalIncomeTaxExpenseBenefitContinuingOperations_9CAFC901E849AE241DF30DE88BE76D5E" xlink:type="locator" />
    <link:presentationArc order="4" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncomeTaxDisclosureAbstract_466FA6604582F9BE9F5B0DE88BE6319A" xlink:to="loc_us-gaap_StateAndLocalIncomeTaxExpenseBenefitContinuingOperations_9CAFC901E849AE241DF30DE88BE76D5E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_IncomeTaxExpenseBenefit" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_C4599597876417DCD90E0DE88BE72B42" xlink:type="locator" />
    <link:presentationArc order="5" preferredLabel="http://www.xbrl.org/2003/role/totalLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncomeTaxDisclosureAbstract_466FA6604582F9BE9F5B0DE88BE6319A" xlink:to="loc_us-gaap_IncomeTaxExpenseBenefit_C4599597876417DCD90E0DE88BE72B42" xlink:type="arc" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.oesx.com/role/IncomeTaxesScheduleOfDeferredTaxAssetsAndLiabilitiesDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_IncomeTaxDisclosureAbstract" xlink:label="loc_us-gaap_IncomeTaxDisclosureAbstract_8EE5C9E76DF0FCCCE1BF5FEF2AD641EB" xlink:type="locator" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_DeferredTaxAssetsInventoryAccrualsAndReserves" xlink:label="loc_oesx_DeferredTaxAssetsInventoryAccrualsAndReserves_6DEB118344AE4A02A3275FEF2AD6F6D2" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncomeTaxDisclosureAbstract_8EE5C9E76DF0FCCCE1BF5FEF2AD641EB" xlink:to="loc_oesx_DeferredTaxAssetsInventoryAccrualsAndReserves_6DEB118344AE4A02A3275FEF2AD6F6D2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DeferredTaxAssetsOther" xlink:label="loc_us-gaap_DeferredTaxAssetsOther_1A3EE9ED5315217C54F35FEF2AD62385" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncomeTaxDisclosureAbstract_8EE5C9E76DF0FCCCE1BF5FEF2AD641EB" xlink:to="loc_us-gaap_DeferredTaxAssetsOther_1A3EE9ED5315217C54F35FEF2AD62385" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_DeferredTaxAssetDeferredIncomeCurrent" xlink:label="loc_oesx_DeferredTaxAssetDeferredIncomeCurrent_AB333EF2A57C15C23FE25FEF2AD6D25C" xlink:type="locator" />
    <link:presentationArc order="3" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncomeTaxDisclosureAbstract_8EE5C9E76DF0FCCCE1BF5FEF2AD641EB" xlink:to="loc_oesx_DeferredTaxAssetDeferredIncomeCurrent_AB333EF2A57C15C23FE25FEF2AD6D25C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DeferredTaxAssetsValuationAllowanceCurrent" xlink:label="loc_us-gaap_DeferredTaxAssetsValuationAllowanceCurrent_1D837A8EA51F79E20CF05FEF2AD70297" xlink:type="locator" />
    <link:presentationArc order="4" preferredLabel="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncomeTaxDisclosureAbstract_8EE5C9E76DF0FCCCE1BF5FEF2AD641EB" xlink:to="loc_us-gaap_DeferredTaxAssetsValuationAllowanceCurrent_1D837A8EA51F79E20CF05FEF2AD70297" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DeferredTaxAssetsNetCurrent" xlink:label="loc_us-gaap_DeferredTaxAssetsNetCurrent_9D4030B76FCBA2D3D9A65FEF2AD73C60" xlink:type="locator" />
    <link:presentationArc order="5" preferredLabel="http://www.xbrl.org/2003/role/totalLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncomeTaxDisclosureAbstract_8EE5C9E76DF0FCCCE1BF5FEF2AD641EB" xlink:to="loc_us-gaap_DeferredTaxAssetsNetCurrent_9D4030B76FCBA2D3D9A65FEF2AD73C60" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DeferredTaxAssetsOperatingLossCarryforwards" xlink:label="loc_us-gaap_DeferredTaxAssetsOperatingLossCarryforwards_4FC267ED1F0462C8E9C25FEF2AD7F4E2" xlink:type="locator" />
    <link:presentationArc order="6" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncomeTaxDisclosureAbstract_8EE5C9E76DF0FCCCE1BF5FEF2AD641EB" xlink:to="loc_us-gaap_DeferredTaxAssetsOperatingLossCarryforwards_4FC267ED1F0462C8E9C25FEF2AD7F4E2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DeferredTaxAssetsTaxCreditCarryforwards" xlink:label="loc_us-gaap_DeferredTaxAssetsTaxCreditCarryforwards_7618D80DB6AF66D51FCB5FEF2AD7C44C" xlink:type="locator" />
    <link:presentationArc order="7" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncomeTaxDisclosureAbstract_8EE5C9E76DF0FCCCE1BF5FEF2AD641EB" xlink:to="loc_us-gaap_DeferredTaxAssetsTaxCreditCarryforwards_7618D80DB6AF66D51FCB5FEF2AD7C44C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsShareBasedCompensationCost" xlink:label="loc_us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsShareBasedCompensationCost_0FBCC5F045AF7B29D5095FEF2AD7E1B5" xlink:type="locator" />
    <link:presentationArc order="8" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncomeTaxDisclosureAbstract_8EE5C9E76DF0FCCCE1BF5FEF2AD641EB" xlink:to="loc_us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsShareBasedCompensationCost_0FBCC5F045AF7B29D5095FEF2AD7E1B5" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_DeferredTaxAssetDeferredIncomeNoncurrent" xlink:label="loc_oesx_DeferredTaxAssetDeferredIncomeNoncurrent_D0A1DCB81855F3E80A845FEF2AD75A9F" xlink:type="locator" />
    <link:presentationArc order="9" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncomeTaxDisclosureAbstract_8EE5C9E76DF0FCCCE1BF5FEF2AD641EB" xlink:to="loc_oesx_DeferredTaxAssetDeferredIncomeNoncurrent_D0A1DCB81855F3E80A845FEF2AD75A9F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DeferredTaxLiabilitiesPropertyPlantAndEquipment" xlink:label="loc_us-gaap_DeferredTaxLiabilitiesPropertyPlantAndEquipment_801F492310B638E26A5B5FEF2AD71076" xlink:type="locator" />
    <link:presentationArc order="10" preferredLabel="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncomeTaxDisclosureAbstract_8EE5C9E76DF0FCCCE1BF5FEF2AD641EB" xlink:to="loc_us-gaap_DeferredTaxLiabilitiesPropertyPlantAndEquipment_801F492310B638E26A5B5FEF2AD71076" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DeferredTaxLiabilitiesGoodwillAndIntangibleAssets" xlink:label="loc_us-gaap_DeferredTaxLiabilitiesGoodwillAndIntangibleAssets_EDA10C3DABD5FFE41C265FEF2AD7C6E9" xlink:type="locator" />
    <link:presentationArc order="11" preferredLabel="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncomeTaxDisclosureAbstract_8EE5C9E76DF0FCCCE1BF5FEF2AD641EB" xlink:to="loc_us-gaap_DeferredTaxLiabilitiesGoodwillAndIntangibleAssets_EDA10C3DABD5FFE41C265FEF2AD7C6E9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DeferredTaxAssetsValuationAllowanceNoncurrent" xlink:label="loc_us-gaap_DeferredTaxAssetsValuationAllowanceNoncurrent_9CDCEFEF0812C86B36545FEF2AD7467F" xlink:type="locator" />
    <link:presentationArc order="12" preferredLabel="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncomeTaxDisclosureAbstract_8EE5C9E76DF0FCCCE1BF5FEF2AD641EB" xlink:to="loc_us-gaap_DeferredTaxAssetsValuationAllowanceNoncurrent_9CDCEFEF0812C86B36545FEF2AD7467F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DeferredTaxAssetsNetNoncurrent" xlink:label="loc_us-gaap_DeferredTaxAssetsNetNoncurrent_7D8C520E96053CEE7B0F5FEF2AD71051" xlink:type="locator" />
    <link:presentationArc order="13" preferredLabel="http://www.xbrl.org/2003/role/totalLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncomeTaxDisclosureAbstract_8EE5C9E76DF0FCCCE1BF5FEF2AD641EB" xlink:to="loc_us-gaap_DeferredTaxAssetsNetNoncurrent_7D8C520E96053CEE7B0F5FEF2AD71051" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DeferredTaxAssetsNet" xlink:label="loc_us-gaap_DeferredTaxAssetsNet_AA0FC193C90050A9F10B5FEF2AD81E54" xlink:type="locator" />
    <link:presentationArc order="14" preferredLabel="http://www.xbrl.org/2003/role/totalLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncomeTaxDisclosureAbstract_8EE5C9E76DF0FCCCE1BF5FEF2AD641EB" xlink:to="loc_us-gaap_DeferredTaxAssetsNet_AA0FC193C90050A9F10B5FEF2AD81E54" xlink:type="arc" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.oesx.com/role/IncomeTaxesTables" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_IncomeTaxDisclosureAbstract" xlink:label="loc_us-gaap_IncomeTaxDisclosureAbstract_15DCB2D01D27D92ECCAB66E04A481FCE" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScheduleOfComponentsOfIncomeTaxExpenseBenefitTableTextBlock" xlink:label="loc_us-gaap_ScheduleOfComponentsOfIncomeTaxExpenseBenefitTableTextBlock_61A5B6457D491308480966E04A481203" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncomeTaxDisclosureAbstract_15DCB2D01D27D92ECCAB66E04A481FCE" xlink:to="loc_us-gaap_ScheduleOfComponentsOfIncomeTaxExpenseBenefitTableTextBlock_61A5B6457D491308480966E04A481203" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScheduleOfEffectiveIncomeTaxRateReconciliationTableTextBlock" xlink:label="loc_us-gaap_ScheduleOfEffectiveIncomeTaxRateReconciliationTableTextBlock_E83ECDCB77CEAB8F457666E04A490BC2" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncomeTaxDisclosureAbstract_15DCB2D01D27D92ECCAB66E04A481FCE" xlink:to="loc_us-gaap_ScheduleOfEffectiveIncomeTaxRateReconciliationTableTextBlock_E83ECDCB77CEAB8F457666E04A490BC2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScheduleOfDeferredTaxAssetsAndLiabilitiesTableTextBlock" xlink:label="loc_us-gaap_ScheduleOfDeferredTaxAssetsAndLiabilitiesTableTextBlock_C8EBA325D41596101AF866E04A49208D" xlink:type="locator" />
    <link:presentationArc order="3" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncomeTaxDisclosureAbstract_15DCB2D01D27D92ECCAB66E04A481FCE" xlink:to="loc_us-gaap_ScheduleOfDeferredTaxAssetsAndLiabilitiesTableTextBlock_C8EBA325D41596101AF866E04A49208D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScheduleOfUnrecognizedTaxBenefitsRollForwardTableTextBlock" xlink:label="loc_us-gaap_ScheduleOfUnrecognizedTaxBenefitsRollForwardTableTextBlock_98485AA08F67261DB66366E04A494008" xlink:type="locator" />
    <link:presentationArc order="4" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncomeTaxDisclosureAbstract_15DCB2D01D27D92ECCAB66E04A481FCE" xlink:to="loc_us-gaap_ScheduleOfUnrecognizedTaxBenefitsRollForwardTableTextBlock_98485AA08F67261DB66366E04A494008" xlink:type="arc" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.oesx.com/role/IncomeTaxesUnrecognizedTaxBenefitActivityDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_IncomeTaxDisclosureAbstract" xlink:label="loc_us-gaap_IncomeTaxDisclosureAbstract_21087EE0DCAA91E1CCD80DE88BC6DB20" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ReconciliationOfUnrecognizedTaxBenefitsExcludingAmountsPertainingToExaminedTaxReturnsRollForward" xlink:label="loc_us-gaap_ReconciliationOfUnrecognizedTaxBenefitsExcludingAmountsPertainingToExaminedTaxReturnsRollForward_A766D7B62B305EBB29160DE88BC764CC" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncomeTaxDisclosureAbstract_21087EE0DCAA91E1CCD80DE88BC6DB20" xlink:to="loc_us-gaap_ReconciliationOfUnrecognizedTaxBenefitsExcludingAmountsPertainingToExaminedTaxReturnsRollForward_A766D7B62B305EBB29160DE88BC764CC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_UnrecognizedTaxBenefits" xlink:label="loc_us-gaap_UnrecognizedTaxBenefits_74D5B35E670973F618130DE88BC7F1A7" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/periodStartLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ReconciliationOfUnrecognizedTaxBenefitsExcludingAmountsPertainingToExaminedTaxReturnsRollForward_A766D7B62B305EBB29160DE88BC764CC" xlink:to="loc_us-gaap_UnrecognizedTaxBenefits_74D5B35E670973F618130DE88BC7F1A7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions" xlink:label="loc_us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions_AA1C783EE2EF8C1504A10DE88BC772D7" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ReconciliationOfUnrecognizedTaxBenefitsExcludingAmountsPertainingToExaminedTaxReturnsRollForward_A766D7B62B305EBB29160DE88BC764CC" xlink:to="loc_us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions_AA1C783EE2EF8C1504A10DE88BC772D7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_UnrecognizedTaxBenefitsDecreasesResultingFromPriorPeriodTaxPositions" xlink:label="loc_us-gaap_UnrecognizedTaxBenefitsDecreasesResultingFromPriorPeriodTaxPositions_77C68CD34C18AA1486DF0E0110C73D30" xlink:type="locator" />
    <link:presentationArc order="3" preferredLabel="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ReconciliationOfUnrecognizedTaxBenefitsExcludingAmountsPertainingToExaminedTaxReturnsRollForward_A766D7B62B305EBB29160DE88BC764CC" xlink:to="loc_us-gaap_UnrecognizedTaxBenefitsDecreasesResultingFromPriorPeriodTaxPositions_77C68CD34C18AA1486DF0E0110C73D30" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_UnrecognizedTaxBenefits" xlink:label="loc_us-gaap_UnrecognizedTaxBenefits_96747ED084568F9EAA220DE88BC736A1" xlink:type="locator" />
    <link:presentationArc order="4" preferredLabel="http://www.xbrl.org/2003/role/periodEndLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ReconciliationOfUnrecognizedTaxBenefitsExcludingAmountsPertainingToExaminedTaxReturnsRollForward_A766D7B62B305EBB29160DE88BC764CC" xlink:to="loc_us-gaap_UnrecognizedTaxBenefits_96747ED084568F9EAA220DE88BC736A1" xlink:type="arc" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.oesx.com/role/Inventories" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_InventoryDisclosureAbstract" xlink:label="loc_us-gaap_InventoryDisclosureAbstract_160D196AEBC05E1B0BF00DBF9B1099F8" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_InventoryDisclosureTextBlock" xlink:label="loc_us-gaap_InventoryDisclosureTextBlock_EA9C9B87718135C4852F0DBF9B1092AA" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_InventoryDisclosureAbstract_160D196AEBC05E1B0BF00DBF9B1099F8" xlink:to="loc_us-gaap_InventoryDisclosureTextBlock_EA9C9B87718135C4852F0DBF9B1092AA" xlink:type="arc" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.oesx.com/role/InventoriesDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_InventoryDisclosureAbstract" xlink:label="loc_us-gaap_InventoryDisclosureAbstract_5BC0B2E51A9409B6719364B047E3682E" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_InventoryCurrentTable" xlink:label="loc_us-gaap_InventoryCurrentTable_2D886BBBD0D4049052E864B047E4E6AB" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_InventoryDisclosureAbstract_5BC0B2E51A9409B6719364B047E3682E" xlink:to="loc_us-gaap_InventoryCurrentTable_2D886BBBD0D4049052E864B047E4E6AB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RangeAxis" xlink:label="loc_us-gaap_RangeAxis_7CB420B3F3B68BD5D14664B047E4376F" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_InventoryCurrentTable_2D886BBBD0D4049052E864B047E4E6AB" xlink:to="loc_us-gaap_RangeAxis_7CB420B3F3B68BD5D14664B047E4376F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember_33EA59614A0D8DE7E53864B047E445B2" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_RangeAxis_7CB420B3F3B68BD5D14664B047E4376F" xlink:to="loc_us-gaap_RangeMember_33EA59614A0D8DE7E53864B047E445B2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_MinimumMember" xlink:label="loc_us-gaap_MinimumMember_13FFFD046709FA404D2E64B047E42B98" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_RangeMember_33EA59614A0D8DE7E53864B047E445B2" xlink:to="loc_us-gaap_MinimumMember_13FFFD046709FA404D2E64B047E42B98" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_MaximumMember" xlink:label="loc_us-gaap_MaximumMember_0313859A35E3A4BF126764B047E4D6A2" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_RangeMember_33EA59614A0D8DE7E53864B047E445B2" xlink:to="loc_us-gaap_MaximumMember_0313859A35E3A4BF126764B047E4D6A2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ValuationAllowancesAndReservesTypeAxis" xlink:label="loc_us-gaap_ValuationAllowancesAndReservesTypeAxis_9797E5429E07B93AE12E64B047E42371" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_InventoryCurrentTable_2D886BBBD0D4049052E864B047E4E6AB" xlink:to="loc_us-gaap_ValuationAllowancesAndReservesTypeAxis_9797E5429E07B93AE12E64B047E42371" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ValuationAllowancesAndReservesDomain" xlink:label="loc_us-gaap_ValuationAllowancesAndReservesDomain_EE354161373E1A6BA2C764B047E44E5C" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ValuationAllowancesAndReservesTypeAxis_9797E5429E07B93AE12E64B047E42371" xlink:to="loc_us-gaap_ValuationAllowancesAndReservesDomain_EE354161373E1A6BA2C764B047E44E5C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_InventoryValuationReserveMember" xlink:label="loc_us-gaap_InventoryValuationReserveMember_79C68D0CF1DB72380D4564B047E4EFB4" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ValuationAllowancesAndReservesDomain_EE354161373E1A6BA2C764B047E44E5C" xlink:to="loc_us-gaap_InventoryValuationReserveMember_79C68D0CF1DB72380D4564B047E4EFB4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_InventoryLineItems" xlink:label="loc_us-gaap_InventoryLineItems_BC4041E5376EAA8A9F3564B047E43DA0" xlink:type="locator" />
    <link:presentationArc order="3" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_InventoryCurrentTable_2D886BBBD0D4049052E864B047E4E6AB" xlink:to="loc_us-gaap_InventoryLineItems_BC4041E5376EAA8A9F3564B047E43DA0" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_InventoryReserveLengthofTimeofInventoryUsageConsidered" xlink:label="loc_oesx_InventoryReserveLengthofTimeofInventoryUsageConsidered_1877DE27F8D7B6C7FA4264B047E4EE47" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_InventoryLineItems_BC4041E5376EAA8A9F3564B047E43DA0" xlink:to="loc_oesx_InventoryReserveLengthofTimeofInventoryUsageConsidered_1877DE27F8D7B6C7FA4264B047E4EE47" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_InventoryRawMaterialsAndSupplies" xlink:label="loc_us-gaap_InventoryRawMaterialsAndSupplies_D0EBF3D6FC92A362F2B864B047E4B3C9" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_InventoryLineItems_BC4041E5376EAA8A9F3564B047E43DA0" xlink:to="loc_us-gaap_InventoryRawMaterialsAndSupplies_D0EBF3D6FC92A362F2B864B047E4B3C9" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_InventoryRawMaterialsandSuppliesValuationReserves" xlink:label="loc_oesx_InventoryRawMaterialsandSuppliesValuationReserves_17F55A479D04F7A2F6B264B047E4C5D2" xlink:type="locator" />
    <link:presentationArc order="3" preferredLabel="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_InventoryLineItems_BC4041E5376EAA8A9F3564B047E43DA0" xlink:to="loc_oesx_InventoryRawMaterialsandSuppliesValuationReserves_17F55A479D04F7A2F6B264B047E4C5D2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_InventoryRawMaterialsAndSuppliesNetOfReserves" xlink:label="loc_us-gaap_InventoryRawMaterialsAndSuppliesNetOfReserves_5F0DD3009340DC4901EB64B047E49B16" xlink:type="locator" />
    <link:presentationArc order="4" preferredLabel="http://www.xbrl.org/2003/role/totalLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_InventoryLineItems_BC4041E5376EAA8A9F3564B047E43DA0" xlink:to="loc_us-gaap_InventoryRawMaterialsAndSuppliesNetOfReserves_5F0DD3009340DC4901EB64B047E49B16" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_InventoryWorkInProcess" xlink:label="loc_us-gaap_InventoryWorkInProcess_052DA13DB0EF090CA8AB64B047E49763" xlink:type="locator" />
    <link:presentationArc order="5" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_InventoryLineItems_BC4041E5376EAA8A9F3564B047E43DA0" xlink:to="loc_us-gaap_InventoryWorkInProcess_052DA13DB0EF090CA8AB64B047E49763" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_InventoryWorkinProcessValuationReserves" xlink:label="loc_oesx_InventoryWorkinProcessValuationReserves_FA8189F66C50B7B6893F64B047E44A2D" xlink:type="locator" />
    <link:presentationArc order="6" preferredLabel="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_InventoryLineItems_BC4041E5376EAA8A9F3564B047E43DA0" xlink:to="loc_oesx_InventoryWorkinProcessValuationReserves_FA8189F66C50B7B6893F64B047E44A2D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_InventoryWorkInProcessNetOfReserves" xlink:label="loc_us-gaap_InventoryWorkInProcessNetOfReserves_67E653E5BB5D7A30B2E564B047E5A4F5" xlink:type="locator" />
    <link:presentationArc order="7" preferredLabel="http://www.xbrl.org/2003/role/totalLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_InventoryLineItems_BC4041E5376EAA8A9F3564B047E43DA0" xlink:to="loc_us-gaap_InventoryWorkInProcessNetOfReserves_67E653E5BB5D7A30B2E564B047E5A4F5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_InventoryFinishedGoods" xlink:label="loc_us-gaap_InventoryFinishedGoods_671BCD1FF35D9450A62564B047E55E24" xlink:type="locator" />
    <link:presentationArc order="8" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_InventoryLineItems_BC4041E5376EAA8A9F3564B047E43DA0" xlink:to="loc_us-gaap_InventoryFinishedGoods_671BCD1FF35D9450A62564B047E55E24" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_InventoryFinishedGoodsValuationReserves" xlink:label="loc_oesx_InventoryFinishedGoodsValuationReserves_31E51FED1412DCA31EC664B047E5600A" xlink:type="locator" />
    <link:presentationArc order="9" preferredLabel="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_InventoryLineItems_BC4041E5376EAA8A9F3564B047E43DA0" xlink:to="loc_oesx_InventoryFinishedGoodsValuationReserves_31E51FED1412DCA31EC664B047E5600A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_InventoryFinishedGoodsNetOfReserves" xlink:label="loc_us-gaap_InventoryFinishedGoodsNetOfReserves_2D226F7F0D17E073AC4164B047E517E1" xlink:type="locator" />
    <link:presentationArc order="10" preferredLabel="http://www.xbrl.org/2003/role/totalLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_InventoryLineItems_BC4041E5376EAA8A9F3564B047E43DA0" xlink:to="loc_us-gaap_InventoryFinishedGoodsNetOfReserves_2D226F7F0D17E073AC4164B047E517E1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_InventoryGross" xlink:label="loc_us-gaap_InventoryGross_C3A012552FD7327B28A064B047E5DB28" xlink:type="locator" />
    <link:presentationArc order="11" preferredLabel="http://www.xbrl.org/2003/role/totalLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_InventoryLineItems_BC4041E5376EAA8A9F3564B047E43DA0" xlink:to="loc_us-gaap_InventoryGross_C3A012552FD7327B28A064B047E5DB28" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_InventoryValuationReserves" xlink:label="loc_us-gaap_InventoryValuationReserves_2EB9AE0F44CE0934703964B047E55EA6" xlink:type="locator" />
    <link:presentationArc order="12" preferredLabel="http://www.xbrl.org/2009/role/negatedTotalLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_InventoryLineItems_BC4041E5376EAA8A9F3564B047E43DA0" xlink:to="loc_us-gaap_InventoryValuationReserves_2EB9AE0F44CE0934703964B047E55EA6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_InventoryNet" xlink:label="loc_us-gaap_InventoryNet_416D27CB5A54BE3F545164B047E5B210" xlink:type="locator" />
    <link:presentationArc order="13" preferredLabel="http://www.xbrl.org/2003/role/totalLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_InventoryLineItems_BC4041E5376EAA8A9F3564B047E43DA0" xlink:to="loc_us-gaap_InventoryNet_416D27CB5A54BE3F545164B047E5B210" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ValuationAllowancesAndReservesPeriodIncreaseDecrease" xlink:label="loc_us-gaap_ValuationAllowancesAndReservesPeriodIncreaseDecrease_5E10212C40AF19F7D98864B047E58AC3" xlink:type="locator" />
    <link:presentationArc order="14" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_InventoryLineItems_BC4041E5376EAA8A9F3564B047E43DA0" xlink:to="loc_us-gaap_ValuationAllowancesAndReservesPeriodIncreaseDecrease_5E10212C40AF19F7D98864B047E58AC3" xlink:type="arc" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.oesx.com/role/InventoriesTables" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_InventoryDisclosureAbstract" xlink:label="loc_us-gaap_InventoryDisclosureAbstract_FA096FB3D54D209C36B2F865CFF27BEC" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScheduleOfInventoryCurrentTableTextBlock" xlink:label="loc_us-gaap_ScheduleOfInventoryCurrentTableTextBlock_17C7ABE8785F00608C80F8679E8B9AD8" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_InventoryDisclosureAbstract_FA096FB3D54D209C36B2F865CFF27BEC" xlink:to="loc_us-gaap_ScheduleOfInventoryCurrentTableTextBlock_17C7ABE8785F00608C80F8679E8B9AD8" xlink:type="arc" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.oesx.com/role/LongTermDebt" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DebtDisclosureAbstract" xlink:label="loc_us-gaap_DebtDisclosureAbstract_D8BE5B4F50827DEFB3CE0DBF9AFFD35F" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LongTermDebtTextBlock" xlink:label="loc_us-gaap_LongTermDebtTextBlock_737D96A78EE433F099B50DBF9AFFBCFA" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DebtDisclosureAbstract_D8BE5B4F50827DEFB3CE0DBF9AFFD35F" xlink:to="loc_us-gaap_LongTermDebtTextBlock_737D96A78EE433F099B50DBF9AFFBCFA" xlink:type="arc" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.oesx.com/role/LongTermDebtAggregateMaturitiesDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DebtDisclosureAbstract" xlink:label="loc_us-gaap_DebtDisclosureAbstract_9EB0CDF48FA624A32E5EFCCAD27F4532" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonths" xlink:label="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonths_7766F18A699B888316EEFCCAD27F74FA" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DebtDisclosureAbstract_9EB0CDF48FA624A32E5EFCCAD27F4532" xlink:to="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonths_7766F18A699B888316EEFCCAD27F74FA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo" xlink:label="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo_0602E313F1A174F71C3AFCCAD27F1802" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DebtDisclosureAbstract_9EB0CDF48FA624A32E5EFCCAD27F4532" xlink:to="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo_0602E313F1A174F71C3AFCCAD27F1802" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree" xlink:label="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree_1C922AB0AB42E236755CFCCAD27FE8E4" xlink:type="locator" />
    <link:presentationArc order="3" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DebtDisclosureAbstract_9EB0CDF48FA624A32E5EFCCAD27F4532" xlink:to="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree_1C922AB0AB42E236755CFCCAD27FE8E4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour" xlink:label="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour_CC5955795567A5DF5068FCCAD27FEF48" xlink:type="locator" />
    <link:presentationArc order="4" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DebtDisclosureAbstract_9EB0CDF48FA624A32E5EFCCAD27F4532" xlink:to="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour_CC5955795567A5DF5068FCCAD27FEF48" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFive" xlink:label="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFive_419122B695ECBE8FFB28FCCAD27F86E0" xlink:type="locator" />
    <link:presentationArc order="5" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DebtDisclosureAbstract_9EB0CDF48FA624A32E5EFCCAD27F4532" xlink:to="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFive_419122B695ECBE8FFB28FCCAD27F86E0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalAfterYearFive" xlink:label="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalAfterYearFive_79D6FABEBC49D5F6ABABFCCAD2801421" xlink:type="locator" />
    <link:presentationArc order="6" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DebtDisclosureAbstract_9EB0CDF48FA624A32E5EFCCAD27F4532" xlink:to="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalAfterYearFive_79D6FABEBC49D5F6ABABFCCAD2801421" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LongTermDebt" xlink:label="loc_us-gaap_LongTermDebt_68B7FB150FDBBEDF2A41FCCAD28038BA" xlink:type="locator" />
    <link:presentationArc order="7" preferredLabel="http://www.xbrl.org/2003/role/totalLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DebtDisclosureAbstract_9EB0CDF48FA624A32E5EFCCAD27F4532" xlink:to="loc_us-gaap_LongTermDebt_68B7FB150FDBBEDF2A41FCCAD28038BA" xlink:type="arc" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.oesx.com/role/LongTermDebtAllOtherDebtDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DebtDisclosureAbstract" xlink:label="loc_us-gaap_DebtDisclosureAbstract_A36FA8E2A3B53A934C6A648C5D3A6939" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DebtInstrumentTable" xlink:label="loc_us-gaap_DebtInstrumentTable_614A761AD67F79EF415A648C5D3A0F7D" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DebtDisclosureAbstract_A36FA8E2A3B53A934C6A648C5D3A6939" xlink:to="loc_us-gaap_DebtInstrumentTable_614A761AD67F79EF415A648C5D3A0F7D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LongtermDebtTypeAxis" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_0ED67C686F0C3286D3F1648C5D3ABE4E" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DebtInstrumentTable_614A761AD67F79EF415A648C5D3A0F7D" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_0ED67C686F0C3286D3F1648C5D3ABE4E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_BD8EE25056175C10E5E4648C5D3AC611" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_0ED67C686F0C3286D3F1648C5D3ABE4E" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_BD8EE25056175C10E5E4648C5D3AC611" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_HarrisSellersNoteMember" xlink:label="loc_oesx_HarrisSellersNoteMember_BB4629E3F62DF7169B70648C5D3A6D7F" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_BD8EE25056175C10E5E4648C5D3AC611" xlink:to="loc_oesx_HarrisSellersNoteMember_BB4629E3F62DF7169B70648C5D3A6D7F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SecuredDebtMember" xlink:label="loc_us-gaap_SecuredDebtMember_DEA267393B5B6E5A6926648C5D3A4A3D" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_BD8EE25056175C10E5E4648C5D3AC611" xlink:to="loc_us-gaap_SecuredDebtMember_DEA267393B5B6E5A6926648C5D3A4A3D" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_June2011OtaFinanceProgramMember" xlink:label="loc_oesx_June2011OtaFinanceProgramMember_8965113D18DEC31329A4648C5D3A2E46" xlink:type="locator" />
    <link:presentationArc order="3" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_BD8EE25056175C10E5E4648C5D3AC611" xlink:to="loc_oesx_June2011OtaFinanceProgramMember_8965113D18DEC31329A4648C5D3A2E46" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_AgreementWithWisconsinDepartmentOfCommerceMember" xlink:label="loc_oesx_AgreementWithWisconsinDepartmentOfCommerceMember_E664768F5C6501E04ED6648C5D3AFF0D" xlink:type="locator" />
    <link:presentationArc order="4" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_BD8EE25056175C10E5E4648C5D3AC611" xlink:to="loc_oesx_AgreementWithWisconsinDepartmentOfCommerceMember_E664768F5C6501E04ED6648C5D3AFF0D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ExtinguishmentOfDebtAxis" xlink:label="loc_us-gaap_ExtinguishmentOfDebtAxis_3D0EE8CCB04239D25269648C5D3A703D" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DebtInstrumentTable_614A761AD67F79EF415A648C5D3A0F7D" xlink:to="loc_us-gaap_ExtinguishmentOfDebtAxis_3D0EE8CCB04239D25269648C5D3A703D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ExtinguishmentOfDebtTypeDomain" xlink:label="loc_us-gaap_ExtinguishmentOfDebtTypeDomain_415CAB9AA9D9ADB93B8E648C5D3A9118" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ExtinguishmentOfDebtAxis_3D0EE8CCB04239D25269648C5D3A703D" xlink:to="loc_us-gaap_ExtinguishmentOfDebtTypeDomain_415CAB9AA9D9ADB93B8E648C5D3A9118" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CapitalLeaseObligationsMember" xlink:label="loc_us-gaap_CapitalLeaseObligationsMember_E4E67E4B005BE7F52E77648C5D3A3203" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ExtinguishmentOfDebtTypeDomain_415CAB9AA9D9ADB93B8E648C5D3A9118" xlink:to="loc_us-gaap_CapitalLeaseObligationsMember_E4E67E4B005BE7F52E77648C5D3A3203" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DebtInstrumentAxis" xlink:label="loc_us-gaap_DebtInstrumentAxis_9A8025A7F7111020C24E648C5D3ADEF3" xlink:type="locator" />
    <link:presentationArc order="3" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DebtInstrumentTable_614A761AD67F79EF415A648C5D3A0F7D" xlink:to="loc_us-gaap_DebtInstrumentAxis_9A8025A7F7111020C24E648C5D3ADEF3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_6CFFFCF9842A83A66DF0648C5D3A169A" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DebtInstrumentAxis_9A8025A7F7111020C24E648C5D3ADEF3" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_6CFFFCF9842A83A66DF0648C5D3A169A" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_December2014OTAFinanceProgramMember" xlink:label="loc_oesx_December2014OTAFinanceProgramMember_F79867EE1A09B7314B65648C5D3AF754" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_6CFFFCF9842A83A66DF0648C5D3A169A" xlink:to="loc_oesx_December2014OTAFinanceProgramMember_F79867EE1A09B7314B65648C5D3AF754" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LineOfCreditFacilityAxis" xlink:label="loc_us-gaap_LineOfCreditFacilityAxis_76F7ACB7C6FE26D9C9F4648C5D3A718A" xlink:type="locator" />
    <link:presentationArc order="4" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DebtInstrumentTable_614A761AD67F79EF415A648C5D3A0F7D" xlink:to="loc_us-gaap_LineOfCreditFacilityAxis_76F7ACB7C6FE26D9C9F4648C5D3A718A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LineOfCreditFacilityLenderDomain" xlink:label="loc_us-gaap_LineOfCreditFacilityLenderDomain_3508CC2793F0637A209F648C5D3B8810" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LineOfCreditFacilityAxis_76F7ACB7C6FE26D9C9F4648C5D3A718A" xlink:to="loc_us-gaap_LineOfCreditFacilityLenderDomain_3508CC2793F0637A209F648C5D3B8810" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_DeLageLandenFinancialServicesInc.Member" xlink:label="loc_oesx_DeLageLandenFinancialServicesInc.Member_4FF1A22046F0C04CF727648C5D3BAC56" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LineOfCreditFacilityLenderDomain_3508CC2793F0637A209F648C5D3B8810" xlink:to="loc_oesx_DeLageLandenFinancialServicesInc.Member_4FF1A22046F0C04CF727648C5D3BAC56" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DebtInstrumentLineItems" xlink:label="loc_us-gaap_DebtInstrumentLineItems_1BFE0685728684C274C7648C5D3BEF82" xlink:type="locator" />
    <link:presentationArc order="5" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DebtInstrumentTable_614A761AD67F79EF415A648C5D3A0F7D" xlink:to="loc_us-gaap_DebtInstrumentLineItems_1BFE0685728684C274C7648C5D3BEF82" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DebtInstrumentFaceAmount" xlink:label="loc_us-gaap_DebtInstrumentFaceAmount_A3CD9BB56C78DA27DA70648C5D3B0163" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DebtInstrumentLineItems_1BFE0685728684C274C7648C5D3BEF82" xlink:to="loc_us-gaap_DebtInstrumentFaceAmount_A3CD9BB56C78DA27DA70648C5D3B0163" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_27DCDB5671989AC6BC5C648C5D3BAB60" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DebtInstrumentLineItems_1BFE0685728684C274C7648C5D3BEF82" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_27DCDB5671989AC6BC5C648C5D3BAB60" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DebtInstrumentCarryingAmount" xlink:label="loc_us-gaap_DebtInstrumentCarryingAmount_DFFC9DCB0E78297453AF648C5D3BB4FD" xlink:type="locator" />
    <link:presentationArc order="3" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DebtInstrumentLineItems_1BFE0685728684C274C7648C5D3BEF82" xlink:to="loc_us-gaap_DebtInstrumentCarryingAmount_DFFC9DCB0E78297453AF648C5D3BB4FD" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_DebtInstrumentBuyoutOption" xlink:label="loc_oesx_DebtInstrumentBuyoutOption_81DB0D48C7D1D4282AFA648C5D3B42BE" xlink:type="locator" />
    <link:presentationArc order="4" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DebtInstrumentLineItems_1BFE0685728684C274C7648C5D3BEF82" xlink:to="loc_oesx_DebtInstrumentBuyoutOption_81DB0D48C7D1D4282AFA648C5D3B42BE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SecuredDebt" xlink:label="loc_us-gaap_SecuredDebt_E4F761C91961FC59609E648C5D3B0615" xlink:type="locator" />
    <link:presentationArc order="5" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DebtInstrumentLineItems_1BFE0685728684C274C7648C5D3BEF82" xlink:to="loc_us-gaap_SecuredDebt_E4F761C91961FC59609E648C5D3B0615" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_DebtInstrumentNumberOfContractsForCollateral" xlink:label="loc_oesx_DebtInstrumentNumberOfContractsForCollateral_F8B7E04A149C61B185B6648C5D3B4E83" xlink:type="locator" />
    <link:presentationArc order="6" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DebtInstrumentLineItems_1BFE0685728684C274C7648C5D3BEF82" xlink:to="loc_oesx_DebtInstrumentNumberOfContractsForCollateral_F8B7E04A149C61B185B6648C5D3B4E83" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_NumberOfSupportingIndividualOtaCustomerContracts" xlink:label="loc_oesx_NumberOfSupportingIndividualOtaCustomerContracts_7230152DA919D07A4E31648C5D3B3203" xlink:type="locator" />
    <link:presentationArc order="7" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DebtInstrumentLineItems_1BFE0685728684C274C7648C5D3BEF82" xlink:to="loc_oesx_NumberOfSupportingIndividualOtaCustomerContracts_7230152DA919D07A4E31648C5D3B3203" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_PeriodOfTimeWithoutInterestAccruingOrPrincipalPaymentsDue" xlink:label="loc_oesx_PeriodOfTimeWithoutInterestAccruingOrPrincipalPaymentsDue_DEE9D1512997DA35D85D648C5D3BC736" xlink:type="locator" />
    <link:presentationArc order="8" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DebtInstrumentLineItems_1BFE0685728684C274C7648C5D3BEF82" xlink:to="loc_oesx_PeriodOfTimeWithoutInterestAccruingOrPrincipalPaymentsDue_DEE9D1512997DA35D85D648C5D3BC736" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DebtInstrumentPeriodicPayment" xlink:label="loc_us-gaap_DebtInstrumentPeriodicPayment_5E8A13A37DE6B0FE3A54648C5D3B9BC1" xlink:type="locator" />
    <link:presentationArc order="9" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DebtInstrumentLineItems_1BFE0685728684C274C7648C5D3BEF82" xlink:to="loc_us-gaap_DebtInstrumentPeriodicPayment_5E8A13A37DE6B0FE3A54648C5D3B9BC1" xlink:type="arc" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.oesx.com/role/LongTermDebtRevolvingCreditFacilityDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DebtDisclosureAbstract" xlink:label="loc_us-gaap_DebtDisclosureAbstract_4091CD34CDD9560D585364B04773F177" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LineOfCreditFacilityTable" xlink:label="loc_us-gaap_LineOfCreditFacilityTable_9E171FDC373D104A203664B04773442B" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DebtDisclosureAbstract_4091CD34CDD9560D585364B04773F177" xlink:to="loc_us-gaap_LineOfCreditFacilityTable_9E171FDC373D104A203664B04773442B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LineOfCreditFacilityAxis" xlink:label="loc_us-gaap_LineOfCreditFacilityAxis_BF5B1D61BC9DAC3494A664B04773132F" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LineOfCreditFacilityTable_9E171FDC373D104A203664B04773442B" xlink:to="loc_us-gaap_LineOfCreditFacilityAxis_BF5B1D61BC9DAC3494A664B04773132F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LineOfCreditFacilityLenderDomain" xlink:label="loc_us-gaap_LineOfCreditFacilityLenderDomain_0E908916B6CD038CDD4F64B04773B315" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LineOfCreditFacilityAxis_BF5B1D61BC9DAC3494A664B04773132F" xlink:to="loc_us-gaap_LineOfCreditFacilityLenderDomain_0E908916B6CD038CDD4F64B04773B315" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_WellsFargoBankNationalAssociationMember" xlink:label="loc_oesx_WellsFargoBankNationalAssociationMember_FDE26620097636EAA9B664B04773DA1A" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LineOfCreditFacilityLenderDomain_0E908916B6CD038CDD4F64B04773B315" xlink:to="loc_oesx_WellsFargoBankNationalAssociationMember_FDE26620097636EAA9B664B04773DA1A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DebtInstrumentAxis" xlink:label="loc_us-gaap_DebtInstrumentAxis_99CD11F499A2A472D3C564B0477361CA" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LineOfCreditFacilityTable_9E171FDC373D104A203664B04773442B" xlink:to="loc_us-gaap_DebtInstrumentAxis_99CD11F499A2A472D3C564B0477361CA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_5725FCCA357A6E18F1E264B04773BB45" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DebtInstrumentAxis_99CD11F499A2A472D3C564B0477361CA" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_5725FCCA357A6E18F1E264B04773BB45" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_CreditAgreementMember" xlink:label="loc_oesx_CreditAgreementMember_A7BA7FB1DDBBBCFE88AB64B047747EA3" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_5725FCCA357A6E18F1E264B04773BB45" xlink:to="loc_oesx_CreditAgreementMember_A7BA7FB1DDBBBCFE88AB64B047747EA3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CreditFacilityAxis" xlink:label="loc_us-gaap_CreditFacilityAxis_684CB8101A4F54B2622664B04774458A" xlink:type="locator" />
    <link:presentationArc order="3" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LineOfCreditFacilityTable_9E171FDC373D104A203664B04773442B" xlink:to="loc_us-gaap_CreditFacilityAxis_684CB8101A4F54B2622664B04774458A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CreditFacilityDomain" xlink:label="loc_us-gaap_CreditFacilityDomain_0740CF15BAE4876F12C964B04774F4D0" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_CreditFacilityAxis_684CB8101A4F54B2622664B04774458A" xlink:to="loc_us-gaap_CreditFacilityDomain_0740CF15BAE4876F12C964B04774F4D0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RevolvingCreditFacilityMember" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_5F607D5C90231B0EB26964B04774954B" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_CreditFacilityDomain_0740CF15BAE4876F12C964B04774F4D0" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_5F607D5C90231B0EB26964B04774954B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LetterOfCreditMember" xlink:label="loc_us-gaap_LetterOfCreditMember_04631415CB9FA03DE55064B04774BA1E" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_CreditFacilityDomain_0740CF15BAE4876F12C964B04774F4D0" xlink:to="loc_us-gaap_LetterOfCreditMember_04631415CB9FA03DE55064B04774BA1E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_VariableRateAxis" xlink:label="loc_us-gaap_VariableRateAxis_B22CF5C35A8A408D6A6364B047745E52" xlink:type="locator" />
    <link:presentationArc order="4" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LineOfCreditFacilityTable_9E171FDC373D104A203664B04773442B" xlink:to="loc_us-gaap_VariableRateAxis_B22CF5C35A8A408D6A6364B047745E52" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_VariableRateDomain" xlink:label="loc_us-gaap_VariableRateDomain_EB8401EB98A8F562AC3864B047746C4F" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_VariableRateAxis_B22CF5C35A8A408D6A6364B047745E52" xlink:to="loc_us-gaap_VariableRateDomain_EB8401EB98A8F562AC3864B047746C4F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LondonInterbankOfferedRateLIBORMember" xlink:label="loc_us-gaap_LondonInterbankOfferedRateLIBORMember_B6E60C2D6E02E1CD437664B04774088D" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_VariableRateDomain_EB8401EB98A8F562AC3864B047746C4F" xlink:to="loc_us-gaap_LondonInterbankOfferedRateLIBORMember_B6E60C2D6E02E1CD437664B04774088D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LineOfCreditFacilityLineItems" xlink:label="loc_us-gaap_LineOfCreditFacilityLineItems_77AE016450D1A661A49464B04774B0AC" xlink:type="locator" />
    <link:presentationArc order="5" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LineOfCreditFacilityTable_9E171FDC373D104A203664B04773442B" xlink:to="loc_us-gaap_LineOfCreditFacilityLineItems_77AE016450D1A661A49464B04774B0AC" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_DebtTextualAbstract" xlink:label="loc_oesx_DebtTextualAbstract_359E2AA1343453889FCF64B0477451EB" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_77AE016450D1A661A49464B04774B0AC" xlink:to="loc_oesx_DebtTextualAbstract_359E2AA1343453889FCF64B0477451EB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LineOfCreditFacilityCurrentBorrowingCapacity" xlink:label="loc_us-gaap_LineOfCreditFacilityCurrentBorrowingCapacity_2A3B928BDF69C4678BAB64B04774A274" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_oesx_DebtTextualAbstract_359E2AA1343453889FCF64B0477451EB" xlink:to="loc_us-gaap_LineOfCreditFacilityCurrentBorrowingCapacity_2A3B928BDF69C4678BAB64B04774A274" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity" xlink:label="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_65BC926566E49ED5E72564B04774141A" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_oesx_DebtTextualAbstract_359E2AA1343453889FCF64B0477451EB" xlink:to="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_65BC926566E49ED5E72564B04774141A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LettersOfCreditOutstandingAmount" xlink:label="loc_us-gaap_LettersOfCreditOutstandingAmount_4ECD8D7CD48E05C8702764B04774EAEE" xlink:type="locator" />
    <link:presentationArc order="3" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_oesx_DebtTextualAbstract_359E2AA1343453889FCF64B0477451EB" xlink:to="loc_us-gaap_LettersOfCreditOutstandingAmount_4ECD8D7CD48E05C8702764B04774EAEE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LongTermLineOfCredit" xlink:label="loc_us-gaap_LongTermLineOfCredit_153E9DF442FD7CA510BD64B04774AEB9" xlink:type="locator" />
    <link:presentationArc order="4" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_oesx_DebtTextualAbstract_359E2AA1343453889FCF64B0477451EB" xlink:to="loc_us-gaap_LongTermLineOfCredit_153E9DF442FD7CA510BD64B04774AEB9" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_LineofCreditFacilityAdditionalBorrowingCapacity" xlink:label="loc_oesx_LineofCreditFacilityAdditionalBorrowingCapacity_291C13B2C135CEDCCDAC64B047747F43" xlink:type="locator" />
    <link:presentationArc order="5" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_oesx_DebtTextualAbstract_359E2AA1343453889FCF64B0477451EB" xlink:to="loc_oesx_LineofCreditFacilityAdditionalBorrowingCapacity_291C13B2C135CEDCCDAC64B047747F43" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_LineOfCreditFacilityPotentialMaximumBorrowingCapacity" xlink:label="loc_oesx_LineOfCreditFacilityPotentialMaximumBorrowingCapacity_A04D44CF47D0AA20892D64B04774455A" xlink:type="locator" />
    <link:presentationArc order="6" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_oesx_DebtTextualAbstract_359E2AA1343453889FCF64B0477451EB" xlink:to="loc_oesx_LineOfCreditFacilityPotentialMaximumBorrowingCapacity_A04D44CF47D0AA20892D64B04774455A" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_LineofCreditFacilityCovenantTermsMinimumIndebtednessRatio" xlink:label="loc_oesx_LineofCreditFacilityCovenantTermsMinimumIndebtednessRatio_17EAB023C09BACD7813664B04774BD60" xlink:type="locator" />
    <link:presentationArc order="7" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_oesx_DebtTextualAbstract_359E2AA1343453889FCF64B0477451EB" xlink:to="loc_oesx_LineofCreditFacilityCovenantTermsMinimumIndebtednessRatio_17EAB023C09BACD7813664B04774BD60" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DebtInstrumentBasisSpreadOnVariableRate1" xlink:label="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_FA5B7C2E01B8F8E00DAB64B0477402A9" xlink:type="locator" />
    <link:presentationArc order="8" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_oesx_DebtTextualAbstract_359E2AA1343453889FCF64B0477451EB" xlink:to="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_FA5B7C2E01B8F8E00DAB64B0477402A9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DebtInstrumentPeriodicPaymentInterest" xlink:label="loc_us-gaap_DebtInstrumentPeriodicPaymentInterest_BBA66CB277E769CA838464B04775C7F1" xlink:type="locator" />
    <link:presentationArc order="9" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_oesx_DebtTextualAbstract_359E2AA1343453889FCF64B0477451EB" xlink:to="loc_us-gaap_DebtInstrumentPeriodicPaymentInterest_BBA66CB277E769CA838464B04775C7F1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DebtInstrumentInterestRateEffectivePercentage" xlink:label="loc_us-gaap_DebtInstrumentInterestRateEffectivePercentage_A802EDFDE30CB2BEF1DE64B04775A811" xlink:type="locator" />
    <link:presentationArc order="10" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_oesx_DebtTextualAbstract_359E2AA1343453889FCF64B0477451EB" xlink:to="loc_us-gaap_DebtInstrumentInterestRateEffectivePercentage_A802EDFDE30CB2BEF1DE64B04775A811" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage" xlink:label="loc_us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage_E38C6659277B06114F9164B04775F35A" xlink:type="locator" />
    <link:presentationArc order="11" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_oesx_DebtTextualAbstract_359E2AA1343453889FCF64B0477451EB" xlink:to="loc_us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage_E38C6659277B06114F9164B04775F35A" xlink:type="arc" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.oesx.com/role/LongTermDebtSummaryOfDebtDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DebtDisclosureAbstract" xlink:label="loc_us-gaap_DebtDisclosureAbstract_D41E9ABBC3C8097A46F317352D065055" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScheduleOfExtinguishmentOfDebtTable" xlink:label="loc_us-gaap_ScheduleOfExtinguishmentOfDebtTable_02982102570D9489EB8717352D061270" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DebtDisclosureAbstract_D41E9ABBC3C8097A46F317352D065055" xlink:to="loc_us-gaap_ScheduleOfExtinguishmentOfDebtTable_02982102570D9489EB8717352D061270" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ExtinguishmentOfDebtAxis" xlink:label="loc_us-gaap_ExtinguishmentOfDebtAxis_F6F9E8C808526C86B52A17352D06FB57" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfExtinguishmentOfDebtTable_02982102570D9489EB8717352D061270" xlink:to="loc_us-gaap_ExtinguishmentOfDebtAxis_F6F9E8C808526C86B52A17352D06FB57" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ExtinguishmentOfDebtTypeDomain" xlink:label="loc_us-gaap_ExtinguishmentOfDebtTypeDomain_43C1CD0D1A363E0A0F2717352D069BAA" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ExtinguishmentOfDebtAxis_F6F9E8C808526C86B52A17352D06FB57" xlink:to="loc_us-gaap_ExtinguishmentOfDebtTypeDomain_43C1CD0D1A363E0A0F2717352D069BAA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RevolvingCreditFacilityMember" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_30319B12B4F515FE680F17352D071F53" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ExtinguishmentOfDebtTypeDomain_43C1CD0D1A363E0A0F2717352D069BAA" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_30319B12B4F515FE680F17352D071F53" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_HarrisSellersNoteMember" xlink:label="loc_oesx_HarrisSellersNoteMember_E52A65966EBB0FEE030B17352D072E92" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ExtinguishmentOfDebtTypeDomain_43C1CD0D1A363E0A0F2717352D069BAA" xlink:to="loc_oesx_HarrisSellersNoteMember_E52A65966EBB0FEE030B17352D072E92" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CapitalLeaseObligationsMember" xlink:label="loc_us-gaap_CapitalLeaseObligationsMember_D13ABD0BD9C946FE58DC17352D07FFE9" xlink:type="locator" />
    <link:presentationArc order="3" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ExtinguishmentOfDebtTypeDomain_43C1CD0D1A363E0A0F2717352D069BAA" xlink:to="loc_us-gaap_CapitalLeaseObligationsMember_D13ABD0BD9C946FE58DC17352D07FFE9" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_CustomerEquipmentFinanceNotesPayableMember" xlink:label="loc_oesx_CustomerEquipmentFinanceNotesPayableMember_BCB783130652EA2CCF7E17352D073A64" xlink:type="locator" />
    <link:presentationArc order="4" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ExtinguishmentOfDebtTypeDomain_43C1CD0D1A363E0A0F2717352D069BAA" xlink:to="loc_oesx_CustomerEquipmentFinanceNotesPayableMember_BCB783130652EA2CCF7E17352D073A64" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_OtherLongTermDebtMember" xlink:label="loc_oesx_OtherLongTermDebtMember_8C19652CC70D3F3AC28817352D074F8C" xlink:type="locator" />
    <link:presentationArc order="5" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ExtinguishmentOfDebtTypeDomain_43C1CD0D1A363E0A0F2717352D069BAA" xlink:to="loc_oesx_OtherLongTermDebtMember_8C19652CC70D3F3AC28817352D074F8C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ExtinguishmentOfDebtLineItems" xlink:label="loc_us-gaap_ExtinguishmentOfDebtLineItems_74348BFCB3DB74E0CDC017352D07C83C" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfExtinguishmentOfDebtTable_02982102570D9489EB8717352D061270" xlink:to="loc_us-gaap_ExtinguishmentOfDebtLineItems_74348BFCB3DB74E0CDC017352D07C83C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LongTermDebtByCurrentAndNoncurrentAbstract" xlink:label="loc_us-gaap_LongTermDebtByCurrentAndNoncurrentAbstract_7E7BAA19DE614425226917352D07A493" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ExtinguishmentOfDebtLineItems_74348BFCB3DB74E0CDC017352D07C83C" xlink:to="loc_us-gaap_LongTermDebtByCurrentAndNoncurrentAbstract_7E7BAA19DE614425226917352D07A493" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LongTermDebt" xlink:label="loc_us-gaap_LongTermDebt_F176672258874D23716817352D082657" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/totalLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LongTermDebtByCurrentAndNoncurrentAbstract_7E7BAA19DE614425226917352D07A493" xlink:to="loc_us-gaap_LongTermDebt_F176672258874D23716817352D082657" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LongTermDebtCurrent" xlink:label="loc_us-gaap_LongTermDebtCurrent_F346EAD950589EE338D017352D086A41" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LongTermDebtByCurrentAndNoncurrentAbstract_7E7BAA19DE614425226917352D07A493" xlink:to="loc_us-gaap_LongTermDebtCurrent_F346EAD950589EE338D017352D086A41" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LongTermDebtNoncurrent" xlink:label="loc_us-gaap_LongTermDebtNoncurrent_F6CE171AF42DD128B57A17352D0892E3" xlink:type="locator" />
    <link:presentationArc order="3" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LongTermDebtByCurrentAndNoncurrentAbstract_7E7BAA19DE614425226917352D07A493" xlink:to="loc_us-gaap_LongTermDebtNoncurrent_F6CE171AF42DD128B57A17352D0892E3" xlink:type="arc" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.oesx.com/role/LongTermDebtTables" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DebtDisclosureAbstract" xlink:label="loc_us-gaap_DebtDisclosureAbstract_624E1355156ADCBD3C8C66E045B6BBF8" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScheduleOfDebtTableTextBlock" xlink:label="loc_us-gaap_ScheduleOfDebtTableTextBlock_A082AB47E3D1D08434C166E045B6C5A7" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DebtDisclosureAbstract_624E1355156ADCBD3C8C66E045B6BBF8" xlink:to="loc_us-gaap_ScheduleOfDebtTableTextBlock_A082AB47E3D1D08434C166E045B6C5A7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScheduleOfMaturitiesOfLongTermDebtTableTextBlock" xlink:label="loc_us-gaap_ScheduleOfMaturitiesOfLongTermDebtTableTextBlock_6922434EDF81ED78494266E045B61352" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DebtDisclosureAbstract_624E1355156ADCBD3C8C66E045B6BBF8" xlink:to="loc_us-gaap_ScheduleOfMaturitiesOfLongTermDebtTableTextBlock_6922434EDF81ED78494266E045B61352" xlink:type="arc" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.oesx.com/role/NetIncomeLossPerCommonShare" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_EarningsPerShareAbstract" xlink:label="loc_us-gaap_EarningsPerShareAbstract_64C865ABA24FEC86AB3C0DBF98411C39" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_EarningsPerShareTextBlock" xlink:label="loc_us-gaap_EarningsPerShareTextBlock_3448688D696D27E242AB0DBF98410A5F" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_EarningsPerShareAbstract_64C865ABA24FEC86AB3C0DBF98411C39" xlink:to="loc_us-gaap_EarningsPerShareTextBlock_3448688D696D27E242AB0DBF98410A5F" xlink:type="arc" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.oesx.com/role/NetIncomeLossPerCommonShareDilutiveSecuritiesDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_EarningsPerShareAbstract" xlink:label="loc_us-gaap_EarningsPerShareAbstract_7789DD40B9117AE414E3844B46D3854A" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable" xlink:label="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_8BF85C2A3BD2950624AC844B46D30173" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_EarningsPerShareAbstract_7789DD40B9117AE414E3844B46D3854A" xlink:to="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_8BF85C2A3BD2950624AC844B46D30173" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_4BAE478B9A40A28D6777844B46D3908B" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_8BF85C2A3BD2950624AC844B46D30173" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_4BAE478B9A40A28D6777844B46D3908B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AntidilutiveSecuritiesNameDomain" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_F00DA0CA3C8C7C4D9C79844B46D37EBF" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_4BAE478B9A40A28D6777844B46D3908B" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_F00DA0CA3C8C7C4D9C79844B46D37EBF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_EmployeeStockOptionMember" xlink:label="loc_us-gaap_EmployeeStockOptionMember_0E379AD11473F59B5E0A844B46D36E72" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_F00DA0CA3C8C7C4D9C79844B46D37EBF" xlink:to="loc_us-gaap_EmployeeStockOptionMember_0E379AD11473F59B5E0A844B46D36E72" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RestrictedStockMember" xlink:label="loc_us-gaap_RestrictedStockMember_B14C27D76EE904DF4933844B46D3BFDF" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_F00DA0CA3C8C7C4D9C79844B46D37EBF" xlink:to="loc_us-gaap_RestrictedStockMember_B14C27D76EE904DF4933844B46D3BFDF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_75B75240E0DC5BD03C1D844B46D31B14" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_8BF85C2A3BD2950624AC844B46D30173" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_75B75240E0DC5BD03C1D844B46D31B14" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_AntidilutiveSharesExcludedFromComputationOfEarningsPerShareAbstract" xlink:label="loc_oesx_AntidilutiveSharesExcludedFromComputationOfEarningsPerShareAbstract_625709BBC99BE03F3395844B46D3A18A" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_75B75240E0DC5BD03C1D844B46D31B14" xlink:to="loc_oesx_AntidilutiveSharesExcludedFromComputationOfEarningsPerShareAbstract_625709BBC99BE03F3395844B46D3A18A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_B705CFF40069863CA138844B46D3DB8B" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_oesx_AntidilutiveSharesExcludedFromComputationOfEarningsPerShareAbstract_625709BBC99BE03F3395844B46D3A18A" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_B705CFF40069863CA138844B46D3DB8B" xlink:type="arc" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.oesx.com/role/NetIncomeLossPerCommonShareEarningsPerShareDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_EarningsPerShareAbstract" xlink:label="loc_us-gaap_EarningsPerShareAbstract_94181685FAB5482C02EF7E804B71AA55" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_EarningsPerShareReconciliationAbstract" xlink:label="loc_us-gaap_EarningsPerShareReconciliationAbstract_53307C0C97BAF48FBE657E804B71508A" xlink:type="locator" />
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_EarningsPerShareAbstract_94181685FAB5482C02EF7E804B71AA55" xlink:to="loc_us-gaap_EarningsPerShareReconciliationAbstract_53307C0C97BAF48FBE657E804B71508A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_NetIncomeLoss" xlink:label="loc_us-gaap_NetIncomeLoss_56909121FF237D0714787E804B761EA8" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_EarningsPerShareReconciliationAbstract_53307C0C97BAF48FBE657E804B71508A" xlink:to="loc_us-gaap_NetIncomeLoss_56909121FF237D0714787E804B761EA8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_WeightedAverageNumberDilutedSharesOutstandingAdjustmentAbstract" xlink:label="loc_us-gaap_WeightedAverageNumberDilutedSharesOutstandingAdjustmentAbstract_9F2506B87CD6E55F30A27E804B760114" xlink:type="locator" />
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_EarningsPerShareAbstract_94181685FAB5482C02EF7E804B71AA55" xlink:to="loc_us-gaap_WeightedAverageNumberDilutedSharesOutstandingAdjustmentAbstract_9F2506B87CD6E55F30A27E804B760114" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingBasic" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_33C765E9A18253D17E337E804B7626F6" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_WeightedAverageNumberDilutedSharesOutstandingAdjustmentAbstract_9F2506B87CD6E55F30A27E804B760114" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_33C765E9A18253D17E337E804B7626F6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding" xlink:label="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_9CC536D34F1ECAE5FD027E804B779D43" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/totalLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_WeightedAverageNumberDilutedSharesOutstandingAdjustmentAbstract_9F2506B87CD6E55F30A27E804B760114" xlink:to="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_9CC536D34F1ECAE5FD027E804B779D43" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_EarningsPerShareBasicAndDilutedAbstract" xlink:label="loc_us-gaap_EarningsPerShareBasicAndDilutedAbstract_CDC74F9B964679AD06FC7E804B771DCB" xlink:type="locator" />
    <link:presentationArc order="3" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_EarningsPerShareAbstract_94181685FAB5482C02EF7E804B71AA55" xlink:to="loc_us-gaap_EarningsPerShareBasicAndDilutedAbstract_CDC74F9B964679AD06FC7E804B771DCB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_EarningsPerShareBasic" xlink:label="loc_us-gaap_EarningsPerShareBasic_CE4863AF36C2209298567E804B77FD90" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2009/role/netLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_EarningsPerShareBasicAndDilutedAbstract_CDC74F9B964679AD06FC7E804B771DCB" xlink:to="loc_us-gaap_EarningsPerShareBasic_CE4863AF36C2209298567E804B77FD90" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_EarningsPerShareDiluted" xlink:label="loc_us-gaap_EarningsPerShareDiluted_CFC67FD194AFF221003D7E804B772AEC" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2009/role/netLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_EarningsPerShareBasicAndDilutedAbstract_CDC74F9B964679AD06FC7E804B771DCB" xlink:to="loc_us-gaap_EarningsPerShareDiluted_CFC67FD194AFF221003D7E804B772AEC" xlink:type="arc" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.oesx.com/role/NetIncomeLossPerCommonShareTables" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_EarningsPerShareAbstract" xlink:label="loc_us-gaap_EarningsPerShareAbstract_8CD9E58FEB5EB2C3255CFDCD56CF19FB" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScheduleOfEarningsPerShareBasicAndDilutedTableTextBlock" xlink:label="loc_us-gaap_ScheduleOfEarningsPerShareBasicAndDilutedTableTextBlock_3B229C4BCFD3BF1CB655FDCF971283C3" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_EarningsPerShareAbstract_8CD9E58FEB5EB2C3255CFDCD56CF19FB" xlink:to="loc_us-gaap_ScheduleOfEarningsPerShareBasicAndDilutedTableTextBlock_3B229C4BCFD3BF1CB655FDCF971283C3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTextBlock" xlink:label="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTextBlock_693FFB2B8967FDC7E24CFDCF97172BC7" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_EarningsPerShareAbstract_8CD9E58FEB5EB2C3255CFDCD56CF19FB" xlink:to="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTextBlock_693FFB2B8967FDC7E24CFDCF97172BC7" xlink:type="arc" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.oesx.com/role/OtherLongTermAssets" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DeferredCostsCapitalizedPrepaidAndOtherAssetsDisclosureAbstract" xlink:label="loc_us-gaap_DeferredCostsCapitalizedPrepaidAndOtherAssetsDisclosureAbstract_F73EDE7AB4F0F2D86D850DBF2C87EAEA" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_OtherAssetsDisclosureTextBlock" xlink:label="loc_us-gaap_OtherAssetsDisclosureTextBlock_24328624182F81CC9B9B0DBF2C87F971" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DeferredCostsCapitalizedPrepaidAndOtherAssetsDisclosureAbstract_F73EDE7AB4F0F2D86D850DBF2C87EAEA" xlink:to="loc_us-gaap_OtherAssetsDisclosureTextBlock_24328624182F81CC9B9B0DBF2C87F971" xlink:type="arc" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.oesx.com/role/OtherLongTermAssetsNarrativeDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DeferredCostsCapitalizedPrepaidAndOtherAssetsDisclosureAbstract" xlink:label="loc_us-gaap_DeferredCostsCapitalizedPrepaidAndOtherAssetsDisclosureAbstract_AA71DD76FBB5F3500965FD764AEB3EC6" xlink:type="locator" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_DeferredFinancingCostsAmortizedOverUsefulLifeOfDebtIssueMinimum" xlink:label="loc_oesx_DeferredFinancingCostsAmortizedOverUsefulLifeOfDebtIssueMinimum_DA6798B88FC610449F5DFD764AEED6BE" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DeferredCostsCapitalizedPrepaidAndOtherAssetsDisclosureAbstract_AA71DD76FBB5F3500965FD764AEB3EC6" xlink:to="loc_oesx_DeferredFinancingCostsAmortizedOverUsefulLifeOfDebtIssueMinimum_DA6798B88FC610449F5DFD764AEED6BE" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_DeferredFinancingCostsAmortizedOverUsefulLifeOfDebtIssueMaximum" xlink:label="loc_oesx_DeferredFinancingCostsAmortizedOverUsefulLifeOfDebtIssueMaximum_05C95D8B35DE391F41D3FD764AEECC32" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DeferredCostsCapitalizedPrepaidAndOtherAssetsDisclosureAbstract_AA71DD76FBB5F3500965FD764AEB3EC6" xlink:to="loc_oesx_DeferredFinancingCostsAmortizedOverUsefulLifeOfDebtIssueMaximum_05C95D8B35DE391F41D3FD764AEECC32" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AmortizationOfFinancingCosts" xlink:label="loc_us-gaap_AmortizationOfFinancingCosts_61CBD2F8D1F3F549FF46FD764AEE40EA" xlink:type="locator" />
    <link:presentationArc order="3" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DeferredCostsCapitalizedPrepaidAndOtherAssetsDisclosureAbstract_AA71DD76FBB5F3500965FD764AEB3EC6" xlink:to="loc_us-gaap_AmortizationOfFinancingCosts_61CBD2F8D1F3F549FF46FD764AEE40EA" xlink:type="arc" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.oesx.com/role/OtherLongTermAssetsSummaryOfOtherLongTermAssetsDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DeferredCostsCapitalizedPrepaidAndOtherAssetsDisclosureAbstract" xlink:label="loc_us-gaap_DeferredCostsCapitalizedPrepaidAndOtherAssetsDisclosureAbstract_E83F79433D268862689F418FFE766C62" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DeferredFinanceCostsNoncurrentNet" xlink:label="loc_us-gaap_DeferredFinanceCostsNoncurrentNet_3FFBEA5E552B72221F6B418FFE76AE91" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DeferredCostsCapitalizedPrepaidAndOtherAssetsDisclosureAbstract_E83F79433D268862689F418FFE766C62" xlink:to="loc_us-gaap_DeferredFinanceCostsNoncurrentNet_3FFBEA5E552B72221F6B418FFE76AE91" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SecurityDeposit" xlink:label="loc_us-gaap_SecurityDeposit_746C3086C994F670CED4418FFE7736F3" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DeferredCostsCapitalizedPrepaidAndOtherAssetsDisclosureAbstract_E83F79433D268862689F418FFE766C62" xlink:to="loc_us-gaap_SecurityDeposit_746C3086C994F670CED4418FFE7736F3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_OtherAssetsMiscellaneousNoncurrent" xlink:label="loc_us-gaap_OtherAssetsMiscellaneousNoncurrent_3386B7CA835BF96C5649418FFE7784B7" xlink:type="locator" />
    <link:presentationArc order="3" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DeferredCostsCapitalizedPrepaidAndOtherAssetsDisclosureAbstract_E83F79433D268862689F418FFE766C62" xlink:to="loc_us-gaap_OtherAssetsMiscellaneousNoncurrent_3386B7CA835BF96C5649418FFE7784B7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_OtherAssetsNoncurrent" xlink:label="loc_us-gaap_OtherAssetsNoncurrent_6DCFCFE277A2313C3605418FFE77572F" xlink:type="locator" />
    <link:presentationArc order="4" preferredLabel="http://www.xbrl.org/2003/role/totalLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DeferredCostsCapitalizedPrepaidAndOtherAssetsDisclosureAbstract_E83F79433D268862689F418FFE766C62" xlink:to="loc_us-gaap_OtherAssetsNoncurrent_6DCFCFE277A2313C3605418FFE77572F" xlink:type="arc" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.oesx.com/role/OtherLongTermAssetsTables" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DeferredCostsCapitalizedPrepaidAndOtherAssetsDisclosureAbstract" xlink:label="loc_us-gaap_DeferredCostsCapitalizedPrepaidAndOtherAssetsDisclosureAbstract_17F02F78CFD679D6F91BFD50C1181AB3" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScheduleOfOtherAssetsNoncurrentTextBlock" xlink:label="loc_us-gaap_ScheduleOfOtherAssetsNoncurrentTextBlock_69AB40BCFEE5410FDB49FD50C118D45E" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DeferredCostsCapitalizedPrepaidAndOtherAssetsDisclosureAbstract_17F02F78CFD679D6F91BFD50C1181AB3" xlink:to="loc_us-gaap_ScheduleOfOtherAssetsNoncurrentTextBlock_69AB40BCFEE5410FDB49FD50C118D45E" xlink:type="arc" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.oesx.com/role/PrepaidExpensesAndOtherCurrentAssets" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DeferredCostsCapitalizedPrepaidAndOtherAssetsDisclosureAbstract" xlink:label="loc_us-gaap_DeferredCostsCapitalizedPrepaidAndOtherAssetsDisclosureAbstract_FF4BB31C3A6613D3A3420DBF9A950041" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_OtherCurrentAssetsTextBlock" xlink:label="loc_us-gaap_OtherCurrentAssetsTextBlock_31EF1E382AB6277431F80DBF9A9530A3" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DeferredCostsCapitalizedPrepaidAndOtherAssetsDisclosureAbstract_FF4BB31C3A6613D3A3420DBF9A950041" xlink:to="loc_us-gaap_OtherCurrentAssetsTextBlock_31EF1E382AB6277431F80DBF9A9530A3" xlink:type="arc" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.oesx.com/role/PrepaidExpensesAndOtherCurrentAssetsDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DeferredCostsCapitalizedPrepaidAndOtherAssetsDisclosureAbstract" xlink:label="loc_us-gaap_DeferredCostsCapitalizedPrepaidAndOtherAssetsDisclosureAbstract_323D6734A17AF5B95B6C0DE88D352908" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_UnbilledReceivablesCurrent" xlink:label="loc_us-gaap_UnbilledReceivablesCurrent_613ACCE2DE0AB91EFE880DE88D35C590" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DeferredCostsCapitalizedPrepaidAndOtherAssetsDisclosureAbstract_323D6734A17AF5B95B6C0DE88D352908" xlink:to="loc_us-gaap_UnbilledReceivablesCurrent_613ACCE2DE0AB91EFE880DE88D35C590" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_OtherPrepaidExpenseCurrent" xlink:label="loc_us-gaap_OtherPrepaidExpenseCurrent_429DF813A7266FD00CC90DE88D35E9F3" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DeferredCostsCapitalizedPrepaidAndOtherAssetsDisclosureAbstract_323D6734A17AF5B95B6C0DE88D352908" xlink:to="loc_us-gaap_OtherPrepaidExpenseCurrent_429DF813A7266FD00CC90DE88D35E9F3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PrepaidExpenseAndOtherAssetsCurrent" xlink:label="loc_us-gaap_PrepaidExpenseAndOtherAssetsCurrent_057DB9EC8E08517559000DE88D35128A" xlink:type="locator" />
    <link:presentationArc order="3" preferredLabel="http://www.xbrl.org/2003/role/totalLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DeferredCostsCapitalizedPrepaidAndOtherAssetsDisclosureAbstract_323D6734A17AF5B95B6C0DE88D352908" xlink:to="loc_us-gaap_PrepaidExpenseAndOtherAssetsCurrent_057DB9EC8E08517559000DE88D35128A" xlink:type="arc" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.oesx.com/role/PrepaidExpensesAndOtherCurrentAssetsTables" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DeferredCostsCapitalizedPrepaidAndOtherAssetsDisclosureAbstract" xlink:label="loc_us-gaap_DeferredCostsCapitalizedPrepaidAndOtherAssetsDisclosureAbstract_948458EA8559E3BDC13CFCC4F18AA6C8" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DeferredCostsCapitalizedPrepaidAndOtherAssetsDisclosureTextBlock" xlink:label="loc_us-gaap_DeferredCostsCapitalizedPrepaidAndOtherAssetsDisclosureTextBlock_0DD26FD9AF1F616D09FDFCC4F1E2DBA7" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DeferredCostsCapitalizedPrepaidAndOtherAssetsDisclosureAbstract_948458EA8559E3BDC13CFCC4F18AA6C8" xlink:to="loc_us-gaap_DeferredCostsCapitalizedPrepaidAndOtherAssetsDisclosureTextBlock_0DD26FD9AF1F616D09FDFCC4F1E2DBA7" xlink:type="arc" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.oesx.com/role/PropertyAndEquipment" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PropertyPlantAndEquipmentAbstract" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentAbstract_07451433563429C76B04410683193606" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PropertyPlantAndEquipmentDisclosureTextBlock" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentDisclosureTextBlock_558519C906D0D636AABD41068319B75C" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentAbstract_07451433563429C76B04410683193606" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentDisclosureTextBlock_558519C906D0D636AABD41068319B75C" xlink:type="arc" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.oesx.com/role/PropertyAndEquipmentEquipmentUnderCapitalLeasesDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PropertyPlantAndEquipmentAbstract" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentAbstract_E92EEB2F773502F0A2C441066B3AC4DE" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScheduleOfCapitalLeasedAsssetsTable" xlink:label="loc_us-gaap_ScheduleOfCapitalLeasedAsssetsTable_26CCBAB582110E1AF76441066B3A698D" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentAbstract_E92EEB2F773502F0A2C441066B3AC4DE" xlink:to="loc_us-gaap_ScheduleOfCapitalLeasedAsssetsTable_26CCBAB582110E1AF76441066B3A698D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_233AFCEE17DEE212D5BA41066B3A5E13" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfCapitalLeasedAsssetsTable_26CCBAB582110E1AF76441066B3A698D" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_233AFCEE17DEE212D5BA41066B3A5E13" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_168A449487D324E0B2AA41066B3AF510" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_233AFCEE17DEE212D5BA41066B3A5E13" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_168A449487D324E0B2AA41066B3AF510" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AssetsHeldUnderCapitalLeasesMember" xlink:label="loc_us-gaap_AssetsHeldUnderCapitalLeasesMember_70538BF54C563EF43E4D41066B3AB37F" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_168A449487D324E0B2AA41066B3AF510" xlink:to="loc_us-gaap_AssetsHeldUnderCapitalLeasesMember_70538BF54C563EF43E4D41066B3AB37F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CapitalLeasedAssetsLineItems" xlink:label="loc_us-gaap_CapitalLeasedAssetsLineItems_BFECE892ABC93C203E6641066B3A2D90" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfCapitalLeasedAsssetsTable_26CCBAB582110E1AF76441066B3A698D" xlink:to="loc_us-gaap_CapitalLeasedAssetsLineItems_BFECE892ABC93C203E6641066B3A2D90" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PropertyPlantAndEquipmentGross" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentGross_B47033706617D13DE17D41066B3A70E3" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_CapitalLeasedAssetsLineItems_BFECE892ABC93C203E6641066B3A2D90" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentGross_B47033706617D13DE17D41066B3A70E3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment" xlink:label="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_57BE6585878BE65C5B0641066B3A9DBB" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2009/role/negatedLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_CapitalLeasedAssetsLineItems_BFECE892ABC93C203E6641066B3A2D90" xlink:to="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_57BE6585878BE65C5B0641066B3A9DBB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PropertyPlantAndEquipmentNet" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNet_D0CE116E0DE9CE3539D241066B3A3EFC" xlink:type="locator" />
    <link:presentationArc order="3" preferredLabel="http://www.xbrl.org/2003/role/totalLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_CapitalLeasedAssetsLineItems_BFECE892ABC93C203E6641066B3A2D90" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentNet_D0CE116E0DE9CE3539D241066B3A3EFC" xlink:type="arc" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.oesx.com/role/PropertyAndEquipmentNarrativeDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PropertyPlantAndEquipmentAbstract" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentAbstract_D4E27DFB5F1E63F7C6678447AD3B05E7" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable" xlink:label="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_CAEAA57E1D45DB9E8DCA8447AD3BD2DC" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentAbstract_D4E27DFB5F1E63F7C6678447AD3B05E7" xlink:to="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_CAEAA57E1D45DB9E8DCA8447AD3BD2DC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SaleLeasebackTransactionDescriptionAxis" xlink:label="loc_us-gaap_SaleLeasebackTransactionDescriptionAxis_25F3B72DC2B3F4B6E0068447AD3CDA55" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_CAEAA57E1D45DB9E8DCA8447AD3BD2DC" xlink:to="loc_us-gaap_SaleLeasebackTransactionDescriptionAxis_25F3B72DC2B3F4B6E0068447AD3CDA55" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SaleLeasebackTransactionNameDomain" xlink:label="loc_us-gaap_SaleLeasebackTransactionNameDomain_448DC41DC2A3DAEEEB478447AD3C5D8E" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_SaleLeasebackTransactionDescriptionAxis_25F3B72DC2B3F4B6E0068447AD3CDA55" xlink:to="loc_us-gaap_SaleLeasebackTransactionNameDomain_448DC41DC2A3DAEEEB478447AD3C5D8E" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_ManitowocManufacturingandDistributionFacilityMember" xlink:label="loc_oesx_ManitowocManufacturingandDistributionFacilityMember_2D706B2A26359DA1FC7B8447AD3C8F06" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_SaleLeasebackTransactionNameDomain_448DC41DC2A3DAEEEB478447AD3C5D8E" xlink:to="loc_oesx_ManitowocManufacturingandDistributionFacilityMember_2D706B2A26359DA1FC7B8447AD3C8F06" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ConsolidationItemsAxis" xlink:label="loc_us-gaap_ConsolidationItemsAxis_3E2CEDFE144DE3CF34EB8447AD3C4EB4" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_CAEAA57E1D45DB9E8DCA8447AD3BD2DC" xlink:to="loc_us-gaap_ConsolidationItemsAxis_3E2CEDFE144DE3CF34EB8447AD3C4EB4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ConsolidationItemsDomain" xlink:label="loc_us-gaap_ConsolidationItemsDomain_6ACC185B4802C09CD7D38447AD3C4886" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ConsolidationItemsAxis_3E2CEDFE144DE3CF34EB8447AD3C4EB4" xlink:to="loc_us-gaap_ConsolidationItemsDomain_6ACC185B4802C09CD7D38447AD3C4886" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_OperatingSegmentsMember" xlink:label="loc_us-gaap_OperatingSegmentsMember_0A954B303D8D5CA196368447AD3C6D11" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ConsolidationItemsDomain_6ACC185B4802C09CD7D38447AD3C4886" xlink:to="loc_us-gaap_OperatingSegmentsMember_0A954B303D8D5CA196368447AD3C6D11" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_C6FEBB408D57F50AFC6E8447AD3C28CD" xlink:type="locator" />
    <link:presentationArc order="3" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_CAEAA57E1D45DB9E8DCA8447AD3BD2DC" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_C6FEBB408D57F50AFC6E8447AD3C28CD" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaap_SegmentDomain_98989CF9734F5AF2FAF38447AD3CBB96" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_C6FEBB408D57F50AFC6E8447AD3C28CD" xlink:to="loc_us-gaap_SegmentDomain_98989CF9734F5AF2FAF38447AD3CBB96" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_U.S.MarketsMember" xlink:label="loc_oesx_U.S.MarketsMember_9472D8F47EDD00D35FD78447AD3C29DA" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_SegmentDomain_98989CF9734F5AF2FAF38447AD3CBB96" xlink:to="loc_oesx_U.S.MarketsMember_9472D8F47EDD00D35FD78447AD3C29DA" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_EngineeredSystemsMember" xlink:label="loc_oesx_EngineeredSystemsMember_186E629DD4A5726BB5568447AD3D7763" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_SegmentDomain_98989CF9734F5AF2FAF38447AD3CBB96" xlink:to="loc_oesx_EngineeredSystemsMember_186E629DD4A5726BB5568447AD3D7763" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_DistributionServicesMember" xlink:label="loc_oesx_DistributionServicesMember_14E97EA84652D1D6B8798447AD3D7ACE" xlink:type="locator" />
    <link:presentationArc order="3" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_SegmentDomain_98989CF9734F5AF2FAF38447AD3CBB96" xlink:to="loc_oesx_DistributionServicesMember_14E97EA84652D1D6B8798447AD3D7ACE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_3C79DF7938EA7498BC828447AD3DEAE9" xlink:type="locator" />
    <link:presentationArc order="4" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_CAEAA57E1D45DB9E8DCA8447AD3BD2DC" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_3C79DF7938EA7498BC828447AD3DEAE9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_A821BAB48884C9D630528447AD3D5329" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_3C79DF7938EA7498BC828447AD3DEAE9" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_A821BAB48884C9D630528447AD3D5329" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ConstructionInProgressMember" xlink:label="loc_us-gaap_ConstructionInProgressMember_B804D64D42F331AA66028447AD3DBEB9" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_A821BAB48884C9D630528447AD3D5329" xlink:to="loc_us-gaap_ConstructionInProgressMember_B804D64D42F331AA66028447AD3DBEB9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PropertyPlantAndEquipmentLineItems" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentLineItems_9C690E3E20195EBF21808447AD3DF91E" xlink:type="locator" />
    <link:presentationArc order="5" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_CAEAA57E1D45DB9E8DCA8447AD3BD2DC" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentLineItems_9C690E3E20195EBF21808447AD3DF91E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ImpairmentOfLongLivedAssetsHeldForUse" xlink:label="loc_us-gaap_ImpairmentOfLongLivedAssetsHeldForUse_1BF934C86411B6E61F1E844A045CBBF1" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_9C690E3E20195EBF21808447AD3DF91E" xlink:to="loc_us-gaap_ImpairmentOfLongLivedAssetsHeldForUse_1BF934C86411B6E61F1E844A045CBBF1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SaleLeasebackTransactionGrossProceedsInvestingActivities" xlink:label="loc_us-gaap_SaleLeasebackTransactionGrossProceedsInvestingActivities_205F4ED920851854C97B8447AD3D8017" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_9C690E3E20195EBF21808447AD3DF91E" xlink:to="loc_us-gaap_SaleLeasebackTransactionGrossProceedsInvestingActivities_205F4ED920851854C97B8447AD3D8017" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_SaleLeasebackTransactionAreaofLeasedProperty" xlink:label="loc_oesx_SaleLeasebackTransactionAreaofLeasedProperty_2D648DBE7E84AAEAD3B98447AD3D8F40" xlink:type="locator" />
    <link:presentationArc order="3" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_9C690E3E20195EBF21808447AD3DF91E" xlink:to="loc_oesx_SaleLeasebackTransactionAreaofLeasedProperty_2D648DBE7E84AAEAD3B98447AD3D8F40" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_SaleLeasebackTransactionLeaseTerm" xlink:label="loc_oesx_SaleLeasebackTransactionLeaseTerm_BEA2FCE8042C0CCA0B748447AD3D17DF" xlink:type="locator" />
    <link:presentationArc order="4" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_9C690E3E20195EBF21808447AD3DF91E" xlink:to="loc_oesx_SaleLeasebackTransactionLeaseTerm_BEA2FCE8042C0CCA0B748447AD3D17DF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ImpairmentOfRealEstate" xlink:label="loc_us-gaap_ImpairmentOfRealEstate_8E84A622EE70F4F0A0168447AD3D9F3A" xlink:type="locator" />
    <link:presentationArc order="5" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_9C690E3E20195EBF21808447AD3DF91E" xlink:to="loc_us-gaap_ImpairmentOfRealEstate_8E84A622EE70F4F0A0168447AD3D9F3A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_NumberOfReportableSegments" xlink:label="loc_us-gaap_NumberOfReportableSegments_2A282E1FC1DE737724BC8447AD3DA9B9" xlink:type="locator" />
    <link:presentationArc order="6" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_9C690E3E20195EBF21808447AD3DF91E" xlink:to="loc_us-gaap_NumberOfReportableSegments_2A282E1FC1DE737724BC8447AD3DA9B9" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_PropertyPlantandEquipmentImpairmentExpense" xlink:label="loc_oesx_PropertyPlantandEquipmentImpairmentExpense_43B3F1383AAF0AD27E628447AD3DE3BD" xlink:type="locator" />
    <link:presentationArc order="7" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_9C690E3E20195EBF21808447AD3DF91E" xlink:to="loc_oesx_PropertyPlantandEquipmentImpairmentExpense_43B3F1383AAF0AD27E628447AD3DE3BD" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_Depreciation" xlink:label="loc_us-gaap_Depreciation_25B530506F9170FCF44F8447AD3D5EE9" xlink:type="locator" />
    <link:presentationArc order="8" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_9C690E3E20195EBF21808447AD3DF91E" xlink:to="loc_us-gaap_Depreciation_25B530506F9170FCF44F8447AD3D5EE9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_InterestCostsCapitalized" xlink:label="loc_us-gaap_InterestCostsCapitalized_4E3BD97BB32D36B85AD88447AD3DAA1B" xlink:type="locator" />
    <link:presentationArc order="9" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_9C690E3E20195EBF21808447AD3DF91E" xlink:to="loc_us-gaap_InterestCostsCapitalized_4E3BD97BB32D36B85AD88447AD3DAA1B" xlink:type="arc" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.oesx.com/role/PropertyAndEquipmentSummaryOfPropertyAndEquipmentDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PropertyPlantAndEquipmentAbstract" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentAbstract_CC94CEFF7415DDAC580B41067109DCFD" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable" xlink:label="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_8CAA5814D0996BF7DDD84106710AD72E" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentAbstract_CC94CEFF7415DDAC580B41067109DCFD" xlink:to="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_8CAA5814D0996BF7DDD84106710AD72E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_3E34600DBC3CD6DC8D854106710A21A0" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_8CAA5814D0996BF7DDD84106710AD72E" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_3E34600DBC3CD6DC8D854106710A21A0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_6FB57EBEF2BB3C79FD2F4106710A1A38" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_3E34600DBC3CD6DC8D854106710A21A0" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_6FB57EBEF2BB3C79FD2F4106710A1A38" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LandImprovementsMember" xlink:label="loc_us-gaap_LandImprovementsMember_5D5E1A9B08D22683034A4106710A0591" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_6FB57EBEF2BB3C79FD2F4106710A1A38" xlink:to="loc_us-gaap_LandImprovementsMember_5D5E1A9B08D22683034A4106710A0591" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_BuildingAndBuildingImprovementsMember" xlink:label="loc_us-gaap_BuildingAndBuildingImprovementsMember_3B2A53C907CE680505044106710A1595" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_6FB57EBEF2BB3C79FD2F4106710A1A38" xlink:to="loc_us-gaap_BuildingAndBuildingImprovementsMember_3B2A53C907CE680505044106710A1595" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FurnitureAndFixturesMember" xlink:label="loc_us-gaap_FurnitureAndFixturesMember_83835114BD4A592EB70A4106710AFEB4" xlink:type="locator" />
    <link:presentationArc order="3" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_6FB57EBEF2BB3C79FD2F4106710A1A38" xlink:to="loc_us-gaap_FurnitureAndFixturesMember_83835114BD4A592EB70A4106710AFEB4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LeaseholdImprovementsMember" xlink:label="loc_us-gaap_LeaseholdImprovementsMember_E51AC456CB3B507A8F084106710A4EB0" xlink:type="locator" />
    <link:presentationArc order="4" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_6FB57EBEF2BB3C79FD2F4106710A1A38" xlink:to="loc_us-gaap_LeaseholdImprovementsMember_E51AC456CB3B507A8F084106710A4EB0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_EquipmentLeasedToOtherPartyMember" xlink:label="loc_us-gaap_EquipmentLeasedToOtherPartyMember_ABF6D4DE4A1E1C735B6B4106710A875F" xlink:type="locator" />
    <link:presentationArc order="5" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_6FB57EBEF2BB3C79FD2F4106710A1A38" xlink:to="loc_us-gaap_EquipmentLeasedToOtherPartyMember_ABF6D4DE4A1E1C735B6B4106710A875F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PropertyPlantAndEquipmentOtherTypesMember" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentOtherTypesMember_CFE15279EC37AD8B9BCC4106710A6318" xlink:type="locator" />
    <link:presentationArc order="6" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_6FB57EBEF2BB3C79FD2F4106710A1A38" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentOtherTypesMember_CFE15279EC37AD8B9BCC4106710A6318" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ConstructionInProgressMember" xlink:label="loc_us-gaap_ConstructionInProgressMember_55905C3860AD6ECF59E04106710ACE74" xlink:type="locator" />
    <link:presentationArc order="7" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_6FB57EBEF2BB3C79FD2F4106710A1A38" xlink:to="loc_us-gaap_ConstructionInProgressMember_55905C3860AD6ECF59E04106710ACE74" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PropertyPlantAndEquipmentLineItems" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentLineItems_3C3A1800D8F2B95D60C64106710AAE95" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_8CAA5814D0996BF7DDD84106710AD72E" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentLineItems_3C3A1800D8F2B95D60C64106710AAE95" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PropertyPlantAndEquipmentNetAbstract" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNetAbstract_6CF3DB270EF80E703CF54106710A520E" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_3C3A1800D8F2B95D60C64106710AAE95" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentNetAbstract_6CF3DB270EF80E703CF54106710A520E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PropertyPlantAndEquipmentGross" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentGross_F6E8FB31B138637D5EA24106710A5DD0" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentNetAbstract_6CF3DB270EF80E703CF54106710A520E" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentGross_F6E8FB31B138637D5EA24106710A5DD0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment" xlink:label="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_9CF2747C0F6FDE84288C4106710A1BC2" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2009/role/negatedLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentNetAbstract_6CF3DB270EF80E703CF54106710A520E" xlink:to="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_9CF2747C0F6FDE84288C4106710A1BC2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PropertyPlantAndEquipmentNet" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNet_37A94CDA9B43EAE1960C4106710B52B1" xlink:type="locator" />
    <link:presentationArc order="3" preferredLabel="http://www.xbrl.org/2003/role/totalLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentNetAbstract_6CF3DB270EF80E703CF54106710A520E" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentNet_37A94CDA9B43EAE1960C4106710B52B1" xlink:type="arc" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.oesx.com/role/PropertyAndEquipmentTables" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PropertyPlantAndEquipmentAbstract" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentAbstract_17451245102E053CAF1541067DD64432" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PropertyPlantAndEquipmentTextBlock" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTextBlock_0BF238DD338C06A9B88541067DD6A09D" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentAbstract_17451245102E053CAF1541067DD64432" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTextBlock_0BF238DD338C06A9B88541067DD6A09D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScheduleOfCapitalLeasedAsssetsTableTextBlock" xlink:label="loc_us-gaap_ScheduleOfCapitalLeasedAsssetsTableTextBlock_5574C3A34399D9D3728341067DD6E718" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentAbstract_17451245102E053CAF1541067DD64432" xlink:to="loc_us-gaap_ScheduleOfCapitalLeasedAsssetsTableTextBlock_5574C3A34399D9D3728341067DD6E718" xlink:type="arc" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.oesx.com/role/PropertyAndEquipmentUsefulLivesDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PropertyPlantAndEquipmentAbstract" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentAbstract_132A49970B564FB4236E64B047C16CAB" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable" xlink:label="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_102F2E03D884709BE0C864B047C1BF43" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentAbstract_132A49970B564FB4236E64B047C16CAB" xlink:to="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_102F2E03D884709BE0C864B047C1BF43" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_B844D9664C919DC0AFC664B047C1926F" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_102F2E03D884709BE0C864B047C1BF43" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_B844D9664C919DC0AFC664B047C1926F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_74C05AD05AEF028CF19A64B047C155E5" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_B844D9664C919DC0AFC664B047C1926F" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_74C05AD05AEF028CF19A64B047C155E5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LandImprovementsMember" xlink:label="loc_us-gaap_LandImprovementsMember_A35C4A1C3AB84D52FE4864B047C269CB" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_74C05AD05AEF028CF19A64B047C155E5" xlink:to="loc_us-gaap_LandImprovementsMember_A35C4A1C3AB84D52FE4864B047C269CB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_BuildingAndBuildingImprovementsMember" xlink:label="loc_us-gaap_BuildingAndBuildingImprovementsMember_8DE88AC334857DF8AF9964B047C24A3C" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_74C05AD05AEF028CF19A64B047C155E5" xlink:to="loc_us-gaap_BuildingAndBuildingImprovementsMember_8DE88AC334857DF8AF9964B047C24A3C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FurnitureAndFixturesMember" xlink:label="loc_us-gaap_FurnitureAndFixturesMember_BAD9D1869B2EAE9462F864B047C2205B" xlink:type="locator" />
    <link:presentationArc order="3" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_74C05AD05AEF028CF19A64B047C155E5" xlink:to="loc_us-gaap_FurnitureAndFixturesMember_BAD9D1869B2EAE9462F864B047C2205B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_EquipmentLeasedToOtherPartyMember" xlink:label="loc_us-gaap_EquipmentLeasedToOtherPartyMember_F1A33701749CB11C36A964B047C2F069" xlink:type="locator" />
    <link:presentationArc order="4" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_74C05AD05AEF028CF19A64B047C155E5" xlink:to="loc_us-gaap_EquipmentLeasedToOtherPartyMember_F1A33701749CB11C36A964B047C2F069" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_EquipmentMember" xlink:label="loc_us-gaap_EquipmentMember_90A2944D48E86B4E5A7064B047C295E5" xlink:type="locator" />
    <link:presentationArc order="5" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_74C05AD05AEF028CF19A64B047C155E5" xlink:to="loc_us-gaap_EquipmentMember_90A2944D48E86B4E5A7064B047C295E5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RangeAxis" xlink:label="loc_us-gaap_RangeAxis_14827DCEC5000EECD1E964B047C2B80E" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_102F2E03D884709BE0C864B047C1BF43" xlink:to="loc_us-gaap_RangeAxis_14827DCEC5000EECD1E964B047C2B80E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember_6C89B95971689478503964B047C2FD8B" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_RangeAxis_14827DCEC5000EECD1E964B047C2B80E" xlink:to="loc_us-gaap_RangeMember_6C89B95971689478503964B047C2FD8B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_MinimumMember" xlink:label="loc_us-gaap_MinimumMember_7318C128F36143DE9F3964B047C25C80" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_RangeMember_6C89B95971689478503964B047C2FD8B" xlink:to="loc_us-gaap_MinimumMember_7318C128F36143DE9F3964B047C25C80" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_MaximumMember" xlink:label="loc_us-gaap_MaximumMember_4D249B1FA1F8383A190564B047C2080A" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_RangeMember_6C89B95971689478503964B047C2FD8B" xlink:to="loc_us-gaap_MaximumMember_4D249B1FA1F8383A190564B047C2080A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PropertyPlantAndEquipmentLineItems" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentLineItems_D22E0550C50E7392C9FE64B047C20D5A" xlink:type="locator" />
    <link:presentationArc order="3" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_102F2E03D884709BE0C864B047C1BF43" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentLineItems_D22E0550C50E7392C9FE64B047C20D5A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PropertyPlantAndEquipmentNetAbstract" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNetAbstract_9581B810C14E3391648064B047C2195C" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_D22E0550C50E7392C9FE64B047C20D5A" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentNetAbstract_9581B810C14E3391648064B047C2195C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PropertyPlantAndEquipmentUsefulLife" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentUsefulLife_2A33C7678CBFA33D3B3E64B047C213A9" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentNetAbstract_9581B810C14E3391648064B047C2195C" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentUsefulLife_2A33C7678CBFA33D3B3E64B047C213A9" xlink:type="arc" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.oesx.com/role/QuarterlyFinancialDataDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_QuarterlyFinancialDataAbstract" xlink:label="loc_us-gaap_QuarterlyFinancialDataAbstract_5421E220341714BDFEAE844B463BA3AD" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SelectedQuarterlyFinancialInformationAbstract" xlink:label="loc_us-gaap_SelectedQuarterlyFinancialInformationAbstract_475D8659EFE735738134844B463B0EA2" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_QuarterlyFinancialDataAbstract_5421E220341714BDFEAE844B463BA3AD" xlink:to="loc_us-gaap_SelectedQuarterlyFinancialInformationAbstract_475D8659EFE735738134844B463B0EA2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_Revenues" xlink:label="loc_us-gaap_Revenues_32E685AC7DCC80B67A0A844B463BBBC7" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_SelectedQuarterlyFinancialInformationAbstract_475D8659EFE735738134844B463B0EA2" xlink:to="loc_us-gaap_Revenues_32E685AC7DCC80B67A0A844B463BBBC7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_GrossProfit" xlink:label="loc_us-gaap_GrossProfit_689E10DB9898E72C4834844B463B13A1" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_SelectedQuarterlyFinancialInformationAbstract_475D8659EFE735738134844B463B0EA2" xlink:to="loc_us-gaap_GrossProfit_689E10DB9898E72C4834844B463B13A1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_NetIncomeLoss" xlink:label="loc_us-gaap_NetIncomeLoss_A16AAA12942E540C0CE5844B463B865A" xlink:type="locator" />
    <link:presentationArc order="3" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_SelectedQuarterlyFinancialInformationAbstract_475D8659EFE735738134844B463B0EA2" xlink:to="loc_us-gaap_NetIncomeLoss_A16AAA12942E540C0CE5844B463B865A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_EarningsPerShareBasic" xlink:label="loc_us-gaap_EarningsPerShareBasic_4C2779DA8286EEB7C7C5844B463B9FE6" xlink:type="locator" />
    <link:presentationArc order="4" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_SelectedQuarterlyFinancialInformationAbstract_475D8659EFE735738134844B463B0EA2" xlink:to="loc_us-gaap_EarningsPerShareBasic_4C2779DA8286EEB7C7C5844B463B9FE6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingBasic" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_4048F1133ABCD3DC60FC844B463BBB5C" xlink:type="locator" />
    <link:presentationArc order="5" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_SelectedQuarterlyFinancialInformationAbstract_475D8659EFE735738134844B463B0EA2" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_4048F1133ABCD3DC60FC844B463BBB5C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_EarningsPerShareDiluted" xlink:label="loc_us-gaap_EarningsPerShareDiluted_B14C1EFD2E76CE928A5D844B463B0C5D" xlink:type="locator" />
    <link:presentationArc order="6" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_SelectedQuarterlyFinancialInformationAbstract_475D8659EFE735738134844B463B0EA2" xlink:to="loc_us-gaap_EarningsPerShareDiluted_B14C1EFD2E76CE928A5D844B463B0C5D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding" xlink:label="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_ABA46B6A0F3DB291EF85844B463B6EAA" xlink:type="locator" />
    <link:presentationArc order="7" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_SelectedQuarterlyFinancialInformationAbstract_475D8659EFE735738134844B463B0EA2" xlink:to="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_ABA46B6A0F3DB291EF85844B463B6EAA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ImpairmentOfIntangibleAssetsExcludingGoodwill" xlink:label="loc_us-gaap_ImpairmentOfIntangibleAssetsExcludingGoodwill_660356C724464AFDEE5584A27AC495C9" xlink:type="locator" />
    <link:presentationArc order="8" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_SelectedQuarterlyFinancialInformationAbstract_475D8659EFE735738134844B463B0EA2" xlink:to="loc_us-gaap_ImpairmentOfIntangibleAssetsExcludingGoodwill_660356C724464AFDEE5584A27AC495C9" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_InventoryReserveAndOtherAdjustments" xlink:label="loc_oesx_InventoryReserveAndOtherAdjustments_130B60E10BAC4F50C18F849FB471F4A2" xlink:type="locator" />
    <link:presentationArc order="9" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_SelectedQuarterlyFinancialInformationAbstract_475D8659EFE735738134844B463B0EA2" xlink:to="loc_oesx_InventoryReserveAndOtherAdjustments_130B60E10BAC4F50C18F849FB471F4A2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_GoodwillImpairmentLoss" xlink:label="loc_us-gaap_GoodwillImpairmentLoss_20DFFCE80A2BC3A2523984A2F41A03E1" xlink:type="locator" />
    <link:presentationArc order="10" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_SelectedQuarterlyFinancialInformationAbstract_475D8659EFE735738134844B463B0EA2" xlink:to="loc_us-gaap_GoodwillImpairmentLoss_20DFFCE80A2BC3A2523984A2F41A03E1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ImpairmentOfRealEstate" xlink:label="loc_us-gaap_ImpairmentOfRealEstate_A66AD7D95EB81B8E1E7384A5AAEFD456" xlink:type="locator" />
    <link:presentationArc order="11" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_SelectedQuarterlyFinancialInformationAbstract_475D8659EFE735738134844B463B0EA2" xlink:to="loc_us-gaap_ImpairmentOfRealEstate_A66AD7D95EB81B8E1E7384A5AAEFD456" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LossContingencyAccrualProvision" xlink:label="loc_us-gaap_LossContingencyAccrualProvision_07C8A07F513D6831C35184A41D4296E9" xlink:type="locator" />
    <link:presentationArc order="12" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_SelectedQuarterlyFinancialInformationAbstract_475D8659EFE735738134844B463B0EA2" xlink:to="loc_us-gaap_LossContingencyAccrualProvision_07C8A07F513D6831C35184A41D4296E9" xlink:type="arc" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.oesx.com/role/QuarterlyFinancialDataUnaudited" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_QuarterlyFinancialDataAbstract" xlink:label="loc_us-gaap_QuarterlyFinancialDataAbstract_CC1ED9E5B8B4CA7DA29A0DBF98184FF5" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_QuarterlyFinancialInformationTextBlock" xlink:label="loc_us-gaap_QuarterlyFinancialInformationTextBlock_0611F7F327EA11D9CB530DBF981862EA" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_QuarterlyFinancialDataAbstract_CC1ED9E5B8B4CA7DA29A0DBF98184FF5" xlink:to="loc_us-gaap_QuarterlyFinancialInformationTextBlock_0611F7F327EA11D9CB530DBF981862EA" xlink:type="arc" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.oesx.com/role/QuarterlyFinancialDataUnauditedTables" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_QuarterlyFinancialDataAbstract" xlink:label="loc_us-gaap_QuarterlyFinancialDataAbstract_AE4CF4B07FF101CADF7C66E04A8365B4" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScheduleOfQuarterlyFinancialInformationTableTextBlock" xlink:label="loc_us-gaap_ScheduleOfQuarterlyFinancialInformationTableTextBlock_9CFE7898FF210129A20266E04A85FFF6" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_QuarterlyFinancialDataAbstract_AE4CF4B07FF101CADF7C66E04A8365B4" xlink:to="loc_us-gaap_ScheduleOfQuarterlyFinancialInformationTableTextBlock_9CFE7898FF210129A20266E04A85FFF6" xlink:type="arc" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.oesx.com/role/RelatedPartyTransactions" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RelatedPartyTransactionsAbstract" xlink:label="loc_us-gaap_RelatedPartyTransactionsAbstract_91ADD285AD5714199BE10DBF9B287A22" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RelatedPartyTransactionsDisclosureTextBlock" xlink:label="loc_us-gaap_RelatedPartyTransactionsDisclosureTextBlock_F770B9DDA5DA17D3C6540DBF9B28C261" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_RelatedPartyTransactionsAbstract_91ADD285AD5714199BE10DBF9B287A22" xlink:to="loc_us-gaap_RelatedPartyTransactionsDisclosureTextBlock_F770B9DDA5DA17D3C6540DBF9B28C261" xlink:type="arc" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.oesx.com/role/RelatedPartyTransactionsDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RelatedPartyTransactionsAbstract" xlink:label="loc_us-gaap_RelatedPartyTransactionsAbstract_01818132863734C71E116031DCD2AB1F" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable" xlink:label="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_6C4FD0DF475520DD2DB66031DCD20929" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_RelatedPartyTransactionsAbstract_01818132863734C71E116031DCD2AB1F" xlink:to="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_6C4FD0DF475520DD2DB66031DCD20929" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RelatedPartyTransactionsByRelatedPartyAxis" xlink:label="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_725252FBF72A703F02076031DCD2F74C" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_6C4FD0DF475520DD2DB66031DCD20929" xlink:to="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_725252FBF72A703F02076031DCD2F74C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RelatedPartyDomain" xlink:label="loc_us-gaap_RelatedPartyDomain_3DA2E25A124F0196C16E6031DCD2B725" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_725252FBF72A703F02076031DCD2F74C" xlink:to="loc_us-gaap_RelatedPartyDomain_3DA2E25A124F0196C16E6031DCD2B725" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_EntitythatCurrentDirectorOwnsMinorityInterestandServesasBoardofDirectorsChairmanMember" xlink:label="loc_oesx_EntitythatCurrentDirectorOwnsMinorityInterestandServesasBoardofDirectorsChairmanMember_D8451F8BE3542B5B7A1B6031DCD37964" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_RelatedPartyDomain_3DA2E25A124F0196C16E6031DCD2B725" xlink:to="loc_oesx_EntitythatCurrentDirectorOwnsMinorityInterestandServesasBoardofDirectorsChairmanMember_D8451F8BE3542B5B7A1B6031DCD37964" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ImmediateFamilyMemberOfManagementOrPrincipalOwnerMember" xlink:label="loc_us-gaap_ImmediateFamilyMemberOfManagementOrPrincipalOwnerMember_9080A8D4057CA6BBABA76031DCD43E34" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_RelatedPartyDomain_3DA2E25A124F0196C16E6031DCD2B725" xlink:to="loc_us-gaap_ImmediateFamilyMemberOfManagementOrPrincipalOwnerMember_9080A8D4057CA6BBABA76031DCD43E34" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RelatedPartyTransactionAxis" xlink:label="loc_us-gaap_RelatedPartyTransactionAxis_501A3C5C5784ACB08FD46031DCD4C69D" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_6C4FD0DF475520DD2DB66031DCD20929" xlink:to="loc_us-gaap_RelatedPartyTransactionAxis_501A3C5C5784ACB08FD46031DCD4C69D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RelatedPartyTransactionDomain" xlink:label="loc_us-gaap_RelatedPartyTransactionDomain_266B3044568BCAB561296031DCD4F857" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_RelatedPartyTransactionAxis_501A3C5C5784ACB08FD46031DCD4C69D" xlink:to="loc_us-gaap_RelatedPartyTransactionDomain_266B3044568BCAB561296031DCD4F857" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_ServicesPurchasedFromAnImmediateFamilyMemberOfAnExecutiveOfficerMember" xlink:label="loc_oesx_ServicesPurchasedFromAnImmediateFamilyMemberOfAnExecutiveOfficerMember_F94CB084CADEDF3FD9D66031DCD45F8B" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_RelatedPartyTransactionDomain_266B3044568BCAB561296031DCD4F857" xlink:to="loc_oesx_ServicesPurchasedFromAnImmediateFamilyMemberOfAnExecutiveOfficerMember_F94CB084CADEDF3FD9D66031DCD45F8B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RelatedPartyTransactionLineItems" xlink:label="loc_us-gaap_RelatedPartyTransactionLineItems_C48E4A63B9BAA322F1776031DCD45497" xlink:type="locator" />
    <link:presentationArc order="3" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_6C4FD0DF475520DD2DB66031DCD20929" xlink:to="loc_us-gaap_RelatedPartyTransactionLineItems_C48E4A63B9BAA322F1776031DCD45497" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RelatedPartyTransactionPurchasesFromRelatedParty" xlink:label="loc_us-gaap_RelatedPartyTransactionPurchasesFromRelatedParty_844A82368B5999BB3B636031DCD4D53D" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_C48E4A63B9BAA322F1776031DCD45497" xlink:to="loc_us-gaap_RelatedPartyTransactionPurchasesFromRelatedParty_844A82368B5999BB3B636031DCD4D53D" xlink:type="arc" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.oesx.com/role/ScheduleIiValuationAndQualifyingAccounts" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ValuationAndQualifyingAccountsAbstract" xlink:label="loc_us-gaap_ValuationAndQualifyingAccountsAbstract_379394F0CFD4AED461107E24B45975A7" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScheduleOfValuationAndQualifyingAccountsDisclosureTextBlock" xlink:label="loc_us-gaap_ScheduleOfValuationAndQualifyingAccountsDisclosureTextBlock_0B4EB742EFA46EA742F17E24B45A99F9" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ValuationAndQualifyingAccountsAbstract_379394F0CFD4AED461107E24B45975A7" xlink:to="loc_us-gaap_ScheduleOfValuationAndQualifyingAccountsDisclosureTextBlock_0B4EB742EFA46EA742F17E24B45A99F9" xlink:type="arc" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.oesx.com/role/ScheduleIiValuationAndQualifyingAccountsDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ValuationAndQualifyingAccountsAbstract" xlink:label="loc_us-gaap_ValuationAndQualifyingAccountsAbstract_7936E4187579A1694474649589355F09" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ValuationAndQualifyingAccountsDisclosureTable" xlink:label="loc_us-gaap_ValuationAndQualifyingAccountsDisclosureTable_CAFB78756BAF6A6238D36497D9666670" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ValuationAndQualifyingAccountsAbstract_7936E4187579A1694474649589355F09" xlink:to="loc_us-gaap_ValuationAndQualifyingAccountsDisclosureTable_CAFB78756BAF6A6238D36497D9666670" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ValuationAllowancesAndReservesTypeAxis" xlink:label="loc_us-gaap_ValuationAllowancesAndReservesTypeAxis_9ED14A7E5A2F35EB8E916497D96780A1" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ValuationAndQualifyingAccountsDisclosureTable_CAFB78756BAF6A6238D36497D9666670" xlink:to="loc_us-gaap_ValuationAllowancesAndReservesTypeAxis_9ED14A7E5A2F35EB8E916497D96780A1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ValuationAllowancesAndReservesDomain" xlink:label="loc_us-gaap_ValuationAllowancesAndReservesDomain_127AA4931C906657EABA6497D967DDD7" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ValuationAllowancesAndReservesTypeAxis_9ED14A7E5A2F35EB8E916497D96780A1" xlink:to="loc_us-gaap_ValuationAllowancesAndReservesDomain_127AA4931C906657EABA6497D967DDD7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AllowanceForDoubtfulAccountsMember" xlink:label="loc_us-gaap_AllowanceForDoubtfulAccountsMember_B0686E01DB755AB6919B649831C6A5D4" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ValuationAllowancesAndReservesDomain_127AA4931C906657EABA6497D967DDD7" xlink:to="loc_us-gaap_AllowanceForDoubtfulAccountsMember_B0686E01DB755AB6919B649831C6A5D4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_InventoryValuationReserveMember" xlink:label="loc_us-gaap_InventoryValuationReserveMember_3014D01E9DCBCA3F28B564988A89B49D" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ValuationAllowancesAndReservesDomain_127AA4931C906657EABA6497D967DDD7" xlink:to="loc_us-gaap_InventoryValuationReserveMember_3014D01E9DCBCA3F28B564988A89B49D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ValuationAndQualifyingAccountsDisclosureLineItems" xlink:label="loc_us-gaap_ValuationAndQualifyingAccountsDisclosureLineItems_ED717AA48172180A62786497D968F114" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ValuationAndQualifyingAccountsDisclosureTable_CAFB78756BAF6A6238D36497D9666670" xlink:to="loc_us-gaap_ValuationAndQualifyingAccountsDisclosureLineItems_ED717AA48172180A62786497D968F114" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_MovementInValuationAllowancesAndReservesRollForward" xlink:label="loc_us-gaap_MovementInValuationAllowancesAndReservesRollForward_10B0BB768873C2E955B56499030FB4B3" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ValuationAndQualifyingAccountsDisclosureLineItems_ED717AA48172180A62786497D968F114" xlink:to="loc_us-gaap_MovementInValuationAllowancesAndReservesRollForward_10B0BB768873C2E955B56499030FB4B3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ValuationAllowancesAndReservesBalance" xlink:label="loc_us-gaap_ValuationAllowancesAndReservesBalance_53BAEE6B71626834531A64979C617CA2" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/periodStartLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_MovementInValuationAllowancesAndReservesRollForward_10B0BB768873C2E955B56499030FB4B3" xlink:to="loc_us-gaap_ValuationAllowancesAndReservesBalance_53BAEE6B71626834531A64979C617CA2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ValuationAllowancesAndReservesChargedToCostAndExpense" xlink:label="loc_us-gaap_ValuationAllowancesAndReservesChargedToCostAndExpense_9F4520CCCFF50E1EF1896499C9322D1A" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_MovementInValuationAllowancesAndReservesRollForward_10B0BB768873C2E955B56499030FB4B3" xlink:to="loc_us-gaap_ValuationAllowancesAndReservesChargedToCostAndExpense_9F4520CCCFF50E1EF1896499C9322D1A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ValuationAllowancesAndReservesDeductions" xlink:label="loc_us-gaap_ValuationAllowancesAndReservesDeductions_B7146E8BC3B49BEF61D1649A4B0EA1A6" xlink:type="locator" />
    <link:presentationArc order="3" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_MovementInValuationAllowancesAndReservesRollForward_10B0BB768873C2E955B56499030FB4B3" xlink:to="loc_us-gaap_ValuationAllowancesAndReservesDeductions_B7146E8BC3B49BEF61D1649A4B0EA1A6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ValuationAllowancesAndReservesBalance" xlink:label="loc_us-gaap_ValuationAllowancesAndReservesBalance_D98AF8B3AFE9F80B7503649943160697" xlink:type="locator" />
    <link:presentationArc order="4" preferredLabel="http://www.xbrl.org/2003/role/periodEndLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_MovementInValuationAllowancesAndReservesRollForward_10B0BB768873C2E955B56499030FB4B3" xlink:to="loc_us-gaap_ValuationAllowancesAndReservesBalance_D98AF8B3AFE9F80B7503649943160697" xlink:type="arc" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.oesx.com/role/SegmentData" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SegmentReportingAbstract" xlink:label="loc_us-gaap_SegmentReportingAbstract_DBE79E860F2CC0DDA57D0DBF9856BBBF" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SegmentReportingDisclosureTextBlock" xlink:label="loc_us-gaap_SegmentReportingDisclosureTextBlock_CF41EDAA3CD8C3E316790DBF985634E1" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_SegmentReportingAbstract_DBE79E860F2CC0DDA57D0DBF9856BBBF" xlink:to="loc_us-gaap_SegmentReportingDisclosureTextBlock_CF41EDAA3CD8C3E316790DBF985634E1" xlink:type="arc" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.oesx.com/role/SegmentDataReconciliationOfSegmentAssetsAndLiabilitiesDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SegmentReportingAbstract" xlink:label="loc_us-gaap_SegmentReportingAbstract_09BA53B798592CACDE8EFCCAD17DB810" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable" xlink:label="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_DC6AFAF9B9A6E41775EBFCCAD17D9098" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_SegmentReportingAbstract_09BA53B798592CACDE8EFCCAD17DB810" xlink:to="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_DC6AFAF9B9A6E41775EBFCCAD17D9098" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_7B414EB14C18C04E7630FCCAD17DDFA3" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_DC6AFAF9B9A6E41775EBFCCAD17D9098" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_7B414EB14C18C04E7630FCCAD17DDFA3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaap_SegmentDomain_C80554B16105681EF418FCCAD17ED483" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_7B414EB14C18C04E7630FCCAD17DDFA3" xlink:to="loc_us-gaap_SegmentDomain_C80554B16105681EF418FCCAD17ED483" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_U.S.MarketsMember" xlink:label="loc_oesx_U.S.MarketsMember_7F0D9AE32EA52BFBA181FCCAD17E912E" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_SegmentDomain_C80554B16105681EF418FCCAD17ED483" xlink:to="loc_oesx_U.S.MarketsMember_7F0D9AE32EA52BFBA181FCCAD17E912E" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_EngineeredSystemsMember" xlink:label="loc_oesx_EngineeredSystemsMember_F9CBCF1912AE84D9BD37FCCAD17E8BA3" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_SegmentDomain_C80554B16105681EF418FCCAD17ED483" xlink:to="loc_oesx_EngineeredSystemsMember_F9CBCF1912AE84D9BD37FCCAD17E8BA3" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_DistributionServicesMember" xlink:label="loc_oesx_DistributionServicesMember_4B8E1693F525713F401BFCCAD17EC6A0" xlink:type="locator" />
    <link:presentationArc order="3" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_SegmentDomain_C80554B16105681EF418FCCAD17ED483" xlink:to="loc_oesx_DistributionServicesMember_4B8E1693F525713F401BFCCAD17EC6A0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CorporateAndOtherMember" xlink:label="loc_us-gaap_CorporateAndOtherMember_A2DC3642E9332A5C3BE8FCCAD17E134F" xlink:type="locator" />
    <link:presentationArc order="4" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_SegmentDomain_C80554B16105681EF418FCCAD17ED483" xlink:to="loc_us-gaap_CorporateAndOtherMember_A2DC3642E9332A5C3BE8FCCAD17E134F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SegmentReportingInformationLineItems" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_F04E6F5365A3D99CF9D7FCCAD17EF64A" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_DC6AFAF9B9A6E41775EBFCCAD17D9098" xlink:to="loc_us-gaap_SegmentReportingInformationLineItems_F04E6F5365A3D99CF9D7FCCAD17EF64A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SegmentReportingInformationRevenueAbstract" xlink:label="loc_us-gaap_SegmentReportingInformationRevenueAbstract_1C8F346E02195669C8ABFCCAD17E9AD4" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_F04E6F5365A3D99CF9D7FCCAD17EF64A" xlink:to="loc_us-gaap_SegmentReportingInformationRevenueAbstract_1C8F346E02195669C8ABFCCAD17E9AD4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_Assets" xlink:label="loc_us-gaap_Assets_9786F17DD324C5D17EC0FCCAD17F1AE4" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_SegmentReportingInformationRevenueAbstract_1C8F346E02195669C8ABFCCAD17E9AD4" xlink:to="loc_us-gaap_Assets_9786F17DD324C5D17EC0FCCAD17F1AE4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DeferredRevenue" xlink:label="loc_us-gaap_DeferredRevenue_C91F77C56BFF234A126AFCCAD17FA22D" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_SegmentReportingInformationRevenueAbstract_1C8F346E02195669C8ABFCCAD17E9AD4" xlink:to="loc_us-gaap_DeferredRevenue_C91F77C56BFF234A126AFCCAD17FA22D" xlink:type="arc" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.oesx.com/role/SegmentDataReconciliationOfSegmentOperationsDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SegmentReportingAbstract" xlink:label="loc_us-gaap_SegmentReportingAbstract_1DA6527B6C1F174E6D6FFCCAD18404F7" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable" xlink:label="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_6DA290A42E65151BA9C8FCCAD18442F1" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_SegmentReportingAbstract_1DA6527B6C1F174E6D6FFCCAD18404F7" xlink:to="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_6DA290A42E65151BA9C8FCCAD18442F1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_9CF8BA3825FD9AF79166FCCAD1847935" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_6DA290A42E65151BA9C8FCCAD18442F1" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_9CF8BA3825FD9AF79166FCCAD1847935" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaap_SegmentDomain_541FF8A0E12DD9940CC8FCCAD184BC51" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_9CF8BA3825FD9AF79166FCCAD1847935" xlink:to="loc_us-gaap_SegmentDomain_541FF8A0E12DD9940CC8FCCAD184BC51" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_U.S.MarketsMember" xlink:label="loc_oesx_U.S.MarketsMember_42ED7FEF290A1413CC9AFCCAD185B5C8" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_SegmentDomain_541FF8A0E12DD9940CC8FCCAD184BC51" xlink:to="loc_oesx_U.S.MarketsMember_42ED7FEF290A1413CC9AFCCAD185B5C8" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_EngineeredSystemsMember" xlink:label="loc_oesx_EngineeredSystemsMember_D39C0338402F8A197CB4FCCAD185AEAD" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_SegmentDomain_541FF8A0E12DD9940CC8FCCAD184BC51" xlink:to="loc_oesx_EngineeredSystemsMember_D39C0338402F8A197CB4FCCAD185AEAD" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_DistributionServicesMember" xlink:label="loc_oesx_DistributionServicesMember_4EBAEC85695DC7626077FCCAD18522DF" xlink:type="locator" />
    <link:presentationArc order="3" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_SegmentDomain_541FF8A0E12DD9940CC8FCCAD184BC51" xlink:to="loc_oesx_DistributionServicesMember_4EBAEC85695DC7626077FCCAD18522DF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CorporateAndOtherMember" xlink:label="loc_us-gaap_CorporateAndOtherMember_743A2CFAB3CBC66AB794FCCAD18596B1" xlink:type="locator" />
    <link:presentationArc order="4" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_SegmentDomain_541FF8A0E12DD9940CC8FCCAD184BC51" xlink:to="loc_us-gaap_CorporateAndOtherMember_743A2CFAB3CBC66AB794FCCAD18596B1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SegmentReportingInformationLineItems" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_7B6BF646A5317343B2DEFCCAD1852908" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_6DA290A42E65151BA9C8FCCAD18442F1" xlink:to="loc_us-gaap_SegmentReportingInformationLineItems_7B6BF646A5317343B2DEFCCAD1852908" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SegmentReportingInformationRevenueAbstract" xlink:label="loc_us-gaap_SegmentReportingInformationRevenueAbstract_A7292A446423D59C74C3FCCAD185D099" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_7B6BF646A5317343B2DEFCCAD1852908" xlink:to="loc_us-gaap_SegmentReportingInformationRevenueAbstract_A7292A446423D59C74C3FCCAD185D099" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_Revenues" xlink:label="loc_us-gaap_Revenues_32209B0E6B54AFF61938FCCAD185FB3E" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_SegmentReportingInformationRevenueAbstract_A7292A446423D59C74C3FCCAD185D099" xlink:to="loc_us-gaap_Revenues_32209B0E6B54AFF61938FCCAD185FB3E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_OperatingIncomeLoss" xlink:label="loc_us-gaap_OperatingIncomeLoss_722AFC0DF12F388FE523FCCAD1855662" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_SegmentReportingInformationRevenueAbstract_A7292A446423D59C74C3FCCAD185D099" xlink:to="loc_us-gaap_OperatingIncomeLoss_722AFC0DF12F388FE523FCCAD1855662" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DepreciationDepletionAndAmortization" xlink:label="loc_us-gaap_DepreciationDepletionAndAmortization_05F50DE0A2F2690183F5FCCAD185FAC5" xlink:type="locator" />
    <link:presentationArc order="3" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_SegmentReportingInformationRevenueAbstract_A7292A446423D59C74C3FCCAD185D099" xlink:to="loc_us-gaap_DepreciationDepletionAndAmortization_05F50DE0A2F2690183F5FCCAD185FAC5" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_PaymentsToAcquirePropertyPlantAndEquipmentAndProductiveAssets" xlink:label="loc_oesx_PaymentsToAcquirePropertyPlantAndEquipmentAndProductiveAssets_40017BD124B94F46A45AFCCAD1867BF6" xlink:type="locator" />
    <link:presentationArc order="4" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_SegmentReportingInformationRevenueAbstract_A7292A446423D59C74C3FCCAD185D099" xlink:to="loc_oesx_PaymentsToAcquirePropertyPlantAndEquipmentAndProductiveAssets_40017BD124B94F46A45AFCCAD1867BF6" xlink:type="arc" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.oesx.com/role/SegmentDataTables" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SegmentReportingAbstract" xlink:label="loc_us-gaap_SegmentReportingAbstract_54D2B6FBB7967D4DB97A66E046B468BD" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTextBlock" xlink:label="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTextBlock_1F723FE95C66613F674D66E046B4529C" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_SegmentReportingAbstract_54D2B6FBB7967D4DB97A66E046B468BD" xlink:to="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTextBlock_1F723FE95C66613F674D66E046B4529C" xlink:type="arc" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.oesx.com/role/ShareholdersEquity" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StockholdersEquityNoteAbstract" xlink:label="loc_us-gaap_StockholdersEquityNoteAbstract_C6F48B9CD95BF5E605380DBF99321923" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StockholdersEquityNoteDisclosureTextBlock" xlink:label="loc_us-gaap_StockholdersEquityNoteDisclosureTextBlock_8839D9EA08907DAAC7630DBF99325AC4" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_StockholdersEquityNoteAbstract_C6F48B9CD95BF5E605380DBF99321923" xlink:to="loc_us-gaap_StockholdersEquityNoteDisclosureTextBlock_8839D9EA08907DAAC7630DBF99325AC4" xlink:type="arc" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.oesx.com/role/ShareholdersEquityNarrativeDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StockholdersEquityNoteAbstract" xlink:label="loc_us-gaap_StockholdersEquityNoteAbstract_54D72650872C7DC0F75F41088232EF15" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ClassOfTreasuryStockTable" xlink:label="loc_us-gaap_ClassOfTreasuryStockTable_D3F53E20232D984AC75C41088232CF0B" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_StockholdersEquityNoteAbstract_54D72650872C7DC0F75F41088232EF15" xlink:to="loc_us-gaap_ClassOfTreasuryStockTable_D3F53E20232D984AC75C41088232CF0B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareRepurchaseProgramAxis" xlink:label="loc_us-gaap_ShareRepurchaseProgramAxis_C01C7BA26672930F6B664108823341EF" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ClassOfTreasuryStockTable_D3F53E20232D984AC75C41088232CF0B" xlink:to="loc_us-gaap_ShareRepurchaseProgramAxis_C01C7BA26672930F6B664108823341EF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareRepurchaseProgramDomain" xlink:label="loc_us-gaap_ShareRepurchaseProgramDomain_90BCB449375C4922E8F741088233B989" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareRepurchaseProgramAxis_C01C7BA26672930F6B664108823341EF" xlink:to="loc_us-gaap_ShareRepurchaseProgramDomain_90BCB449375C4922E8F741088233B989" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_October2011Member" xlink:label="loc_oesx_October2011Member_6CA26ED57B9D6A40138841088233AFA5" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareRepurchaseProgramDomain_90BCB449375C4922E8F741088233B989" xlink:to="loc_oesx_October2011Member_6CA26ED57B9D6A40138841088233AFA5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_EquityClassOfTreasuryStockLineItems" xlink:label="loc_us-gaap_EquityClassOfTreasuryStockLineItems_E236F39D3D038A59D0D741088233862B" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ClassOfTreasuryStockTable_D3F53E20232D984AC75C41088232CF0B" xlink:to="loc_us-gaap_EquityClassOfTreasuryStockLineItems_E236F39D3D038A59D0D741088233862B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesNewIssues" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues_80ED3AC19D3D23DE41D3410882331E2D" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_EquityClassOfTreasuryStockLineItems_E236F39D3D038A59D0D741088233862B" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues_80ED3AC19D3D23DE41D3410882331E2D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SharesIssuedPricePerShare" xlink:label="loc_us-gaap_SharesIssuedPricePerShare_9D3513C0B77585CEF323410882339C19" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_EquityClassOfTreasuryStockLineItems_E236F39D3D038A59D0D741088233862B" xlink:to="loc_us-gaap_SharesIssuedPricePerShare_9D3513C0B77585CEF323410882339C19" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ProceedsFromIssuanceOfCommonStock" xlink:label="loc_us-gaap_ProceedsFromIssuanceOfCommonStock_FE2B999AB652A2C3613641088233180E" xlink:type="locator" />
    <link:presentationArc order="3" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_EquityClassOfTreasuryStockLineItems_E236F39D3D038A59D0D741088233862B" xlink:to="loc_us-gaap_ProceedsFromIssuanceOfCommonStock_FE2B999AB652A2C3613641088233180E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StockRepurchaseProgramAuthorizedAmount1" xlink:label="loc_us-gaap_StockRepurchaseProgramAuthorizedAmount1_1233309D0E2201929DD041088233C17C" xlink:type="locator" />
    <link:presentationArc order="4" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_EquityClassOfTreasuryStockLineItems_E236F39D3D038A59D0D741088233862B" xlink:to="loc_us-gaap_StockRepurchaseProgramAuthorizedAmount1_1233309D0E2201929DD041088233C17C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_TreasuryStockSharesAcquired" xlink:label="loc_us-gaap_TreasuryStockSharesAcquired_F021953F868083E3CEEF41088233928A" xlink:type="locator" />
    <link:presentationArc order="5" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_EquityClassOfTreasuryStockLineItems_E236F39D3D038A59D0D741088233862B" xlink:to="loc_us-gaap_TreasuryStockSharesAcquired_F021953F868083E3CEEF41088233928A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PaymentsForRepurchaseOfCommonStock" xlink:label="loc_us-gaap_PaymentsForRepurchaseOfCommonStock_DDE85FACE35A49C0C93C4108823327C7" xlink:type="locator" />
    <link:presentationArc order="6" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_EquityClassOfTreasuryStockLineItems_E236F39D3D038A59D0D741088233862B" xlink:to="loc_us-gaap_PaymentsForRepurchaseOfCommonStock_DDE85FACE35A49C0C93C4108823327C7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByEachWarrantOrRight" xlink:label="loc_us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByEachWarrantOrRight_EE5468E2A895341948A5410882333193" xlink:type="locator" />
    <link:presentationArc order="7" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_EquityClassOfTreasuryStockLineItems_E236F39D3D038A59D0D741088233862B" xlink:to="loc_us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByEachWarrantOrRight_EE5468E2A895341948A5410882333193" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_RightIssueSharePrice" xlink:label="loc_oesx_RightIssueSharePrice_7F09F78B780A016706B34108823349BC" xlink:type="locator" />
    <link:presentationArc order="8" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_EquityClassOfTreasuryStockLineItems_E236F39D3D038A59D0D741088233862B" xlink:to="loc_oesx_RightIssueSharePrice_7F09F78B780A016706B34108823349BC" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_MinimumSubscriptionPercentage" xlink:label="loc_oesx_MinimumSubscriptionPercentage_4AE91488D2617681851D410882330FCA" xlink:type="locator" />
    <link:presentationArc order="9" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_EquityClassOfTreasuryStockLineItems_E236F39D3D038A59D0D741088233862B" xlink:to="loc_oesx_MinimumSubscriptionPercentage_4AE91488D2617681851D410882330FCA" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_RightsDistributionDateTriggerNumberOfBusinessDaysAfterCommencementOrOfferOfAcquisition" xlink:label="loc_oesx_RightsDistributionDateTriggerNumberOfBusinessDaysAfterCommencementOrOfferOfAcquisition_284716300EC30177CE8F41088233719C" xlink:type="locator" />
    <link:presentationArc order="10" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_EquityClassOfTreasuryStockLineItems_E236F39D3D038A59D0D741088233862B" xlink:to="loc_oesx_RightsDistributionDateTriggerNumberOfBusinessDaysAfterCommencementOrOfferOfAcquisition_284716300EC30177CE8F41088233719C" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_AcquisitionShareVoidPercentage" xlink:label="loc_oesx_AcquisitionShareVoidPercentage_ABA4BE1956FE0088960A41088233764A" xlink:type="locator" />
    <link:presentationArc order="11" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_EquityClassOfTreasuryStockLineItems_E236F39D3D038A59D0D741088233862B" xlink:to="loc_oesx_AcquisitionShareVoidPercentage_ABA4BE1956FE0088960A41088233764A" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_SharePurchaseRightsRedemptionPrice" xlink:label="loc_oesx_SharePurchaseRightsRedemptionPrice_9DA10E08AEE67B4E1396410882333BB9" xlink:type="locator" />
    <link:presentationArc order="12" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_EquityClassOfTreasuryStockLineItems_E236F39D3D038A59D0D741088233862B" xlink:to="loc_oesx_SharePurchaseRightsRedemptionPrice_9DA10E08AEE67B4E1396410882333BB9" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_EmployeeStockPurchasePlansSharesAuthorized" xlink:label="loc_oesx_EmployeeStockPurchasePlansSharesAuthorized_16EFA462F93721F9658341088233666D" xlink:type="locator" />
    <link:presentationArc order="13" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_EquityClassOfTreasuryStockLineItems_E236F39D3D038A59D0D741088233862B" xlink:to="loc_oesx_EmployeeStockPurchasePlansSharesAuthorized_16EFA462F93721F9658341088233666D" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_MaximumAmountLimitForEmployeeStockPurchasePlanPerEmployee" xlink:label="loc_oesx_MaximumAmountLimitForEmployeeStockPurchasePlanPerEmployee_8DCF304B123504E18AA341088234C404" xlink:type="locator" />
    <link:presentationArc order="14" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_EquityClassOfTreasuryStockLineItems_E236F39D3D038A59D0D741088233862B" xlink:to="loc_oesx_MaximumAmountLimitForEmployeeStockPurchasePlanPerEmployee_8DCF304B123504E18AA341088234C404" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_EmployeeStockPurchasePlanPurchasePriceToMarketPriceMatchingPercentage" xlink:label="loc_oesx_EmployeeStockPurchasePlanPurchasePriceToMarketPriceMatchingPercentage_B0DD1C6F77A058BE8C7A4108823466AE" xlink:type="locator" />
    <link:presentationArc order="15" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_EquityClassOfTreasuryStockLineItems_E236F39D3D038A59D0D741088233862B" xlink:to="loc_oesx_EmployeeStockPurchasePlanPurchasePriceToMarketPriceMatchingPercentage_B0DD1C6F77A058BE8C7A4108823466AE" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_EmployeeStockPurchasePlanAllowedLoanAmountPercentageOfAnnualIncome" xlink:label="loc_oesx_EmployeeStockPurchasePlanAllowedLoanAmountPercentageOfAnnualIncome_9351DFB5EF6418741FD6410882340ED9" xlink:type="locator" />
    <link:presentationArc order="16" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_EquityClassOfTreasuryStockLineItems_E236F39D3D038A59D0D741088233862B" xlink:to="loc_oesx_EmployeeStockPurchasePlanAllowedLoanAmountPercentageOfAnnualIncome_9351DFB5EF6418741FD6410882340ED9" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_EmployeeStockPurchasePlansLoanMaximumOutstandingAmount" xlink:label="loc_oesx_EmployeeStockPurchasePlansLoanMaximumOutstandingAmount_F9A69BF22E3BBD1AC5C04108823400F2" xlink:type="locator" />
    <link:presentationArc order="17" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_EquityClassOfTreasuryStockLineItems_E236F39D3D038A59D0D741088233862B" xlink:to="loc_oesx_EmployeeStockPurchasePlansLoanMaximumOutstandingAmount_F9A69BF22E3BBD1AC5C04108823400F2" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_EmployeeStockPurchasePlanLoanIRSInterestRate" xlink:label="loc_oesx_EmployeeStockPurchasePlanLoanIRSInterestRate_3537BC148F225C9594D8410882341E6E" xlink:type="locator" />
    <link:presentationArc order="18" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_EquityClassOfTreasuryStockLineItems_E236F39D3D038A59D0D741088233862B" xlink:to="loc_oesx_EmployeeStockPurchasePlanLoanIRSInterestRate_3537BC148F225C9594D8410882341E6E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ReceivableFromShareholdersOrAffiliatesForIssuanceOfCapitalStock" xlink:label="loc_us-gaap_ReceivableFromShareholdersOrAffiliatesForIssuanceOfCapitalStock_3041AA2445C3498C5F68417FD0341DC4" xlink:type="locator" />
    <link:presentationArc order="19" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_EquityClassOfTreasuryStockLineItems_E236F39D3D038A59D0D741088233862B" xlink:to="loc_us-gaap_ReceivableFromShareholdersOrAffiliatesForIssuanceOfCapitalStock_3041AA2445C3498C5F68417FD0341DC4" xlink:type="arc" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.oesx.com/role/ShareholdersEquityScheduleOfEsppActivityDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StockholdersEquityNoteAbstract" xlink:label="loc_us-gaap_StockholdersEquityNoteAbstract_E8B4FA61F40AB9311C3B5FEF2A9F5FEF" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScheduleOfEmployeeStockOwnershipPlanESOPDisclosuresTable" xlink:label="loc_us-gaap_ScheduleOfEmployeeStockOwnershipPlanESOPDisclosuresTable_08631A3840755B0688205FEF2AA0442F" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_StockholdersEquityNoteAbstract_E8B4FA61F40AB9311C3B5FEF2A9F5FEF" xlink:to="loc_us-gaap_ScheduleOfEmployeeStockOwnershipPlanESOPDisclosuresTable_08631A3840755B0688205FEF2AA0442F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RangeAxis" xlink:label="loc_us-gaap_RangeAxis_D4A94E7108B88D90FF8B5FEF2AA081D5" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfEmployeeStockOwnershipPlanESOPDisclosuresTable_08631A3840755B0688205FEF2AA0442F" xlink:to="loc_us-gaap_RangeAxis_D4A94E7108B88D90FF8B5FEF2AA081D5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember_73808E76CED425CF084A5FEF2AA0B748" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_RangeAxis_D4A94E7108B88D90FF8B5FEF2AA081D5" xlink:to="loc_us-gaap_RangeMember_73808E76CED425CF084A5FEF2AA0B748" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_MinimumMember" xlink:label="loc_us-gaap_MinimumMember_D286930F0532038FC3E55FEF2AA05FB6" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_RangeMember_73808E76CED425CF084A5FEF2AA0B748" xlink:to="loc_us-gaap_MinimumMember_D286930F0532038FC3E55FEF2AA05FB6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_MaximumMember" xlink:label="loc_us-gaap_MaximumMember_CB2DA41DCB5FC937DEB45FEF2AA02CF6" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_RangeMember_73808E76CED425CF084A5FEF2AA0B748" xlink:to="loc_us-gaap_MaximumMember_CB2DA41DCB5FC937DEB45FEF2AA02CF6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_EmployeeStockOwnershipPlanESOPDisclosuresLineItems" xlink:label="loc_us-gaap_EmployeeStockOwnershipPlanESOPDisclosuresLineItems_F6C577FD34BEBC1954EB5FEF2AA08FEC" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfEmployeeStockOwnershipPlanESOPDisclosuresTable_08631A3840755B0688205FEF2AA0442F" xlink:to="loc_us-gaap_EmployeeStockOwnershipPlanESOPDisclosuresLineItems_F6C577FD34BEBC1954EB5FEF2AA08FEC" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_SummaryOfIssuanceOfStockUnderEmployeeStockOwnershipPlanAbstract" xlink:label="loc_oesx_SummaryOfIssuanceOfStockUnderEmployeeStockOwnershipPlanAbstract_87856DA0A908554E6B1E5FEF2AA0C565" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_EmployeeStockOwnershipPlanESOPDisclosuresLineItems_F6C577FD34BEBC1954EB5FEF2AA08FEC" xlink:to="loc_oesx_SummaryOfIssuanceOfStockUnderEmployeeStockOwnershipPlanAbstract_87856DA0A908554E6B1E5FEF2AA0C565" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans_2485FAE7E0459C4B0C705FEF2AA175E2" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_oesx_SummaryOfIssuanceOfStockUnderEmployeeStockOwnershipPlanAbstract_87856DA0A908554E6B1E5FEF2AA0C565" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans_2485FAE7E0459C4B0C705FEF2AA175E2" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_EmployeeStockPurchasePlanClosingMarketPriceOfSharesPurchased" xlink:label="loc_oesx_EmployeeStockPurchasePlanClosingMarketPriceOfSharesPurchased_F1D51F4C5DBB8E9F2CB15FEF2AA1408E" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_oesx_SummaryOfIssuanceOfStockUnderEmployeeStockOwnershipPlanAbstract_87856DA0A908554E6B1E5FEF2AA0C565" xlink:to="loc_oesx_EmployeeStockPurchasePlanClosingMarketPriceOfSharesPurchased_F1D51F4C5DBB8E9F2CB15FEF2AA1408E" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_EmployeeStockPurchasePlansDebtStructureSharesIssued" xlink:label="loc_oesx_EmployeeStockPurchasePlansDebtStructureSharesIssued_CAAD635AAD8EFFAE3F3C5FEF2AA1C9A7" xlink:type="locator" />
    <link:presentationArc order="3" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_oesx_SummaryOfIssuanceOfStockUnderEmployeeStockOwnershipPlanAbstract_87856DA0A908554E6B1E5FEF2AA0C565" xlink:to="loc_oesx_EmployeeStockPurchasePlansDebtStructureSharesIssued_CAAD635AAD8EFFAE3F3C5FEF2AA1C9A7" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_EmployeeStockPurchasePlansDebtStructureDirectLoanAmount" xlink:label="loc_oesx_EmployeeStockPurchasePlansDebtStructureDirectLoanAmount_AD7096705EA9AD50C8505FEF2AA1CF1B" xlink:type="locator" />
    <link:presentationArc order="4" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_oesx_SummaryOfIssuanceOfStockUnderEmployeeStockOwnershipPlanAbstract_87856DA0A908554E6B1E5FEF2AA0C565" xlink:to="loc_oesx_EmployeeStockPurchasePlansDebtStructureDirectLoanAmount_AD7096705EA9AD50C8505FEF2AA1CF1B" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_EmployeeStockPurchasePlansDebtStructureDirectLoanRepaymentAmount" xlink:label="loc_oesx_EmployeeStockPurchasePlansDebtStructureDirectLoanRepaymentAmount_42790A450A11E1A7C1685FEF2AA121F1" xlink:type="locator" />
    <link:presentationArc order="5" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_oesx_SummaryOfIssuanceOfStockUnderEmployeeStockOwnershipPlanAbstract_87856DA0A908554E6B1E5FEF2AA0C565" xlink:to="loc_oesx_EmployeeStockPurchasePlansDebtStructureDirectLoanRepaymentAmount_42790A450A11E1A7C1685FEF2AA121F1" xlink:type="arc" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.oesx.com/role/ShareholdersEquityTables" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StockholdersEquityNoteAbstract" xlink:label="loc_us-gaap_StockholdersEquityNoteAbstract_94B998C173C63518818766E0438BFFB7" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationEmployeeStockPurchasePlanActivityTableTextBlock" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationEmployeeStockPurchasePlanActivityTableTextBlock_CCB56EDD572934BAF30766E0438BBAB0" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_StockholdersEquityNoteAbstract_94B998C173C63518818766E0438BFFB7" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationEmployeeStockPurchasePlanActivityTableTextBlock_CCB56EDD572934BAF30766E0438BBAB0" xlink:type="arc" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.oesx.com/role/StatementsOfShareholdersEquity" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StatementOfStockholdersEquityAbstract" xlink:label="loc_us-gaap_StatementOfStockholdersEquityAbstract_CFF3A46F934285625CCA7E7FE1AD66F4" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaap_StatementTable_37E218B944EB1FD8923D7E7FE1AE4066" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_StatementOfStockholdersEquityAbstract_CFF3A46F934285625CCA7E7FE1AD66F4" xlink:to="loc_us-gaap_StatementTable_37E218B944EB1FD8923D7E7FE1AE4066" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StatementEquityComponentsAxis" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_6576E0B46590D9DA92E07E7FE1AF2062" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_StatementTable_37E218B944EB1FD8923D7E7FE1AE4066" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_6576E0B46590D9DA92E07E7FE1AF2062" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaap_EquityComponentDomain_25B9625B631371FB1F3B7E7FE1B0BA01" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_6576E0B46590D9DA92E07E7FE1AF2062" xlink:to="loc_us-gaap_EquityComponentDomain_25B9625B631371FB1F3B7E7FE1B0BA01" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CommonStockMember" xlink:label="loc_us-gaap_CommonStockMember_29860B30C18529D86C277E7FE1B0FDC5" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_EquityComponentDomain_25B9625B631371FB1F3B7E7FE1B0BA01" xlink:to="loc_us-gaap_CommonStockMember_29860B30C18529D86C277E7FE1B0FDC5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CommonStockIncludingAdditionalPaidInCapitalMember" xlink:label="loc_us-gaap_CommonStockIncludingAdditionalPaidInCapitalMember_FE1806EBA1E5B01015507E7FE1B022DC" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_EquityComponentDomain_25B9625B631371FB1F3B7E7FE1B0BA01" xlink:to="loc_us-gaap_CommonStockIncludingAdditionalPaidInCapitalMember_FE1806EBA1E5B01015507E7FE1B022DC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_TreasuryStockMember" xlink:label="loc_us-gaap_TreasuryStockMember_521B4243434B690111727E7FE1B063CC" xlink:type="locator" />
    <link:presentationArc order="3" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_EquityComponentDomain_25B9625B631371FB1F3B7E7FE1B0BA01" xlink:to="loc_us-gaap_TreasuryStockMember_521B4243434B690111727E7FE1B063CC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ReceivablesFromStockholderMember" xlink:label="loc_us-gaap_ReceivablesFromStockholderMember_5F4B91E193A92E53126A7E7FE1B2630B" xlink:type="locator" />
    <link:presentationArc order="4" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_EquityComponentDomain_25B9625B631371FB1F3B7E7FE1B0BA01" xlink:to="loc_us-gaap_ReceivablesFromStockholderMember_5F4B91E193A92E53126A7E7FE1B2630B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RetainedEarningsMember" xlink:label="loc_us-gaap_RetainedEarningsMember_4896798F3FBDF8599D0C7E7FE1B2D076" xlink:type="locator" />
    <link:presentationArc order="5" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_EquityComponentDomain_25B9625B631371FB1F3B7E7FE1B0BA01" xlink:to="loc_us-gaap_RetainedEarningsMember_4896798F3FBDF8599D0C7E7FE1B2D076" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaap_StatementLineItems_9B4651035D3018C9559A7E7FE1B22B84" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_StatementTable_37E218B944EB1FD8923D7E7FE1AE4066" xlink:to="loc_us-gaap_StatementLineItems_9B4651035D3018C9559A7E7FE1B22B84" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_IncreaseDecreaseInStockholdersEquityRollForward" xlink:label="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_04E0FC75604630B109B67E7FE1B3DC1C" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_StatementLineItems_9B4651035D3018C9559A7E7FE1B22B84" xlink:to="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_04E0FC75604630B109B67E7FE1B3DC1C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SharesOutstanding" xlink:label="loc_us-gaap_SharesOutstanding_5DF456A7EEE9C6E7302D7E7FE1B31803" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/periodStartLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_04E0FC75604630B109B67E7FE1B3DC1C" xlink:to="loc_us-gaap_SharesOutstanding_5DF456A7EEE9C6E7302D7E7FE1B31803" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StockholdersEquity" xlink:label="loc_us-gaap_StockholdersEquity_75F7E7E194CF2919AC8F7E7FE1B3B928" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/periodStartLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_04E0FC75604630B109B67E7FE1B3DC1C" xlink:to="loc_us-gaap_StockholdersEquity_75F7E7E194CF2919AC8F7E7FE1B3B928" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesNewIssues" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues_F2BB5186C17C83C9D53C7E7FE1B3D3BA" xlink:type="locator" />
    <link:presentationArc order="3" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_04E0FC75604630B109B67E7FE1B3DC1C" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues_F2BB5186C17C83C9D53C7E7FE1B3D3BA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueNewIssues" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueNewIssues_D5514F623015B921984E7E7FE1B320BF" xlink:type="locator" />
    <link:presentationArc order="4" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_04E0FC75604630B109B67E7FE1B3DC1C" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueNewIssues_D5514F623015B921984E7E7FE1B320BF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesIssuedForServices" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesIssuedForServices_695C375F101F0893799E7E7FE1B3887D" xlink:type="locator" />
    <link:presentationArc order="5" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_04E0FC75604630B109B67E7FE1B3DC1C" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesIssuedForServices_695C375F101F0893799E7E7FE1B3887D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueIssuedForServices" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueIssuedForServices_DEEF1E0668B3F61BE0A37E7FE1B397FA" xlink:type="locator" />
    <link:presentationArc order="6" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_04E0FC75604630B109B67E7FE1B3DC1C" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueIssuedForServices_DEEF1E0668B3F61BE0A37E7FE1B397FA" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_Stockissuedduringperiodsharesstockoptionsandwarrantsexercised" xlink:label="loc_oesx_Stockissuedduringperiodsharesstockoptionsandwarrantsexercised_034BCA6D23107E6A38127E7FE1B49384" xlink:type="locator" />
    <link:presentationArc order="7" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_04E0FC75604630B109B67E7FE1B3DC1C" xlink:to="loc_oesx_Stockissuedduringperiodsharesstockoptionsandwarrantsexercised_034BCA6D23107E6A38127E7FE1B49384" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_StockIssuedDuringPeriodValueStockOptionsandWarrantsExercised" xlink:label="loc_oesx_StockIssuedDuringPeriodValueStockOptionsandWarrantsExercised_002B78DDBAA71FC47B527E7FE1B425F3" xlink:type="locator" />
    <link:presentationArc order="8" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_04E0FC75604630B109B67E7FE1B3DC1C" xlink:to="loc_oesx_StockIssuedDuringPeriodValueStockOptionsandWarrantsExercised_002B78DDBAA71FC47B527E7FE1B425F3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans_0A34CDDC56FD276C911F7E7FE1B46D39" xlink:type="locator" />
    <link:presentationArc order="9" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_04E0FC75604630B109B67E7FE1B3DC1C" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans_0A34CDDC56FD276C911F7E7FE1B46D39" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueEmployeeStockPurchasePlan" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueEmployeeStockPurchasePlan_4614E1C908B5C28322F47E7FE1B402F6" xlink:type="locator" />
    <link:presentationArc order="10" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_04E0FC75604630B109B67E7FE1B3DC1C" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueEmployeeStockPurchasePlan_4614E1C908B5C28322F47E7FE1B402F6" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_StockholdersEquityReceivablefromShareholdersorAffiliatesforIssuanceofCapitalStock" xlink:label="loc_oesx_StockholdersEquityReceivablefromShareholdersorAffiliatesforIssuanceofCapitalStock_F64E066EEA68A5011F717E7FE1B4D301" xlink:type="locator" />
    <link:presentationArc order="11" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_04E0FC75604630B109B67E7FE1B3DC1C" xlink:to="loc_oesx_StockholdersEquityReceivablefromShareholdersorAffiliatesforIssuanceofCapitalStock_F64E066EEA68A5011F717E7FE1B4D301" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardGross" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardGross_C69B4B1A45F7C24233077E7FE1B434C6" xlink:type="locator" />
    <link:presentationArc order="12" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_04E0FC75604630B109B67E7FE1B3DC1C" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardGross_C69B4B1A45F7C24233077E7FE1B434C6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue" xlink:label="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_DD82D7C0ED0F7E03D0DE7E7FE1B48512" xlink:type="locator" />
    <link:presentationArc order="13" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_04E0FC75604630B109B67E7FE1B3DC1C" xlink:to="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_DD82D7C0ED0F7E03D0DE7E7FE1B48512" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation" xlink:label="loc_us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation_84A9F9A1A4DD2CE400B77E7FE1B465D7" xlink:type="locator" />
    <link:presentationArc order="14" preferredLabel="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_04E0FC75604630B109B67E7FE1B3DC1C" xlink:to="loc_us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation_84A9F9A1A4DD2CE400B77E7FE1B465D7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AdjustmentsRelatedToTaxWithholdingForShareBasedCompensation" xlink:label="loc_us-gaap_AdjustmentsRelatedToTaxWithholdingForShareBasedCompensation_B61EBA28C0B9EB46B36F7E7FE1B4E7E9" xlink:type="locator" />
    <link:presentationArc order="15" preferredLabel="http://www.xbrl.org/2009/role/negatedLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_04E0FC75604630B109B67E7FE1B3DC1C" xlink:to="loc_us-gaap_AdjustmentsRelatedToTaxWithholdingForShareBasedCompensation_B61EBA28C0B9EB46B36F7E7FE1B4E7E9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_NetIncomeLoss" xlink:label="loc_us-gaap_NetIncomeLoss_319207D9D015308004CD7E7FE1B457A3" xlink:type="locator" />
    <link:presentationArc order="16" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_04E0FC75604630B109B67E7FE1B3DC1C" xlink:to="loc_us-gaap_NetIncomeLoss_319207D9D015308004CD7E7FE1B457A3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SharesOutstanding" xlink:label="loc_us-gaap_SharesOutstanding_2A9B8C37987BE1404AA67E7FE1B56536" xlink:type="locator" />
    <link:presentationArc order="17" preferredLabel="http://www.xbrl.org/2003/role/periodEndLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_04E0FC75604630B109B67E7FE1B3DC1C" xlink:to="loc_us-gaap_SharesOutstanding_2A9B8C37987BE1404AA67E7FE1B56536" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StockholdersEquity" xlink:label="loc_us-gaap_StockholdersEquity_E086DD1771D11F462DD57E7FE1B58620" xlink:type="locator" />
    <link:presentationArc order="18" preferredLabel="http://www.xbrl.org/2003/role/periodEndLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_04E0FC75604630B109B67E7FE1B3DC1C" xlink:to="loc_us-gaap_StockholdersEquity_E086DD1771D11F462DD57E7FE1B58620" xlink:type="arc" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.oesx.com/role/StockOptionsRestrictedSharesAndWarrants" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract" xlink:label="loc_us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract_DF11AD3DD6BF0E1F67FE0DBF98F2B5F3" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DisclosureOfCompensationRelatedCostsShareBasedPaymentsTextBlock" xlink:label="loc_us-gaap_DisclosureOfCompensationRelatedCostsShareBasedPaymentsTextBlock_AC84A4800CDF2562B8BF0DBF98F243AA" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract_DF11AD3DD6BF0E1F67FE0DBF98F2B5F3" xlink:to="loc_us-gaap_DisclosureOfCompensationRelatedCostsShareBasedPaymentsTextBlock_AC84A4800CDF2562B8BF0DBF98F243AA" xlink:type="arc" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.oesx.com/role/StockOptionsRestrictedSharesAndWarrantsNarrativeDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract" xlink:label="loc_us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract_2D63DD06E04F5DE6D65160123CAA080A" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_BEDA40EC82B63C19BF6A60123CAC55C7" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract_2D63DD06E04F5DE6D65160123CAA080A" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_BEDA40EC82B63C19BF6A60123CAC55C7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AwardTypeAxis" xlink:label="loc_us-gaap_AwardTypeAxis_D4A0DF19144B03C6421360123CAC3949" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_BEDA40EC82B63C19BF6A60123CAC55C7" xlink:to="loc_us-gaap_AwardTypeAxis_D4A0DF19144B03C6421360123CAC3949" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_0571ADABF88AF4E443D960123CAD6AC1" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AwardTypeAxis_D4A0DF19144B03C6421360123CAC3949" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_0571ADABF88AF4E443D960123CAD6AC1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RestrictedStockMember" xlink:label="loc_us-gaap_RestrictedStockMember_9F82EA5CFA23C902552560123CAD9620" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_0571ADABF88AF4E443D960123CAD6AC1" xlink:to="loc_us-gaap_RestrictedStockMember_9F82EA5CFA23C902552560123CAD9620" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_NonEmployeeDirectorMember" xlink:label="loc_oesx_NonEmployeeDirectorMember_6A913D0451BF89CEEE6A60123CAD9A67" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_0571ADABF88AF4E443D960123CAD6AC1" xlink:to="loc_oesx_NonEmployeeDirectorMember_6A913D0451BF89CEEE6A60123CAD9A67" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RangeAxis" xlink:label="loc_us-gaap_RangeAxis_D3945D295D862C39320C60123CAD5AE1" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_BEDA40EC82B63C19BF6A60123CAC55C7" xlink:to="loc_us-gaap_RangeAxis_D3945D295D862C39320C60123CAD5AE1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember_7D0D3C9F43DBF38B0B8760123CAD7518" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_RangeAxis_D3945D295D862C39320C60123CAD5AE1" xlink:to="loc_us-gaap_RangeMember_7D0D3C9F43DBF38B0B8760123CAD7518" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_MinimumMember" xlink:label="loc_us-gaap_MinimumMember_2F6D29729D4138B227B560123CADEEEC" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_RangeMember_7D0D3C9F43DBF38B0B8760123CAD7518" xlink:to="loc_us-gaap_MinimumMember_2F6D29729D4138B227B560123CADEEEC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_MaximumMember" xlink:label="loc_us-gaap_MaximumMember_EAFF47F005C4A9ED99D560123CAD530A" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_RangeMember_7D0D3C9F43DBF38B0B8760123CAD7518" xlink:to="loc_us-gaap_MaximumMember_EAFF47F005C4A9ED99D560123CAD530A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PlanNameAxis" xlink:label="loc_us-gaap_PlanNameAxis_4C0234B6BF83581B3EB560123CAC8CA8" xlink:type="locator" />
    <link:presentationArc order="3" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_BEDA40EC82B63C19BF6A60123CAC55C7" xlink:to="loc_us-gaap_PlanNameAxis_4C0234B6BF83581B3EB560123CAC8CA8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PlanNameDomain" xlink:label="loc_us-gaap_PlanNameDomain_A35B7C805A7064FA0ABD60123CAC1207" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_PlanNameAxis_4C0234B6BF83581B3EB560123CAC8CA8" xlink:to="loc_us-gaap_PlanNameDomain_A35B7C805A7064FA0ABD60123CAC1207" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_TwoThousandFourStockAndIncentiveAndAwardPlanMember" xlink:label="loc_oesx_TwoThousandFourStockAndIncentiveAndAwardPlanMember_9D2374C9F71B26E6906560123CAC7246" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_PlanNameDomain_A35B7C805A7064FA0ABD60123CAC1207" xlink:to="loc_oesx_TwoThousandFourStockAndIncentiveAndAwardPlanMember_9D2374C9F71B26E6906560123CAC7246" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StatementClassOfStockAxis" xlink:label="loc_us-gaap_StatementClassOfStockAxis_3CFB6C3A181E51AFA6EE60123CAED49A" xlink:type="locator" />
    <link:presentationArc order="4" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_BEDA40EC82B63C19BF6A60123CAC55C7" xlink:to="loc_us-gaap_StatementClassOfStockAxis_3CFB6C3A181E51AFA6EE60123CAED49A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_385C6131CBF8A3CAC13160123CAE8094" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_StatementClassOfStockAxis_3CFB6C3A181E51AFA6EE60123CAED49A" xlink:to="loc_us-gaap_ClassOfStockDomain_385C6131CBF8A3CAC13160123CAE8094" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CommonStockMember" xlink:label="loc_us-gaap_CommonStockMember_9DDCAEDA677B57704C7160123CAEEFE1" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ClassOfStockDomain_385C6131CBF8A3CAC13160123CAE8094" xlink:to="loc_us-gaap_CommonStockMember_9DDCAEDA677B57704C7160123CAEEFE1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_TitleOfIndividualAxis" xlink:label="loc_us-gaap_TitleOfIndividualAxis_D2D44A6E96D8B9ACEB2160123CAE1EF9" xlink:type="locator" />
    <link:presentationArc order="5" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_BEDA40EC82B63C19BF6A60123CAC55C7" xlink:to="loc_us-gaap_TitleOfIndividualAxis_D2D44A6E96D8B9ACEB2160123CAE1EF9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_TitleOfIndividualWithRelationshipToEntityDomain" xlink:label="loc_us-gaap_TitleOfIndividualWithRelationshipToEntityDomain_6A60F115C409383686F960123CAECA11" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_TitleOfIndividualAxis_D2D44A6E96D8B9ACEB2160123CAE1EF9" xlink:to="loc_us-gaap_TitleOfIndividualWithRelationshipToEntityDomain_6A60F115C409383686F960123CAECA11" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ExecutiveOfficerMember" xlink:label="loc_us-gaap_ExecutiveOfficerMember_47F07BF944BAD233EAC760123CAE2602" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_TitleOfIndividualWithRelationshipToEntityDomain_6A60F115C409383686F960123CAECA11" xlink:to="loc_us-gaap_ExecutiveOfficerMember_47F07BF944BAD233EAC760123CAE2602" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DirectorMember" xlink:label="loc_us-gaap_DirectorMember_BE5D7201513D3272AC5560123CAE636D" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_TitleOfIndividualWithRelationshipToEntityDomain_6A60F115C409383686F960123CAECA11" xlink:to="loc_us-gaap_DirectorMember_BE5D7201513D3272AC5560123CAE636D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_4138A5C38C3887FA261F60123CAF295A" xlink:type="locator" />
    <link:presentationArc order="6" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_BEDA40EC82B63C19BF6A60123CAC55C7" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_4138A5C38C3887FA261F60123CAF295A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CommonStockCapitalSharesReservedForFutureIssuance" xlink:label="loc_us-gaap_CommonStockCapitalSharesReservedForFutureIssuance_B2A2FBB3538A00C3688660123CAFC855" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_4138A5C38C3887FA261F60123CAF295A" xlink:to="loc_us-gaap_CommonStockCapitalSharesReservedForFutureIssuance_B2A2FBB3538A00C3688660123CAFC855" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInPeriod" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInPeriod_B7C3E5524F347472FE4C60123CAF488A" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_4138A5C38C3887FA261F60123CAF295A" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInPeriod_B7C3E5524F347472FE4C60123CAF488A" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_ShareBasedCompensationArrangementByShareBasedPaymentAwardPerSharePrice" xlink:label="loc_oesx_ShareBasedCompensationArrangementByShareBasedPaymentAwardPerSharePrice_766126E3850B36D282CA60123CAF1247" xlink:type="locator" />
    <link:presentationArc order="3" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_4138A5C38C3887FA261F60123CAF295A" xlink:to="loc_oesx_ShareBasedCompensationArrangementByShareBasedPaymentAwardPerSharePrice_766126E3850B36D282CA60123CAF1247" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedGoodsAndNonemployeeServicesTransactionQuantityOfSecuritiesIssued" xlink:label="loc_us-gaap_ShareBasedGoodsAndNonemployeeServicesTransactionQuantityOfSecuritiesIssued_41555AAA473116AA922D60123CAF49BB" xlink:type="locator" />
    <link:presentationArc order="4" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_4138A5C38C3887FA261F60123CAF295A" xlink:to="loc_us-gaap_ShareBasedGoodsAndNonemployeeServicesTransactionQuantityOfSecuritiesIssued_41555AAA473116AA922D60123CAF49BB" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_FairValueOfClosingCommonStockPrice" xlink:label="loc_oesx_FairValueOfClosingCommonStockPrice_373A1F4ADA9AB62DDA7260123CAF0B4A" xlink:type="locator" />
    <link:presentationArc order="5" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_4138A5C38C3887FA261F60123CAF295A" xlink:to="loc_oesx_FairValueOfClosingCommonStockPrice_373A1F4ADA9AB62DDA7260123CAF0B4A" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_SharebasedGoodsandNonemployeeServicesTransactionSecuritiesIssuedValuationPricePerShare" xlink:label="loc_oesx_SharebasedGoodsandNonemployeeServicesTransactionSecuritiesIssuedValuationPricePerShare_7439FEA27550A46991F860123CAF41AF" xlink:type="locator" />
    <link:presentationArc order="6" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_4138A5C38C3887FA261F60123CAF295A" xlink:to="loc_oesx_SharebasedGoodsandNonemployeeServicesTransactionSecuritiesIssuedValuationPricePerShare_7439FEA27550A46991F860123CAF41AF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensationGross" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensationGross_986154C8DA187E21283760123CB07178" xlink:type="locator" />
    <link:presentationArc order="7" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_4138A5C38C3887FA261F60123CAF295A" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensationGross_986154C8DA187E21283760123CB07178" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_NumberofRecentlyRetiredMembersoftheBoard" xlink:label="loc_oesx_NumberofRecentlyRetiredMembersoftheBoard_159246F89CB1BF2E9B0660123CB0DABB" xlink:type="locator" />
    <link:presentationArc order="8" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_4138A5C38C3887FA261F60123CAF295A" xlink:to="loc_oesx_NumberofRecentlyRetiredMembersoftheBoard_159246F89CB1BF2E9B0660123CB0DABB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_8AB9584F2A4457E95AE660123CB0326D" xlink:type="locator" />
    <link:presentationArc order="9" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_4138A5C38C3887FA261F60123CAF295A" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_8AB9584F2A4457E95AE660123CB0326D" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_ClassOfWarrantOrRightExercised" xlink:label="loc_oesx_ClassOfWarrantOrRightExercised_DFCE1542D61DF5EEC88860123CB04234" xlink:type="locator" />
    <link:presentationArc order="10" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_4138A5C38C3887FA261F60123CAF295A" xlink:to="loc_oesx_ClassOfWarrantOrRightExercised_DFCE1542D61DF5EEC88860123CB04234" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_ClassofWarrantorRightExercisePriceofWarrantsorRightsExercised" xlink:label="loc_oesx_ClassofWarrantorRightExercisePriceofWarrantsorRightsExercised_8293AF433EF69C845C4060123CB0C2B6" xlink:type="locator" />
    <link:presentationArc order="11" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_4138A5C38C3887FA261F60123CAF295A" xlink:to="loc_oesx_ClassofWarrantorRightExercisePriceofWarrantsorRightsExercised_8293AF433EF69C845C4060123CB0C2B6" xlink:type="arc" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.oesx.com/role/StockOptionsRestrictedSharesAndWarrantsScheduleOfRestrictedSharesDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract" xlink:label="loc_us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract_B4E0D38056F67EEB2258418CEF426059" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_AF57695F7F3181FA5B78418CEF42E738" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract_B4E0D38056F67EEB2258418CEF426059" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_AF57695F7F3181FA5B78418CEF42E738" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AwardTypeAxis" xlink:label="loc_us-gaap_AwardTypeAxis_45A54062BC40A74DB15F418CEF43D077" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_AF57695F7F3181FA5B78418CEF42E738" xlink:to="loc_us-gaap_AwardTypeAxis_45A54062BC40A74DB15F418CEF43D077" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_0D1F34F6287F8B926C57418CEF43E78D" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AwardTypeAxis_45A54062BC40A74DB15F418CEF43D077" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_0D1F34F6287F8B926C57418CEF43E78D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RestrictedStockMember" xlink:label="loc_us-gaap_RestrictedStockMember_31E40D216AFC41CA87D9418CEF434DC4" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_0D1F34F6287F8B926C57418CEF43E78D" xlink:to="loc_us-gaap_RestrictedStockMember_31E40D216AFC41CA87D9418CEF434DC4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RangeAxis" xlink:label="loc_us-gaap_RangeAxis_F57A2BE1C051F895A669418CEF436A62" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_AF57695F7F3181FA5B78418CEF42E738" xlink:to="loc_us-gaap_RangeAxis_F57A2BE1C051F895A669418CEF436A62" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember_53234589B622241BE87A418CEF434089" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_RangeAxis_F57A2BE1C051F895A669418CEF436A62" xlink:to="loc_us-gaap_RangeMember_53234589B622241BE87A418CEF434089" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_MinimumMember" xlink:label="loc_us-gaap_MinimumMember_F00E43EF429486DEA0A4418CEF44F162" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_RangeMember_53234589B622241BE87A418CEF434089" xlink:to="loc_us-gaap_MinimumMember_F00E43EF429486DEA0A4418CEF44F162" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_MaximumMember" xlink:label="loc_us-gaap_MaximumMember_94EAA2AD029434A2EBE4418CEF448982" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_RangeMember_53234589B622241BE87A418CEF434089" xlink:to="loc_us-gaap_MaximumMember_94EAA2AD029434A2EBE4418CEF448982" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_AE3C977FC2C9A0A79A2B418CEF443278" xlink:type="locator" />
    <link:presentationArc order="3" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_AF57695F7F3181FA5B78418CEF42E738" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_AE3C977FC2C9A0A79A2B418CEF443278" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_F08249A3C4674DE801CC418CEF4412B7" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_AE3C977FC2C9A0A79A2B418CEF443278" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_F08249A3C4674DE801CC418CEF4412B7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_BE89782660F486A23569418CEF442182" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/periodStartLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_F08249A3C4674DE801CC418CEF4412B7" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_BE89782660F486A23569418CEF442182" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_BA0440AE89B01DBE994A418CEF442910" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_F08249A3C4674DE801CC418CEF4412B7" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_BA0440AE89B01DBE994A418CEF442910" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_682E5586CB364267FDF4418CEF447E17" xlink:type="locator" />
    <link:presentationArc order="3" preferredLabel="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_F08249A3C4674DE801CC418CEF4412B7" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_682E5586CB364267FDF4418CEF447E17" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_D4DF96DB18A1ABAD6C75418CEF450A47" xlink:type="locator" />
    <link:presentationArc order="4" preferredLabel="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_F08249A3C4674DE801CC418CEF4412B7" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_D4DF96DB18A1ABAD6C75418CEF450A47" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_70176BBAECE49BE5C487418CEF45626C" xlink:type="locator" />
    <link:presentationArc order="5" preferredLabel="http://www.xbrl.org/2003/role/periodEndLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_F08249A3C4674DE801CC418CEF4412B7" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_70176BBAECE49BE5C487418CEF45626C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_28BE4FEEF4FF07BF1E7A418CEF456496" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_AE3C977FC2C9A0A79A2B418CEF443278" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_28BE4FEEF4FF07BF1E7A418CEF456496" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AllocatedShareBasedCompensationExpense" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpense_B38CEF97205FB0C9A271418CEF453C36" xlink:type="locator" />
    <link:presentationArc order="3" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_AE3C977FC2C9A0A79A2B418CEF443278" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpense_B38CEF97205FB0C9A271418CEF453C36" xlink:type="arc" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.oesx.com/role/StockOptionsRestrictedSharesAndWarrantsScheduleOfSharesAvailableForGrantDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract" xlink:label="loc_us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract_825133118D8F1D4A283E844B46660873" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_0B954E40D6732B63CA83844B4666D44A" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract_825133118D8F1D4A283E844B46660873" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_0B954E40D6732B63CA83844B4666D44A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AwardTypeAxis" xlink:label="loc_us-gaap_AwardTypeAxis_8C6DA505BA3B1ABFDC5B844B466640BB" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_0B954E40D6732B63CA83844B4666D44A" xlink:to="loc_us-gaap_AwardTypeAxis_8C6DA505BA3B1ABFDC5B844B466640BB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_B9735E9A4518ADB8969D844B4666BA2D" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AwardTypeAxis_8C6DA505BA3B1ABFDC5B844B466640BB" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_B9735E9A4518ADB8969D844B4666BA2D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_EmployeeStockOptionMember" xlink:label="loc_us-gaap_EmployeeStockOptionMember_2086624B122CB0E32A59844B4666294D" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_B9735E9A4518ADB8969D844B4666BA2D" xlink:to="loc_us-gaap_EmployeeStockOptionMember_2086624B122CB0E32A59844B4666294D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RestrictedStockMember" xlink:label="loc_us-gaap_RestrictedStockMember_3839FF9761487E16733B844B466691C0" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_B9735E9A4518ADB8969D844B4666BA2D" xlink:to="loc_us-gaap_RestrictedStockMember_3839FF9761487E16733B844B466691C0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_6644DDBC74CFD181459A844B46669342" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_0B954E40D6732B63CA83844B4666D44A" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_6644DDBC74CFD181459A844B46669342" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrantRollForward" xlink:label="loc_oesx_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrantRollForward_A41FAAF586346B1A3EEB844B4666C4B7" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_6644DDBC74CFD181459A844B46669342" xlink:to="loc_oesx_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrantRollForward_A41FAAF586346B1A3EEB844B4666C4B7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant_547D0B1342B9014CFF28844B4666F14D" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/periodStartLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_oesx_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrantRollForward_A41FAAF586346B1A3EEB844B4666C4B7" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant_547D0B1342B9014CFF28844B4666F14D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CommonStockCapitalSharesReservedForFutureIssuance" xlink:label="loc_us-gaap_CommonStockCapitalSharesReservedForFutureIssuance_737379D3B4F686E6CAD9846557D9C3DB" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_oesx_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrantRollForward_A41FAAF586346B1A3EEB844B4666C4B7" xlink:to="loc_us-gaap_CommonStockCapitalSharesReservedForFutureIssuance_737379D3B4F686E6CAD9846557D9C3DB" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrantSharesCanceled" xlink:label="loc_oesx_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrantSharesCanceled_8A5327C011258A91F70B848E2F60D349" xlink:type="locator" />
    <link:presentationArc order="3" preferredLabel="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_oesx_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrantRollForward_A41FAAF586346B1A3EEB844B4666C4B7" xlink:to="loc_oesx_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrantSharesCanceled_8A5327C011258A91F70B848E2F60D349" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrantSharesIssuedToEmployee" xlink:label="loc_oesx_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrantSharesIssuedToEmployee_7A1743BF1F80069F618A844B4666E1E0" xlink:type="locator" />
    <link:presentationArc order="4" preferredLabel="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_oesx_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrantRollForward_A41FAAF586346B1A3EEB844B4666C4B7" xlink:to="loc_oesx_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrantSharesIssuedToEmployee_7A1743BF1F80069F618A844B4666E1E0" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrantSharesIssuedToNonEmployee" xlink:label="loc_oesx_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrantSharesIssuedToNonEmployee_FCC71E9EAE657FC187C1844B4666B949" xlink:type="locator" />
    <link:presentationArc order="5" preferredLabel="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_oesx_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrantRollForward_A41FAAF586346B1A3EEB844B4666C4B7" xlink:to="loc_oesx_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrantSharesIssuedToNonEmployee_FCC71E9EAE657FC187C1844B4666B949" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrantRestrictedShares" xlink:label="loc_oesx_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrantRestrictedShares_524F437B925AC2A2E5E8844B46661118" xlink:type="locator" />
    <link:presentationArc order="6" preferredLabel="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_oesx_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrantRollForward_A41FAAF586346B1A3EEB844B4666C4B7" xlink:to="loc_oesx_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrantRestrictedShares_524F437B925AC2A2E5E8844B46661118" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrantForfeited" xlink:label="loc_oesx_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrantForfeited_ADAD7E16D5A692CC273B844B4666F9E2" xlink:type="locator" />
    <link:presentationArc order="7" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_oesx_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrantRollForward_A41FAAF586346B1A3EEB844B4666C4B7" xlink:to="loc_oesx_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrantForfeited_ADAD7E16D5A692CC273B844B4666F9E2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant_5EDAB621CA1B86CB2E0F844B4667E235" xlink:type="locator" />
    <link:presentationArc order="8" preferredLabel="http://www.xbrl.org/2003/role/periodEndLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_oesx_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrantRollForward_A41FAAF586346B1A3EEB844B4666C4B7" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant_5EDAB621CA1B86CB2E0F844B4667E235" xlink:type="arc" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.oesx.com/role/StockOptionsRestrictedSharesAndWarrantsStockBasedCompensationDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract" xlink:label="loc_us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract_3DE395A4D2B2274052A666E0490ADCFA" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable" xlink:label="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_7A037E068E843E610BC166E0490A99B6" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract_3DE395A4D2B2274052A666E0490ADCFA" xlink:to="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_7A037E068E843E610BC166E0490A99B6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_IncomeStatementLocationAxis" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_621301AB8375442E394866E0490A3C92" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_7A037E068E843E610BC166E0490A99B6" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_621301AB8375442E394866E0490A3C92" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_FAB5B9958C884612ED9066E0490AA2EE" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_621301AB8375442E394866E0490A3C92" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_FAB5B9958C884612ED9066E0490AA2EE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CostOfSalesMember" xlink:label="loc_us-gaap_CostOfSalesMember_7DE108C4480D5716C5E766E0490B605C" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_FAB5B9958C884612ED9066E0490AA2EE" xlink:to="loc_us-gaap_CostOfSalesMember_7DE108C4480D5716C5E766E0490B605C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_GeneralAndAdministrativeExpenseMember" xlink:label="loc_us-gaap_GeneralAndAdministrativeExpenseMember_9FABEBAECAB02FDF2F5366E0490B2D33" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_FAB5B9958C884612ED9066E0490AA2EE" xlink:to="loc_us-gaap_GeneralAndAdministrativeExpenseMember_9FABEBAECAB02FDF2F5366E0490B2D33" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SellingAndMarketingExpenseMember" xlink:label="loc_us-gaap_SellingAndMarketingExpenseMember_D9A17DC3BD4924B581F666E0490C4440" xlink:type="locator" />
    <link:presentationArc order="3" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_FAB5B9958C884612ED9066E0490AA2EE" xlink:to="loc_us-gaap_SellingAndMarketingExpenseMember_D9A17DC3BD4924B581F666E0490C4440" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ResearchAndDevelopmentExpenseMember" xlink:label="loc_us-gaap_ResearchAndDevelopmentExpenseMember_8EDD43CA6481AD6555A866E0490C2F0E" xlink:type="locator" />
    <link:presentationArc order="4" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_FAB5B9958C884612ED9066E0490AA2EE" xlink:to="loc_us-gaap_ResearchAndDevelopmentExpenseMember_8EDD43CA6481AD6555A866E0490C2F0E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_11B628AD640B2393EF1566E0490C8C3E" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_7A037E068E843E610BC166E0490A99B6" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_11B628AD640B2393EF1566E0490C8C3E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensationAllocationAndClassificationInFinancialStatementsAbstract" xlink:label="loc_us-gaap_ShareBasedCompensationAllocationAndClassificationInFinancialStatementsAbstract_56DDBB39E48F93126B4266E0490DC3D8" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_11B628AD640B2393EF1566E0490C8C3E" xlink:to="loc_us-gaap_ShareBasedCompensationAllocationAndClassificationInFinancialStatementsAbstract_56DDBB39E48F93126B4266E0490DC3D8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AllocatedShareBasedCompensationExpense" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpense_1F02D5A06F18BDF492BE66E0490DC439" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationAllocationAndClassificationInFinancialStatementsAbstract_56DDBB39E48F93126B4266E0490DC3D8" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpense_1F02D5A06F18BDF492BE66E0490DC439" xlink:type="arc" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.oesx.com/role/StockOptionsRestrictedSharesAndWarrantsSummaryOfExercisePriceRangeDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract" xlink:label="loc_us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract_ADA0965964670FF422E65FA93DF387D3" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeTable" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeTable_87FC8C86C9A561F2FB045FA93DF313B5" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract_ADA0965964670FF422E65FA93DF387D3" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeTable_87FC8C86C9A561F2FB045FA93DF313B5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis" xlink:label="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis_38F125B12682D9F819A35FA93DF925F2" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeTable_87FC8C86C9A561F2FB045FA93DF313B5" xlink:to="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis_38F125B12682D9F819A35FA93DF925F2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain" xlink:label="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_F5F725ED29EBDBF3B1785FA93DF9966F" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis_38F125B12682D9F819A35FA93DF925F2" xlink:to="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_F5F725ED29EBDBF3B1785FA93DF9966F" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_RangeTwoMember" xlink:label="loc_oesx_RangeTwoMember_E348E78E7D1F16ED36005FA93DF99470" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_F5F725ED29EBDBF3B1785FA93DF9966F" xlink:to="loc_oesx_RangeTwoMember_E348E78E7D1F16ED36005FA93DF99470" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_RangeThreeMember" xlink:label="loc_oesx_RangeThreeMember_1DB417A050BAC84D9F655FA93DFA989D" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_F5F725ED29EBDBF3B1785FA93DF9966F" xlink:to="loc_oesx_RangeThreeMember_1DB417A050BAC84D9F655FA93DFA989D" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_RangeFourMember" xlink:label="loc_oesx_RangeFourMember_B3F89FAEAE06CC3DBF195FA93DFA5374" xlink:type="locator" />
    <link:presentationArc order="3" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_F5F725ED29EBDBF3B1785FA93DF9966F" xlink:to="loc_oesx_RangeFourMember_B3F89FAEAE06CC3DBF195FA93DFA5374" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_RangeFiveMember" xlink:label="loc_oesx_RangeFiveMember_647B0AEC7863C54CCD635FA93DFAC160" xlink:type="locator" />
    <link:presentationArc order="4" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_F5F725ED29EBDBF3B1785FA93DF9966F" xlink:to="loc_oesx_RangeFiveMember_647B0AEC7863C54CCD635FA93DFAC160" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_RangeSixMember" xlink:label="loc_oesx_RangeSixMember_FE78DC8572ECEAFA57F25FA93DFADBF1" xlink:type="locator" />
    <link:presentationArc order="5" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_F5F725ED29EBDBF3B1785FA93DF9966F" xlink:to="loc_oesx_RangeSixMember_FE78DC8572ECEAFA57F25FA93DFADBF1" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_RangeSevenMember" xlink:label="loc_oesx_RangeSevenMember_342B91856704F874216F5FA93DFB84E4" xlink:type="locator" />
    <link:presentationArc order="6" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_F5F725ED29EBDBF3B1785FA93DF9966F" xlink:to="loc_oesx_RangeSevenMember_342B91856704F874216F5FA93DFB84E4" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_RangeEightMember" xlink:label="loc_oesx_RangeEightMember_218256719B1282A3313C5FA93DFBBBDF" xlink:type="locator" />
    <link:presentationArc order="7" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_F5F725ED29EBDBF3B1785FA93DF9966F" xlink:to="loc_oesx_RangeEightMember_218256719B1282A3313C5FA93DFBBBDF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems" xlink:label="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems_E498ADE13E9B77979F955FA93DFB1594" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeTable_87FC8C86C9A561F2FB045FA93DF313B5" xlink:to="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems_E498ADE13E9B77979F955FA93DFB1594" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit" xlink:label="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit_9D22178A0FC2FAC907815FA93DFBC73C" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems_E498ADE13E9B77979F955FA93DFB1594" xlink:to="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit_9D22178A0FC2FAC907815FA93DFBC73C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit" xlink:label="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit_CB5AE1BB00BD55B5EE425FA93DFBD2DF" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems_E498ADE13E9B77979F955FA93DFB1594" xlink:to="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit_CB5AE1BB00BD55B5EE425FA93DFBD2DF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_53603FBA0B08890BFE925FA93DFBF24C" xlink:type="locator" />
    <link:presentationArc order="3" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems_E498ADE13E9B77979F955FA93DFB1594" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_53603FBA0B08890BFE925FA93DFBF24C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2_9F688A3CA031B34CBFBA5FA93DFC79A2" xlink:type="locator" />
    <link:presentationArc order="4" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems_E498ADE13E9B77979F955FA93DFB1594" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2_9F688A3CA031B34CBFBA5FA93DFC79A2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_4916B14A8DB9EE86B6335FA93DFCC811" xlink:type="locator" />
    <link:presentationArc order="5" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems_E498ADE13E9B77979F955FA93DFB1594" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_4916B14A8DB9EE86B6335FA93DFCC811" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber_7CF6F87BBEFC5E71044A5FA93DFC2B59" xlink:type="locator" />
    <link:presentationArc order="6" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems_E498ADE13E9B77979F955FA93DFB1594" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber_7CF6F87BBEFC5E71044A5FA93DFC2B59" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageExercisePrice" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageExercisePrice_2A98B8C445B88A1506D35FA93DFC291A" xlink:type="locator" />
    <link:presentationArc order="7" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems_E498ADE13E9B77979F955FA93DFB1594" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageExercisePrice_2A98B8C445B88A1506D35FA93DFC291A" xlink:type="arc" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.oesx.com/role/StockOptionsRestrictedSharesAndWarrantsSummaryOfOutstandingStockOptionsDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract" xlink:label="loc_us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract_5B4DB3B7E6B7DA88AD2A0DE88B69CB6B" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_9EA79C7A581FB1B994020DE88B69844B" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract_5B4DB3B7E6B7DA88AD2A0DE88B69CB6B" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_9EA79C7A581FB1B994020DE88B69844B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_75580CB4ED4F4DE951870DE88B69FFB8" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/periodStartLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_9EA79C7A581FB1B994020DE88B69844B" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_75580CB4ED4F4DE951870DE88B69FFB8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_BE3492ED2C50EF7E13F90DE88B69FB48" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_9EA79C7A581FB1B994020DE88B69844B" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_BE3492ED2C50EF7E13F90DE88B69FB48" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_3911299D35CF1CF37E0F0DE88B699FDE" xlink:type="locator" />
    <link:presentationArc order="3" preferredLabel="http://www.xbrl.org/2009/role/negatedLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_9EA79C7A581FB1B994020DE88B69844B" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_3911299D35CF1CF37E0F0DE88B699FDE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod_CE52C9949601E0CC9E6C0DE88B692126" xlink:type="locator" />
    <link:presentationArc order="4" preferredLabel="http://www.xbrl.org/2009/role/negatedLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_9EA79C7A581FB1B994020DE88B69844B" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod_CE52C9949601E0CC9E6C0DE88B692126" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_EC9F1B8D9656700B28E90DE88B6933CC" xlink:type="locator" />
    <link:presentationArc order="5" preferredLabel="http://www.xbrl.org/2003/role/periodEndLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_9EA79C7A581FB1B994020DE88B69844B" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_EC9F1B8D9656700B28E90DE88B6933CC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber_C55A8CF4F262751522AA0DE88B6A51AA" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract_5B4DB3B7E6B7DA88AD2A0DE88B69CB6B" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber_C55A8CF4F262751522AA0DE88B6A51AA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_681F32372BA81528A9650DE88B6A0B79" xlink:type="locator" />
    <link:presentationArc order="3" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract_5B4DB3B7E6B7DA88AD2A0DE88B69CB6B" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_681F32372BA81528A9650DE88B6A0B79" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_B1F78736308275795A6D0DE88B6AFB15" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/periodStartLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_681F32372BA81528A9650DE88B6A0B79" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_B1F78736308275795A6D0DE88B6AFB15" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice_CD0C23700BEEFE28F9710DE88B6ACC99" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_681F32372BA81528A9650DE88B6A0B79" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice_CD0C23700BEEFE28F9710DE88B6ACC99" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice_56A4653938F812EBCAA00DE88B6A2C96" xlink:type="locator" />
    <link:presentationArc order="3" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_681F32372BA81528A9650DE88B6A0B79" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice_56A4653938F812EBCAA00DE88B6A2C96" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice_E2780826B96352D82FA80DE88B6A1857" xlink:type="locator" />
    <link:presentationArc order="4" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_681F32372BA81528A9650DE88B6A0B79" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice_E2780826B96352D82FA80DE88B6A1857" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_83B4828DF443130769020DE88B6A2D0D" xlink:type="locator" />
    <link:presentationArc order="5" preferredLabel="http://www.xbrl.org/2003/role/periodEndLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_681F32372BA81528A9650DE88B6A0B79" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_83B4828DF443130769020DE88B6A2D0D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_60D8AC3F3432C0A18EF30DE88B6A051B" xlink:type="locator" />
    <link:presentationArc order="4" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract_5B4DB3B7E6B7DA88AD2A0DE88B69CB6B" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_60D8AC3F3432C0A18EF30DE88B6A051B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue_36810B1E64B5B47C26030DE88B6A834B" xlink:type="locator" />
    <link:presentationArc order="5" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract_5B4DB3B7E6B7DA88AD2A0DE88B69CB6B" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue_36810B1E64B5B47C26030DE88B6A834B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1_0FECE2FB42F6FD0772500DE88B6B5BEF" xlink:type="locator" />
    <link:presentationArc order="6" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract_5B4DB3B7E6B7DA88AD2A0DE88B69CB6B" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1_0FECE2FB42F6FD0772500DE88B6B5BEF" xlink:type="arc" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.oesx.com/role/StockOptionsRestrictedSharesAndWarrantsSummaryOfUnrecognizedCompensationCostDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract" xlink:label="loc_us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract_CD858AF5FF3D82F11233FCCAD1E2AB98" xlink:type="locator" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_EmployeeServiceShareBasedCompensationNonvestedAwardsCompensationCostNotYetRecognizedNextTwelveMonths" xlink:label="loc_oesx_EmployeeServiceShareBasedCompensationNonvestedAwardsCompensationCostNotYetRecognizedNextTwelveMonths_1D954909229CF1C4B5E8FCCAD1E2B3F1" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract_CD858AF5FF3D82F11233FCCAD1E2AB98" xlink:to="loc_oesx_EmployeeServiceShareBasedCompensationNonvestedAwardsCompensationCostNotYetRecognizedNextTwelveMonths_1D954909229CF1C4B5E8FCCAD1E2B3F1" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_EmployeeServiceShareBasedCompensationNonvestedAwardsCompensationCostNotYetRecognizedDueInTwoYears" xlink:label="loc_oesx_EmployeeServiceShareBasedCompensationNonvestedAwardsCompensationCostNotYetRecognizedDueInTwoYears_9E63F07905B4053E7BA1FCCAD1E2F623" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract_CD858AF5FF3D82F11233FCCAD1E2AB98" xlink:to="loc_oesx_EmployeeServiceShareBasedCompensationNonvestedAwardsCompensationCostNotYetRecognizedDueInTwoYears_9E63F07905B4053E7BA1FCCAD1E2F623" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_EmployeeServiceShareBasedCompensationNonvestedAwardsCompensationCostNotYetRecognizedDueInThreeYears" xlink:label="loc_oesx_EmployeeServiceShareBasedCompensationNonvestedAwardsCompensationCostNotYetRecognizedDueInThreeYears_E3B2AA3F83714447784BFCCAD1E25A83" xlink:type="locator" />
    <link:presentationArc order="3" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract_CD858AF5FF3D82F11233FCCAD1E2AB98" xlink:to="loc_oesx_EmployeeServiceShareBasedCompensationNonvestedAwardsCompensationCostNotYetRecognizedDueInThreeYears_E3B2AA3F83714447784BFCCAD1E25A83" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_EmployeeServiceShareBasedCompensationNonvestedAwardsCompensationCostNotYetRecognizedDueInFourYears" xlink:label="loc_oesx_EmployeeServiceShareBasedCompensationNonvestedAwardsCompensationCostNotYetRecognizedDueInFourYears_D8FDFFAD8BC68AB73A63FCCAD1E2C94B" xlink:type="locator" />
    <link:presentationArc order="4" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract_CD858AF5FF3D82F11233FCCAD1E2AB98" xlink:to="loc_oesx_EmployeeServiceShareBasedCompensationNonvestedAwardsCompensationCostNotYetRecognizedDueInFourYears_D8FDFFAD8BC68AB73A63FCCAD1E2C94B" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_EmployeeServiceShareBasedCompensationNonvestedAwardsCompensationCostNotYetRecognizedDueInFiveYears" xlink:label="loc_oesx_EmployeeServiceShareBasedCompensationNonvestedAwardsCompensationCostNotYetRecognizedDueInFiveYears_A1348C560C26FC5773C1FCCAD1E3323E" xlink:type="locator" />
    <link:presentationArc order="5" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract_CD858AF5FF3D82F11233FCCAD1E2AB98" xlink:to="loc_oesx_EmployeeServiceShareBasedCompensationNonvestedAwardsCompensationCostNotYetRecognizedDueInFiveYears_A1348C560C26FC5773C1FCCAD1E3323E" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_EmployeeServiceShareBasedCompensationNonvestedAwardsCompensationCostNotYetRecognizedDueThereafter" xlink:label="loc_oesx_EmployeeServiceShareBasedCompensationNonvestedAwardsCompensationCostNotYetRecognizedDueThereafter_3F78E599F13B51B3AC7BFCCAD1E3802A" xlink:type="locator" />
    <link:presentationArc order="6" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract_CD858AF5FF3D82F11233FCCAD1E2AB98" xlink:to="loc_oesx_EmployeeServiceShareBasedCompensationNonvestedAwardsCompensationCostNotYetRecognizedDueThereafter_3F78E599F13B51B3AC7BFCCAD1E3802A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_E65CFE12052A880716F9FCCAD1E398C8" xlink:type="locator" />
    <link:presentationArc order="7" preferredLabel="http://www.xbrl.org/2003/role/totalLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract_CD858AF5FF3D82F11233FCCAD1E2AB98" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_E65CFE12052A880716F9FCCAD1E398C8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_90991F1DF4DDA7A0351DFCCAD1E3C409" xlink:type="locator" />
    <link:presentationArc order="8" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract_CD858AF5FF3D82F11233FCCAD1E2AB98" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_90991F1DF4DDA7A0351DFCCAD1E3C409" xlink:type="arc" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.oesx.com/role/StockOptionsRestrictedSharesAndWarrantsTables" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract" xlink:label="loc_us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract_7B738CF0029457B88518844B46756CC7" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTextBlock" xlink:label="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTextBlock_B06923B037A585602605844B4675D37F" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract_7B738CF0029457B88518844B46756CC7" xlink:to="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTextBlock_B06923B037A585602605844B4675D37F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DisclosureOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTextBlock" xlink:label="loc_us-gaap_DisclosureOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTextBlock_ACBFC28B95632C15F152844B46759D8B" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract_7B738CF0029457B88518844B46756CC7" xlink:to="loc_us-gaap_DisclosureOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTextBlock_ACBFC28B95632C15F152844B46759D8B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationStockOptionsActivityTableTextBlock" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationStockOptionsActivityTableTextBlock_12E6E85C5A3032D334AA844B4675ED03" xlink:type="locator" />
    <link:presentationArc order="3" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract_7B738CF0029457B88518844B46756CC7" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationStockOptionsActivityTableTextBlock_12E6E85C5A3032D334AA844B4675ED03" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeTextBlock" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeTextBlock_949D2280A80B70CC87D6844B46750255" xlink:type="locator" />
    <link:presentationArc order="4" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract_7B738CF0029457B88518844B46756CC7" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeTextBlock_949D2280A80B70CC87D6844B46750255" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScheduleOfSharebasedCompensationRestrictedStockAndRestrictedStockUnitsActivityTableTextBlock" xlink:label="loc_us-gaap_ScheduleOfSharebasedCompensationRestrictedStockAndRestrictedStockUnitsActivityTableTextBlock_7940CD2AF0C4F00533C0844B4675BCEB" xlink:type="locator" />
    <link:presentationArc order="5" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract_7B738CF0029457B88518844B46756CC7" xlink:to="loc_us-gaap_ScheduleOfSharebasedCompensationRestrictedStockAndRestrictedStockUnitsActivityTableTextBlock_7940CD2AF0C4F00533C0844B4675BCEB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScheduleOfUnrecognizedCompensationCostNonvestedAwardsTableTextBlock" xlink:label="loc_us-gaap_ScheduleOfUnrecognizedCompensationCostNonvestedAwardsTableTextBlock_6AA40AAAF5BBFEB06A09844B4675AE78" xlink:type="locator" />
    <link:presentationArc order="6" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract_7B738CF0029457B88518844B46756CC7" xlink:to="loc_us-gaap_ScheduleOfUnrecognizedCompensationCostNonvestedAwardsTableTextBlock_6AA40AAAF5BBFEB06A09844B4675AE78" xlink:type="arc" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.oesx.com/role/SubsequentEvents" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SubsequentEventsAbstract" xlink:label="loc_us-gaap_SubsequentEventsAbstract_659542EE0E7E852934760DBF981C8139" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SubsequentEventsTextBlock" xlink:label="loc_us-gaap_SubsequentEventsTextBlock_1321AA3762CDDD98038B0DBF981D74EE" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_SubsequentEventsAbstract_659542EE0E7E852934760DBF981C8139" xlink:to="loc_us-gaap_SubsequentEventsTextBlock_1321AA3762CDDD98038B0DBF981D74EE" xlink:type="arc" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.oesx.com/role/SubsequentEventsDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SubsequentEventsAbstract" xlink:label="loc_us-gaap_SubsequentEventsAbstract_D1CD4CF93603CBEF4848846E1ECBBDFA" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SubsequentEventTable" xlink:label="loc_us-gaap_SubsequentEventTable_94FF029F0280A6B6E0D1846E206F6F8D" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_SubsequentEventsAbstract_D1CD4CF93603CBEF4848846E1ECBBDFA" xlink:to="loc_us-gaap_SubsequentEventTable_94FF029F0280A6B6E0D1846E206F6F8D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SubsequentEventTypeAxis" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_E8DE315F94CD888B1D66846E207009CB" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_SubsequentEventTable_94FF029F0280A6B6E0D1846E206F6F8D" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_E8DE315F94CD888B1D66846E207009CB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_EA4F5E34C2DC80B75DED846E20712F80" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_E8DE315F94CD888B1D66846E207009CB" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_EA4F5E34C2DC80B75DED846E20712F80" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SubsequentEventMember" xlink:label="loc_us-gaap_SubsequentEventMember_C6BA102EFF039FB5CE48846FCC9A9DE5" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_EA4F5E34C2DC80B75DED846E20712F80" xlink:to="loc_us-gaap_SubsequentEventMember_C6BA102EFF039FB5CE48846FCC9A9DE5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RestructuringCostAndReserveAxis" xlink:label="loc_us-gaap_RestructuringCostAndReserveAxis_9DC6D3D6D45AF7571FA4846F426220E8" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_SubsequentEventTable_94FF029F0280A6B6E0D1846E206F6F8D" xlink:to="loc_us-gaap_RestructuringCostAndReserveAxis_9DC6D3D6D45AF7571FA4846F426220E8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_TypeOfRestructuringDomain" xlink:label="loc_us-gaap_TypeOfRestructuringDomain_E60C13D2C57441357017846F9C6368D7" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_RestructuringCostAndReserveAxis_9DC6D3D6D45AF7571FA4846F426220E8" xlink:to="loc_us-gaap_TypeOfRestructuringDomain_E60C13D2C57441357017846F9C6368D7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SpecialTerminationBenefitsMember" xlink:label="loc_us-gaap_SpecialTerminationBenefitsMember_B2D4CFB712F757AD7FBB847051F4E251" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_TypeOfRestructuringDomain_E60C13D2C57441357017846F9C6368D7" xlink:to="loc_us-gaap_SpecialTerminationBenefitsMember_B2D4CFB712F757AD7FBB847051F4E251" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RangeAxis" xlink:label="loc_us-gaap_RangeAxis_BB2336DD66D5ACDE6C29847118E0246B" xlink:type="locator" />
    <link:presentationArc order="3" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_SubsequentEventTable_94FF029F0280A6B6E0D1846E206F6F8D" xlink:to="loc_us-gaap_RangeAxis_BB2336DD66D5ACDE6C29847118E0246B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember_8F99AA4938499206FBB1847118E1F850" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_RangeAxis_BB2336DD66D5ACDE6C29847118E0246B" xlink:to="loc_us-gaap_RangeMember_8F99AA4938499206FBB1847118E1F850" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_MinimumMember" xlink:label="loc_us-gaap_MinimumMember_A3A15B9185E536446E73847145D5B9B4" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_RangeMember_8F99AA4938499206FBB1847118E1F850" xlink:to="loc_us-gaap_MinimumMember_A3A15B9185E536446E73847145D5B9B4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_MaximumMember" xlink:label="loc_us-gaap_MaximumMember_B77B20FEC9083375CEA084716A4259FF" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_RangeMember_8F99AA4938499206FBB1847118E1F850" xlink:to="loc_us-gaap_MaximumMember_B77B20FEC9083375CEA084716A4259FF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SubsequentEventLineItems" xlink:label="loc_us-gaap_SubsequentEventLineItems_D3DF78D21F606B8FF602846E20724C3F" xlink:type="locator" />
    <link:presentationArc order="4" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_SubsequentEventTable_94FF029F0280A6B6E0D1846E206F6F8D" xlink:to="loc_us-gaap_SubsequentEventLineItems_D3DF78D21F606B8FF602846E20724C3F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RestructuringAndRelatedCostExpectedCost1" xlink:label="loc_us-gaap_RestructuringAndRelatedCostExpectedCost1_A014707FD8CC3527F821846F056529AD" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_SubsequentEventLineItems_D3DF78D21F606B8FF602846E20724C3F" xlink:to="loc_us-gaap_RestructuringAndRelatedCostExpectedCost1_A014707FD8CC3527F821846F056529AD" xlink:type="arc" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.oesx.com/role/SummaryOfSignificantAccountingPolicies" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AccountingPoliciesAbstract" xlink:label="loc_us-gaap_AccountingPoliciesAbstract_6833D7666EB7EFEB2A9040C28C542E36" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SignificantAccountingPoliciesTextBlock" xlink:label="loc_us-gaap_SignificantAccountingPoliciesTextBlock_589593CD148D4EDEBC2240C28C540287" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AccountingPoliciesAbstract_6833D7666EB7EFEB2A9040C28C542E36" xlink:to="loc_us-gaap_SignificantAccountingPoliciesTextBlock_589593CD148D4EDEBC2240C28C540287" xlink:type="arc" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.oesx.com/role/SummaryOfSignificantAccountingPoliciesConcentrationRiskDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AccountingPoliciesAbstract" xlink:label="loc_us-gaap_AccountingPoliciesAbstract_0CB5E3D95473AB225C6964B047FE5F5D" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ConcentrationRiskTable" xlink:label="loc_us-gaap_ConcentrationRiskTable_058952DD9DD81E49DEA264B047FF5877" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AccountingPoliciesAbstract_0CB5E3D95473AB225C6964B047FE5F5D" xlink:to="loc_us-gaap_ConcentrationRiskTable_058952DD9DD81E49DEA264B047FF5877" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ConcentrationRiskByTypeAxis" xlink:label="loc_us-gaap_ConcentrationRiskByTypeAxis_3D061B50CC64FE5F93F164B047FF2532" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ConcentrationRiskTable_058952DD9DD81E49DEA264B047FF5877" xlink:to="loc_us-gaap_ConcentrationRiskByTypeAxis_3D061B50CC64FE5F93F164B047FF2532" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ConcentrationRiskTypeDomain" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_747352DB91A74D33C01864B047FF1BCE" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_3D061B50CC64FE5F93F164B047FF2532" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_747352DB91A74D33C01864B047FF1BCE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CustomerConcentrationRiskMember" xlink:label="loc_us-gaap_CustomerConcentrationRiskMember_FF23DD4D0C4F903528A964B047FF45E3" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ConcentrationRiskTypeDomain_747352DB91A74D33C01864B047FF1BCE" xlink:to="loc_us-gaap_CustomerConcentrationRiskMember_FF23DD4D0C4F903528A964B047FF45E3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ConcentrationRiskByBenchmarkAxis" xlink:label="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_CC0A7D7A5D04755A496264B047FFA90B" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ConcentrationRiskTable_058952DD9DD81E49DEA264B047FF5877" xlink:to="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_CC0A7D7A5D04755A496264B047FFA90B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ConcentrationRiskBenchmarkDomain" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_B9479CAAF99F78823C1764B047FF017F" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_CC0A7D7A5D04755A496264B047FFA90B" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_B9479CAAF99F78823C1764B047FF017F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SalesMember" xlink:label="loc_us-gaap_SalesMember_540D40C9D82761C30F6664B047FF6613" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ConcentrationRiskBenchmarkDomain_B9479CAAF99F78823C1764B047FF017F" xlink:to="loc_us-gaap_SalesMember_540D40C9D82761C30F6664B047FF6613" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AccountsReceivableMember" xlink:label="loc_us-gaap_AccountsReceivableMember_BBAD0AD3909F5C3D0BA964B047FF9287" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ConcentrationRiskBenchmarkDomain_B9479CAAF99F78823C1764B047FF017F" xlink:to="loc_us-gaap_AccountsReceivableMember_BBAD0AD3909F5C3D0BA964B047FF9287" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_MajorCustomersAxis" xlink:label="loc_us-gaap_MajorCustomersAxis_EB2371C0BEA42238551264B047FF74B3" xlink:type="locator" />
    <link:presentationArc order="3" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ConcentrationRiskTable_058952DD9DD81E49DEA264B047FF5877" xlink:to="loc_us-gaap_MajorCustomersAxis_EB2371C0BEA42238551264B047FF74B3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_NameOfMajorCustomerDomain" xlink:label="loc_us-gaap_NameOfMajorCustomerDomain_A34D1A8C5A06268A8E9064B047FFE576" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_MajorCustomersAxis_EB2371C0BEA42238551264B047FF74B3" xlink:to="loc_us-gaap_NameOfMajorCustomerDomain_A34D1A8C5A06268A8E9064B047FFE576" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_CustomerOneMember" xlink:label="loc_oesx_CustomerOneMember_074E9DB19DED52189C6164B047FFEBDB" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_NameOfMajorCustomerDomain_A34D1A8C5A06268A8E9064B047FFE576" xlink:to="loc_oesx_CustomerOneMember_074E9DB19DED52189C6164B047FFEBDB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ConcentrationRiskLineItems" xlink:label="loc_us-gaap_ConcentrationRiskLineItems_FD6A5213781B49DF713D64B047FF3D7F" xlink:type="locator" />
    <link:presentationArc order="4" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ConcentrationRiskTable_058952DD9DD81E49DEA264B047FF5877" xlink:to="loc_us-gaap_ConcentrationRiskLineItems_FD6A5213781B49DF713D64B047FF3D7F" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_NumberofFinancialInstitutions" xlink:label="loc_oesx_NumberofFinancialInstitutions_A9FA343485CE08D2CBA364B047FFF8B4" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_FD6A5213781B49DF713D64B047FF3D7F" xlink:to="loc_oesx_NumberofFinancialInstitutions_A9FA343485CE08D2CBA364B047FFF8B4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ConcentrationRiskPercentage1" xlink:label="loc_us-gaap_ConcentrationRiskPercentage1_4A7E938FAFC8944E05D264B047FF37C4" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_FD6A5213781B49DF713D64B047FF3D7F" xlink:to="loc_us-gaap_ConcentrationRiskPercentage1_4A7E938FAFC8944E05D264B047FF37C4" xlink:type="arc" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.oesx.com/role/SummaryOfSignificantAccountingPoliciesIncentiveCompensationDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AccountingPoliciesAbstract" xlink:label="loc_us-gaap_AccountingPoliciesAbstract_535B0D74CD169841781940C2858CE451" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScheduleOfDeferredCompensationArrangementWithIndividualExcludingShareBasedPaymentsAndPostretirementBenefitsByTitleOfIndividualAndByTypeOfDeferredCompensationTable" xlink:label="loc_us-gaap_ScheduleOfDeferredCompensationArrangementWithIndividualExcludingShareBasedPaymentsAndPostretirementBenefitsByTitleOfIndividualAndByTypeOfDeferredCompensationTable_09447BFAEDE1ED553C1A40C2858CF7E5" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AccountingPoliciesAbstract_535B0D74CD169841781940C2858CE451" xlink:to="loc_us-gaap_ScheduleOfDeferredCompensationArrangementWithIndividualExcludingShareBasedPaymentsAndPostretirementBenefitsByTitleOfIndividualAndByTypeOfDeferredCompensationTable_09447BFAEDE1ED553C1A40C2858CF7E5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DeferredCompensationArrangementWithIndividualExcludingShareBasedPaymentsAndPostretirementBenefitsByTypeOfDeferredCompensationAxis" xlink:label="loc_us-gaap_DeferredCompensationArrangementWithIndividualExcludingShareBasedPaymentsAndPostretirementBenefitsByTypeOfDeferredCompensationAxis_3C1C9A7A843E1EEB267940C2858C03DC" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfDeferredCompensationArrangementWithIndividualExcludingShareBasedPaymentsAndPostretirementBenefitsByTitleOfIndividualAndByTypeOfDeferredCompensationTable_09447BFAEDE1ED553C1A40C2858CF7E5" xlink:to="loc_us-gaap_DeferredCompensationArrangementWithIndividualExcludingShareBasedPaymentsAndPostretirementBenefitsByTypeOfDeferredCompensationAxis_3C1C9A7A843E1EEB267940C2858C03DC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DeferredBonusAndProfitSharingArrangementIndividualContractTypeOfDeferredCompensationDomain" xlink:label="loc_us-gaap_DeferredBonusAndProfitSharingArrangementIndividualContractTypeOfDeferredCompensationDomain_7EAB3BEF1C41751BCAFC40C2858C5978" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DeferredCompensationArrangementWithIndividualExcludingShareBasedPaymentsAndPostretirementBenefitsByTypeOfDeferredCompensationAxis_3C1C9A7A843E1EEB267940C2858C03DC" xlink:to="loc_us-gaap_DeferredBonusAndProfitSharingArrangementIndividualContractTypeOfDeferredCompensationDomain_7EAB3BEF1C41751BCAFC40C2858C5978" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DeferredBonusMember" xlink:label="loc_us-gaap_DeferredBonusMember_F4A7B235740CA19DC3FA40C2858CD2FC" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DeferredBonusAndProfitSharingArrangementIndividualContractTypeOfDeferredCompensationDomain_7EAB3BEF1C41751BCAFC40C2858C5978" xlink:to="loc_us-gaap_DeferredBonusMember_F4A7B235740CA19DC3FA40C2858CD2FC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RangeAxis" xlink:label="loc_us-gaap_RangeAxis_EE7405D279484A3A1EB040C2858C7E45" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfDeferredCompensationArrangementWithIndividualExcludingShareBasedPaymentsAndPostretirementBenefitsByTitleOfIndividualAndByTypeOfDeferredCompensationTable_09447BFAEDE1ED553C1A40C2858CF7E5" xlink:to="loc_us-gaap_RangeAxis_EE7405D279484A3A1EB040C2858C7E45" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember_FB080FE28E1ABAA40EFD40C2858CFF00" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_RangeAxis_EE7405D279484A3A1EB040C2858C7E45" xlink:to="loc_us-gaap_RangeMember_FB080FE28E1ABAA40EFD40C2858CFF00" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_MinimumMember" xlink:label="loc_us-gaap_MinimumMember_D3A9071B04906C8A58F140C2858D5037" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_RangeMember_FB080FE28E1ABAA40EFD40C2858CFF00" xlink:to="loc_us-gaap_MinimumMember_D3A9071B04906C8A58F140C2858D5037" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_MaximumMember" xlink:label="loc_us-gaap_MaximumMember_A785C818A8E006F1EB9E40C2858DD9E9" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_RangeMember_FB080FE28E1ABAA40EFD40C2858CFF00" xlink:to="loc_us-gaap_MaximumMember_A785C818A8E006F1EB9E40C2858DD9E9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DeferredCompensationArrangementWithIndividualExcludingShareBasedPaymentsAndPostretirementBenefitsLineItems" xlink:label="loc_us-gaap_DeferredCompensationArrangementWithIndividualExcludingShareBasedPaymentsAndPostretirementBenefitsLineItems_91B9BE6496910BC72A6740C2858D6656" xlink:type="locator" />
    <link:presentationArc order="3" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfDeferredCompensationArrangementWithIndividualExcludingShareBasedPaymentsAndPostretirementBenefitsByTitleOfIndividualAndByTypeOfDeferredCompensationTable_09447BFAEDE1ED553C1A40C2858CF7E5" xlink:to="loc_us-gaap_DeferredCompensationArrangementWithIndividualExcludingShareBasedPaymentsAndPostretirementBenefitsLineItems_91B9BE6496910BC72A6740C2858D6656" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_DeferredCompensationArrangementWithIndividualDiscretionaryBonusPaymentPercentage" xlink:label="loc_oesx_DeferredCompensationArrangementWithIndividualDiscretionaryBonusPaymentPercentage_01F8AB12DF3AC2C8405940C2858D0432" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DeferredCompensationArrangementWithIndividualExcludingShareBasedPaymentsAndPostretirementBenefitsLineItems_91B9BE6496910BC72A6740C2858D6656" xlink:to="loc_oesx_DeferredCompensationArrangementWithIndividualDiscretionaryBonusPaymentPercentage_01F8AB12DF3AC2C8405940C2858D0432" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_DeferredCompensationArrangementwithIndividualCashAwardThresholdProfitBeforeTaxes" xlink:label="loc_oesx_DeferredCompensationArrangementwithIndividualCashAwardThresholdProfitBeforeTaxes_A4EDF024EEE02430A01540C2858DBFD9" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DeferredCompensationArrangementWithIndividualExcludingShareBasedPaymentsAndPostretirementBenefitsLineItems_91B9BE6496910BC72A6740C2858D6656" xlink:to="loc_oesx_DeferredCompensationArrangementwithIndividualCashAwardThresholdProfitBeforeTaxes_A4EDF024EEE02430A01540C2858DBFD9" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_DeferredCompensationArrangementwithIndividualCashAwardThresholdRevenueGrowthPercent" xlink:label="loc_oesx_DeferredCompensationArrangementwithIndividualCashAwardThresholdRevenueGrowthPercent_3C592322AC92E39D92F640C2858D90DE" xlink:type="locator" />
    <link:presentationArc order="3" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DeferredCompensationArrangementWithIndividualExcludingShareBasedPaymentsAndPostretirementBenefitsLineItems_91B9BE6496910BC72A6740C2858D6656" xlink:to="loc_oesx_DeferredCompensationArrangementwithIndividualCashAwardThresholdRevenueGrowthPercent_3C592322AC92E39D92F640C2858D90DE" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_DeferredCompensationArrangementWithIndividualCashAwardThresholdRevenue" xlink:label="loc_oesx_DeferredCompensationArrangementWithIndividualCashAwardThresholdRevenue_FAFAE9DDF6A65CD075CC40C2858D6636" xlink:type="locator" />
    <link:presentationArc order="4" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DeferredCompensationArrangementWithIndividualExcludingShareBasedPaymentsAndPostretirementBenefitsLineItems_91B9BE6496910BC72A6740C2858D6656" xlink:to="loc_oesx_DeferredCompensationArrangementWithIndividualCashAwardThresholdRevenue_FAFAE9DDF6A65CD075CC40C2858D6636" xlink:type="arc" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.oesx.com/role/SummaryOfSignificantAccountingPoliciesNarrativeDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AccountingPoliciesAbstract" xlink:label="loc_us-gaap_AccountingPoliciesAbstract_F41ED450D094A51201D47E804C90080B" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DeferredCostsCurrent" xlink:label="loc_us-gaap_DeferredCostsCurrent_5A52376663D71868813B7E804C901C5B" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AccountingPoliciesAbstract_F41ED450D094A51201D47E804C90080B" xlink:to="loc_us-gaap_DeferredCostsCurrent_5A52376663D71868813B7E804C901C5B" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_PowerPurchaseAgreementProductRevenueRecognizableTerm" xlink:label="loc_oesx_PowerPurchaseAgreementProductRevenueRecognizableTerm_A48546BCAC731835671D7E804C903F96" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AccountingPoliciesAbstract_F41ED450D094A51201D47E804C90080B" xlink:to="loc_oesx_PowerPurchaseAgreementProductRevenueRecognizableTerm_A48546BCAC731835671D7E804C903F96" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_SolarPowerSystemsCompletionPeriodMinimum" xlink:label="loc_oesx_SolarPowerSystemsCompletionPeriodMinimum_18327B94DE479531C91E7E804C90F475" xlink:type="locator" />
    <link:presentationArc order="3" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AccountingPoliciesAbstract_F41ED450D094A51201D47E804C90080B" xlink:to="loc_oesx_SolarPowerSystemsCompletionPeriodMinimum_18327B94DE479531C91E7E804C90F475" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_SolarPowerSystemsCompletionPeriodMaximum" xlink:label="loc_oesx_SolarPowerSystemsCompletionPeriodMaximum_EBC1D37A4E93B31EDCC77E804C9056F9" xlink:type="locator" />
    <link:presentationArc order="4" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AccountingPoliciesAbstract_F41ED450D094A51201D47E804C90080B" xlink:to="loc_oesx_SolarPowerSystemsCompletionPeriodMaximum_EBC1D37A4E93B31EDCC77E804C9056F9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AdvertisingExpense" xlink:label="loc_us-gaap_AdvertisingExpense_49B209D29227C76324357E804C903B44" xlink:type="locator" />
    <link:presentationArc order="5" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AccountingPoliciesAbstract_F41ED450D094A51201D47E804C90080B" xlink:to="loc_us-gaap_AdvertisingExpense_49B209D29227C76324357E804C903B44" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_IncomeTaxReconciliationChangeInDeferredTaxAssetsValuationAllowance" xlink:label="loc_us-gaap_IncomeTaxReconciliationChangeInDeferredTaxAssetsValuationAllowance_08133DF7030461D622007E804C912B2D" xlink:type="locator" />
    <link:presentationArc order="6" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AccountingPoliciesAbstract_F41ED450D094A51201D47E804C90080B" xlink:to="loc_us-gaap_IncomeTaxReconciliationChangeInDeferredTaxAssetsValuationAllowance_08133DF7030461D622007E804C912B2D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ExcessTaxBenefitFromShareBasedCompensationFinancingActivities" xlink:label="loc_us-gaap_ExcessTaxBenefitFromShareBasedCompensationFinancingActivities_FCE93DB7DD169A6FC1FF7E804C915FB7" xlink:type="locator" />
    <link:presentationArc order="7" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AccountingPoliciesAbstract_F41ED450D094A51201D47E804C90080B" xlink:to="loc_us-gaap_ExcessTaxBenefitFromShareBasedCompensationFinancingActivities_FCE93DB7DD169A6FC1FF7E804C915FB7" xlink:type="arc" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.oesx.com/role/SummaryOfSignificantAccountingPoliciesPolicies" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AccountingPoliciesAbstract" xlink:label="loc_us-gaap_AccountingPoliciesAbstract_5A8E29EBA1E65AA399EA5FEF2E38CF71" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ConsolidationPolicyTextBlock" xlink:label="loc_us-gaap_ConsolidationPolicyTextBlock_6406924807DC2E39F1BF5FEF2E384AB3" xlink:type="locator" />
    <link:presentationArc order="1" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AccountingPoliciesAbstract_5A8E29EBA1E65AA399EA5FEF2E38CF71" xlink:to="loc_us-gaap_ConsolidationPolicyTextBlock_6406924807DC2E39F1BF5FEF2E384AB3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PriorPeriodReclassificationAdjustmentDescription" xlink:label="loc_us-gaap_PriorPeriodReclassificationAdjustmentDescription_4F1F3D636C412E3186C85FEF2E387143" xlink:type="locator" />
    <link:presentationArc order="2" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AccountingPoliciesAbstract_5A8E29EBA1E65AA399EA5FEF2E38CF71" xlink:to="loc_us-gaap_PriorPeriodReclassificationAdjustmentDescription_4F1F3D636C412E3186C85FEF2E387143" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_UseOfEstimates" xlink:label="loc_us-gaap_UseOfEstimates_BA6A6984BE8C2E7BE1635FEF2E389518" xlink:type="locator" />
    <link:presentationArc order="3" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AccountingPoliciesAbstract_5A8E29EBA1E65AA399EA5FEF2E38CF71" xlink:to="loc_us-gaap_UseOfEstimates_BA6A6984BE8C2E7BE1635FEF2E389518" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CashAndCashEquivalentsPolicyTextBlock" xlink:label="loc_us-gaap_CashAndCashEquivalentsPolicyTextBlock_6B3864772AD2BEDF6A115FEF2E38E4CF" xlink:type="locator" />
    <link:presentationArc order="4" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AccountingPoliciesAbstract_5A8E29EBA1E65AA399EA5FEF2E38CF71" xlink:to="loc_us-gaap_CashAndCashEquivalentsPolicyTextBlock_6B3864772AD2BEDF6A115FEF2E38E4CF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueOfFinancialInstrumentsPolicy" xlink:label="loc_us-gaap_FairValueOfFinancialInstrumentsPolicy_F00A76C2039F173883565FEF2E3D0A96" xlink:type="locator" />
    <link:presentationArc order="5" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AccountingPoliciesAbstract_5A8E29EBA1E65AA399EA5FEF2E38CF71" xlink:to="loc_us-gaap_FairValueOfFinancialInstrumentsPolicy_F00A76C2039F173883565FEF2E3D0A96" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ReceivablesTradeAndOtherAccountsReceivableAllowanceForDoubtfulAccountsPolicy" xlink:label="loc_us-gaap_ReceivablesTradeAndOtherAccountsReceivableAllowanceForDoubtfulAccountsPolicy_FE94BCD6A37C28374EAC60052C35EC2A" xlink:type="locator" />
    <link:presentationArc order="6" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AccountingPoliciesAbstract_5A8E29EBA1E65AA399EA5FEF2E38CF71" xlink:to="loc_us-gaap_ReceivablesTradeAndOtherAccountsReceivableAllowanceForDoubtfulAccountsPolicy_FE94BCD6A37C28374EAC60052C35EC2A" xlink:type="arc" />
    <link:loc xlink:href="oesx-20170331.xsd#oesx_LongTermReceivablesPolicyTextBlock" xlink:label="loc_oesx_LongTermReceivablesPolicyTextBlock_FDA10B884D30D4E74FF45FEF2E3D9110" xlink:type="locator" />
    <link:presentationArc order="7" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AccountingPoliciesAbstract_5A8E29EBA1E65AA399EA5FEF2E38CF71" xlink:to="loc_oesx_LongTermReceivablesPolicyTextBlock_FDA10B884D30D4E74FF45FEF2E3D9110" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DeferredChargesPolicyTextBlock" xlink:label="loc_us-gaap_DeferredChargesPolicyTextBlock_138A924568775F92EFF35FEF2E3DCA76" xlink:type="locator" />
    <link:presentationArc order="8" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AccountingPoliciesAbstract_5A8E29EBA1E65AA399EA5FEF2E38CF71" xlink:to="loc_us-gaap_DeferredChargesPolicyTextBlock_138A924568775F92EFF35FEF2E3DCA76" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CompensationRelatedCostsPolicyTextBlock" xlink:label="loc_us-gaap_CompensationRelatedCostsPolicyTextBlock_A2EA1BA00F2B4A9BA03A5FEF2E3EED47" xlink:type="locator" />
    <link:presentationArc order="9" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AccountingPoliciesAbstract_5A8E29EBA1E65AA399EA5FEF2E38CF71" xlink:to="loc_us-gaap_CompensationRelatedCostsPolicyTextBlock_A2EA1BA00F2B4A9BA03A5FEF2E3EED47" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RevenueRecognitionPolicyTextBlock" xlink:label="loc_us-gaap_RevenueRecognitionPolicyTextBlock_D5F791F40E34FBE6244E5FEF2E3EC944" xlink:type="locator" />
    <link:presentationArc order="10" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AccountingPoliciesAbstract_5A8E29EBA1E65AA399EA5FEF2E38CF71" xlink:to="loc_us-gaap_RevenueRecognitionPolicyTextBlock_D5F791F40E34FBE6244E5FEF2E3EC944" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShippingAndHandlingCostPolicyTextBlock" xlink:label="loc_us-gaap_ShippingAndHandlingCostPolicyTextBlock_9DFFF10FA322FAF067945FEF2E3E86EA" xlink:type="locator" />
    <link:presentationArc order="11" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AccountingPoliciesAbstract_5A8E29EBA1E65AA399EA5FEF2E38CF71" xlink:to="loc_us-gaap_ShippingAndHandlingCostPolicyTextBlock_9DFFF10FA322FAF067945FEF2E3E86EA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AdvertisingCostsPolicyTextBlock" xlink:label="loc_us-gaap_AdvertisingCostsPolicyTextBlock_C3718B70A6BA24D60B575FEF2E3E7969" xlink:type="locator" />
    <link:presentationArc order="12" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AccountingPoliciesAbstract_5A8E29EBA1E65AA399EA5FEF2E38CF71" xlink:to="loc_us-gaap_AdvertisingCostsPolicyTextBlock_C3718B70A6BA24D60B575FEF2E3E7969" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ResearchAndDevelopmentExpensePolicy" xlink:label="loc_us-gaap_ResearchAndDevelopmentExpensePolicy_3567B2FE15C98219AC7B5FEF2E3E8D22" xlink:type="locator" />
    <link:presentationArc order="13" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AccountingPoliciesAbstract_5A8E29EBA1E65AA399EA5FEF2E38CF71" xlink:to="loc_us-gaap_ResearchAndDevelopmentExpensePolicy_3567B2FE15C98219AC7B5FEF2E3E8D22" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_IncomeTaxPolicyTextBlock" xlink:label="loc_us-gaap_IncomeTaxPolicyTextBlock_71878045C5A819093BCA5FEF2E3E65EC" xlink:type="locator" />
    <link:presentationArc order="14" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AccountingPoliciesAbstract_5A8E29EBA1E65AA399EA5FEF2E38CF71" xlink:to="loc_us-gaap_IncomeTaxPolicyTextBlock_71878045C5A819093BCA5FEF2E3E65EC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensationOptionAndIncentivePlansPolicy" xlink:label="loc_us-gaap_ShareBasedCompensationOptionAndIncentivePlansPolicy_A209CADF3835CC633F895FEF2E3E3930" xlink:type="locator" />
    <link:presentationArc order="15" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AccountingPoliciesAbstract_5A8E29EBA1E65AA399EA5FEF2E38CF71" xlink:to="loc_us-gaap_ShareBasedCompensationOptionAndIncentivePlansPolicy_A209CADF3835CC633F895FEF2E3E3930" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ConcentrationRiskCreditRisk" xlink:label="loc_us-gaap_ConcentrationRiskCreditRisk_47299B7EC26301E96C485FEF2E3E8EB8" xlink:type="locator" />
    <link:presentationArc order="16" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AccountingPoliciesAbstract_5A8E29EBA1E65AA399EA5FEF2E38CF71" xlink:to="loc_us-gaap_ConcentrationRiskCreditRisk_47299B7EC26301E96C485FEF2E3E8EB8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_NewAccountingPronouncementsPolicyPolicyTextBlock" xlink:label="loc_us-gaap_NewAccountingPronouncementsPolicyPolicyTextBlock_EAB8510783228E6280245FEF2E3E7D69" xlink:type="locator" />
    <link:presentationArc order="17" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AccountingPoliciesAbstract_5A8E29EBA1E65AA399EA5FEF2E38CF71" xlink:to="loc_us-gaap_NewAccountingPronouncementsPolicyPolicyTextBlock_EAB8510783228E6280245FEF2E3E7D69" xlink:type="arc" />
  </link:presentationLink>
</link:linkbase>