

<!-- XBRL Generated with XBRLMark Copyright (C) by RR Donnelley -->
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<!--Modified on: 11/9/2012 4:06:49 AM-->
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  <element id="oesx_AccruedExpensesPercentageExceedingLimitOnCurrentLiability" name="AccruedExpensesPercentageExceedingLimitOnCurrentLiability" type="num:percentItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" />
  <element id="oesx_RelatedPartyTransactionsTextualAbstract" name="RelatedPartyTransactionsTextualAbstract" abstract="true" type="xbrli:stringItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <element id="oesx_DebtTextualAbstract" name="DebtTextualAbstract" abstract="true" type="xbrli:stringItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <element id="oesx_IncomeTaxTextualAbstract" name="IncomeTaxTextualAbstract" abstract="true" type="xbrli:stringItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <element id="oesx_ShareholdersEquityTextualAbstract" name="ShareholdersEquityTextualAbstract" abstract="true" type="xbrli:stringItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <element id="oesx_CommitmentsAndContingenciesTextualAbstract" name="CommitmentsAndContingenciesTextualAbstract" abstract="true" type="xbrli:stringItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
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  <element id="oesx_RightShareDistributionDateCondition" name="RightShareDistributionDateCondition" type="xbrli:stringItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <element id="oesx_MinimumSubscriptionPercentage" name="MinimumSubscriptionPercentage" type="num:percentItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <element id="oesx_ScheduleOfWarrants" name="ScheduleOfWarrants" abstract="true" type="xbrli:stringItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <element id="oesx_EnergyManagementMember" name="EnergyManagementMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <element id="oesx_EngineeredSystemsMember" name="EngineeredSystemsMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <element id="oesx_LongTermReceivablesPolicyTextBlock" name="LongTermReceivablesPolicyTextBlock" type="nonnum:textBlockItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <element id="oesx_NotPastDueMember" name="NotPastDueMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <element id="oesx_OneToNinetyDaysMember" name="OneToNinetyDaysMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <element id="oesx_GreaterThanNinetyDaysMember" name="GreaterThanNinetyDaysMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <element id="oesx_PastDueLeaseNetMember" name="PastDueLeaseNetMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <element id="oesx_SalesTypeNetMember" name="SalesTypeNetMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <element id="oesx_PropertyPlantAndEquipmentEstimatedUsefulLife" name="PropertyPlantAndEquipmentEstimatedUsefulLife" type="xbrli:stringItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <element id="oesx_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedForfeitureRate" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedForfeitureRate" type="num:percentItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <element id="oesx_AccountsReceivablesDueMinimumPeriod" name="AccountsReceivablesDueMinimumPeriod" type="xbrli:durationItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <element id="oesx_AccountsReceivablesDueMaximumPeriod" name="AccountsReceivablesDueMaximumPeriod" type="xbrli:durationItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <element id="oesx_PowerPurchaseAgreementProductRevenueRecognizableTerm" name="PowerPurchaseAgreementProductRevenueRecognizableTerm" type="xbrli:durationItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <element id="oesx_LongTermReceivablesPresentValueOfFutureCashFlowsDiscountedRateMaximum" name="LongTermReceivablesPresentValueOfFutureCashFlowsDiscountedRateMaximum" type="num:percentItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <element id="oesx_CustomerEquipmentFinanceNotesPayableMember" name="CustomerEquipmentFinanceNotesPayableMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <element id="oesx_DebenturePayableMember" name="DebenturePayableMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <element id="oesx_OtherLongTermDebtMember" name="OtherLongTermDebtMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <element id="oesx_SharePurchaseRightsRedemptionPrice" name="SharePurchaseRightsRedemptionPrice" type="num:perShareItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" />
  <element id="oesx_MaximumAmountLimitForEmployeeStockPurchasePlanPerEmployee" name="MaximumAmountLimitForEmployeeStockPurchasePlanPerEmployee" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" />
  <element id="oesx_AllowedLoanAmountPercentageOfAnnualIncome" name="AllowedLoanAmountPercentageOfAnnualIncome" type="num:percentItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <element id="oesx_TwoThousandThreeStockOptionMember" name="TwoThousandThreeStockOptionMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <element id="oesx_ShareBasedGoodsAndNonemployeeServicesTransactionQuantityOfSecuritiesIssuedValuationPricePerShare" name="ShareBasedGoodsAndNonemployeeServicesTransactionQuantityOfSecuritiesIssuedValuationPricePerShare" type="num:perShareItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <element id="oesx_SummaryOfIssuanceOfStockUnderEmployeeStockOwnershipPlanAbstract" name="SummaryOfIssuanceOfStockUnderEmployeeStockOwnershipPlanAbstract" abstract="true" type="xbrli:stringItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <element id="oesx_DeferredFinancingCostsAmortizedOverUsefulLifeOfDebtIssueMinimum" name="DeferredFinancingCostsAmortizedOverUsefulLifeOfDebtIssueMinimum" type="xbrli:durationItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <element id="oesx_DeferredFinancingCostsAmortizedOverUsefulLifeOfDebtIssueMaximum" name="DeferredFinancingCostsAmortizedOverUsefulLifeOfDebtIssueMaximum" type="xbrli:durationItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <element id="oesx_ChangeInTaxContingencyReserve" name="ChangeInTaxContingencyReserve" type="num:percentItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <element id="oesx_InterestLoanCharged" name="InterestLoanCharged" type="xbrli:durationItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" />
  <element id="oesx_PurchasePriceToMarketPriceMatchingPercentage" name="PurchasePriceToMarketPriceMatchingPercentage" type="num:percentItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <element id="oesx_AcquisitionShareVoidPercentage" name="AcquisitionShareVoidPercentage" type="num:percentItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <element id="oesx_ClassOfWarrantOrRightsExpirationDate" name="ClassOfWarrantOrRightsExpirationDate" type="xbrli:gYearItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <element id="oesx_AcquisitionOfSharesVoidCondition" name="AcquisitionOfSharesVoidCondition" type="xbrli:stringItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <element id="oesx_ExerciseOfNonQualifiedStockOptions" name="ExerciseOfNonQualifiedStockOptions" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" />
  <element id="oesx_LiabilitiesToNetworthRatioMinimum" name="LiabilitiesToNetworthRatioMinimum" type="xbrli:decimalItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" />
  <element id="oesx_LiabilitiesToTangibleNetworthRatioMaximum" name="LiabilitiesToTangibleNetworthRatioMaximum" type="xbrli:decimalItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" />
  <element id="oesx_ShareBasedCompensationArrangementsByShareBasedPaymentsAwardOptionMaximumLife" name="ShareBasedCompensationArrangementsByShareBasedPaymentsAwardOptionMaximumLife" type="xbrli:durationItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <element id="oesx_TwoThousandFourStockAndIncentiveAndAwardPlanMember" name="TwoThousandFourStockAndIncentiveAndAwardPlanMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <element id="oesx_LongTermInventoriesPolicyTextBlock" name="LongTermInventoriesPolicyTextBlock" type="nonnum:textBlockItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <element id="oesx_RestrictedSharesIssuedToKeyEmployeesAbstract" name="RestrictedSharesIssuedToKeyEmployeesAbstract" abstract="true" type="xbrli:stringItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <element id="oesx_DeferredCompensationArrangementWithIndividualCompensationExpensePeriodOfRecognition" name="DeferredCompensationArrangementWithIndividualCompensationExpensePeriodOfRecognition" type="xbrli:durationItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <element id="oesx_ShareBasedCompensationArrangementFairValueAssumptionsExpectedShareBasedPaymentAbstract" name="ShareBasedCompensationArrangementFairValueAssumptionsExpectedShareBasedPaymentAbstract" abstract="true" type="xbrli:stringItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
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  <element id="oesx_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlansNet" name="StockIssuedDuringPeriodSharesEmployeeStockPurchasePlansNet" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <element id="oesx_EmployeeStockPurchasePlansWeightedAveragesPurchasePriceOfSharesPurchased" name="EmployeeStockPurchasePlansWeightedAveragesPurchasePriceOfSharesPurchased" type="num:perShareItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <element id="oesx_EmployeeStockPurchasePlansWeightedAveragePurchasePriceOfSharesPurchasedNet" name="EmployeeStockPurchasePlansWeightedAveragePurchasePriceOfSharesPurchasedNet" type="num:perShareItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <element id="oesx_EmployeeStockPurchasePlansDebtStructureSharesIssued" name="EmployeeStockPurchasePlansDebtStructureSharesIssued" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <element id="oesx_EmployeeStockPurchasePlansDebtStructureSharesIssuedNet" name="EmployeeStockPurchasePlansDebtStructureSharesIssuedNet" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <element id="oesx_EmployeeStockPurchasePlansDebtStructureDirectLoanAmount" name="EmployeeStockPurchasePlansDebtStructureDirectLoanAmount" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" />
  <element id="oesx_EmployeeStockPurchasePlansDebtStructureDirectLoanAmountNet" name="EmployeeStockPurchasePlansDebtStructureDirectLoanAmountNet" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" />
  <element id="oesx_EmployeeStockPurchasePlansDebtStructureDirectLoanRepaymentAmount" name="EmployeeStockPurchasePlansDebtStructureDirectLoanRepaymentAmount" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" />
  <element id="oesx_EmployeeStockPurchasePlansDebtStructureDirectLoanRepaymentAmountNet" name="EmployeeStockPurchasePlansDebtStructureDirectLoanRepaymentAmountNet" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" />
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  <element id="oesx_EmployeeStockPurchasePlansLoanMaximumOutstandingAmount" name="EmployeeStockPurchasePlansLoanMaximumOutstandingAmount" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" />
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  <element id="oesx_LetterOfCreditFacilityUnusedCapacityCommitmentFeePercentage" name="LetterOfCreditFacilityUnusedCapacityCommitmentFeePercentage" type="num:percentItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <element id="oesx_FiscalYearAxis" name="FiscalYearAxis" abstract="true" type="xbrli:stringItemType" substitutionGroup="xbrldt:dimensionItem" nillable="true" xbrli:periodType="duration" />
  <element id="oesx_FiscalYearDomain" name="FiscalYearDomain" type="nonnum:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <element id="oesx_FiscalYearMember" name="FiscalYearMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <element id="oesx_SummaryOfSignificantAccountingPoliciesAdditionalTextualAbstract" name="SummaryOfSignificantAccountingPoliciesAdditionalTextualAbstract" abstract="true" type="xbrli:stringItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <element id="oesx_StockOptionsRestrictedSharesAndWarrantsAdditionalTextualAbstract" name="StockOptionsRestrictedSharesAndWarrantsAdditionalTextualAbstract" abstract="true" type="xbrli:stringItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
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  <element id="oesx_SolarPowerSystemsCompletionPeriodMaximum" name="SolarPowerSystemsCompletionPeriodMaximum" type="xbrli:durationItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <element id="oesx_SolarPowerSystemsCompletionPeriodMinimum" name="SolarPowerSystemsCompletionPeriodMinimum" type="xbrli:durationItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <element id="oesx_StockRepurchaseProgramIncreaseInAuthorizedRepurchaseAmount" name="StockRepurchaseProgramIncreaseInAuthorizedRepurchaseAmount" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" />
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  <element id="oesx_ConcentrationRiskPercentageThree" name="ConcentrationRiskPercentageThree" type="num:percentItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <element id="oesx_ConcentrationRiskPercentageTwo" name="ConcentrationRiskPercentageTwo" type="num:percentItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <element id="oesx_ConcentrationRiskPercentageFive" name="ConcentrationRiskPercentageFive" type="num:percentItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <element id="oesx_ConcentrationRiskPercentageSix" name="ConcentrationRiskPercentageSix" type="num:percentItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <element id="oesx_AntidilutiveSharesExcludedFromComputationOfEarningsPerShareAbstract" name="AntidilutiveSharesExcludedFromComputationOfEarningsPerShareAbstract" abstract="true" type="xbrli:stringItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
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  <element id="oesx_AgreedAmountOfShareRepurchaseOfOutstandingCommonStock" name="AgreedAmountOfShareRepurchaseOfOutstandingCommonStock" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" />
  <element id="oesx_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfRestrictedSharesAvailableForGrant" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfRestrictedSharesAvailableForGrant" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <element id="oesx_SupplierOneMember" name="SupplierOneMember" abstract="true" type="nonnum:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <element id="oesx_SupplierTwoMember" name="SupplierTwoMember" abstract="true" type="nonnum:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <element id="oesx_PercentageOfDeferredTaxAssetBeReducedByValuationAllowance" name="PercentageOfDeferredTaxAssetBeReducedByValuationAllowance" type="num:percentItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" />
  <element id="oesx_PercentageOfRevenueAccountedFromNoSingleCustomer" name="PercentageOfRevenueAccountedFromNoSingleCustomer" type="num:percentItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <element id="oesx_TimeSpanForRecognizationOfUnrecognizedTax" name="TimeSpanForRecognizationOfUnrecognizedTax" type="xbrli:durationItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <element id="oesx_ReclassificationsPolicyTextBlock" name="ReclassificationsPolicyTextBlock" type="nonnum:textBlockItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <element id="oesx_AccruedReorganizationCostsAndContractualCommitments" name="AccruedReorganizationCostsAndContractualCommitments" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" />
</schema>





