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<!-- DFIN New ActiveDisclosure (SM) XBRL Linkbase Document - http://www.dfinsolutions.com/ -->
<!-- Creation Date :2023-06-12T10:09:08.3382+00:00 -->
<!-- Copyright (c) 2023 Donnelly Financial Solutions, Inc. All Rights Reserved. -->
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_IntangibleAssetsGrossExcludingGoodwill_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Intangible Assets, Gross (Excluding Goodwill), Total</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_IntangibleAssetsGrossExcludingGoodwill_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Other Intangible Assets, Gross Carrying Amount</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_IntangibleAssetsGrossExcludingGoodwill_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Intangible Assets, Gross (Excluding Goodwill)</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_UnbilledContractsReceivable_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Revenue earned but not billed</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_UnbilledContractsReceivable_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Unbilled Contracts Receivable</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LineOfCredit_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Long-Term Line of Credit, Total</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LineOfCredit_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Credit agreement, amounts borrowed</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LineOfCredit_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Long-Term Line of Credit</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_LesseeOperatingLeaseLiabilityToBePaidAfterYearFour_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Thereafter</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_LesseeOperatingLeaseLiabilityToBePaidAfterYearFour_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Lessee Operating Lease Liability To Be Paid After Year Four</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_LesseeOperatingLeaseLiabilityToBePaidAfterYearFour_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Lessee, operating lease, liability, to be paid, after year four.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_AmendmentFlag_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Amendment Flag</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_AmendmentFlag_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Amendment Flag</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CapitalLeaseObligationsMember_lbl" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">Equipment debt obligations</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CapitalLeaseObligationsMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Capital Lease Obligations [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_SellingAndMarketingExpenseMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Sales and marketing</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_SellingAndMarketingExpenseMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Selling and Marketing Expense [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_InventoryLineItems_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Inventory [Line Items]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_InventoryLineItems_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Inventory [Line Items]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_SubsequentEventTypeDomain_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Subsequent Event Type</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_SubsequentEventTypeDomain_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Subsequent Event Type [Domain]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_BusinessCombinationAdditionalEarnoutRelatedPurchasePrice_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Business combination additional earnout related purchase price</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_BusinessCombinationAdditionalEarnoutRelatedPurchasePrice_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Business Combination Additional Earnout Related Purchase Price</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_BusinessCombinationAdditionalEarnoutRelatedPurchasePrice_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Business Combination Additional Earnout Related Purchase Price</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_OperatingLossCarryforwardsTable_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Operating Loss Carryforwards [Table]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_OperatingLossCarryforwardsTable_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Operating Loss Carryforwards [Table]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ExtinguishmentOfDebtAxis_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Extinguishment of Debt</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ExtinguishmentOfDebtAxis_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Extinguishment of Debt [Axis]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_lbl" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Accumulated Amortization</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Finite-Lived Intangible Assets, Accumulated Amortization</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CostOfSalesMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Cost of product revenue [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CostOfSalesMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Cost of Sales [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_LongTermDebtAndCapitalLeaseObligationsLessCurrentMaturities_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Long-term debt, less current maturities</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_LongTermDebtAndCapitalLeaseObligationsLessCurrentMaturities_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Long Term Debt And Capital Lease Obligations Less Current Maturities</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_LongTermDebtAndCapitalLeaseObligationsLessCurrentMaturities_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Long term debt and capital lease obligations less current maturities.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_IssuanceOfCommonStockForAcquisitionShare_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Issuance of common stock for acquisition, share</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_IssuanceOfCommonStockForAcquisitionShare_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Issuance of common stock for acquisition, share</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_Goodwill_lbl" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel">Goodwill, Ending Balance</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_Goodwill_lbl" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel">Goodwill, Beginning Balance</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_Goodwill_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Goodwill, Total</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_Goodwill_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Goodwill</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_Goodwill_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Goodwill</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DeferredIncomeTaxAssetsNet_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Deferred tax assets</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DeferredIncomeTaxAssetsNet_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Deferred Income Tax Assets, Net</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_OperatingLeaseRightOfUseAsset_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Operating lease assets</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_OperatingLeaseRightOfUseAsset_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Operating Lease, Right-of-Use Asset</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PaymentsForRepurchaseOfCommonStock_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Repurchase of common stock into treasury</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PaymentsForRepurchaseOfCommonStock_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Payments for Repurchase of Common Stock</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_OperatingLeaseRightOfUseAssetStatementOfFinancialPositionExtensibleList_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_OperatingLeaseRightOfUseAssetStatementOfFinancialPositionExtensibleList_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible Enumeration]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount_lbl" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Less: Interest</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Lessee, Operating Lease, Liability, Undiscounted Excess Amount</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_DistributionServicesMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Orion Distribution Services</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_DistributionServicesMember_lbl" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">Orion Distribution Systems</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_DistributionServicesMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Distribution Services [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_DistributionServicesMember_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Distribution Services [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_InventoryCurrentTable_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Inventory Current [Table]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_InventoryCurrentTable_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Inventory, Current [Table]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_StatementTable_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Statement [Table]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_StatementTable_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Statement [Table]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_OperatingLeaseLiabilityNoncurrent_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Operating lease liabilities non-current</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_OperatingLeaseLiabilityNoncurrent_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Operating Lease, Liability, Noncurrent</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_InventoryGrossAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Cost</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_InventoryGrossAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Inventory, Gross [Abstract]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_UnrecognizedTaxBenefitsThatWouldImpactEffectiveTaxRate_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Unrecognized tax benefits that would impact effective tax rate</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_UnrecognizedTaxBenefitsThatWouldImpactEffectiveTaxRate_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Unrecognized Tax Benefits that Would Impact Effective Tax Rate</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_TwoThousandElevenAndTwoThousandTwelveMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">2011 &amp; 2012</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_TwoThousandElevenAndTwoThousandTwelveMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Two Thousand Eleven And Two Thousand Twelve [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_TwoThousandElevenAndTwoThousandTwelveMember_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Two thousand eleven and two thousand twelve.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedOptionsForfeitedWeightedAverageGrantDateFairValue_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Weighted Average Fair Value Price Shares forfeited</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedOptionsForfeitedWeightedAverageGrantDateFairValue_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Nonvested Options Forfeited, Weighted Average Grant Date Fair Value</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans_lbl" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">Shares Issued Under ESPP Plan</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Shares issued under Employee Stock Purchase Plan (shares)</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Stock Issued During Period, Shares, Employee Stock Purchase Plans</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ServiceMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Service revenue</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ServiceMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Service [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PreferredStockSharesOutstanding_lbl" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel">Preferred Stock, Shares Outstanding, Ending Balance</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PreferredStockSharesOutstanding_lbl" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel">Preferred Stock, Shares Outstanding, Beginning Balance</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PreferredStockSharesOutstanding_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Preferred stock, shares outstanding (in shares)</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PreferredStockSharesOutstanding_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Preferred Stock, Shares Outstanding</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_BusinessAcquisitionAxis_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Business Acquisition</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_BusinessAcquisitionAxis_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Business Acquisition [Axis]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_RestructuringCharges_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Restructuring Charges, Total</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_RestructuringCharges_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Total restructuring charges</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_RestructuringCharges_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Restructuring Charges</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CommonStockCapitalSharesReservedForFutureIssuance_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Reserved shares for issuance to eligible participants (in shares)</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CommonStockCapitalSharesReservedForFutureIssuance_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Common Stock, Capital Shares Reserved for Future Issuance</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LandImprovementsMember_lbl" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">Land improvements</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LandImprovementsMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Land and land improvements</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LandImprovementsMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Land Improvements [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CommonStockNoParValue_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Common stock, par value (USD per share)</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CommonStockNoParValue_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Common Stock, No Par Value</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_AuditorFirmId_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Auditor Firm ID</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_AuditorFirmId_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Auditor Firm ID</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedInventory_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Inventory</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedInventory_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Inventory</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LineOfCreditFacilityLineItems_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Line Of Credit Facility [Line Items]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LineOfCreditFacilityLineItems_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Line of Credit Facility [Line Items]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_ServicesGroupMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Orion Services Group</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_ServicesGroupMember_lbl" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">Orion Services Group</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_ServicesGroupMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Services Group [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_ServicesGroupMember_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Services Group.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_DebtMaturityMonthAndYear_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Debt maturity month and year</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_DebtMaturityMonthAndYear_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Debt Maturity Month And Year</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_DebtMaturityMonthAndYear_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Debt maturity month and year.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_BusinessCombinationDisclosureTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">ACQUISITION</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_BusinessCombinationDisclosureTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Business Combination Disclosure [Text Block]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_IncomeTaxAuthorityDomain_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Income Tax Authority</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_IncomeTaxAuthorityDomain_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Income Tax Authority [Domain]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAccruedExpensesAndOther_lbl" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Accrued expenses and other</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAccruedExpensesAndOther_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed Current Liabilities Accrued Expenses And Other</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAccruedExpensesAndOther_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Business combination recognized identifiable assets acquired and liabilities assumed current liabilities accrued expenses and other.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DeferredTaxAssetsTaxCreditCarryforwards_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Deferred Tax Assets, Tax Credit Carryforwards, Total</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DeferredTaxAssetsTaxCreditCarryforwards_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Tax credit carry-forwards</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DeferredTaxAssetsTaxCreditCarryforwards_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Deferred Tax Assets, Tax Credit Carryforwards</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="srt_ProductOrServiceAxis_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Product and Service</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ContractWithCustomerAssetReclassifiedToReceivable_lbl" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">Contract assets</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ContractWithCustomerAssetReclassifiedToReceivable_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Change in contract asset reclassified to accounts receivable</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ContractWithCustomerAssetReclassifiedToReceivable_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Contract with Customer, Asset, Reclassified to Receivable</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_EmployeeStockMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Employee Stock Purchase Plan</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_EmployeeStockMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Employee Stock [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_BusinessCombinationContingentConsiderationLiability_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Business Combination, Contingent Consideration, Liability, Total</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_BusinessCombinationContingentConsiderationLiability_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Business combination, earnout related purchase price</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_BusinessCombinationContingentConsiderationLiability_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Business Combination, Contingent Consideration, Liability</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_InventoryRawMaterialsAndSuppliesValuationReserves_lbl" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Raw materials and components</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_InventoryRawMaterialsAndSuppliesValuationReserves_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Inventory Raw Materials And Supplies Valuation Reserves</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_InventoryRawMaterialsAndSuppliesValuationReserves_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Inventory, Raw Materials and Supplies, Valuation Reserves</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="srt_CumulativeEffectPeriodOfAdoptionAdjustmentMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Cumulative Effect, Period of Adoption, Adjustment</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="srt_CumulativeEffectPeriodOfAdoptionAdjustmentMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Cumulative Effect, Period of Adoption, Adjustment [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_FiniteLivedIntangibleAssetUsefulLife_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Intangible assets, useful life</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_FiniteLivedIntangibleAssetUsefulLife_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Finite-Lived Intangible Asset, Useful Life</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_EmployeeRelatedLiabilitiesCurrent_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Employee-related Liabilities, Current, Total</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_EmployeeRelatedLiabilitiesCurrent_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Compensation and benefits</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_EmployeeRelatedLiabilitiesCurrent_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Employee-related Liabilities, Current</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Exercise Price Range, Lower Range Limit (usd per share)</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Share-Based Payment Arrangement, Option, Exercise Price Range, Lower Range Limit</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_EmployeeServiceShareBasedCompensationNonvestedAwardsCompensationCostNotYetRecognizedNextTwelveMonths_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Fiscal 2024</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_EmployeeServiceShareBasedCompensationNonvestedAwardsCompensationCostNotYetRecognizedNextTwelveMonths_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Employee Service Share Based Compensation Nonvested Awards Compensation Cost Not Yet Recognized Next Twelve Months</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_EmployeeServiceShareBasedCompensationNonvestedAwardsCompensationCostNotYetRecognizedNextTwelveMonths_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Next Twelve Months.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_EmployeeStockOptionMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Common stock options</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_EmployeeStockOptionMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Share-Based Payment Arrangement, Option [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ConcentrationRiskByTypeAxis_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Concentration Risk Type</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ConcentrationRiskByTypeAxis_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Concentration Risk Type [Axis]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_OperatingLeaseWeightedAverageRemainingLeaseTerm1_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Operating lease, weighted average remaining lease term</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_OperatingLeaseWeightedAverageRemainingLeaseTerm1_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Operating Lease, Weighted Average Remaining Lease Term</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LiabilitiesAndStockholdersEquity_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Total liabilities and shareholders&#8217; equity</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LiabilitiesAndStockholdersEquity_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Liabilities and Equity</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_TaxPeriodAxis_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Tax Period</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_TaxPeriodAxis_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Tax Period [Axis]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DeferredTaxLiabilitiesLeasingArrangements_lbl" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Lease ROU asset</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DeferredTaxLiabilitiesLeasingArrangements_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Deferred Tax Liabilities, Leasing Arrangements</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_OperatingLossCarryforwardsLineItems_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Operating Loss Carryforwards [Line Items]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_OperatingLossCarryforwardsLineItems_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Operating Loss Carryforwards [Line Items]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_AdjustedOpeningBalanceSheetMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Adjusted Opening Balance Sheet</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_AdjustedOpeningBalanceSheetMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Adjusted Opening Balance Sheet [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_AdjustedOpeningBalanceSheetMember_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Adjusted Opening Balance Sheet [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PlanNameDomain_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Plan Name</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PlanNameDomain_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Plan Name [Domain]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedOptionsForfeitedNumberOfShares_lbl" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Forfeited (shares)</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedOptionsForfeitedNumberOfShares_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Nonvested Options Forfeited, Number of Shares</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LineOfCreditFacilityLenderDomain_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Line of Credit Facility, Lender</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LineOfCreditFacilityLenderDomain_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Line of Credit Facility, Lender [Domain]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_VoltrekMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Voltrek [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_VoltrekMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Voltrek [Member</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_VoltrekMember_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Voltrek [Member</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_InventoriesMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Inventories</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_InventoriesMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Inventories [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_EntityIncorporationStateCountryCode_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Entity Incorporation, State or Country Code</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_EntityIncorporationStateCountryCode_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Entity Incorporation, State or Country Code</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_IncomeStatementAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Income Statement [Abstract]</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesOther_lbl" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Other long-term liabilities</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesOther_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Other</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_OperatingSegmentsMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Operating Segments</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_OperatingSegmentsMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Operating Segments [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_SaleOfStockNameOfTransactionDomain_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Sale of Stock</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_EffectiveIncomeTaxRateReconciliationTaxContingencies_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Effective Income Tax Rate Reconciliation, Tax Contingency, Percent, Total</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_EffectiveIncomeTaxRateReconciliationTaxContingencies_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Change in tax contingency reserve</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Exercise Price Range, Upper Range Limit (usd per share)</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Share-Based Payment Arrangement, Option, Exercise Price Range, Upper Range Limit</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LiabilitiesCurrent_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Total current liabilities</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LiabilitiesCurrent_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Liabilities, Current</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_StockIssuedDuringPeriodValueEmployeeStockPurchasePlan_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Shares issued under Employee Stock Purchase Plan</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_EffectiveIncomeTaxRateReconciliationNondeductibleExpense_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Permanent items</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Fiscal 2026</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_ProductLightFixtureSalesTypeLeaseMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Light fixture sales-type lease</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_ProductLightFixtureSalesTypeLeaseMember_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Product, Light Fixture Sales-Type Lease [Member]</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_TradeNamesMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Trade name</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_TradeNamesMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Trade Names [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_TradenameMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Tradename [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_TradenameMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Tradename [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_TradenameMember_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Tradename.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_IncomeTaxPolicyTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Income Taxes</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_IncomeTaxPolicyTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Income Tax, Policy [Policy Text Block]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AdjustmentsNoncashItemsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Adjustments to reconcile net income to net cash (used in)</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AdjustmentsNoncashItemsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Adjustments, Noncash Items, to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_IncreaseDecreaseInContractWithCustomerLiability_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Deferred revenue, current and long-term</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_IncreaseDecreaseInContractWithCustomerLiability_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Increase (Decrease) in Contract with Customer, Liability</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_AreaOfOperatingLeasedProperty_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Area of operating leased property</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_AreaOfOperatingLeasedProperty_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Area Of Operating Leased Property</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_AreaOfOperatingLeasedProperty_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Area of operating eased property.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LongTermPurchaseCommitmentCategoryOfItemPurchasedDomain_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Long-term Purchase Commitment, Category of Item Purchased</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LongTermPurchaseCommitmentCategoryOfItemPurchasedDomain_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Long-Term Purchase Commitment, Category of Item Purchased [Domain]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PreferredStockSharesAuthorized_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Preferred stock, shares authorized (in shares)</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PreferredStockSharesAuthorized_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Preferred Stock, Shares Authorized</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_CustomersThreeMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Customers Three</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_CustomersThreeMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Customers Three [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_CustomersThreeMember_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Customers three.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Schedule Of Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Table]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Table]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="srt_CumulativeEffectPeriodOfAdoptionAxis_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Cumulative Effect, Period of Adoption</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="srt_CumulativeEffectPeriodOfAdoptionAxis_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Cumulative Effect, Period of Adoption [Axis]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ScheduleOfComponentsOfIncomeTaxExpenseBenefitTableTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Schedule of Components of Income Tax Expense (Benefit)</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ScheduleOfComponentsOfIncomeTaxExpenseBenefitTableTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Schedule of Components of Income Tax Expense (Benefit) [Table Text Block]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_OperatingLeaseWeightedAverageDiscountRatePercent_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Operating lease, weighted average discount rate</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_OperatingLeaseWeightedAverageDiscountRatePercent_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Operating Lease, Weighted Average Discount Rate, Percent</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_StateAndLocalIncomeTaxExpenseBenefitContinuingOperations_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Total State</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_StateAndLocalIncomeTaxExpenseBenefitContinuingOperations_lbl" xlink:role="http://www.xbrl.org/2003/role/label">State and Local Income Tax Expense (Benefit), Continuing Operations</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_EffectiveIncomeTaxRateReconciliationStateReturnToProvision_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">State return to provision</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_EffectiveIncomeTaxRateReconciliationStateReturnToProvision_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Effective Income Tax Rate Reconciliation State Return To Provision</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_EffectiveIncomeTaxRateReconciliationStateReturnToProvision_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Effective income tax rate reconciliation state return to provision.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CorporateNonSegmentMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Corporate and Other</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CorporateNonSegmentMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Corporate, Non-Segment [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_EntitySmallBusiness_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Entity Small Business</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_EntitySmallBusiness_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Entity Small Business</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_BusinessCombinationProFormaInformationEarningsOrLossOfAcquireeSinceAcquisitionDateActual_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Operating income</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_BusinessCombinationProFormaInformationEarningsOrLossOfAcquireeSinceAcquisitionDateActual_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Business Combination, Pro Forma Information, Earnings or Loss of Acquiree since Acquisition Date, Actual</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CompensationRelatedCostsPolicyTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Incentive Plan</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CompensationRelatedCostsPolicyTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Compensation Related Costs, Policy [Policy Text Block]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAccountsPayable_lbl" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Accounts payable</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAccountsPayable_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Accounts Payable</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_StockIssuedDuringPeriodSharesStockOptionsExercisedForCash_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Exercise of stock options for cash (shares)</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_StockIssuedDuringPeriodSharesStockOptionsExercisedForCash_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Stock Issued During Period Shares Stock Options Exercised For Cash</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_StockIssuedDuringPeriodSharesStockOptionsExercisedForCash_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Stock issued during period shares stock options exercised for cash.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ScheduleOfExtinguishmentOfDebtTable_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Schedule Of Extinguishment Of Debt [Table]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ScheduleOfExtinguishmentOfDebtTable_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Schedule of Extinguishment of Debt [Table]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_RestructuringAndRelatedActivitiesAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Restructuring and Related Activities [Abstract]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseTableTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Summary of Estimated Amortization Expense</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseTableTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Finite-Lived Intangible Assets Amortization Expense [Table Text Block]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_ScheduleOfIntangibleAssetsTableTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Summary of Components and Changes in Other Intangible Assets</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_ScheduleOfIntangibleAssetsTableTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Schedule Of Intangible Assets Table [Text Block]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_ScheduleOfIntangibleAssetsTableTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Schedule of intangible assets.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_SalesTypeLeaseLeaseIncomeTableTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Schedule of Revenue and Cost of Sales Arising from Sales-Type Leases</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_SalesTypeLeaseLeaseIncomeTableTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Sales-type Lease, Lease Income [Table Text Block]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AssetsCurrent_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Total current assets</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AssetsCurrent_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Assets, Current</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PropertyPlantAndEquipmentLineItems_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Property and equipment</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PropertyPlantAndEquipmentLineItems_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Property, Plant and Equipment [Line Items]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ContractWithCustomerAssetAndLiabilityTableTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Summary of Contract Assets and Liabilities</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ContractWithCustomerAssetAndLiabilityTableTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Contract with Customer, Contract Asset, Contract Liability, and Receivable [Table Text Block]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Indefinite-lived Intangible Assets</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Indefinite-Lived Intangible Assets [Axis]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_TrademarksAndTradeNamesMember_lbl" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">Trade name and trademarks</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_TrademarksAndTradeNamesMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Trade name and trademarks</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_TrademarksAndTradeNamesMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Trademarks and Trade Names [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill_lbl" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel">Indefinite-Lived Intangible Assets (Excluding Goodwill), Ending Balance</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill_lbl" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel">Indefinite-Lived Intangible Assets (Excluding Goodwill), Beginning Balance</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Indefinite-Lived Intangible Assets (Excluding Goodwill), Total</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Indefinite-lived Intangible Assets</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Indefinite-Lived Intangible Assets (Excluding Goodwill)</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Weighted-average common shares outstanding</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_lbl" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">Shares used in basic per share calculation</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Weighted Average Number of Shares Outstanding, Basic, Total</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Weighted Average Number of Shares Outstanding, Basic</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_ChangeInContractWithCustomerLiability_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Change in contract with customer liability</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_ChangeInContractWithCustomerLiability_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Change In Contract With Customer Liability</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_ChangeInContractWithCustomerLiability_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Change in contract liability</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_CityAreaCode_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">City Area Code</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_CityAreaCode_lbl" xlink:role="http://www.xbrl.org/2003/role/label">City Area Code</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Outstanding stock options</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ScheduleOfDebtTableTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Summary of Long-Term Debt</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AccountsReceivableGrossCurrent_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Accounts receivable, gross</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AccountsReceivableGrossCurrent_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Accounts Receivable, before Allowance for Credit Loss, Current</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_PreliminaryOpeningBalanceSheetMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Preliminary Opening Balance Sheet</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_PreliminaryOpeningBalanceSheetMember_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Preliminary Opening Balance Sheet [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Share-Based Payment Arrangement [Abstract]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_MovementInStandardProductWarrantyAccrualRollForward_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Movement in Standard Product Warranty Accrual</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_Liabilities_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Liabilities</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_DocumentPeriodEndDate_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Document Period End Date</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_DocumentPeriodEndDate_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Document Period End Date</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_RestrictedStockMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Restricted shares</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_RestrictedStockMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Restricted Stock [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Schedule Of Finite Lived Intangible Assets [Table]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Schedule of Finite-Lived Intangible Assets [Table]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ConstructionInProgressMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Construction in progress</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ConstructionInProgressMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Construction in Progress [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DeferredTaxLiabilitiesGoodwillAndIntangibleAssets_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Deferred Tax Liabilities, Goodwill and Intangible Assets, Total</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DeferredTaxLiabilitiesGoodwillAndIntangibleAssets_lbl" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Intangible assets</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DeferredTaxLiabilitiesGoodwillAndIntangibleAssets_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Deferred Tax Liabilities, Goodwill and Intangible Assets</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsShareBasedCompensationCost_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Equity compensation</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsShareBasedCompensationCost_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Deferred Tax Assets, Tax Deferred Expense, Compensation and Benefits, Share-Based Compensation Cost</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Weighted Average Fair Value Price Shares issued</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_IncreaseDecreaseInContractWithCustomerAsset_lbl" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Revenue earned but not billed</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_IncreaseDecreaseInContractWithCustomerAsset_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Increase (Decrease) in Contract with Customer, Asset</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ScheduleOfSegmentReportingInformationBySegmentTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Schedule of Segment Information</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ScheduleOfSegmentReportingInformationBySegmentTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Schedule of Segment Reporting Information, by Segment [Table Text Block]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_SolarEnergyMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Solar energy related revenues</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_SolarEnergyMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Solar Energy [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_SolarEnergyMember_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Solar Energy [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ContractWithCustomerLiabilityNoncurrent_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Deferred revenue, long-term</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ContractWithCustomerLiabilityNoncurrent_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Contract with Customer, Liability, Noncurrent</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Fiscal 2024</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Finite-Lived Intangible Asset, Expected Amortization, Year One</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="srt_RangeAxis_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Statistical Measurement</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="srt_RangeAxis_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Statistical Measurement [Axis]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_TrademarksMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Trade name and trademarks [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_TrademarksMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Trademarks [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_LesseeOperatingFinanceLeasesAndSaleLeasebackTransactionsTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">LEASES</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_LesseeOperatingFinanceLeasesAndSaleLeasebackTransactionsTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Lessee Operating Finance Leases And Sale Leaseback Transactions [Text Block]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_LesseeOperatingFinanceLeasesAndSaleLeasebackTransactionsTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Lessee operating, finance leases and sale leaseback transactions.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_RevenueNotFromContractWithCustomer_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Revenue accounted for under other guidance</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_RevenueNotFromContractWithCustomer_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Revenue Not from Contract with Customer</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_DebtInstrumentTwoMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Debt Instrument 2</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_DebtInstrumentTwoMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Debt Instrument Two [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_DebtInstrumentTwoMember_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Debt instrument two member.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ScheduleOfIntangibleAssetsAndGoodwillTableTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Summary of Amortizable Intangible Assets</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ScheduleOfIntangibleAssetsAndGoodwillTableTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Schedule of Intangible Assets and Goodwill [Table Text Block]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_EquityClassOfTreasuryStockLineItems_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Equity Class Of Treasury Stock [Line Items]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_EquityClassOfTreasuryStockLineItems_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Equity, Class of Treasury Stock [Line Items]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LicensingAgreementsMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Licenses [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LicensingAgreementsMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Licensing Agreements [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseAfterYearFive_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Thereafter</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseAfterYearFive_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Finite-Lived Intangible Asset, Expected Amortization, after Year Five</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_VehiclesMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Vehicles</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_VehiclesMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Vehicles [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_Assets_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Total Assets</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_Assets_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Total Assets</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_Assets_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Assets</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_BusinessCombinationProFormaInformationRevenueOfAcquireeSinceAcquisitionDateActual_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Net sales</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_BusinessCombinationProFormaInformationRevenueOfAcquireeSinceAcquisitionDateActual_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Business Combination, Pro Forma Information, Revenue of Acquiree since Acquisition Date, Actual</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ContractWithCustomerAssetNet_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Contract with Customer, Asset, after Allowance for Credit Loss, Total</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ContractWithCustomerAssetNet_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Contract assets</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ContractWithCustomerAssetNet_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Contract with Customer, Asset, after Allowance for Credit Loss</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_NotFoundDuringMigrationDeprecatedConceptEquipmentLeasedToOtherPartyMember_lbl" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">Equipment leased to customers under Power Purchase Agreements</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_NotFoundDuringMigrationDeprecatedConceptEquipmentLeasedToOtherPartyMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Equipment leased to customers</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_NotFoundDuringMigrationDeprecatedConceptEquipmentLeasedToOtherPartyMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Not Found During Migration Deprecated Concept Equipment Leased To Other Party [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_StateAndLocalJurisdictionMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">State and Local Jurisdiction</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_StateAndLocalJurisdictionMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">State and Local Jurisdiction [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LongTermDebtNoncurrent_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Long-Term Debt, Excluding Current Maturities, Total</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LongTermDebtNoncurrent_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Long-term debt, less current maturities</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LongTermDebtNoncurrent_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Long-Term Debt, Excluding Current Maturities</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_EarningsPerShareDiluted_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Diluted net (loss) income per share</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_EarningsPerShareDiluted_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Earnings Per Share, Diluted, Total</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_EarningsPerShareDiluted_lbl" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">Diluted net income (loss) per share</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_EarningsPerShareDiluted_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Earnings Per Share, Diluted</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Number of Potentially Dilutive Securities Excluded from the Calculation of Diluted Net Income (Loss) per Common Share</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table Text Block]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DeferredCostsCapitalizedPrepaidAndOtherAssetsDisclosureAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_SalesTypeLeaseRevenue_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Product revenue</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_SalesTypeLeaseRevenue_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Sales-type Lease, Revenue</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_EntityAddressPostalZipCode_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Entity Address, Postal Zip Code</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_EntityAddressPostalZipCode_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Entity Address, Postal Zip Code</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_EarningsPerShareBasicAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Net income per common share: Basic</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_EarningsPerShareBasicAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Earnings Per Share, Basic [Abstract]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_RevenueFromContractWithCustomerIncludingAssessedTax_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Total revenues from contracts with customers</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_RevenueFromContractWithCustomerIncludingAssessedTax_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Revenue from Contract with Customer, Including Assessed Tax</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_DocumentFiscalPeriodFocus_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Document Fiscal Period Focus</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_DocumentFiscalPeriodFocus_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Document Fiscal Period Focus</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AcquisitionCosts_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Acquisition related costs</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AcquisitionCosts_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Acquisition Costs, Period Cost</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CostOfGoodsAndServicesSold_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Cost of Goods and Services Sold, Total</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CostOfGoodsAndServicesSold_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Cost of revenue</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CostOfGoodsAndServicesSold_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Cost of Goods and Services Sold</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CurrentIncomeTaxExpenseBenefit_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Current Income Tax Expense (Benefit), Total</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CurrentIncomeTaxExpenseBenefit_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Current</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CurrentIncomeTaxExpenseBenefit_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Current Income Tax Expense (Benefit)</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_IncreaseDecreaseInAccountsReceivable_lbl" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Accounts receivable</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_IncreaseDecreaseInAccountsReceivable_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Increase (Decrease) in Accounts Receivable</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_RevolvingCreditFacilityMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Revolving credit facility</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_RevolvingCreditFacilityMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Revolving Credit Facility [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DeferredTaxAssetsValuationAllowance_lbl" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Valuation allowance</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">APIC, Share-Based Payment Arrangement, Increase for Cost Recognition, Total</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Stock-based compensation</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_lbl" xlink:role="http://www.xbrl.org/2003/role/label">APIC, Share-Based Payment Arrangement, Increase for Cost Recognition</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LessorOperatingLeaseExistenceOfOptionToExtend_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Lessor, Operating Lease, Existence of Option to Extend [true false]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LessorOperatingLeaseExistenceOfOptionToExtend_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Lessor, Operating Lease, Existence of Option to Extend [true false]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_SpringingMinimumFixedCostCoverageRatioCovenantPercentageOfCommittedFacility_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Credit agreement, springing minimum fixed cost coverage ratio covenant percentage of committed facility</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_SpringingMinimumFixedCostCoverageRatioCovenantPercentageOfCommittedFacility_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Springing Minimum Fixed Cost Coverage Ratio Covenant Percentage Of Committed Facility</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_SpringingMinimumFixedCostCoverageRatioCovenantPercentageOfCommittedFacility_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Springing minimum fixed cost coverage ratio covenant percentage of committed facility.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_InvestmentIncomeInterest_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Interest income</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_InvestmentIncomeInterest_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Investment Income, Interest</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_OtherNonoperatingIncome_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Other income</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_OtherNonoperatingIncome_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Other Nonoperating Income</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_OperatingLeaseLiability_lbl" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">Present value of lease liabilities</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_OperatingLeaseLiability_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Total lease liabilities</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_OperatingLeaseLiability_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Operating Lease, Liability</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_NetCashProvidedByUsedInFinancingActivities_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Net cash provided by (used in) financing activities</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_NetCashProvidedByUsedInFinancingActivities_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Net Cash Provided by (Used in) Financing Activities</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DeferredTaxLiabilitiesPropertyPlantAndEquipment_lbl" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Fixed assets</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DeferredTaxLiabilitiesPropertyPlantAndEquipment_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Deferred Tax Liabilities, Property, Plant and Equipment</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_StatementOfFinancialPositionAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Statement of Financial Position [Abstract]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_RangeThreeMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">$2.41</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_RangeThreeMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Range Three [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_RangeThreeMember_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Range three.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_EntityFileNumber_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Entity File Number</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_EntityFileNumber_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Securities Act File Number</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_StatementOfCashFlowsAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Statement of Cash Flows [Abstract]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ScheduleOfShareBasedCompensationEmployeeStockPurchasePlanActivityTableTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Shares Issued from Treasury</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ScheduleOfShareBasedCompensationEmployeeStockPurchasePlanActivityTableTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Schedule of Share-Based Compensation, Employee Stock Purchase Plan, Activity [Table Text Block]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ScheduleOfFiniteLivedIntangibleAssetsAcquiredAsPartOfBusinessCombinationTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Schedule of Intangible Assets Acquired at Date of Acquisition</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ScheduleOfFiniteLivedIntangibleAssetsAcquiredAsPartOfBusinessCombinationTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Schedule of Finite-Lived Intangible Assets Acquired as Part of Business Combination [Table Text Block]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_BuildingAndBuildingImprovementsMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Buildings and building improvements</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_BuildingAndBuildingImprovementsMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Building and Building Improvements [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_AtMarketIssuanceSalesAgreementMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">At Market Issuance Sales Agreement</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_AtMarketIssuanceSalesAgreementMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">At Market Issuance Sales Agreement [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_AtMarketIssuanceSalesAgreementMember_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">At market issuance sales agreement.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="srt_SegmentGeographicalDomain_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Geographical</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="srt_SegmentGeographicalDomain_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Geographical [Domain]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Exercise Price Range</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Exercise Price Range [Axis]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="srt_RangeMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Statistical Measurement</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="srt_RangeMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Statistical Measurement [Domain]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_StatementOfStockholdersEquityAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Statement of Stockholders' Equity [Abstract]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_SubsidiarySaleOfStockAxis_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Sale of Stock</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_SubsidiarySaleOfStockAxis_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Sale of Stock [Axis]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_AuditorLocation_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Auditor Location</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_AuditorLocation_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Auditor Location</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_USMarketsMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Orion U.S. Markets</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_USMarketsMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">U S Markets [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_USMarketsMember_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">U.S. Markets [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_SalesRevenueNetMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Revenue</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_SalesRevenueNetMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Revenue Benchmark [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_IncreaseInTaxExpense_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Increase in tax expense</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_IncreaseInTaxExpense_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Increase in Tax Expense</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_IncreaseInTaxExpense_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Increase in Tax Expense</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_InventoryWorkInProcessNetOfReserves_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Work in process</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_InventoryWorkInProcessNetOfReserves_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Inventory, Work in Process, Net of Reserves</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_StockholdersEquityNoteAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Stockholders' Equity Note [Abstract]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_SubsequentEventsAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Subsequent Events [Abstract]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_EquityMethodInvestmentAggregateCost_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Equity method investment at cost</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_EquityMethodInvestmentAggregateCost_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Equity Method Investment, Aggregate Cost</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_PaymentsToAcquirePropertyPlantAndEquipmentAndProductiveAssets_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Capital Expenditures</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_PaymentsToAcquirePropertyPlantAndEquipmentAndProductiveAssets_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Payments To Acquire Property Plant And Equipment And Productive Assets</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_PaymentsToAcquirePropertyPlantAndEquipmentAndProductiveAssets_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Payments to Acquire Property, Plant, and Equipment and Productive Assets</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ProceedsFromIssuanceOfCommonStock_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Issuance of common stock in connection with acquisition</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ProceedsFromIssuanceOfCommonStock_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Proceeds from Issuance of Common Stock</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LongtermDebtTypeAxis_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Long-term Debt, Type</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LongtermDebtTypeAxis_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Long-Term Debt, Type [Axis]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DeferredIncomeTaxExpenseBenefit_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Deferred Income Tax Expense (Benefit), Total</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DeferredIncomeTaxExpenseBenefit_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Deferred income tax benefit</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DeferredIncomeTaxExpenseBenefit_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Deferred Income Tax Expense (Benefit)</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ProductWarrantyAccrualClassifiedCurrent_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Warranty</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ProductWarrantyAccrualClassifiedCurrent_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Product Warranty Accrual, Current</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PropertyPlantAndEquipmentTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Property and Equipment</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PropertyPlantAndEquipmentTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Property, Plant and Equipment [Table Text Block]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_ProceedsFromIssuanceOfDebtOrSaleOfEquitySecurities_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Proceeds from issuance of debt or sale of equity securities</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_ProceedsFromIssuanceOfDebtOrSaleOfEquitySecurities_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Proceeds From Issuance Of Debt Or Sale Of Equity Securities</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_ProceedsFromIssuanceOfDebtOrSaleOfEquitySecurities_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Proceeds from issuance of debt or sale of equity securities.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_FederalGovernmentMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Federal government</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_FederalGovernmentMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Federal Government [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_FederalGovernmentMember_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Federal Government [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_RevenueFromContractWithCustomerTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">REVENUE</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_RevenueFromContractWithCustomerTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Revenue from Contract with Customer [Text Block]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_LineOfCreditFacilityEarlyTerminationFee_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Credit agreement, early termination fees</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_LineOfCreditFacilityEarlyTerminationFee_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Line Of Credit Facility Early Termination Fee</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_LineOfCreditFacilityEarlyTerminationFee_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Line of credit facility early termination fee.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ConcentrationRiskCreditRisk_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Concentration of Credit Risk and Other Risks and Uncertainties</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ConcentrationRiskCreditRisk_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Concentration Risk, Credit Risk, Policy [Policy Text Block]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_WeightedAverageNumberDilutedSharesOutstandingAdjustmentAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Denominator:</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_WeightedAverageNumberDilutedSharesOutstandingAdjustmentAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Weighted Average Number of Shares Outstanding, Diluted, Adjustment [Abstract]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AccountingStandardsUpdateExtensibleList_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Accounting Standards Update [Extensible List]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AccountingStandardsUpdateExtensibleList_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Accounting Standards Update [Extensible Enumeration]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Antidilutive Securities</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Antidilutive Securities [Axis]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Credit facility, amount</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Line of Credit Facility, Maximum Borrowing Capacity</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PreferredStockParOrStatedValuePerShare_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Preferred stock, par value (USD per share)</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PreferredStockParOrStatedValuePerShare_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Preferred Stock, Par or Stated Value Per Share</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ContractWithCustomerLiabilityCurrent_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Deferred revenue, current</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ContractWithCustomerLiabilityCurrent_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Contract with Customer, Liability, Current</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LesseeLeaseDescriptionLineItems_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Lessee Lease Description [Line Items]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LesseeLeaseDescriptionLineItems_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Lessee, Lease, Description [Line Items]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Net purchase consideration</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_BusinessAcquisitionCostOfAcquiredEntityTransactionCosts_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Transaction costs</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_BusinessAcquisitionCostOfAcquiredEntityTransactionCosts_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Business Acquisition, Transaction Costs</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CreditFacilityDomain_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Credit Facility</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CreditFacilityDomain_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Credit Facility [Domain]</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_ElectricVehicleChargingMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Electric Vehicles</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_ElectricVehicleChargingMember_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Electric Vehicle Charging [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_ManitowocMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Manitowoc, WI</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_ManitowocMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Manitowoc [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_ManitowocMember_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Manitowoc.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Weighted-average common shares and share equivalents outstanding</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_lbl" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">Shares used in diluted per share calculation</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Weighted Average Number of Shares Outstanding, Diluted, Total</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Weighted Average Number of Shares Outstanding, Diluted</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LoansNotesTradeAndOtherReceivablesDisclosureTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">ACCOUNTS RECEIVABLE</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LoansNotesTradeAndOtherReceivablesDisclosureTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Loans, Notes, Trade and Other Receivables Disclosure [Text Block]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_BusinessCombinationEstimateOfEarnOutLiability_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Business combination, estimate of earn-out liability</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_BusinessCombinationEstimateOfEarnOutLiability_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Business Combination Estimate Of Earn Out Liability</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_BusinessCombinationEstimateOfEarnOutLiability_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Business Combination Estimate Of Earn Out Liability.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_EmployeeStockPurchasePlansSharesAuthorized_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Employee stock purchase plan, shares authorized</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_EmployeeStockPurchasePlansSharesAuthorized_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Employee Stock Purchase Plans Shares Authorized</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_EmployeeStockPurchasePlansSharesAuthorized_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Employee stock purchase plans shares authorized.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Finite-Lived Intangible Assets, Major Class Name</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Finite-Lived Intangible Assets, Major Class Name [Domain]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CreditFacilityAxis_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Credit Facility</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CreditFacilityAxis_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Credit Facility [Axis]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_RevolvingCreditFacility_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Revolving credit facility</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_RevolvingCreditFacility_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Revolving credit facility</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_RevolvingCreditFacility_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Revolving credit facility</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ContractWithCustomerLiabilityCumulativeCatchUpAdjustmentToRevenueChangeInMeasureOfProgress_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Contract liabilities</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ContractWithCustomerLiabilityCumulativeCatchUpAdjustmentToRevenueChangeInMeasureOfProgress_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Contract with Customer, Liability, Cumulative Catch-up Adjustment to Revenue, Change in Measure of Progress</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_GeneralAndAdministrativeExpenseMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">General and administrative</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_GeneralAndAdministrativeExpenseMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">General and Administrative Expense [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_SummaryOfIssuanceOfStockUnderEmployeeStockOwnershipPlanAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Shares issued from treasury</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_SummaryOfIssuanceOfStockUnderEmployeeStockOwnershipPlanAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Summary Of Issuance Of Stock Under Employee Stock Ownership Plan [Abstract]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_SummaryOfIssuanceOfStockUnderEmployeeStockOwnershipPlanAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Summary of Issuance of Stock Under Employee Stock Ownership Plan.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_ProceedsFromExerciseOfWarrantsAndStockOptions_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Net proceeds from employee equity exercises</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_ProceedsFromExerciseOfWarrantsAndStockOptions_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Proceeds From Exercise Of Warrants And Stock Options</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_ProceedsFromExerciseOfWarrantsAndStockOptions_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Proceeds from Exercise of Warrants and Stock Options</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_LineOfCreditSpringingMinimumFixedCostCoverageRatio_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Credit agreement, springing minimum fixed cost coverage ratio</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_LineOfCreditSpringingMinimumFixedCostCoverageRatio_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Line Of Credit Springing Minimum Fixed Cost Coverage Ratio</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_LineOfCreditSpringingMinimumFixedCostCoverageRatio_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Line of credit springing minimum fixed cost coverage ratio.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_CurrentFiscalYearEndDate_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Current Fiscal Year End Date</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_CurrentFiscalYearEndDate_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Current Fiscal Year End Date</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_Depreciation_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Depreciation, Total</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_Depreciation_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Depreciation</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_Depreciation_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Depreciation</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LongTermDebtByCurrentAndNoncurrentAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Long-term debt</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LongTermDebtByCurrentAndNoncurrentAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Long-Term Debt, by Current and Noncurrent [Abstract]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents, Including Disposal Group and Discontinued Operations, Total</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations_lbl" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel">Cash and cash equivalents at beginning of period</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents, Including Disposal Group and Discontinued Operations</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_StockRepurchasedDuringPeriodShares_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Stock repurchased during period, shares</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_OtherAssetsNoncurrent_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Other long-term assets</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_DocumentAnnualReport_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Document Annual Report</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_DocumentAnnualReport_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Document Annual Report</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ScheduleOfUnrecognizedCompensationCostNonvestedAwardsTableTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Summary of Unrecognized Compensation Cost Related to Non-vested Awards</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Finite-Lived Intangible Assets by Major Class</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Finite-Lived Intangible Assets by Major Class [Axis]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_SupplementalCashFlowInformationAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Supplemental cash flow information:</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareRepurchaseProgramDomain_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Share Repurchase Program</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LeaseExpirationDate1_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Termination of lease</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_PrepaidExpensesAndOtherCurrentAssetsLineItems_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Prepaid expenses and other current assets.</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_EffectiveIncomeTaxRateReconciliationNondeductibleExpenseShareBasedCompensationCost_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Equity compensation cancellations</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_EffectiveIncomeTaxRateReconciliationNondeductibleExpenseShareBasedCompensationCost_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Effective Income Tax Rate Reconciliation, Nondeductible Expense, Share-Based Payment Arrangement, Percent</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_IncomeTaxDisclosureAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Income Tax Disclosure [Abstract]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_ProductLegacySolarFacilitiesMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Legacy solar facilities</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_ProductLegacySolarFacilitiesMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Product Legacy Solar Facilities [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_ProductLegacySolarFacilitiesMember_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Product, Legacy Solar Facilities [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LineOfCreditFacilityTable_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Line Of Credit Facility [Table]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LineOfCreditFacilityTable_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Line of Credit Facility [Table]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_SaleLeasebackTransactionLeaseTerm_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Lease term of agreement</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_SaleLeasebackTransactionLeaseTerm_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Sale Leaseback Transaction Lease Term</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_SaleLeasebackTransactionLeaseTerm_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Sale leaseback transaction lease term.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_EmployeeServiceShareBasedCompensationNonvestedAwardsCompensationCostNotYetRecognizedDueInFourYears_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Fiscal 2026</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_EmployeeServiceShareBasedCompensationNonvestedAwardsCompensationCostNotYetRecognizedDueInFourYears_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Employee Service Share Based Compensation Nonvested Awards Compensation Cost Not Yet Recognized Due In Four Years</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_EmployeeServiceShareBasedCompensationNonvestedAwardsCompensationCostNotYetRecognizedDueInFourYears_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Due in Four Years.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_MaximumAmountLimitForEmployeeStockPurchasePlanPerEmployee_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Maximum amount limit for ESPP per employee</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_MaximumAmountLimitForEmployeeStockPurchasePlanPerEmployee_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Maximum Amount Limit For Employee Stock Purchase Plan Per Employee</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_MaximumAmountLimitForEmployeeStockPurchasePlanPerEmployee_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Maximum amount limit for employee stock purchase plan per employee.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_OutsideTheUnitedStatesMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Outside the United States</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_OutsideTheUnitedStatesMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Outside the United States [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_OutsideTheUnitedStatesMember_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Outside the United States [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_EffectiveIncomeTaxRateReconciliationOtherAdjustments_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Other, net</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_EffectiveIncomeTaxRateReconciliationOtherAdjustments_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Effective Income Tax Rate Reconciliation, Other Adjustments, Percent</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_UnusualOrInfrequentItemDomain_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Unusual or Infrequent Item, or Both</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_UnusualOrInfrequentItemDomain_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Unusual or Infrequent Item, or Both [Domain]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_IncreaseInNumberOfCommonStockSharesAvailableForIssuance_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Increase in number of common stock shares available for issuance</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_IncreaseInNumberOfCommonStockSharesAvailableForIssuance_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Increase In Number Of Common Stock Shares Available For Issuance</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_IncreaseInNumberOfCommonStockSharesAvailableForIssuance_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Increase in number of common stock shares available for Issuance.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ProductWarrantyAccrualPeriodIncreaseDecrease_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Standard and Extended Product Warranty Accrual, Period Increase (Decrease), Total</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ProductWarrantyAccrualPeriodIncreaseDecrease_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Accruals</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ProductWarrantyAccrualPeriodIncreaseDecrease_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Standard and Extended Product Warranty Accrual, Period Increase (Decrease)</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_GoodwillAndIntangibleAssetsDisclosureAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Goodwill and Intangible Assets Disclosure [Abstract]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensationOptionAndIncentivePlansPolicy_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Stock Based Compensation</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensationOptionAndIncentivePlansPolicy_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Share-Based Payment Arrangement [Policy Text Block]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_AuditorName_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Auditor Name</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_AuditorName_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Auditor Name</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Forfeited (in dollars per share)</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Share-Based Compensation Arrangements by Share-Based Payment Award, Options, Forfeitures in Period, Weighted Average Exercise Price</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_OperatingIncomeLoss_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Income from operations</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_OperatingIncomeLoss_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Operating Income (Loss)</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_OperatingIncomeLoss_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Operating Income (Loss)</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DebtInstrumentInterestRateStatedPercentage_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Stated interest rate, percentage</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DebtInstrumentInterestRateStatedPercentage_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Debt Instrument, Interest Rate, Stated Percentage</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AdditionalPaidInCapitalCommonStock_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Additional paid-in capital</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AdditionalPaidInCapitalCommonStock_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Additional Paid in Capital, Common Stock</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_FiniteLivedIntangibleAssetsFutureAmortizationExpenseAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Finite-Lived Intangible Assets, Estimated Amortization Expense</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_FiniteLivedIntangibleAssetsFutureAmortizationExpenseAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ConcentrationRiskBenchmarkDomain_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Concentration Risk Benchmark</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ConcentrationRiskBenchmarkDomain_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Concentration Risk Benchmark [Domain]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AccruedProfessionalFeesCurrent_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Legal and professional fees</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AccruedProfessionalFeesCurrent_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Accrued Professional Fees, Current</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_EntityFilerCategory_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Entity Filer Category</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_EntityFilerCategory_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Entity Filer Category</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_DeferredTaxAssetsLeaseLiability_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Lease liability</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_DeferredTaxAssetsLeaseLiability_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Deferred Tax Assets Lease Liability</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_DeferredTaxAssetsLeaseLiability_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Deferred tax assets lease liability.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_OtherLongTermDebtNoncurrent_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Other long-term liabilities</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_OtherLongTermDebtNoncurrent_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Other Long-Term Debt, Noncurrent</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_UnusualOrInfrequentItemsDisclosureTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">IMPACT OF COVID-19</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_UnusualOrInfrequentItemsDisclosureTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Unusual or Infrequent Items, or Both, Disclosure [Text Block]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_VoltrekLlcMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Voltrek LLC</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_VoltrekLlcMember_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Voltrek LLC [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment, Total</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Property and equipment</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_OperatingExpenses_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Total operating expenses</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_OperatingExpenses_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Operating Expenses</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_EntityCurrentReportingStatus_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Entity Current Reporting Status</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_EntityCurrentReportingStatus_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Entity Current Reporting Status</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_InventoryNet_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Total</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_InventoryNet_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Inventories, net</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_InventoryNet_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Inventory, Net</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CurrentStateAndLocalTaxExpenseBenefit_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">State, Current</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CurrentStateAndLocalTaxExpenseBenefit_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Current State and Local Tax Expense (Benefit)</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_IcfrAuditorAttestationFlag_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">ICFR Auditor Attestation Flag</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LineOfCreditMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Line of credit</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LineOfCreditMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Line of Credit [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_InventoryDisclosureTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">INVENTORIES</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation_lbl" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Employee tax withholdings on stock-based compensation (shares)</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Share-Based Payment Arrangement, Shares Withheld for Tax Withholding Obligation</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_StockholdersEquityNoteDisclosureTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">SHAREHOLDERS' EQUITY</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_BusinessCombinationsAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Business Combinations [Abstract]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_FiniteLivedIntangibleAssetsNet_lbl" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel">Finite-Lived Intangible Assets, Net, Ending Balance</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_FiniteLivedIntangibleAssetsNet_lbl" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel">Finite-Lived Intangible Assets, Net, Beginning Balance</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_FiniteLivedIntangibleAssetsNet_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Amortized Intangible Assets, Net</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_EarningsPerShareDilutedAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Net income per common share: Diluted</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_DeferredCompensationArrangementWithIndividualCashAwardThresholdAccruedExpenses_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Discretionary bonus payments, accrued expenses</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_DeferredCompensationArrangementWithIndividualCashAwardThresholdAccruedExpenses_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Deferred compensation arrangement with individual cash award threshold accrued expenses.</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Fiscal 2025</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_EntityTaxIdentificationNumber_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Entity Tax Identification Number</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_IncomeStatementLocationAxis_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Income Statement Location</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_lbl" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Shares forfeited (shares)</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CommonStockValue_lbl" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">Value of Common Stock</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CommonStockValue_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Common stock, no par value: Shares authorized: 200,000,000 at March 31, 2023 and 2022; shares issued: 41,767,092 and 40,279,050 at March 31, 2023 and 2022; shares outstanding: 32,295,408 and 30,805,300 at March 31, 2023 and 2022</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_RetainedEarningsAccumulatedDeficit_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Retained deficit</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="srt_CumulativeEffectPeriodOfAdoptionDomain_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Cumulative Effect, Period of Adoption [Domain]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_InventoryValuationReserves_lbl" xlink:role="http://www.xbrl.org/2009/role/negatedTotalLabel">Total</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_EquipmentMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Plant equipment</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_InventoryReserveLengthOfTimeOfInventoryUsageConsidered_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Inventory consideration usage</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_InventoryReserveLengthOfTimeOfInventoryUsageConsidered_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Inventory reserve length of time of inventory usage considered.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CashAndCashEquivalentsPolicyTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Cash and Cash Equivalents</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ProductWarrantyLiabilityLineItems_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Product Warranty Liability [Line Items]</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LeasesAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Leases [Abstract]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ContractWithCustomerLiability_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Contract with Customer, Liability, Total</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ContractWithCustomerLiability_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Contract liabilities</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ContractWithCustomerLiability_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Contract with Customer, Liability</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_UnbilledReceivables_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Unbilled accounts receivable</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_UnbilledReceivables_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Unbilled Receivables</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_UnbilledReceivables_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Unbilled receivables.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CustomerRelationshipsMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Customer relationships</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CustomerRelationshipsMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Customer Relationships [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DisaggregationOfRevenueTable_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Disaggregation Of Revenue [Table]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DisaggregationOfRevenueTable_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Disaggregation of Revenue [Table]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_RangeOneMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">$2.41</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_RangeOneMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Range One [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_RangeOneMember_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Range One [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_EntityEmergingGrowthCompany_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Entity Emerging Growth Company</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_EntityEmergingGrowthCompany_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Entity Emerging Growth Company</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_TaxCreditCarryforwardValuationAllowance_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Net valuation allowance release</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Schedule Of Business Acquisitions By Acquisition [Table]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Schedule of Business Acquisitions, by Acquisition [Table]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_OperatingExpensesAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Operating expenses:</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PropertyPlantAndEquipmentNetAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Property and equipment</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PropertyPlantAndEquipmentNetAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Property, Plant and Equipment, Net [Abstract]</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_RecordedInOpeningBalanceSheet_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Recorded In Opening Balance Sheet</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_OtherCurrentAssetsTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">PREPAID EXPENSES AND OTHER CURRENT ASSETS</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_LightingMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Total lighting</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_LightingMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Lighting [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_LightingMember_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Lighting [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CurrentFederalTaxExpenseBenefit_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Federal, Current</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Accounts Receivable and Allowance for Doubtful Accounts Balances</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_SellingAndMarketingExpense_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Selling and Marketing Expense, Total</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_EntityVoluntaryFilers_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Entity Voluntary Filers</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_JacksonvilleMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Jacksonville [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_JacksonvilleMember_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Jacksonville.</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AccountsPayableAccruedLiabilitiesAndOtherLiabilitiesDisclosureCurrentTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Accounts Payable, Accrued Liabilities, and Other Liabilities Disclosure, Current [Text Block]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DepreciationDepletionAndAmortization_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Depreciation, Depletion and Amortization, Total</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DepreciationDepletionAndAmortization_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Depreciation and Amortization</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DepreciationDepletionAndAmortization_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Depreciation, Depletion and Amortization</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Schedule Of Segment Reporting Information By Segment [Table]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Schedule of Segment Reporting Information, by Segment [Table]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_RightsAgreementExtendedTerm_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Rights agreement extended term</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_RightsAgreementExtendedTerm_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Rights Agreement Extended Term</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_RightsAgreementExtendedTerm_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Rights agreement extended term.</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CommitmentsAndContingenciesDisclosureTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Commitments and Contingencies Disclosure [Text Block]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Exercised (in dollars per share)</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Share-Based Compensation Arrangements by Share-Based Payment Award, Options, Exercises in Period, Weighted Average Exercise Price</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_TaxPeriodDomain_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Tax Period</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_TaxPeriodDomain_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Tax Period [Domain]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AccountsReceivableNetCurrent_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Accounts receivable, net</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AccountsReceivableNetCurrent_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Accounts receivable, net</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AccountsReceivableNetCurrent_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Accounts Receivable, after Allowance for Credit Loss, Current</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_EmployeeServiceShareBasedCompensationNonvestedAwardsCompensationCostNotYetRecognizedDueThereafter_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Thereafter</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_EmployeeServiceShareBasedCompensationNonvestedAwardsCompensationCostNotYetRecognizedDueThereafter_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Employee Service Share Based Compensation Nonvested Awards Compensation Cost Not Yet Recognized Due Thereafter</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_EmployeeServiceShareBasedCompensationNonvestedAwardsCompensationCostNotYetRecognizedDueThereafter_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Due Thereafter.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_EntityCommonStockSharesOutstanding_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Entity Common Stock, Shares Outstanding</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_EntityCommonStockSharesOutstanding_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Entity Common Stock, Shares Outstanding</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DeferredStateAndLocalIncomeTaxExpenseBenefit_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">State, Deferred</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DeferredStateAndLocalIncomeTaxExpenseBenefit_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Deferred State and Local Income Tax Expense (Benefit)</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_CustomerTwoMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Customer Two</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_CustomerTwoMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Customer Two [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_CustomerTwoMember_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Customer two.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_OperatingLeaseLiabilityNoncurrentStatementOfFinancialPositionExtensibleList_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_OperatingLeaseLiabilityNoncurrentStatementOfFinancialPositionExtensibleList_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible Enumeration]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_EarningsPerShareReconciliationAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Numerator:</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_EarningsPerShareReconciliationAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Earnings Per Share Reconciliation [Abstract]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AmortizationOfFinancingCosts_lbl" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Amortization of debt issue costs</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AmortizationOfFinancingCosts_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Amortization of debt issue costs</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AmortizationOfFinancingCosts_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Amortization of Debt Issuance Costs</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_NetIncomeLoss_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Net (loss) income</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_NetIncomeLoss_lbl" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">Net income (dollars in thousands)</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_NetIncomeLoss_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Net income (loss)</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_NetIncomeLoss_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Net Income (Loss) Attributable to Parent</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ConcentrationRiskLineItems_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Concentration of Credit Risk and Other Risks and Uncertainties</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ConcentrationRiskLineItems_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Concentration Risk [Line Items]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="srt_WeightedAverageMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Weighted average [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="srt_WeightedAverageMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Weighted Average [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LongTermPurchaseCommitmentLineItems_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Long-term Purchase Commitment [Line Items]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LongTermPurchaseCommitmentLineItems_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Long-Term Purchase Commitment [Line Items]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_OperatingLeaseLiabilityCurrent_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Operating lease liabilities current</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Exercise Price Range</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Exercise Price Range [Domain]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_VendorRelationshipsMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Vendor relationships [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_VendorRelationshipsMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Vendor relationships [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_VendorRelationshipsMember_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Vendor relationships [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_LesseeSaleLeasebackOptionToTerminateMinimumPeriod_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Lessee, sale leaseback, option to terminate, minimum period</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_LesseeSaleLeasebackOptionToTerminateMinimumPeriod_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Lessee Sale Leaseback Option To Terminate Minimum Period</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_LesseeSaleLeasebackOptionToTerminateMinimumPeriod_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Lessee sale leaseback option to terminate minimum period.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DeferredBonusAndProfitSharingArrangementIndividualContractTypeOfDeferredCompensationDomain_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Deferred Bonus and Profit Sharing Arrangement, Individual Contract, Type of Deferred Compensation</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DeferredBonusAndProfitSharingArrangementIndividualContractTypeOfDeferredCompensationDomain_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Deferred Bonus and Profit Sharing Arrangement, Individual Contract, Type of Deferred Compensation [Domain]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation_lbl" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Payments to settle employee tax withholdings on stock-based compensation</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCashAndEquivalents_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Cash</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LineOfCreditFacilityExpirationDate1_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Credit agreement, maturity date</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LineOfCreditFacilityExpirationDate1_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Line of Credit Facility, Expiration Date</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DeferredTaxAssetsOperatingLossCarryforwards_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Deferred Tax Assets, Operating Loss Carryforwards, Total</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DeferredTaxAssetsOperatingLossCarryforwards_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Federal and state operating loss carry-forwards</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ScheduleOfMaturitiesOfLongTermDebtTableTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Schedule of Maturities of Long-Term Debt</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ScheduleOfShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Summary of Range of Exercise Prices</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_EntityRegistrantName_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Entity Registrant Name</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_EntityRegistrantName_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Entity Registrant Name</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CashAndCashEquivalentsAtCarryingValue_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Cash and Cash Equivalents, at Carrying Value, Total</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensation_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Stock-based compensation</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensation_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Share-Based Payment Arrangement, Noncash Expense</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PropertyPlantAndEquipmentNet_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Net property and equipment</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PropertyPlantAndEquipmentNet_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Property and equipment, net</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PropertyPlantAndEquipmentNet_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Property, Plant and Equipment, Net</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Award Type</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Award Type [Domain]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_StatementLineItems_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Statement [Line Items]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_StatementLineItems_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Statement [Line Items]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_AccretionEarnoutLiability_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Accretion earnout liability</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_AccretionEarnoutLiability_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Accretion Earnout Liability</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_AccretionEarnoutLiability_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Accretion Earnout Liability</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_PrepaidExpensesAndOtherCurrentAssetsTable_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Prepaid Expenses And Other Current Assets [Table]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_PrepaidExpensesAndOtherCurrentAssetsTable_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Prepaid Expenses And Other Current Assets [Table]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_PrepaidExpensesAndOtherCurrentAssetsTable_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Prepaid expenses and other current assets.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_Security12bTitle_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Title of 12(b) Security</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_Security12bTitle_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Title of 12(b) Security</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_FiniteLivedIntangibleAssetsGross_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Finite-Lived Intangible Assets, Gross, Total</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_FiniteLivedIntangibleAssetsGross_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Amortized Intangible Assets, Gross Carrying Amount</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_FiniteLivedIntangibleAssetsGross_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Finite-Lived Intangible Assets, Gross</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_IncreaseDecreaseInAccountsPayable_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Increase (Decrease) in Accounts Payable, Total</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_IncreaseDecreaseInAccountsPayable_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Accounts payable</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_IncreaseDecreaseInAccountsPayable_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Increase (Decrease) in Accounts Payable</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_RestructuringCostAndReserveLineItems_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Restructuring Cost And Reserve [Line Items]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_RestructuringCostAndReserveLineItems_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Restructuring Cost and Reserve [Line Items]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CommonStockMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Common Stock, Shares</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CommonStockMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Common Stock [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_StockIssuedDuringPeriodSharesStockOptionsAndWarrantsExercisedForCash_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Exercise of stock options and warrants for cash (shares)</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_StockIssuedDuringPeriodSharesStockOptionsAndWarrantsExercisedForCash_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Stock Issued During Period Shares Stock Options And Warrants Exercised For Cash</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_StockIssuedDuringPeriodSharesStockOptionsAndWarrantsExercisedForCash_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Stock issued during period share stock options and warrants exercised for cash.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_SalesAndExciseTaxPayableCurrent_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Sales tax</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_SalesAndExciseTaxPayableCurrent_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Sales and Excise Tax Payable, Current</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Operating activities</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Net Cash Provided by (Used in) Operating Activities [Abstract]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_BusinessAcquisitionsProFormaIncomeLossFromContinuingOperationsBeforeChangesInAccountingAndExtraordinaryItemsNetOfTax_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Business acquisition, pro forma operating income loss</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_BusinessAcquisitionsProFormaIncomeLossFromContinuingOperationsBeforeChangesInAccountingAndExtraordinaryItemsNetOfTax_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Business Acquisition, Pro Forma Income (Loss) from Continuing Operations, Net of Tax</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_BankOfAmericaNAMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Bank Of America N A</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_BankOfAmericaNAMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Bank Of America N A [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_BankOfAmericaNAMember_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Bank of America, N.A.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_EquityComponentDomain_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Equity Component</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_EquityComponentDomain_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Equity Component [Domain]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ProductWarrantyLiabilityTable_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Product Warranty Liability [Table]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ProductWarrantyLiabilityTable_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Product Warranty Liability [Table]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Income before income tax</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_ProceedsFromSaleOfUnbilledContractsReceivable_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Proceeds from sale of revenue earned but not billed</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_ProceedsFromSaleOfUnbilledContractsReceivable_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Proceeds From Sale Of Unbilled Contracts Receivable</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_ProceedsFromSaleOfUnbilledContractsReceivable_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Proceeds from sale of unbilled contracts receivable.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_EntityAddressStateOrProvince_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Entity Address, State or Province</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_EntityAddressStateOrProvince_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Entity Address, State or Province</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFour_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Fiscal 2027</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFour_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Lessee, Operating Lease, Liability, to be Paid, Year Four</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="srt_StatementGeographicalAxis_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Geographical</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="srt_StatementGeographicalAxis_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Geographical [Axis]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Net (decrease) increase in cash and cash equivalents</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_DocumentType_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Document Type</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_DocumentType_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Document Type</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_InterestPaidNet_lbl" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Cash paid for interest</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_InterestPaidNet_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Interest Paid, Excluding Capitalized Interest, Operating Activities</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_InventoryWorkInProcessValuationReserves_lbl" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Work in process</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_InventoryWorkInProcessValuationReserves_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Inventory Work In Process Valuation Reserves</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_InventoryWorkInProcessValuationReserves_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Inventory, Work in Process, Valuation Reserves</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ReceivablesAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Receivables [Abstract]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareRepurchaseProgramAxis_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Share Repurchase Program</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareRepurchaseProgramAxis_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Share Repurchase Program [Axis]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ReceivablesTradeAndOtherAccountsReceivableAllowanceForDoubtfulAccountsPolicy_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Allowance for Doubtful Accounts</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ReceivablesTradeAndOtherAccountsReceivableAllowanceForDoubtfulAccountsPolicy_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Receivables, Trade and Other Accounts Receivable, Allowance for Doubtful Accounts, Policy [Policy Text Block]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_EntityShellCompany_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Entity Shell Company</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_EntityShellCompany_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Entity Shell Company</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_IncreaseDecreaseInInventories_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Increase (Decrease) in Inventories, Total</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_IncreaseDecreaseInInventories_lbl" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Inventories</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_IncreaseDecreaseInInventories_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Increase (Decrease) in Inventories</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AllocatedShareBasedCompensationExpense_lbl" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">Compensation expense</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AllocatedShareBasedCompensationExpense_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Total</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AllocatedShareBasedCompensationExpense_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Share-Based Payment Arrangement, Expense</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_SegmentReportingInformationLineItems_lbl" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">Corporate and Other</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_FairValueOfFinancialInstrumentsPolicy_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Fair Value of Financial Instruments</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CostOfGoodsSoldSalesTypeLease_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Cost of product revenue</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_DeferredTaxAssetsInventoryAccrualsAndReservesCurrent_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Inventory, accruals and reserves</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_PaymentsAndProceedsFromAcquireIntangibleAssets_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Payments and proceeds from acquire intangible assets.</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_CostOfProductsMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Cost of product revenue</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_CostOfProductsMember_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Cost of products.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_EarnestMoneyDeposits_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Customary closing adjustments</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_EarnestMoneyDeposits_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Earnest Money Deposits</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_SecurityExchangeName_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Security Exchange Name</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_SecurityExchangeName_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Security Exchange Name</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_ProductWarrantyAccrualPaymentsNetOfVendorReimbursements_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Warranty claims (net of vendor reimbursements)</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_ProductWarrantyAccrualPaymentsNetOfVendorReimbursements_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Product Warranty Accrual Payments Net Of Vendor Reimbursements</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_ProductWarrantyAccrualPaymentsNetOfVendorReimbursements_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Product warranty accrual payments net of vendor reimbursements.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_RevenueFromContractWithCustomerAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Revenue from Contract with Customer [Abstract]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Number of potentially dilutive securities</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_AccruedAcquisitionEarnout_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Accrued acquisition earnout</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_AccruedAcquisitionEarnout_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Accrued acquisition earnout</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_AccruedAcquisitionEarnout_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Accrued acquisition earnout</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_SignificantAccountingPoliciesTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_SignificantAccountingPoliciesTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Significant Accounting Policies [Text Block]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_NetCashProvidedByUsedInOperatingActivities_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Net cash (used in) provided by operating activities</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_NetCashProvidedByUsedInOperatingActivities_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Net Cash Provided by (Used in) Operating Activities</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Remaining weighted average expected term</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Share-Based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Weighted Average Remaining Contractual Life (Years)</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PaymentsToAcquireBusinessesGross_lbl" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Cash to fund acquisition, net of cash received</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PaymentsToAcquireBusinessesGross_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Business combination, cash purchase price</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PaymentsToAcquireBusinessesGross_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Payments to Acquire Businesses, Gross</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CommitmentsAndContingenciesDisclosureAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Commitments and Contingencies Disclosure [Abstract]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAmortizationMethod_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Intangible assets, useful life description</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAmortizationMethod_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Finite-Lived Intangible Assets, Amortization Method</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_AmericanRescuePlanActOf2021Member_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">American Rescue Plan Act of 2021</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_AmericanRescuePlanActOf2021Member_lbl" xlink:role="http://www.xbrl.org/2003/role/label">American Rescue Plan Act Of2021 [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_AmericanRescuePlanActOf2021Member_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">American Rescue Plan Act of 2021.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AdjustmentsRelatedToTaxWithholdingForShareBasedCompensation_lbl" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Employee tax withholdings on stock-based compensation</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AdjustmentsRelatedToTaxWithholdingForShareBasedCompensation_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Share-Based Payment Arrangement, Decrease for Tax Withholding Obligation</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_OperatingLeaseCost_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Operating lease costs</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_OperatingLeaseCost_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Operating Lease, Cost</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_AccruedProjectCostsCurrent_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Accrued project costs</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_AccruedProjectCostsCurrent_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Accrued Project Costs Current</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_AccruedProjectCostsCurrent_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Accrued project costs current.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_CustomerOneMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Customer One</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_CustomerOneMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Customer One [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_CustomerOneMember_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Customer One [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityMaturityTableTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Summary of Estimated Maturity of Lease Liabilities</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityMaturityTableTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Lessee, Operating Lease, Liability, Maturity [Table Text Block]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ScheduleOfUnrecognizedTaxBenefitsRollForwardTableTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Unrecognized Tax Benefit Activity</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ScheduleOfUnrecognizedTaxBenefitsRollForwardTableTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Schedule of Unrecognized Tax Benefits Roll Forward [Table Text Block]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_NumberOfFinancialInstitutions_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Number of financial institutions</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_NumberOfFinancialInstitutions_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Number Of Financial Institutions</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_NumberOfFinancialInstitutions_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Number of Financial Institutions</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ConsolidationPolicyTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Principles of Consolidation</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ConsolidationPolicyTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Consolidation, Policy [Policy Text Block]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ScheduleOfProductWarrantyLiabilityTableTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Changes in Warranty Accrual</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ScheduleOfProductWarrantyLiabilityTableTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Schedule of Product Warranty Liability [Table Text Block]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_BusinessAcquisitionsProFormaRevenue_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Pro forma revenue</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_BusinessAcquisitionsProFormaRevenue_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Business Acquisition, Pro Forma Revenue</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_EffectiveIncomeTaxRateReconciliationChangeInDeferredTaxAssetsValuationAllowance_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Change in valuation reserve</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_EffectiveIncomeTaxRateReconciliationChangeInDeferredTaxAssetsValuationAllowance_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Percent</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Other intangible assets</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ScheduleOfShareBasedCompensationStockOptionsActivityTableTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Summary of Outstanding Stock Options</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ScheduleOfShareBasedCompensationStockOptionsActivityTableTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Share-Based Payment Arrangement, Option, Activity [Table Text Block]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_NewAccountingPronouncementsPolicyPolicyTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Recent Accounting Pronouncements</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_NewAccountingPronouncementsPolicyPolicyTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/label">New Accounting Pronouncements, Policy [Policy Text Block]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CommonStockSharesOutstanding_lbl" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel">Common Stock, Shares, Outstanding, Ending Balance</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CommonStockSharesOutstanding_lbl" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel">Common Stock, Shares, Outstanding, Beginning Balance</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CommonStockSharesOutstanding_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Common stock, shares outstanding (in shares)</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CommonStockSharesOutstanding_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Common Stock, Shares, Outstanding</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_BusinessAcquisitionLineItems_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Business Acquisition [Line Items]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_BusinessAcquisitionLineItems_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Business Acquisition [Line Items]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_GainsLossesOnExtinguishmentOfDebt_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Gain (Loss) on Extinguishment of Debt, Total</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_GainsLossesOnExtinguishmentOfDebt_lbl" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Loss on debt extinguishment</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_GainsLossesOnExtinguishmentOfDebt_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Loss on debt extinguishment</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_GainsLossesOnExtinguishmentOfDebt_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Gain (Loss) on Extinguishment of Debt</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsReceivables_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Accounts receivable</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsReceivables_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Receivables</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_InventoryWorkInProcess_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Work in process</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_InventoryWorkInProcess_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Inventory, Work in Process, Gross</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Investing activities</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Net Cash Provided by (Used in) Investing Activities [Abstract]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensationAllocationAndClassificationInFinancialStatementsAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Stock-based compensation</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensationAllocationAndClassificationInFinancialStatementsAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Share-Based Payment Arrangement, Recognized Amount [Abstract]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_PercentageOfContractForSaleEqualsMonthlyProgressPayments_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Percentage of contract for sale equal monthly progress payments</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_PercentageOfContractForSaleEqualsMonthlyProgressPayments_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Percentage Of Contract For Sale Equals Monthly Progress Payments</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_PercentageOfContractForSaleEqualsMonthlyProgressPayments_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Percentage of contract for sale equals monthly progress payments.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Additions based on tax positions related to the current period positions</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Unrecognized Tax Benefits, Increase Resulting from Current Period Tax Positions</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_TaxYear2022To2040Member_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Tax Year 2022 To 2040</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_TaxYear2022To2040Member_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Tax Year2022 To2040 [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_TaxYear2022To2040Member_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Tax year 2022 to 2040.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DeferredTaxAssetInterestCarryforward_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Interest deduction carry-forward</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DeferredTaxAssetInterestCarryforward_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Deferred Tax Asset, Interest Carryforward</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CommitmentsAndContingencies_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Commitments and contingencies (Note 14)</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CommitmentsAndContingencies_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Commitments and Contingencies</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CommonStockSharesIssued_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Common stock, shares issued (in shares)</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CommonStockSharesIssued_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Common Stock, Shares, Issued</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="srt_MinimumMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Minimum [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="srt_MinimumMember_lbl" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">Minimum</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="srt_MinimumMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Minimum [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ScheduleOfRestructuringAndRelatedCostsTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Restructuring Costs</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ScheduleOfRestructuringAndRelatedCostsTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Restructuring and Related Costs [Table Text Block]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_EmployeeStockPurchasePlanPurchasePriceToMarketPriceMatchingPercentage_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Purchase price to market price matching percentage</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_EmployeeStockPurchasePlanPurchasePriceToMarketPriceMatchingPercentage_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Employee Stock Purchase Plan Purchase Price To Market Price Matching Percentage</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_EmployeeStockPurchasePlanPurchasePriceToMarketPriceMatchingPercentage_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Purchase price to market price matching percentage.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_WesternAllianceBankMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Western Alliance Bank</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_WesternAllianceBankMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Western Alliance Bank [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_WesternAllianceBankMember_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Western Alliance Bank [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_SegmentDomain_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Segments</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_SegmentDomain_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Segments [Domain]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_StockIssuedDuringPeriodValueIssuedForServices_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Issuance of stock and shares for services</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_StockIssuedDuringPeriodValueIssuedForServices_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Stock Issued During Period, Value, Issued for Services</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PatentsMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Patents [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PatentsMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Patents [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AccruedLiabilitiesCurrent_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Total</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AccruedLiabilitiesCurrent_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Accrued expenses and other</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AccruedLiabilitiesCurrent_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Accrued Liabilities, Current</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedWeightedAverageGrantDateFairValue_lbl" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel">Shares outstanding at March 31, 2023</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedWeightedAverageGrantDateFairValue_lbl" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel">Balance at March 31, 2022</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedWeightedAverageGrantDateFairValue_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Share-Based Compensation Arrangement by Share-Based Payment Award, Option, Nonvested, Weighted Average Exercise Price</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_QuarterlyFinancialDataAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Quarterly Financial Data [Abstract]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DebtInstrumentAxis_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Debt Instrument</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DebtInstrumentAxis_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Debt Instrument [Axis]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_StockholdersEquityAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Shareholders&#8217; equity:</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_StockholdersEquityAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Stockholders' Equity Attributable to Parent [Abstract]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">State taxes, net</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Percent</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_TreasuryStockMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Treasury Stock</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_TreasuryStockMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Treasury Stock [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_StatementBusinessSegmentsAxis_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Segments</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_StatementBusinessSegmentsAxis_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Segments [Axis]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ProductMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Product revenue</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ProductMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Product [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AmortizationOfIntangibleAssets_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Amortization of intangible assets</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AmortizationOfIntangibleAssets_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Amortization of Intangible Assets</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AwardTypeAxis_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Award Type</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AwardTypeAxis_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Award Type [Axis]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_PewaukeeMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Pewaukee Wisconsin</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_PewaukeeMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Pewaukee [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_PewaukeeMember_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Pewaukee.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ProductWarrantyAccrual_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Standard and Extended Product Warranty Accrual, Total</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ProductWarrantyAccrual_lbl" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel">Beginning of year</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ProductWarrantyAccrual_lbl" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel">End of year</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ProductWarrantyAccrual_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Standard and Extended Product Warranty Accrual</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_OtherNoncashIncomeExpense_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Other Noncash Income (Expense), Total</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_OtherNoncashIncomeExpense_lbl" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Other</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_OtherNoncashIncomeExpense_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Other Noncash Income (Expense)</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_SubsequentEventMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Subsequent Event</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_SubsequentEventMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Subsequent Event [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Total</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Share-Based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_InventoryAdjustmentsAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Reserve</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_InventoryAdjustmentsAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Inventory Adjustments [Abstract]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_BusinessCombinationConsiderationTransferred1_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Business Combination, Consideration Transferred, Total</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_BusinessCombinationConsiderationTransferred1_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Purchase price</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_BusinessCombinationConsiderationTransferred1_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Business Combination, Consideration Transferred</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DeferredTaxAssetsGross_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Total deferred tax assets</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DeferredTaxAssetsGross_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Deferred Tax Assets, Gross</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LongTermDebtCurrent_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Long-Term Debt, Current Maturities, Total</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LongTermDebtCurrent_lbl" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Less current maturities</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LongTermDebtCurrent_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Current maturities of long-term debt</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LongTermDebtCurrent_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Long-Term Debt, Current Maturities</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_PeriodOfTimeStateIncomeTaxReturnsSubjectToExamination_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Examination period for state income tax returns</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_PeriodOfTimeStateIncomeTaxReturnsSubjectToExamination_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Period Of Time State Income Tax Returns Subject To Examination</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_PeriodOfTimeStateIncomeTaxReturnsSubjectToExamination_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Period of time state income tax returns subject to examination.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_NonoperatingIncomeExpenseAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Other income (expense):</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_NonoperatingIncomeExpenseAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Nonoperating Income (Expense) [Abstract]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ResearchAndDevelopmentExpense_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Research and Development Expense, Total</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ResearchAndDevelopmentExpense_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Research and development</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ResearchAndDevelopmentExpense_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Research and Development Expense</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Total lease payments</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Lessee, Operating Lease, Liability, to be Paid</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_UnrecognizedTaxBenefitsDecreasesResultingFromPriorPeriodTaxPositions_lbl" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">(Reductions) for tax positions of prior years</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_UnrecognizedTaxBenefitsDecreasesResultingFromPriorPeriodTaxPositions_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Unrecognized Tax Benefits, Decrease Resulting from Prior Period Tax Positions</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LesseeOperatingLeaseTermOfContract_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Term of other leases</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LesseeOperatingLeaseTermOfContract_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Lessee, Operating Lease, Term of Contract</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_CommercialAndIndustrialMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Commercial and industrial</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_CommercialAndIndustrialMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Commercial And Industrial [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_CommercialAndIndustrialMember_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Commercial And Industrial [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DeferredTaxAssetsGoodwillAndIntangibleAssets_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Intangible assets</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DeferredTaxAssetsGoodwillAndIntangibleAssets_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Deferred Tax Assets, Goodwill and Intangible Assets</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_EntityCentralIndexKey_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Entity Central Index Key</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_EntityCentralIndexKey_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Entity Central Index Key</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ValuationAllowanceDeferredTaxAssetChangeInAmount_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Increase (decrease) in valuation allowance</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ValuationAllowanceDeferredTaxAssetChangeInAmount_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LesseeOperatingLeaseExistenceOfOptionToTerminate_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Lessee, operating lease, existence of option to terminate</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LesseeOperatingLeaseExistenceOfOptionToTerminate_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Lessee, Operating Lease, Existence of Option to Terminate [true false]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_FiniteLivedIntangibleAssetsLineItems_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Finite-Lived Intangible Assets [Line Items]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_FiniteLivedIntangibleAssetsLineItems_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Finite-Lived Intangible Assets [Line Items]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_BusinessCombinationWorkingCapitalAdjustmentReceived_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Business combination, working capital adjustment received</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_BusinessCombinationWorkingCapitalAdjustmentReceived_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Business Combination Working Capital Adjustment Received</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_BusinessCombinationWorkingCapitalAdjustmentReceived_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Business combination working capital adjustment received.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_FiniteLivedIntangibleAssetWeightedAverageUsefulLife_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Amortized Intangible Assets, Weighted Average Useful Life</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_FiniteLivedIntangibleAssetWeightedAverageUsefulLife_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Finite-Lived Intangible Asset Weighted Average Useful Life</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_FiniteLivedIntangibleAssetWeightedAverageUsefulLife_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Finite-Lived Intangible Asset Weighted Average Useful Life</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="srt_MajorCustomersAxis_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Customer</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="srt_MajorCustomersAxis_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Customer [Axis]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AccountingPoliciesAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Accounting Policies [Abstract]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedWeightedAverageGrantDateFairValue_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Weighted Average Fair Value Price Shares vested</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedWeightedAverageGrantDateFairValue_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Vested, Weighted Average Grant Date Fair Value</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DisaggregationOfRevenueLineItems_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Disaggregation Of Revenue [Line Items]</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_lbl" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel">Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment, Beginning Balance</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment, Total</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_lbl" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Less: accumulated depreciation and amortization</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="srt_ConsolidationItemsDomain_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Consolidation Items [Domain]</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Number of shares available for grant</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Share-Based Compensation Arrangement by Share-Based Payment Award, Number of Shares Available for Grant</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_ContractWithCustomerCreditLiabilityCurrent_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Credits due to customers</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_ContractWithCustomerCreditLiabilityCurrent_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Contract With Customer Credit Liability Current</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_ContractWithCustomerCreditLiabilityCurrent_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Contract with customer credit liability current.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DisclosureOfCompensationRelatedCostsShareBasedPaymentsTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">STOCK OPTIONS AND RESTRICTED SHARES</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DisclosureOfCompensationRelatedCostsShareBasedPaymentsTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Share-Based Payment Arrangement [Text Block]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_GeneralAndAdministrativeExpense_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">General and Administrative Expense, Total</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_GeneralAndAdministrativeExpense_lbl" xlink:role="http://www.xbrl.org/2003/role/label">General and Administrative Expense</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_OrganizationConsolidationAndPresentationOfFinancialStatementsAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Organization, Consolidation and Presentation of Financial Statements [Abstract]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Weighted Average Exercise Price (usd per share)</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_lbl" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel">Beginning Balance (in dollars per share)</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_lbl" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel">Ending Balance (in dollars per share)</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Weighted Average Exercise Price</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ResearchAndDevelopmentExpenseMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Research and development</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ResearchAndDevelopmentExpenseMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Research and Development Expense [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_InventoryRawMaterialsAndSupplies_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Inventory, Raw Materials and Supplies, Gross, Total</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_InventoryRawMaterialsAndSupplies_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Raw materials and components</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_InventoryRawMaterialsAndSupplies_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Inventory, Raw Materials and Supplies, Gross</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Operating lease assets obtained in exchange for new operating lease liabilities</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Right-of-Use Asset Obtained in Exchange for Operating Lease Liability</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_EmployeeServiceShareBasedCompensationNonvestedAwardsCompensationCostNotYetRecognizedDueInThreeYears_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Fiscal 2026</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_EmployeeServiceShareBasedCompensationNonvestedAwardsCompensationCostNotYetRecognizedDueInThreeYears_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Employee Service Share Based Compensation Nonvested Awards Compensation Cost Not Yet Recognized Due In Three Years</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_EmployeeServiceShareBasedCompensationNonvestedAwardsCompensationCostNotYetRecognizedDueInThreeYears_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Due in Three Years.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_MaintenanceServicesMember_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Maintenance services.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_MaintenanceServicesMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Maintenance Services [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_MaintenanceServicesMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Maintenance services</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_RetainedEarningsMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Retained Earnings (Deficit)</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_RetainedEarningsMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Retained Earnings [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ExtinguishmentOfDebtTypeDomain_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Extinguishment of Debt, Type</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ExtinguishmentOfDebtTypeDomain_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Extinguishment of Debt, Type [Domain]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_WeightedAverageEffectOfAssumedConversionOfStockOptionsAndRestrictedStockUnits_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Weighted-average effect of assumed conversion of stock options and restricted stock</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_WeightedAverageEffectOfAssumedConversionOfStockOptionsAndRestrictedStockUnits_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Weighted Average Effect Of Assumed Conversion Of Stock Options And Restricted Stock Units</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_WeightedAverageEffectOfAssumedConversionOfStockOptionsAndRestrictedStockUnits_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Weighted-average effect of assumed conversion of stock options and restricted stock.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_PriorCreditAgreementMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Prior Credit Agreement</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_PriorCreditAgreementMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Prior Credit Agreement [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_PriorCreditAgreementMember_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Prior credit agreement.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AccountsPayableAndAccruedLiabilitiesNoncurrent_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Accrued expenses</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AccountsPayableAndAccruedLiabilitiesNoncurrent_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Accounts Payable and Accrued Liabilities, Noncurrent</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AccountsPayableAndAccruedLiabilitiesNoncurrent_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Accounts Payable and Accrued Liabilities, Noncurrent, Total</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="srt_NameOfMajorCustomerDomain_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Customer</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="srt_NameOfMajorCustomerDomain_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Customer [Domain]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_SegmentReportingAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Segment Reporting [Abstract]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_EffectiveIncomeTaxRateContinuingOperations_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Effective income tax rate</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_EffectiveIncomeTaxRateContinuingOperations_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Effective Income Tax Rate Reconciliation, Percent</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_lbl" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">Stock-based compensation</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_OtherLongTermInvestments_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Other Long-Term Investments</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_GainLossOnSaleOfPropertyPlantEquipment_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Gain (Loss) on Disposition of Property Plant Equipment, Total</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_GainLossOnSaleOfPropertyPlantEquipment_lbl" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">(Gain) loss on sale of property and equipment</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_GainLossOnSaleOfPropertyPlantEquipment_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Gain (Loss) on Disposition of Property Plant Equipment</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_OperatingLeaseLiabilityCurrentStatementOfFinancialPositionExtensibleList_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_OperatingLeaseLiabilityCurrentStatementOfFinancialPositionExtensibleList_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Operating Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_TreasuryStockCommonShares_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Treasury stock (in shares)</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_TreasuryStockCommonShares_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Treasury Stock, Common, Shares</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PropertyPlantAndEquipmentGross_lbl" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel">Property, Plant and Equipment, Gross, Ending Balance</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PropertyPlantAndEquipmentGross_lbl" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel">Property, Plant and Equipment, Gross, Beginning Balance</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PropertyPlantAndEquipmentGross_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Property, Plant and Equipment, Gross, Total</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PropertyPlantAndEquipmentGross_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Gross property and equipment</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PropertyPlantAndEquipmentGross_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Property, Plant and Equipment, Gross</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_PayrollTaxCreditCurrent_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Payroll tax credit</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_PayrollTaxCreditCurrent_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Payroll Tax Credit Current</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_PayrollTaxCreditCurrent_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Payroll tax credit current.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_FinitelivedIntangibleAssetsAcquired1_lbl" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">Intangible assets</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_EmployeeStockPurchasePlanClosingMarketPriceOfSharesPurchased_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Closing Market Price</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_EmployeeStockPurchasePlanClosingMarketPriceOfSharesPurchased_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Employee Stock Purchase Plan Closing Market Price Of Shares Purchased</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_EmployeeStockPurchasePlanClosingMarketPriceOfSharesPurchased_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Employee stock purchase plans weighted averages purchase price of shares purchased.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_LimitedProductWarrantyTerm_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Limited warranty term</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_LimitedProductWarrantyTerm_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Limited Product Warranty, Term</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_EntityInteractiveDataCurrent_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Entity Interactive Data Current</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_EntityPublicFloat_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Entity Public Float</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_GainLossOnSaleOfUnbilledContractRevenue_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Gain (loss) on sale of revenue earned but not billed</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Fiscal 2024</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_TreasuryStockCommonValue_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Treasury Stock, Common, Value</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LeaseholdImprovementsMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Leasehold Improvements</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LeaseholdImprovementsMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Leasehold Improvements [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_RepaymentsOfLongTermDebtExcludingRevolvingLinesOfCredit_lbl" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Payment of long-term debt</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_RepaymentsOfLongTermDebtExcludingRevolvingLinesOfCredit_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Repayments Of Long Term Debt Excluding Revolving Lines Of Credit</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_RepaymentsOfLongTermDebtExcludingRevolvingLinesOfCredit_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Repayments of long term debt excluding revolving lines of credit.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_LocalPhoneNumber_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Local Phone Number</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_LocalPhoneNumber_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Local Phone Number</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Statutory federal tax rate</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_UnrecognizedTaxBenefits_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Unrecognized tax benefits</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_UnrecognizedTaxBenefits_lbl" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel">Unrecognized tax benefits as of beginning of fiscal year</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_UnrecognizedTaxBenefits_lbl" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel">Unrecognized tax benefits as of end of fiscal year</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_UnrecognizedTaxBenefits_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Unrecognized Tax Benefits</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsRevenueEarnedButNotBilled_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Revenue earned but not billed</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsRevenueEarnedButNotBilled_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed Current Assets Revenue Earned But Not Billed</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsRevenueEarnedButNotBilled_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Business combination recognized identifiable assets acquired and liabilities assumed current assets revenue earned but not billed.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ScheduleOfRecognizedIdentifiedAssetsAcquiredAndLiabilitiesAssumedTableTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Schedule of Preliminary Allocation of Purchase Consideration to Fair Value of Assets Acquired and Liabilities Assumed</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ScheduleOfRecognizedIdentifiedAssetsAcquiredAndLiabilitiesAssumedTableTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Schedule of Recognized Identified Assets Acquired and Liabilities Assumed [Table Text Block]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ScheduleOfEarningsPerShareBasicAndDilutedTableTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Summary of the Effect of Net Income (Loss) Per Common Share</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ScheduleOfEarningsPerShareBasicAndDilutedTableTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Schedule of Earnings Per Share, Basic and Diluted [Table Text Block]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_DebtInstrumentOneMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Debt Instrument 1</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_DebtInstrumentOneMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Debt Instrument One [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_DebtInstrumentOneMember_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Debt instrument one member.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_AdjustmentsMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Adjustments</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_AdjustmentsMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Adjustments [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_AdjustmentsMember_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Adjustments [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageExercisePrice1_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Exercisable at March 31, 2023</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageExercisePrice1_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Share-Based Payment Arrangement, Option, Exercise Price Range, Exercisable, Weighted Average Exercise Price</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DebtDisclosureAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Debt Disclosure [Abstract]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ScheduleOfQuarterlyFinancialInformationTableTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Schedule of Quarterly Financial Information</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ScheduleOfQuarterlyFinancialInformationTableTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Quarterly Financial Information [Table Text Block]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Share-based Compensation Arrangement by Share-based Payment Award [Line Items]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Number of Shares, Exercisable (shares)</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Exercisable, Number</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ScheduleOfShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeTable_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Schedule Of Share Based Compensation Shares Authorized Under Stock Option Plans By Exercise Price Range [Table]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ScheduleOfShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeTable_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Share-Based Payment Arrangement, Option, Exercise Price Range [Table]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LineOfCreditFacilityAxis_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Lender Name</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LineOfCreditFacilityAxis_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Lender Name [Axis]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DisaggregationOfRevenueTableTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Disaggregation of Revenue</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DisaggregationOfRevenueTableTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Disaggregation of Revenue [Table Text Block]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Granted (shares)</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Grants in Period, Gross</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_VendorRelationshipMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Vendor relationship</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_VendorRelationshipMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Vendor Relationship [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_VendorRelationshipMember_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Vendor Relationship [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LongTermPurchaseCommitmentByCategoryOfItemPurchasedAxis_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Category of Item Purchased</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LongTermPurchaseCommitmentByCategoryOfItemPurchasedAxis_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Category of Item Purchased [Axis]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_NumberOfCustomerMoreThanTenPercentOfRevenue_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Number of customer more than ten percent of revenue</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_NumberOfCustomerMoreThanTenPercentOfRevenue_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Number Of Customer More Than Ten Percent Of Revenue</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_NumberOfCustomerMoreThanTenPercentOfRevenue_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Number of customer more than ten percent of revenue.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_OtherLiabilitiesNoncurrent_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Other long-term liabilities</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_OtherLiabilitiesNoncurrent_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Other Liabilities, Noncurrent</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_IncomeStatementLocationDomain_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Income Statement Location</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_IncomeStatementLocationDomain_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Income Statement Location [Domain]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonths_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Fiscal 2024</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonths_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Long-Term Debt, Maturity, Year One</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PropertyPlantAndEquipmentAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Property, Plant and Equipment [Abstract]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_lbl" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel">Shares outstanding, beginning of the period (shares)</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_lbl" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel">Shares outstanding, end of the period (shares)</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Nonvested, Number</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_StayLiteLightingAcquisitionMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Stay Lite Lighting Acquisition [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_StayLiteLightingAcquisitionMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Stay Lite Lighting Acquisition [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_StayLiteLightingAcquisitionMember_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Stay Lite Lighting Acquisition.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LongTermDebt_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Total long-term debt</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LongTermDebt_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Long-Term Debt</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_SharesOutstanding_lbl" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel">Shareholders' equity, beginning of period (Shares)</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_SharesOutstanding_lbl" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel">Shareholders' equity, at end of period (shares)</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_SharesOutstanding_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Shares, Outstanding</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Credit facility, available amount</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets_lbl" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Prepaid expenses and other assets</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Schedule Of Share Based Compensation Arrangements By Share Based Payment Award [Table]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Schedule of Share-Based Compensation Arrangements by Share-Based Payment Award [Table]</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_InventoryDisclosureAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Inventory Disclosure [Abstract]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CustomerConcentrationRiskMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Customer Concentration Risk</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CustomerConcentrationRiskMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Customer Concentration Risk [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_UnusualOrInfrequentItemAxis_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Unusual or Infrequent Item, or Both</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_UnusualOrInfrequentItemAxis_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Unusual or Infrequent Item, or Both [Axis]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_OperatingExpenseMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Operating Expenses [Member]</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Outstanding and Vested (shares)</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_lbl" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel">Beginning Balance (shares)</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_lbl" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel">Ending Balance (shares)</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Number</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_SharePrice_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Share Price</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DebtInstrumentNameDomain_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Debt Instrument, Name</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_IntangibleAssetsNetExcludingGoodwill_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Other Intangible Assets, Net</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_IntangibleAssetsNetExcludingGoodwill_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Other intangible assets, net</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_IntangibleAssetsNetExcludingGoodwill_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Intangible Assets, Net (Excluding Goodwill)</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued, Total</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Unrecognized tax benefits, accrued interest and penalties</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_InventoryFinishedGoodsNetOfReserves_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Finished goods</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_InventoryFinishedGoodsNetOfReserves_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Inventory, Finished Goods, Net of Reserves</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PaymentsOfDebtIssuanceCosts_lbl" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Debt issue costs</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PaymentsOfDebtIssuanceCosts_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Payments of Debt Issuance Costs</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PurchaseObligation_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Purchase Obligation, Total</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PurchaseObligation_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Purchase commitments</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PurchaseObligation_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Purchase Obligation</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Fiscal 2025</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Lessee, Operating Lease, Liability, to be Paid, Year Two</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_ElectricVehicleChargingSystemsMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Orion Electric Vehicle Charging Systems</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_ElectricVehicleChargingSystemsMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Electric Vehicle Charging Systems [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_ElectricVehicleChargingSystemsMember_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Electric Vehicle Charging Systems [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_RangeTwoMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">$2.00 - 2.03</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_RangeTwoMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Range Two [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_RangeTwoMember_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Range two.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_TwoThousandSixteenOmnibusIncentivePlanMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">2016 Omnibus Incentive Plan</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_TwoThousandSixteenOmnibusIncentivePlanMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Two Thousand Sixteen Omnibus Incentive Plan [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_TwoThousandSixteenOmnibusIncentivePlanMember_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">2016 Omnibus Incentive Plan.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_EarningsPerShareBasic_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Basic net (loss) income per share attributable to common shareholders</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_EarningsPerShareBasic_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Earnings Per Share, Basic, Total</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_EarningsPerShareBasic_lbl" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">Basic net income (loss) per share</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_EarningsPerShareBasic_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Earnings Per Share, Basic</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_RepaymentsOfLongTermLinesOfCredit_lbl" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Payment of revolving credit facility</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_RepaymentsOfLongTermLinesOfCredit_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Repayments of Long-Term Lines of Credit</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_OtherPrepaidExpenseCurrent_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Other prepaid expenses</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_OtherPrepaidExpenseCurrent_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Other Prepaid Expense, Current</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Weighted Average Exercise Price</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AssetsAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Assets</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AssetsAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Assets [Abstract]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_IncreaseDecreaseInAccruedLiabilities_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Increase (Decrease) in Accrued Liabilities, Total</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_IncreaseDecreaseInAccruedLiabilities_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Accrued expenses and other liabilities</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_IncreaseDecreaseInAccruedLiabilities_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Increase (Decrease) in Accrued Liabilities</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DebtInstrumentAnnualPrincipalPayment_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Annual lease payment</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DebtInstrumentAnnualPrincipalPayment_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Debt Instrument, Annual Principal Payment</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DeferredTaxAssetsLiabilitiesNet_lbl" xlink:role="http://www.xbrl.org/2009/role/negatedTotalLabel">Total net deferred tax (liabilities) assets</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DeferredTaxAssetsLiabilitiesNet_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Total net deferred tax assets</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DeferredTaxAssetsLiabilitiesNet_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Deferred Tax Assets, Net</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CostOfGoodsTotalMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Cost of revenue</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CostOfGoodsTotalMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Cost of Goods and Service Benchmark [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_GrossProfit_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Gross profit</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_GrossProfit_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Gross profit</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_GrossProfit_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Gross Profit</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PrepaidExpenseAndOtherAssetsCurrent_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Total</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PrepaidExpenseAndOtherAssetsCurrent_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Prepaid expenses and other current assets</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PrepaidExpenseAndOtherAssetsCurrent_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Prepaid Expense and Other Assets, Current</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LineOfCreditFacilityExpirationPeriod_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Credit agreement period</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LineOfCreditFacilityExpirationPeriod_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Line of Credit Facility, Expiration Period</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_SharesIssuedPricePerShare_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Per share price on grant date</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_SharesIssuedPricePerShare_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Shares Issued, Price Per Share</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_IssuanceOfCommonStockForAcquisition_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Issuance of common stock for acquisition</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_IssuanceOfCommonStockForAcquisition_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Issuance of common stock for acquisition</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_SpringingMinimumFixedCostCoverageRatioCovenantAmountOfExcessAvailabilityUnderCreditFacility_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Credit agreement, springing minimum fixed cost coverage ratio covenant amount of excess availability under credit facility</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_SpringingMinimumFixedCostCoverageRatioCovenantAmountOfExcessAvailabilityUnderCreditFacility_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Springing Minimum Fixed Cost Coverage Ratio Covenant Amount Of Excess Availability Under Credit Facility</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_SpringingMinimumFixedCostCoverageRatioCovenantAmountOfExcessAvailabilityUnderCreditFacility_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Springing minimum fixed cost coverage ratio covenant amount of excess availability under credit facility.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ContractWithCustomerRefundLiabilityCurrent_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Sales returns reserve</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ContractWithCustomerRefundLiabilityCurrent_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Contract with Customer, Refund Liability, Current</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CreditConcentrationRiskMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Credit Concentration Risk</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CreditConcentrationRiskMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Credit Concentration Risk [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_ProvisionForInventoryReserves_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Provision for inventory reserves</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_ProvisionForInventoryReserves_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Provision For Inventory Reserves</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_ProvisionForInventoryReserves_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Provision for inventory reserves</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PropertyPlantAndEquipmentByTypeAxis_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Long-Lived Tangible Asset</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PropertyPlantAndEquipmentByTypeAxis_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Long-Lived Tangible Asset [Axis]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Schedule Of Restructuring And Related Costs [Table]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Schedule of Restructuring and Related Costs [Table]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ConcentrationRiskByBenchmarkAxis_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Concentration Risk Benchmark</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ConcentrationRiskByBenchmarkAxis_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Concentration Risk Benchmark [Axis]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DeferredTaxAssetsDeferredIncome_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Deferred tax assets</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DeferredTaxAssetsDeferredIncome_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Deferred Tax Assets, Deferred Income</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ProvisionForLoanAndLeaseLosses_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Provision for bad debts</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ProvisionForLoanAndLeaseLosses_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Provision for Loan and Lease Losses</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Number of Shares</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding [Roll Forward]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LiabilitiesAndStockholdersEquityAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Liabilities and Shareholders&#8217; Equity</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LiabilitiesAndStockholdersEquityAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Liabilities and Equity [Abstract]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_InventoryGross_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Total</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_InventoryGross_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Inventory, Gross</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_IncomeTaxesPaidNet_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Income Taxes Paid, Net, Total</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_IncomeTaxesPaidNet_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Cash paid for income taxes</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_IncomeTaxesPaidNet_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Income Taxes Paid, Net</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_StayLiteLightingIncMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Stay-Lite Lighting, Inc.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_StayLiteLightingIncMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Stay Lite Lighting Inc [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_StayLiteLightingIncMember_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Stay-Lite Lighting, Inc</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AntidilutiveSecuritiesNameDomain_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Antidilutive Securities, Name</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AntidilutiveSecuritiesNameDomain_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Antidilutive Securities, Name [Domain]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DevelopedTechnologyRightsMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Developed technology [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DevelopedTechnologyRightsMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Developed Technology Rights [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_IncomeTaxAuthorityAxis_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Income Tax Authority</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_IncomeTaxAuthorityAxis_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Income Tax Authority [Axis]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DeferredTaxAssetsNet_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Deferred tax assets, net of valuation allowance</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DeferredTaxAssetsNet_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Deferred Tax Assets, Net of Valuation Allowance</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ProfitLoss_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Net Income (Loss), Including Portion Attributable to Noncontrolling Interest, Total</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ProfitLoss_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Net income</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ProfitLoss_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Net Income (Loss), Including Portion Attributable to Noncontrolling Interest</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Fiscal 2027</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Finite-Lived Intangible Asset, Expected Amortization, Year Four</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Fiscal 2025</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Finite-Lived Intangible Asset, Expected Amortization, Year Two</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ExtinguishmentOfDebtLineItems_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Extinguishment Of Debt [Line Items]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ExtinguishmentOfDebtLineItems_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Extinguishment of Debt [Line Items]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_SegmentReportingDisclosureTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">SEGMENT DATA</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_SegmentReportingDisclosureTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Segment Reporting Disclosure [Text Block]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_PaymentsForPreviousAcquisitionInShare_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Payments for previous acquisition, shares</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_PaymentsForPreviousAcquisitionInShare_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Payments For Previous Acquisition in Share</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_PaymentsForPreviousAcquisitionInShare_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Payments For Previous Acquisition in Share</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ScheduleOfDeferredTaxAssetsAndLiabilitiesTableTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Schedule of Deferred Tax Assets</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ScheduleOfDeferredTaxAssetsAndLiabilitiesTableTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Schedule of Deferred Tax Assets and Liabilities [Table Text Block]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromPriorPeriodTaxPositions_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Additions for tax positions of prior years</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromPriorPeriodTaxPositions_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Unrecognized Tax Benefits, Increase Resulting from Prior Period Tax Positions</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DefinedContributionPlanEmployerDiscretionaryContributionAmount_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Discretionary company contributions to retirement savings plan</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DefinedContributionPlanEmployerDiscretionaryContributionAmount_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Defined Contribution Plan, Employer Discretionary Contribution Amount</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_PeriodOfCumulativePretaxIncome_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Period of cumulative pretax income</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_PeriodOfCumulativePretaxIncome_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Period Of Cumulative Pretax Income</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_PeriodOfCumulativePretaxIncome_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Period of cumulative pretax income.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_CreditAgreementMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Credit Agreement</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_CreditAgreementMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Credit Agreement [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_CreditAgreementMember_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Credit Agreement</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Changes in operating assets and liabilities:</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Increase (Decrease) in Operating Capital [Abstract]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_FederalIncomeTaxExpenseBenefitContinuingOperations_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Total Federal</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_FederalIncomeTaxExpenseBenefitContinuingOperations_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Federal Income Tax Expense (Benefit), Continuing Operations</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_SelectedQuarterlyFinancialInformationAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Selected Quarterly Financial Information [Abstract]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_RestructuringAndRelatedActivitiesDisclosureTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">RESTRUCTURING EXPENSE</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_CoverAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Cover [Abstract]</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_GoodwillAndOtherIntangibleAssetsDisclosureTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Goodwill and other intangible assets disclosure.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ConcentrationRiskPercentage1_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Concentration risk, percentage</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ConcentrationRiskPercentage1_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Concentration Risk, Percentage</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="srt_ProductsAndServicesDomain_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Product and Service</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="srt_ProductsAndServicesDomain_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Product and Service [Domain]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Estimated Useful Life (Years)</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Acquired Finite-Lived Intangible Assets, Weighted Average Useful Life</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ReconciliationOfUnrecognizedTaxBenefitsExcludingAmountsPertainingToExaminedTaxReturnsRollForward_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Reconciliation of Unrecognized Tax Benefits [Roll Forward]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ReconciliationOfUnrecognizedTaxBenefitsExcludingAmountsPertainingToExaminedTaxReturnsRollForward_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_lbl" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Shares vested (shares)</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Vested in Period</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_InventoryFinishedGoods_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Finished goods</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_InventoryFinishedGoods_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Inventory, Finished Goods, Gross</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LongTermLineOfCredit_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Revolving credit facility</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LongTermLineOfCredit_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Long-Term Line of Credit, Noncurrent</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_InventoryNetAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Net</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_InventoryNetAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Inventory, Net [Abstract]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AccountsReceivableNetNoncurrent_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Accounts Receivable, after Allowance for Credit Loss, Noncurrent, Total</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AccountsReceivableNetNoncurrent_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Accounts Receivable, after Allowance for Credit Loss, Noncurrent</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="srt_MaximumMember_lbl" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">Maximum [Member]</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="srt_MaximumMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Maximum [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_TaxNotSubjectToTimeRestrictionMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Tax Not Subject To Time Restriction</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_TaxNotSubjectToTimeRestrictionMember_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Tax not subject to time restriction.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_NumberOfSupplierMoreThanTenPercentOfCostOfRevenue_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Number of supplier more than ten percent of cost of revenue</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_NumberOfSupplierMoreThanTenPercentOfCostOfRevenue_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Number Of Supplier More Than Ten Percent Of Cost Of Revenue</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_NumberOfSupplierMoreThanTenPercentOfCostOfRevenue_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Number of supplier more than ten percent of cost of revenue.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Summary of Stock-based Compensation</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_NetCashProvidedByUsedInInvestingActivities_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Net cash used in investing activities</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_FurnitureAndFixturesMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Furniture, fixtures and office equipment</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_EffectiveIncomeTaxRateReconciliationTaxCreditStatePercent_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">State tax credits, net</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_lbl" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Exercised (shares)</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LongTermPurchaseCommitmentTable_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Long Term Purchase Commitment [Table]</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DebtInstrumentCarryingAmount_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Principal amount of debt</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DebtInstrumentCarryingAmount_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Long-Term Debt, Gross</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Fiscal 2026</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Finite-Lived Intangible Asset, Expected Amortization, Year Three</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_OtherLiabilitiesDisclosureAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Other Liabilities Disclosure [Abstract]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CommonStockSharesAuthorized_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Common stock, shares authorized (in shares)</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CommonStockSharesAuthorized_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Common Stock, Shares Authorized</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_DeferredTaxAssetDeferredIncomeNoncurrent_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Deferred revenue</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_DeferredTaxAssetDeferredIncomeNoncurrent_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Deferred Tax Asset Deferred Income Noncurrent</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_DeferredTaxAssetDeferredIncomeNoncurrent_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Deferred tax asset deferred income noncurrent.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_TradingSymbol_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Trading Symbol</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_TradingSymbol_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Trading Symbol</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_InventoryRawMaterialsAndSuppliesNetOfReserves_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Inventory, Raw Materials and Supplies, Net of Reserves, Total</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_InventoryRawMaterialsAndSuppliesNetOfReserves_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Raw materials and components</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_InventoryRawMaterialsAndSuppliesNetOfReserves_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Inventory, Raw Materials and Supplies, Net of Reserves</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_LawrenceMassachusettsMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Lawrence, Massachusetts</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_LawrenceMassachusettsMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Lawrence, Massachusetts [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_LawrenceMassachusettsMember_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Lawrence, Massachusetts [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_PercentageOfAdjustedTaxableIncomeToOffset_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">NOL carryforwards, percentage of adjusted taxable income to offset</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_PercentageOfAdjustedTaxableIncomeToOffset_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Percentage Of Adjusted Taxable Income To Offset</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_PercentageOfAdjustedTaxableIncomeToOffset_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Percentage of adjusted taxable income to offset.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_NumberOfCustomerMoreThanTenPercentOfAccountsReceivable_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Number of customer more than ten percent of accounts receivable</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_NumberOfCustomerMoreThanTenPercentOfAccountsReceivable_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Number Of Customer More Than Ten Percent Of Accounts Receivable</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_NumberOfCustomerMoreThanTenPercentOfAccountsReceivable_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Number of customer more than ten percent of accounts receivable.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_SubsequentEventTypeAxis_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Subsequent Event Type</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_SubsequentEventTypeAxis_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Subsequent Event Type [Axis]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DeferredTaxAssetsOther_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Other</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DeferredTaxAssetsOther_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Deferred Tax Assets, Other</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_SummaryOfAssetsLeasedFromThirdPartiesTableTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Summary of Assets Leased from Third Parties</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_SummaryOfAssetsLeasedFromThirdPartiesTableTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Summary Of Assets Leased From Third Parties Table [Text Block]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_SummaryOfAssetsLeasedFromThirdPartiesTableTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Summary of assets leased from third parties.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_BalanceSheetLocationAxis_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Balance Sheet Location [Axis]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_LightingProductAndInstallationMember_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Lighting product and installation.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_LightingProductAndInstallationMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Lighting Product And Installation [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_LightingProductAndInstallationMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Lighting product and installation</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_RevenuePracticalExpedientFinancingComponent_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Revenue, Practical Expedient, Financing Component [true false]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_RevenuePracticalExpedientFinancingComponent_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Revenue, Practical Expedient, Financing Component [true false]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_InterestCostsCapitalized_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Interest capitalized for construction in progress</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_InterestCostsCapitalized_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Interest Costs Capitalized</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ProceedsFromSaleOfPropertyPlantAndEquipment_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Proceeds from Sale of Property, Plant, and Equipment, Total</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ProceedsFromSaleOfPropertyPlantAndEquipment_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Proceeds from sales of property, plant and equipment</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ProceedsFromSaleOfPropertyPlantAndEquipment_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Proceeds from Sale of Property, Plant, and Equipment</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AccountsPayableCurrent_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Accounts Payable, Current, Total</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AccountsPayableCurrent_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Accounts payable</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AccountsPayableCurrent_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Accounts Payable, Current</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PlanNameAxis_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Plan Name</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PlanNameAxis_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Plan Name [Axis]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_TreasuryStockSharesAcquired_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Treasury stock acquired</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_TreasuryStockSharesAcquired_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Treasury Stock, Shares, Acquired</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ConcentrationRiskTypeDomain_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Concentration Risk Type</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ConcentrationRiskTypeDomain_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Concentration Risk Type [Domain]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PropertyPlantAndEquipmentTypeDomain_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Long-Lived Tangible Asset</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PropertyPlantAndEquipmentTypeDomain_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Long-Lived Tangible Asset [Domain]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_EntityWellKnownSeasonedIssuer_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Entity Well-known Seasoned Issuer</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_EntityWellKnownSeasonedIssuer_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Entity Well-known Seasoned Issuer</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_StockIssuedDuringPeriodSharesAcquisitions_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Issuance of common stock for acquisition (shares)</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_StockIssuedDuringPeriodSharesAcquisitions_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Stock Issued During Period, Shares, Acquisitions</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_EarnOutExpense_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Earn-out expense</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_EarnOutExpense_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Earn-Out Expense</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_EarnOutExpense_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Earn-out expense</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ScheduleOfSharebasedCompensationRestrictedStockAndRestrictedStockUnitsActivityTableTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Summary of performance-vesting restricted stock and time vesting-restricted stock</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ScheduleOfSharebasedCompensationRestrictedStockAndRestrictedStockUnitsActivityTableTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Share-Based Payment Arrangement, Restricted Stock and Restricted Stock Unit, Activity [Table Text Block]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Share-Based Payment Arrangement, Option, Exercise Price Range [Line Items]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_StockRepurchaseProgramAuthorizedAmount1_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Stock repurchase program, authorized amount</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_StockRepurchaseProgramAuthorizedAmount1_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Stock Repurchase Program, Authorized Amount</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_AcquisitionCostPolicyPolicyTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Acquisition Related Costs</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_AcquisitionCostPolicyPolicyTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Acquisition Cost Policy [Policy Text Block]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_AcquisitionCostPolicyPolicyTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Acquisition Cost Policy [Policy Text Block]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Shares issued (shares)</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_StockIssuedDuringPeriodValueAcquisitions_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Issuance of common stock for acquisition</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_StockIssuedDuringPeriodValueAcquisitions_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Stock Issued During Period, Value, Acquisitions</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PropertyPlantAndEquipmentDisclosureTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">PROPERTY AND EQUIPMENT</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PropertyPlantAndEquipmentDisclosureTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Property, Plant and Equipment Disclosure [Text Block]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PropertyPlantAndEquipmentEstimatedUsefulLives_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Property, plant and equipment, useful life</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PropertyPlantAndEquipmentEstimatedUsefulLives_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Property, Plant and Equipment, Estimated Useful Lives</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_SaleLeasebackTransactionAreaOfLeasedProperty_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Area of leased property</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_SaleLeasebackTransactionAreaOfLeasedProperty_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Sale Leaseback Transaction Area Of Leased Property</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="oesx_SaleLeasebackTransactionAreaOfLeasedProperty_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Sale leaseback transaction area of leased property.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Granted Stock Options (in dollars per share)</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Share-Based Compensation Arrangements by Share-Based Payment Award, Options, Grants in Period, Weighted Average Exercise Price</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LongTermDebtTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">LONG-TERM DEBT</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LongTermDebtTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Long-Term Debt [Text Block]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherNoncurrentAssets_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Other long-term assets</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherNoncurrentAssets_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Other Noncurrent Assets</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ClassOfTreasuryStockTable_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Class Of Treasury Stock [Table]</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LongtermDebtTypeDomain_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Long-term Debt, Type</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ConcentrationRiskTable_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Concentration Risk [Table]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ConcentrationRiskTable_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Concentration Risk [Table]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Indefinite-lived Intangible Assets, Major Class Name</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Indefinite-Lived Intangible Assets, Major Class Name [Domain]</link:label>
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