Debt maturity month and year.

No definition available.

Name:	oesx_DebtMaturityMonthAndYear
Namespace Prefix:	oesx_
Data Type:	xbrli:gYearMonthItemType
Balance Type:	na
Period Type:	duration

- Definition

Line of credit facility early termination fee.

+ References

No definition available.

+ Details

Name:	oesx_LineOfCreditFacilityEarlyTerminationFee
Namespace Prefix:	oesx_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Line of credit springing minimum fixed cost coverage ratio.

+ References

No definition available.

+ Details

Name:	oesx_LineOfCreditSpringingMinimumFixedCostCoverageRatio
Namespace Prefix:	oesx_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Definition

Springing minimum fixed cost coverage ratio covenant amount of excess availability under credit facility.

+ References

No definition available.

+ Details

Name:	oesx_SpringingMinimumFixedCostCoverageRatioCovenantAmountOfExcessAvailabilityUnderCreditFacility
Namespace Prefix:	oesx_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Springing minimum fixed cost coverage ratio covenant percentage of committed facility.

+ References

No definition available.

+ Details

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Namespace Prefix:	oesx_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

+ References

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+ Details

Name:	us-gaap_DebtInstrumentCarryingAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
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+ Details

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Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Difference between the fair value of payments made and the carrying amount of debt which is extinguished prior to maturity.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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-Subparagraph (b)
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+ Details

Name:	us-gaap_GainsLossesOnExtinguishmentOfDebt
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

+ References

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-Topic 210
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+ Details

Name:	us-gaap_LineOfCredit
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Date the credit facility terminates, in YYYY-MM-DD format.

+ References

+ Details

Name:	us-gaap_LineOfCreditFacilityExpirationDate1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Period remaining on line of credit facility before it terminates, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

Name:	us-gaap_LineOfCreditFacilityExpirationPeriod
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_LineOfCreditFacilityLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

+ Details

Name:	us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

+ References

+ Details

Name:	us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

Name:	us-gaap_DebtInstrumentAxis=oesx_PriorCreditAgreementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LineOfCreditFacilityAxis=oesx_WesternAllianceBankMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_LineOfCreditMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=us-gaap_RevolvingCreditFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=oesx_CreditAgreementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LineOfCreditFacilityAxis=oesx_BankOfAmericaNAMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=oesx_DebtInstrumentOneMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ExtinguishmentOfDebtAxis=us-gaap_CapitalLeaseObligationsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=oesx_DebtInstrumentTwoMember
Namespace Prefix:
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Period Type:

LONG-TERM DEBT (Narrative) (Details)		12 Months Ended
LONG-TERM DEBT (Narrative) (Details)	Dec. 29, 2020 USD ($)	Mar. 31, 2022 USD ($)	Mar. 31, 2021 USD ($)	Feb. 28, 2019 USD ($)	Oct. 26, 2018 USD ($)
Line Of Credit Facility [Line Items]
Loss on debt extinguishment			$ 90,000
Prior Credit Agreement \| Western Alliance Bank \| Line of credit \| Revolving credit facility
Line Of Credit Facility [Line Items]
Credit facility, amount					$ 20,150,000
Credit agreement, maturity date		Oct. 26, 2021
Credit agreement, early termination fees	$ 0
Loss on debt extinguishment	100,000
Credit Agreement \| Bank Of America N A \| Line of credit \| Revolving credit facility
Line Of Credit Facility [Line Items]
Credit facility, amount	$ 25,000,000.0
Credit agreement period	5 years
Credit agreement, maturity date		Dec. 29, 2025
Credit facility, available amount		$ 21,500,000
Credit agreement, amounts borrowed		$ 0
Credit agreement, springing minimum fixed cost coverage ratio	1.0
Credit agreement, springing minimum fixed cost coverage ratio covenant amount of excess availability under credit facility	$ 3,000,000.0
Credit agreement, springing minimum fixed cost coverage ratio covenant percentage of committed facility	15.00%
Debt Instrument 1 \| Equipment debt obligations
Line Of Credit Facility [Line Items]
Principal amount of debt				$ 44,000
Stated interest rate, percentage				6.43%
Debt maturity month and year		2024-01
Debt Instrument 2 \| Equipment debt obligations
Line Of Credit Facility [Line Items]
Principal amount of debt				$ 30,000
Stated interest rate, percentage				8.77%
Debt maturity month and year		2024-01