STOCK OPTIONS AND RESTRICTED SHARES (Summary of Unrecognized Compensation Cost) (Details) $ in Thousands	12 Months Ended
Mar. 31, 2022 USD ($)
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Fiscal 2023	$ 799
Fiscal 2024	532
Fiscal 2025	126
Fiscal 2026	4
Thereafter	3
Total	$ 1,464
Remaining weighted average expected term	3 years

Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Due in Four Years.

No definition available.

Name:	oesx_EmployeeServiceShareBasedCompensationNonvestedAwardsCompensationCostNotYetRecognizedDueInFourYears
Namespace Prefix:	oesx_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Due in Three Years.

+ References

No definition available.

+ Details

Name:	oesx_EmployeeServiceShareBasedCompensationNonvestedAwardsCompensationCostNotYetRecognizedDueInThreeYears
Namespace Prefix:	oesx_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Due in Two Years.

+ References

No definition available.

+ Details

Name:	oesx_EmployeeServiceShareBasedCompensationNonvestedAwardsCompensationCostNotYetRecognizedDueInTwoYears
Namespace Prefix:	oesx_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Due Thereafter.

+ References

No definition available.

+ Details

Name:	oesx_EmployeeServiceShareBasedCompensationNonvestedAwardsCompensationCostNotYetRecognizedDueThereafter
Namespace Prefix:	oesx_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Next Twelve Months.

+ References

No definition available.

+ Details

Name:	oesx_EmployeeServiceShareBasedCompensationNonvestedAwardsCompensationCostNotYetRecognizedNextTwelveMonths
Namespace Prefix:	oesx_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- References

No definition available.

+ Details

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

- Definition

Amount of cost not yet recognized for nonvested award under share-based payment arrangement.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (i)
-URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901

+ Details

Name:	us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Weighted-average period over which cost not yet recognized is expected to be recognized for award under share-based payment arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ References

+ Details

Name:	us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration