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Schedule of Significant Changes in Contract Liabilities (Details) - USD ($) $ in Thousands | 12 Months Ended
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Apr. 30, 2025 | Apr. 30, 2024
Account Receivable Contract Assets And Contract Liabilities |  |
Revenue recognized | $ (2,107) | $ (2,424)
Payments collected for which revenue has not been recognized | 1,805 | 1,348
Net change in contract liabilities | $ (302) | $ (1,076)

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- Definition Contract with customer liability revenue recognized including opening balance. + References No definition available. + Details
Name: | OPTT_ContractWithCustomerLiabilityRevenueRecognizedIncludingOpeningBalance
Namespace Prefix: | OPTT_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

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- References No definition available. + Details
Name: | OPTT_DisclosureAccountReceivableContractAssetsAndContractLiabilitiesAbstract
Namespace Prefix: | OPTT_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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- Definition Revenue recognized and not billed as of the end of the period. + References No definition available. + Details
Name: | OPTT_PaymentsCollectedForWhichRevenueHasNotBeenRecognized
Namespace Prefix: | OPTT_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

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- Definition Amount of increase (decrease) in obligation to transfer good or service to customer for which consideration has been received or is receivable. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 230 -SubTopic 10 -Name Accounting Standards Codification -Section 45 -Paragraph 28 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482740/230-10-45-28 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 912 -SubTopic 310 -Name Accounting Standards Codification -Section 45 -Paragraph 11 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478345/912-310-45-11 + Details
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Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration