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Accounts Receivable, Contract Assets and Contract Liabilities (Tables) | 6 Months Ended
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Oct. 31, 2025
Accounts Receivable Contract Assets And Contract Liabilities |
Schedule of Accounts Receivable, Contract Assets and Contract Liabilities | The following provides further details on the balance sheet accounts of accounts receivable, contract assets and contract liabilities from contracts with customers: Schedule of Accounts Receivable, Contract Assets and Contract Liabilities
|  | October 31, 2025 |  |  | April 30, 2025 |  |  | April 30, 2024 |
|  | (in thousands) |
Accounts receivable |  | $ | 1,100 |  |  | $ | 1,191 |  |  | $ | 796 |
Contract assets |  | $ | 752 |  |  | $ | 1,088 |  |  | $ | 18 |
Contract liabilities |  | $ | 135 |  |  | $ | — |  |  | $ | 302 |
Schedule of Significant Changes in Contract Assets | Significant changes in the contract assets balances during the period were as follows: Schedule of Significant Changes in Contract Assets
|  | Six months ended October 31, 2025 |  |  | Six months ended October 31, 2024 |
|  | (in thousands) |
Transferred to receivables from contract assets recognized |  | $ | (853 | ) |  | $ | (583 | )
Revenue recognized and not billed |  |  | 517 |  |  |  | 651 |
Net change in contract assets |  | $ | (336 | ) |  | $ | 68 |
Schedule of Significant Changes in Contract Liabilities | Significant changes in the contract liabilities balances during the period are as follows: Schedule of Significant Changes in Contract Liabilities
|  | Six months ended October 31, 2025 |  |  | Six months ended October 31, 2024 |
|  | (in thousands) |
Revenue recognized |  | $ | (115 | ) |  | $ | (1,515 | )
Payments collected for which revenue has not been recognized |  |  | 250 |  |  |  | 1,332 |
Net change in contract liabilities |  | $ | 135 |  |  | $ | (183 | )

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- Definition Contract With Customer Asset [Table Text Block] + References No definition available. + Details
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- Definition Contract With Customer Liabilities [Table Text Block] + References No definition available. + Details
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Namespace Prefix: | OPTT_
Data Type: | dtr-types:textBlockItemType
Balance Type: | na
Period Type: | duration

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- References No definition available. + Details
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Namespace Prefix: | OPTT_
Data Type: | xbrli:stringItemType
Balance Type: | na
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- Definition Schedule of accounts receivable contract assets and contract liabilities [Table Text Block] + References No definition available. + Details
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Namespace Prefix: | OPTT_
Data Type: | dtr-types:textBlockItemType
Balance Type: | na
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