Consolidated Balance Sheets - USD ($) $ in Thousands	Jan. 31, 2022	Apr. 30, 2021
Current assets:
Cash and cash equivalents	$ 63,454	$ 83,028
Restricted cash, short-term	384	384
Accounts receivable	113	350
Contract assets	407	190
Inventory	193
Other current assets	436	487
Total current assets	64,987	84,439
Property and equipment, net	365	406
Intangibles, net	4,203	274
Right-of-use asset, net	825	1,036
Restricted cash, long-term	222	222
Goodwill	7,754
Total assets	78,356	86,377
Current liabilities:
Accounts payable	522	687
Accrued expenses	1,292	1,881
Contract liabilities	15
Right-of-use liability, current portion	323	347
Advance payable	456
Litigation payable		1,224
Contingent liabilities	1,591	60
Paycheck protection program loan- current		495
Total current liabilities	4,199	4,694
Paycheck protection program loan, less current portion		396
Right-of-use liability, less current portion	615	819
Total liabilities	4,814	5,909
Commitments and contingencies (Note 15)
Shareholders’ Equity:
Preferred stock, $0.001 par value; authorized 5,000,000 shares, none issued or outstanding
Common stock, $0.001 par value; authorized 100,000,000 shares, issued 55,894,213 and 52,458,011 shares, respectively	56	52
Treasury stock, at cost; 21,040 shares	(338)	(338)
Additional paid-in capital	322,626	315,821
Accumulated deficit	(248,617)	(234,896)
Accumulated other comprehensive loss	(185)	(171)
Total shareholders’ equity	73,542	80,468
Total liabilities and shareholders’ equity	$ 78,356	$ 86,377

Advance payable current.

No definition available.

Name:	OPTT_AdvancePayableCurrent
Namespace Prefix:	OPTT_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Carrying value as of the balance sheet date of liabilities incurred (and for which invoices have typically been received) and payable to vendors for goods and services received that are used in an entity's business. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).