Commitments and Contingencies	12 Months Ended
Apr. 30, 2020
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	(15) Commitments and Contingencies Employment Litigation On June 10, 2014, the Company announced that it had terminated Charles Dunleavy as its Chief Executive Officer and as an employee of the Company for cause, effective June 9, 2014, and that Mr. Dunleavy had also been removed from his position as Chairman of the Board of Directors. On June 17, 2014, Mr. Dunleavy wrote to the Company stating that he had retained counsel to represent him in connection with an alleged wrongful termination of his employment. On July 28, 2014, Mr. Dunleavy resigned from the Board and the boards of directors of the Company’s subsidiaries. In 2014, the Company and Mr. Dunleavy entered into a tolling agreement with respect to his alleged employment claims pending resolution of a securities class action and shareholder derivative litigation. The securities class action was resolved in November 2017 and the derivatives litigation was resolved in June 2018. On August 28, 2018, counsel for Mr. Dunleavy filed a demand for arbitration, captioned Charles F. Dunleavy v. Ocean Power Technologies, Inc., Case No. 01-18-0003-2374, before the American Arbitration Association in New Jersey. The demand names Ocean Power Technologies, Inc. as the respondent and alleges various claims and seeks declaratory relief and permanent injunction. The demand seeks damages in the amount of $5 million for compensatory and punitive damages, plus interest and attorneys’ fees as well as certain equitable relief. On November 8, 2018, the Company through counsel responded to the demand for arbitration, denied all allegations, and asserted various affirmative defenses. On April 5, 2019, a three-person arbitration panel scheduled the discovery process to run from April 12, 2019 until November 9, 2019, set a pre-hearing case management conference for October 14, 2019, and set the hearing for December 9-13, 2019. On September 30, 2019, the parties completed the factual discovery process and the Company identified its expert witnesses. On October 14, 2019, the parties participated in a pre-hearing case management conference with arbitration panel and altered slightly the dates for the hearing. The hearing was conducted between December 9-11, 2019, and between December 16-18, 2019, and on December 18, 2019 the panel decided to continue the hearing for at least another day of testimony. The final day of hearing has now been scheduled for July 15, 2020, and the hearing will be conducted in Princeton, New Jersey. As of April 30, 2020, the Company has not accrued any provision related to this matter since it is not probable and cannot reasonably estimate the loss contingency. NASDAQ Delisting Notification On March 3, 2020, the Company received a notification from the NASDAQ Stock Market (the “NASDAQ”) indicating that the minimum bid price of the Company’s common stock has been below $1.00 per share for 30 consecutive business days and as a result, the Company is not in compliance with the minimum bid price requirement for continued listing. The NASDAQ notice has no immediate effect on the listing or trading of the Company’s common stock. Under the NASDAQ Listing Rules, the Company has a grace period of 180 calendar days, or until August 31, 2020, in which to regain compliance with the minimum bid price rule. To regain compliance, the closing bid price of the Company’s common stock must meet or exceed $1.00 per share for a minimum of ten consecutive business days during this grace period. On April 20, 2020, the Company received a written notice from NASDAQ indicating that, as a result of the tolling of the bid price requirements due to COVID-19, the period within which the Company has to regain compliance was extended from August 31, 2020 to November 13, 2020. Spain Income Tax Audit The Company is currently undergoing an income tax audit in Spain for the period from 2011 to 2014, the Spanish tax inspector has raised questions with respect to the Company’s recognition of funds received during this time period from a governmental grant from the European Commission in connection with the Waveport project. It is anticipated that the Company will be assessed a penalty relating to these tax years. The Company has estimated this penalty to be $177,000 and as of April 30, 2020 and 2019 has recorded the penalty in Accrued expenses in the Consolidated Balance Sheet.

Commitments and Contingencies

12 Months Ended

Apr. 30, 2020

Commitments and Contingencies Disclosure [Abstract]

(15) Commitments and Contingencies

Employment Litigation

On June 10, 2014, the Company announced that it had terminated Charles Dunleavy as its Chief Executive Officer and as an employee of the Company for cause, effective June 9, 2014, and that Mr. Dunleavy had also been removed from his position as Chairman of the Board of Directors. On June 17, 2014, Mr. Dunleavy wrote to the Company stating that he had retained counsel to represent him in connection with an alleged wrongful termination of his employment. On July 28, 2014, Mr. Dunleavy resigned from the Board and the boards of directors of the Company’s subsidiaries. In 2014, the Company and Mr. Dunleavy entered into a tolling agreement with respect to his alleged employment claims pending resolution of a securities class action and shareholder derivative litigation. The securities class action was resolved in November 2017 and the derivatives litigation was resolved in June 2018.

On August 28, 2018, counsel for Mr. Dunleavy filed a demand for arbitration, captioned Charles F. Dunleavy v. Ocean Power Technologies, Inc., Case No. 01-18-0003-2374, before the American Arbitration Association in New Jersey. The demand names Ocean Power Technologies, Inc. as the respondent and alleges various claims and seeks declaratory relief and permanent injunction. The demand seeks damages in the amount of $5 million for compensatory and punitive damages, plus interest and attorneys’ fees as well as certain equitable relief. On November 8, 2018, the Company through counsel responded to the demand for arbitration, denied all allegations, and asserted various affirmative defenses. On April 5, 2019, a three-person arbitration panel scheduled the discovery process to run from April 12, 2019 until November 9, 2019, set a pre-hearing case management conference for October 14, 2019, and set the hearing for December 9-13, 2019. On September 30, 2019, the parties completed the factual discovery process and the Company identified its expert witnesses. On October 14, 2019, the parties participated in a pre-hearing case management conference with arbitration panel and altered slightly the dates for the hearing. The hearing was conducted between December 9-11, 2019, and between December 16-18, 2019, and on December 18, 2019 the panel decided to continue the hearing for at least another day of testimony. The final day of hearing has now been scheduled for July 15, 2020, and the hearing will be conducted in Princeton, New Jersey. As of April 30, 2020, the Company has not accrued any provision related to this matter since it is not probable and cannot reasonably estimate the loss contingency.

NASDAQ Delisting Notification

On March 3, 2020, the Company received a notification from the NASDAQ Stock Market (the “NASDAQ”) indicating that the minimum bid price of the Company’s common stock has been below $1.00 per share for 30 consecutive business days and as a result, the Company is not in compliance with the minimum bid price requirement for continued listing. The NASDAQ notice has no immediate effect on the listing or trading of the Company’s common stock. Under the NASDAQ Listing Rules, the Company has a grace period of 180 calendar days, or until August 31, 2020, in which to regain compliance with the minimum bid price rule. To regain compliance, the closing bid price of the Company’s common stock must meet or exceed $1.00 per share for a minimum of ten consecutive business days during this grace period. On April 20, 2020, the Company received a written notice from NASDAQ indicating that, as a result of the tolling of the bid price requirements due to COVID-19, the period within which the Company has to regain compliance was extended from August 31, 2020 to November 13, 2020.

Spain Income Tax Audit

The Company is currently undergoing an income tax audit in Spain for the period from 2011 to 2014, the Spanish tax inspector has raised questions with respect to the Company’s recognition of funds received during this time period from a governmental grant from the European Commission in connection with the Waveport project. It is anticipated that the Company will be assessed a penalty relating to these tax years. The Company has estimated this penalty to be $177,000 and as of April 30, 2020 and 2019 has recorded the penalty in Accrued expenses in the Consolidated Balance Sheet.