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Document and Entity Information - USD ($)	12 Months Ended
Document and Entity Information - USD ($)	Apr. 30, 2019	Jul. 15, 2019	Oct. 31, 2018
Document And Entity Information
Entity Registrant Name	Ocean Power Technologies, Inc.
Entity Central Index Key	0001378140
Document Type	10-K
Document Period End Date	Apr. 30, 2019
Amendment Flag	false
Current Fiscal Year End Date	--04-30
Entity a Well-known Seasoned Issuer	No
Entity a Voluntary Filer	No
Entity's Reporting Status Current	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business Flag	true
Entity Emerging Growth Company	false
Entity Ex Transition Period	false
Entity Shell Company	false
Entity Public Float			$ 9,500,000
Entity Common Stock, Shares Outstanding		5,771,747
Document Fiscal Period Focus	FY
Document Fiscal Year Focus	2019

Consolidated Balance Sheets - USD ($)	Apr. 30, 2019	Apr. 30, 2018
Current assets:
Cash and cash equivalents	$ 16,660,000	$ 11,499,000
Marketable securities		25,000
Restricted cash- short-term	344,000	572,000
Accounts receivable	63,000	171,000
Unbilled receivables		71,000
Contract assets	15,000
Litigation receivable		350,000
Other current assets	537,000	567,000
Total current assets	17,619,000	13,255,000
Property and equipment, net	592,000	712,000
Restricted cash- long-term	155,000	154,000
Total assets	18,366,000	14,121,000
Current liabilities:
Accounts payable	312,000	290,000
Accrued expenses	1,938,000	2,261,000
Litigation payable		350,000
Unearned revenue		18,000
Contract liabilities	188,000
Warrant liabilities	6,000	201,000
Current portion of capital lease obligations		23,000
Deferred credits payable current		600,000
Total current liabilities	2,444,000	3,743,000
Deferred rent	147,000	142,000
Total liabilities	2,591,000	3,885,000
Commitments and contingencies
Ocean Power Technologies, Inc. stockholders' 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 5,425,517 and 921,247 shares, respectively	5,000	1,000
Treasury stock, at cost; 3,770 and 3,701 shares, respectively	(301,000)	(300,000)
Additional paid-in capital	226,026,000	208,233,000
Accumulated deficit	(209,784,000)	(197,538,000)
Accumulated other comprehensive loss	(171,000)	(160,000)
Total stockholders' equity	15,775,000	10,236,000
Total liabilities and stockholders' equity	$ 18,366,000	$ 14,121,000

Consolidated Balance Sheets (Parenthetical) - $ / shares	Apr. 30, 2019	Apr. 30, 2018
Statement of Financial Position [Abstract]
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares issued
Preferred stock, shares outstanding
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares issued	5,425,517	921,247
Treasury stock, shares	3,770	3,701

Consolidated Statements of Operations - USD ($)	12 Months Ended
Consolidated Statements of Operations - USD ($)	Apr. 30, 2019	Apr. 30, 2018
Income Statement [Abstract]
Revenues	$ 632,000	$ 511,000
Cost of revenues	1,303,000	763,000
Gross profit/(loss)	(671,000)	(252,000)
Operating expenses:
Engineering and product development costs	4,984,000	4,320,000
Selling, general and administrative costs	7,616,000	6,988,000
Total operating expenses	12,600,000	11,308,000
Operating loss	(13,271,000)	(11,560,000)
Gain due to the change in fair value of warrant liabilities	195,000	122,000
Interest income, net	35,000	83,000
Other income		4,000
Foreign exchange gain/(loss)	(55,000)	75,000
Loss before income taxes	(13,096,000)	(11,276,000)
Income tax benefit	850,000	1,119,000
Net loss	$ (12,246,000)	$ (10,157,000)
Basic and diluted net loss per share	$ (9.52)	$ (13.24)
Weighted average shares used to compute basic and diluted net loss per share	1,286,727	767,330

Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Apr. 30, 2019	Apr. 30, 2018
Statement of Comprehensive Income [Abstract]
Net loss	$ (12,246)	$ (10,157)
Foreign currency translation adjustment	(11)
Total comprehensive loss	$ (12,257)	$ (10,157)

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References + Details

Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Common Shares [Member]	Treasury Shares [Member]	Additional Paid-In Capital [Member]	Accumulated Deficit [Member]	Accumulated Other Comprehensive Loss [Member]	Total
Balance at Apr. 30, 2017		$ (263)	$ 193,240	$ (187,370)	$ (160)	$ 5,447
Balance, shares at Apr. 30, 2017	315,700	(2,403)
Net loss				(10,157)		(10,157)
Stock based compensation			329			329
Issuance/(forfeiture) of restricted stock, net
Issuance/(forfeiture) of restricted stock, net, shares	8,937
Sale of stock	$ 1		14,653			14,654
Sale of stock, shares	596,610
Acquisition of treasury stock		$ (37)				(37)
Acquisition of treasury stock, shares		(1,298)
Adoption of accounting standard update related to stock compensation accounting (ASU 2016-09)			11	(11)
Other comprehensive loss
Balance at Apr. 30, 2018	$ 1	$ (300)	208,233	(197,538)	(160)	10,236
Balance, shares at Apr. 30, 2018	921,247	(3,701)
Net loss				(12,246)		(12,246)
Stock based compensation			295			295
Issuance/(forfeiture) of restricted stock, net
Issuance/(forfeiture) of restricted stock, net, shares	(5,090)
Acquisition of treasury stock		$ (1)				(1)
Acquisition of treasury stock, shares		(89)
Other comprehensive loss					(11)	(11)
Common stock issued for commitment fee			295			295
Common stock issued for commitment fee, shares	21,429
Issuance of common stock- Aspire financing, net of issuance costs			593			593
Issuance of common stock- Aspire financing, net of issuance costs, shares	162,162
Issuance of common stock- AGP At The Market offering, net of issuance costs			882			882
Issuance of common stock- AGP At The Market offering, net of issuance costs, shares	151,561
Issuance of common stock, common and pre-funded warrants, net of issuance costs	$ 1		15,711			15,712
Issuance of common stock, common and pre-funded warrants, net of issuance costs, shares	1,542,000
Exercise of pre-funded warrants	$ 3		17			20
Exercise of pre-funded warrants, shares	2,632,120
Other
Other, shares	88	20
Balance at Apr. 30, 2019	$ 5	$ (301)	$ 226,026	$ (209,784)	$ (171)	$ 15,775
Balance, shares at Apr. 30, 2019	5,425,517	(3,770)

Consolidated Statements of Cash Flows - USD ($)	12 Months Ended
Consolidated Statements of Cash Flows - USD ($)	Apr. 30, 2019	Apr. 30, 2018
Cash flows from operating activities:
Net loss	$ (12,246,000)	$ (10,157,000)
Adjustments to reconcile net loss to net cash used in operating activities:
Foreign exchange loss/(gain)	55,000	(75,000)
Depreciation	180,000	122,000
Loss on disposal of property, plant and equipment		5,000
Compensation expense related to stock option grants and restricted stock	295,000	329,000
Gain due to the change in fair value of warrant liabilities	(195,000)	(122,000)
Changes in operating assets and liabilities:
Accounts receivable	108,000	(123,000)
Unbilled receivables	71,000	225,000
Contract assets	(15,000)
Other assets	325,000	194,000
Accounts payable	23,000	(296,000)
Accrued expenses	(316,000)	(821,000)
Deferred rent	5,000	5,000
Deferred credit payable	(600,000)
Unearned revenue	(18,000)	18,000
Contract liabilities	188,000
Net cash used in operating activities	(12,140,000)	(10,696,000)
Cash flows from investing activities:
Purchases of marketable securities	(25,000)	(25,000)
Maturities of marketable securities	50,000	25,000
Leasehold improvements and purchase of equipment	(54,000)	(658,000)
Net cash used in investing activities	(29,000)	(658,000)
Cash flows from financing activities:
Proceeds from issuance of common stock, net of issuance costs		14,654,000
Proceeds from issuance of common stock- Aspire financing net of issuance costs	593,000
Proceeds from issuance of common stock- AGP At The Market offering, net of issuance costs	882,000
Proceeds from issuance of common stock, common and pre-funded warrants, net of issuance costs	15,712,000
Proceeds from exercise of pre-funded warrants	20,000
Payment of capital lease obligations	(23,000)	(35,000)
Acquisition of treasury stock	(1,000)	(37,000)
Net cash provided by financing activities	17,183,000	14,582,000
Effect of exchange rate changes on cash, cash equivalents and restricted cash	(80,000)	88,000
Net increase in cash, cash equivalents and restricted cash	4,934,000	3,316,000
Cash, cash equivalents and restricted cash, beginning of period	12,225,000	8,909,000
Cash, cash equivalents and restricted cash, end of period	17,159,000	12,225,000
Supplemental schedule of cash flows information:
Cash paid for interest	1,000	3,000
Supplemental disclosure of noncash investing activities:
Acquisition of leasehold improvements and equipment through accrued expenses	5,000	11,000
Supplemental disclosure of noncash financing activities:
Common stock issued for payment of commitment fee	$ 295,000

Background and Liquidity

12 Months Ended

Apr. 30, 2019

Accounting Policies [Abstract]

Background and Liquidity

(1) Background and Liquidity

(a) Background

Ocean Power Technologies, Inc. (the “Company”) was founded in 1984 in New Jersey, commenced business operations in 1994 and re-incorporated in Delaware in 2007. The Company is developing and commercializing its proprietary systems that generate electricity by harnessing the renewable energy of ocean waves. The Company uses proprietary technologies that convert the mechanical energy created by the heaving motion of ocean waves into electricity. The Company has designed and continues to develop the PowerBuoy® product line which is based on modular, ocean-going buoys, which the Company has been periodically ocean testing since 1997. The Company markets its PowerBuoys® in the United States and internationally. Since fiscal 2002, government agencies have accounted for a significant portion of the Company’s revenues. These revenues were largely for the support of product development efforts relating to our technology. Today our goal is to generate the majority our revenue from the sale or lease of products, and sales and services to support our business operations. As we continue to develop and commercialize our products and services, we expect to have a net use of cash from operating activities unless and until we achieve positive cash flow from the commercialization of products and services.

(b) Liquidity/Going Concern

Our consolidated financial statements have been prepared assuming the Company will continue as a going concern. The Company has experienced substantial and recurring losses from operations, which have contributed to an accumulated deficit of $209.8 million at April 30, 2019. At April 30, 2019, the Company had approximately $17.2 million in cash, cash equivalents and restricted cash on hand. The Company generated revenues of only $0.6 million and $0.5 million during the years ended April 30, 2019 and 2018, respectively. Based on the Company’s cash, cash equivalents and restricted cash balances as of April 30, 2019, the Company believes that it will be able to finance its capital requirements and operations into the quarter ending July 31, 2020. The Company will require additional equity and/or debt financing to continue its operations. The Company cannot provide assurances that it will be able to secure additional funding when needed or at all, or, if secured, that such funding would be on favorable terms. These factors raise substantial doubt about the Company’s ability to continue as a going concern.

The consolidated financial statements have been prepared on a going concern basis, which contemplates the realization of assets and satisfaction of liabilities in the normal course of business. The consolidated financial statements do not include any adjustments relating to the recoverability and classification of recorded assets amounts or the amounts and classification of liabilities that might result from the outcome of this uncertainty.

Management is evaluating different strategies to obtain the required additional funding for future operations. These strategies may include, but are not limited to, additional funding from current or new investors, officers and directors; borrowings of debt; a public offering of the Company’s equity or debt securities; partnerships and/or collaborations. There can be no assurance that any of these future-funding efforts will be successful.

In fiscal 2019 and 2018, the Company has continued to make investments in ongoing product development efforts in anticipation of future growth. The Company’s future results of operations involve significant risks and uncertainties. Factors that could affect the Company’s future operating results and cause actual results to vary materially from expectations include, but are not limited to, risks from lack of available financing and insufficient capital, performance of PowerBuoys®, its inability to market and commercialize its PowerBuoys®, technology development, scalability of technology and production, dependence on skills of key personnel, concentration of customers and suppliers, deployment risks and laws, regulations and permitting. In order to continue to implement its business strategy, the Company requires additional equity and/or debt financing. The Company closed five equity financing arrangements during the two-year period ended April 30, 2019. The Company does not currently have any committed sources of debt or equity financing, and the Company cannot assure that additional equity and/or debt financing will be available to the Company as needed on acceptable terms, or at all. Historically, the Company has raised capital through securities sales in the public capital markets. If sufficient additional financing is not obtained when needed, the Company may be required to further curtail or limit operations, engineering and product development costs, and/or selling, general and administrative activities in order to reduce its cash expenditures. This could cause the Company to be unable to execute its business plan, take advantage of future opportunities and may cause it to scale back, delay or eliminate some or all of its product development activities and/or reduce the scope of or cease its operations.

On June 2, 2016, the Company entered into a securities purchase agreement, which was amended on June 7, 2016 (as amended, the “Purchase Agreement”) with certain institutional purchasers (the “June Purchasers”). Pursuant to the terms of the Purchase Agreement, the Company sold an aggregate of 20,850 shares of Common Stock together with warrants to purchase up to an aggregate of 7,298 shares of Common Stock. Each share of Common Stock was sold together with a warrant to purchase 0.35 of a share of Common Stock at a combined purchase price of $92.00. The net proceeds to the Company from the offering were approximately $1.7 million, after deducting placement agent fees and estimated offering expenses payable by the Company, but excluding the proceeds, if any, from the exercise of the warrants issued in the offering. The warrants have an exercise price of $121.60 per share, became exercisable on December 3, 2016 (“Initial Exercise Date”), and will expire five years following the Initial Exercise Date. The Company paid the placement agents approximately $100,000 as placement agent fees in connection with the sale of securities in the offering. The Company also reimbursed the placement agents $35,000 for their out of pocket and legal expenses in connection with the offering.

On July 22, 2016, the Company entered into the Second Amendment to the Purchase Agreement (the “Second Amended Purchase Agreement”) with certain purchasers (the “July Purchasers”). Pursuant to the terms of the Second Amended Purchase Agreement, the Company sold an aggregate of 29,750 shares of Common Stock together with warrants to purchase up to an aggregate of 8,925 shares of Common Stock. Each share of Common Stock was sold together with a warrant to purchase 0.30 of a share of Common Stock at a combined purchase price of $135.00. The net proceeds to the Company from the offering were approximately $3.6 million, after deducting placement agent fees and estimated offering expenses payable by the Company, but excluding the proceeds, if any, from the exercise of the warrants issued in the offering. The Warrants were exercisable immediately at an exercise price of $187.20 per share. The Warrants will expire on the fifth (5th) anniversary of the initial date of issuance.

On October 19, 2016, the Company sold 138,000 shares of common stock at a price of $55.00 per share, which includes the sale of 18,000 shares of the Company’s common stock sold by the Company pursuant to the exercise, in full, of the over-allotment option by the underwriters in a public offering. The net proceeds to the Company from the offering were approximately $6.9 million, after deducting underwriter fees and offering expenses payable by the Company.

On May 2, 2017, the Company sold 309,638 shares of common stock at a price of $26.00 per share, which includes the sale of 40,388 shares of the Company’s common stock sold by the Company pursuant to the exercise, in full, of the over-allotment option by the underwriters in a public offering. The net proceeds to the Company from the offering were approximately $7.2 million, after deducting underwriter fees and offering expenses payable by the Company.

On October 23, 2017, the Company sold 286,972 shares of common stock at a price of $28.40 per share in a best efforts public offering. The net proceeds to the Company from the offering were approximately $7.4 million, after deducting placement fees and offering expenses payable by the Company.

On August 13, 2018, the Company entered into a common stock purchase agreement with Aspire Capital Fund, LLC (“Aspire Capital”) which provides that, subject to certain terms, conditions and limitations, Aspire Capital is committed to purchase up to an aggregate of $10.0 million of shares of the Company’s common stock over a 30-month period that does not exceed 19.99% of the outstanding common stock on the date of the agreement. Shareholder approval was not needed since the number of common stock offered for sale in the common stock purchase agreement did not exceed 19.99% of the outstanding common stock on the date of the agreement. In consideration for entering into the agreement, the Company issued to Aspire Capital 21,429 shares of our common stock as a commitment fee. As of April 30, 2019, the Company has sold 162,162 shares of common stock with an aggregate market value of $949,259 at an average price of $5.85 per share pursuant to this common stock purchase agreement.

On January 7, 2019, the Company entered into an At the Market Offering Agreement (“2019 ATM Facility”) with A.G.P./Alliance Global Partners (“AGP”), under which the Company may issue and sell to or through A.G.P./Alliance Global Partners, acting as agent and/or principal, shares of the Company’s common stock having an aggregate offering price of up to $25 million. As of April 30, 2019, under the 2019 ATM Facility the Company issued and sold 151,561 shares of its common stock with an aggregate market value of $958,229 at an average price of $6.32 per share and paid AGP a sales commission of approximately $33,469 related to those shares.

On April 8, 2019, the Company sold 1,542,000 shares of common stock, which includes the sale of 642,000 shares of the Company’s common stock sold by the Company pursuant to the exercise, in full, of the over-allotment option by the underwriters in a public offering, prefunded warrants to purchase up to 3,385,680 shares of common stock and common warrants to purchase up to 4,927,680 shares of our common stock in an underwritten public offering. The net proceeds to the Company from the offering were approximately $15.7 million, after deducting underwriter fees and offering expenses payable by the Company.

The sale of additional equity or convertible securities could result in dilution to stockholders. If additional funds are raised through the issuance of debt securities, these securities could have rights senior to those associated with the Company’s Common Stock and could contain covenants that would restrict its operations. Financing may not be available in amounts or on terms acceptable to the Company, or at all. If the Company is unable to obtain required financing, it may be required to reduce the scope of its operations, including its planned product development and marketing efforts, which could materially and adversely harm its financial condition and operating results. If the Company is unable to secure additional financing, it may be forced to cease operations.

(c) Reverse Stock-Split

At the special meeting of the Company’s stockholders on March 8, 2019, our stockholders approved a proposal to amend our Certificate of Incorporation to affect a reverse split of our common stock at a ratio to be determined by the Company’s Board of Directors within a specific range. After the special meeting of stockholders, the Company’s Board of Directors convened and decided to initiate the reverse split, chose a ratio, and directed management to take the necessary steps to effectuate the reverse split as soon as possible. Pursuant to the direction of the Board, the Company filed a Certificate of Amendment to our Certificate of Incorporation to affect a one-for-twenty reverse stock split of our common stock (the “Reverse Stock Split”). As of the close of markets on March 11, 2019, the effective date of the Reverse Stock Split, every twenty shares of issued and outstanding common stock were combined into one issued and outstanding share of common stock, without any change in the par value per share. Any fractional shares in connection with the Reverse Stock Split were rounded up to the nearest whole share and no cash payments were made by the Company to stockholders in lieu of fractional shares. The common stock began trading on a reverse stock split-adjusted basis on the Nasdaq Stock Market (“Nasdaq”) on March 12, 2019. All share and per share data included in this annual report has been retroactively restated to reflect the Reverse Stock Split.

Summary of Significant Accounting Policies

12 Months Ended

Apr. 30, 2019

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

(2) Summary of Significant Accounting Policies

(a) Consolidation

The accompanying consolidated financial statements include the accounts of the Company and its majority-owned subsidiaries. All significant intercompany balances and transactions have been eliminated in consolidation. The Company also periodically evaluates its relationships with other entities to identify whether they are variable interest entities, and to assess whether it is the primary beneficiary of such entities. If the determination is made that the Company is the primary beneficiary, then that entity is included in the consolidated financial statements. As of April 30, 2019, there were no such entities.

(b) Use of Estimates

The preparation of the consolidated financial statements requires management of the Company to make a number of estimates and assumptions relating to the reported amounts of assets and liabilities and the disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenues and expenses during the period. Significant items subject to such estimates and assumptions include fair value of warrant liabilities; estimated costs to complete projects and percentage of completion of customer contracts for purposes of revenue recognition. Actual results could differ from those estimates. The current economic environment, particularly the macroeconomic pressures in certain European countries, has increased the degree of uncertainty inherent in those estimates and assumptions.

(c) Revenue Recognition

A performance obligation is the unit of account for revenue recognition. The Company assesses the goods or services promised in a contract with a customer and identifies as a performance obligation either: a) a good or service (or a bundle of goods or services) that is distinct; or b) a series of distinct goods or services that are substantially the same and that have the same pattern of transfer to the customer. A contract may contain a single or multiple performance obligations. For contracts with multiple performance obligations, the Company allocates the contracted transaction price to each performance obligation based upon the relative standalone selling price, which represents the price the Company would sell a promised good or service separately to a customer. The Company determines the standalone selling price based upon the facts and circumstances of each obligated good or service. The majority of the Company’s contracts have no observable standalone selling price since the associated products and services are customized to customer specifications. As such, the standalone selling price generally reflects the Company’s forecast of the total cost to satisfy the performance obligation plus an appropriate profit margin.

The nature of the Company’s contracts may give rise to several types of variable consideration, including claims and unpriced change orders; awards and incentive fees; and liquidated damages and penalties. Variable consideration can also arise from modifications to the scope of services. Variable consideration is included in the transaction price to the extent it is probable that a significant reversal of cumulative revenue recognized will not occur once the uncertainty associated with the variable consideration is resolved. Our estimates of variable consideration and determination of whether to include such amounts in the transaction price are based largely on our assessment of legal enforceability, performance and any other information (historical, current, and forecasted) that is reasonably available to us.

The Company recognizes revenue when or as it satisfies a performance obligation by transferring a good or service to a customer, either (1) at a point in time or (2) over time. A good or service is transferred when or as the customer obtains control of it. The evaluation of whether control of each performance obligation is transferred at a point in time or over time is made at contract inception. Input measures such as costs incurred or time elapsed are utilized to assess progress against specific contractual performance obligations for the Company’s services. The selection of the method to measure progress towards completion requires judgment and is based on the nature of the services to be provided. For the Company, the input method using costs incurred or time elapsed best represents the measure of progress against the performance obligations incorporated within the contractual agreements. When the Company’s estimate of total costs to be incurred to satisfy the performance obligations exceed revenue, the Company recognizes the loss immediately.

The Company classifies leases as either operating or capital lease arrangements in accordance with the authoritative accounting guidance contained within Accounting Standards Codification (“ASC”) Topic 840, “Leases”. At inception of the contract, the Company evaluates the lease against the four lease classification criteria within ASC Topic 840. In general, if one of the four criteria is met, then the lease is accounted for as a capital lease. All others are treated as an operating lease. For operating leases, lessee payments are recorded to revenue on a straight-line basis over the term of the lease.

The Company’s contracts are either cost plus or fixed price contracts. Under cost plus contracts, customers are billed for actual expenses incurred plus an agreed-upon fee. Under cost plus contracts, a profit or loss on a project is recognized depending on whether actual costs are more or less than the agreed upon amount.

The Company has two types of fixed price contracts, firm fixed price and cost-sharing. Under firm fixed price contracts, the Company receives an agreed-upon amount for providing products and services specified in the contract, a profit or loss is recognized depending on whether actual costs are more or less than the agreed upon amount. Under cost-sharing contracts, the fixed amount agreed upon with the customer is only intended to fund a portion of the costs on a specific project. Under cost sharing contracts, an amount corresponding to the revenue is recorded in cost of revenues, resulting in gross profit on these contracts of zero. The Company’s share of the costs is recorded as product development expense. For the twelve-month period ended April 30, 2019 and 2018 all of the Company’s contracts were classified as firm fixed price.

As of April 30, 2019, the Company’s total remaining performance obligations, also referred to as backlog, totaled $0.9 million. The Company expects to recognize approximately 81%, or $0.7 million, of the remaining performance obligations as revenue over the next twelve months and an additional 19% the following twelve months.

(d) Cash and Cash Equivalents, Restricted Cash and Security Agreements

Cash and Cash Equivalents

The Company considers all highly liquid investments with a maturity of three months or less when purchased to be cash equivalents. The Company invests excess cash in a money market account. The following table summarizes cash and cash equivalents for the years ended April 30, 2019 and 2018:

	April 30, 2019		April 30, 2018
	(in thousands)

Checking and savings accounts	$	860	$	1,332
Money market account		15,800		10,167
	$	16,660	$	11,499

Restricted Cash and Security Agreements

A portion of the Company’s cash is restricted under the terms of two security agreements.

One agreement is between the Company and Barclays Bank. Under this agreement, the cash is on deposit at Barclays Bank and serves as security for letters of credit and bank guarantees that are expected to be issued by Barclays Bank on behalf of OPT LTD, one of the Company’s subsidiaries, under a credit facility established by Barclays Bank for OPT LTD. The credit facility is approximately €0.3 million ($0.3 million) and carries a fee of 1% per annum of the amount of any such obligations issued by Barclays Bank. The credit facility does not have an expiration date but is cancelable at the discretion of the bank. As of April 30, 2019, there was €0.3 million ($0.3 million) in letters of credit outstanding under this agreement.

The other agreement is between the Company and Santander Bank. Under the agreement, the cash is on deposit at Santander Bank and serves as security for letter of credit issued by Santander Bank for the lease of new warehouse/office space in Monroe Township, New Jersey. The agreement cannot be extended beyond January 31, 2025 and is cancelable at the discretion of the bank. The following table summarizes restricted cash for the years ended April 30, 2019 and 2018:

	April 30, 2019		April 30, 2018
	(in thousands)

Barclay’s Bank Agreement	$	344	$	372
Santander Bank		155		354
	$	499	$	726

The following table provides a reconciliation of cash, cash equivalents and restricted cash reported within the statement of financial position that sum to the total of the same such amounts shown in the statement of cash flows for the years ended April 30, 2019 and 2018:

	April 30, 2019		April 30, 2018
	(in thousands)

Cash and cash equivalents	$	16,660	$	11,499
Restricted cash- short term		344		572
Restricted cash- long term		155		154
	$	17,159	$	12,225

(e) Marketable Securities

Marketable securities with original maturities longer than three months but that mature in less than one year from the balance sheet date are classified as current assets. Marketable securities that the Company has the intent and ability to hold to maturity are classified as investments held-to-maturity and are reported at amortized cost. The difference between the acquisition cost and face values of held-to-maturity investments is amortized over the remaining term of the investments and added to or subtracted from the acquisition cost and interest income. As of April 30, 2019, the Company did not have any marketable securities. As of April 30, 2018, the Company had $25,000 in certificates of deposit and all of the Company’s investments were classified as held-to-maturity.

(f) Property and Equipment

Property and equipment consists primarily of equipment, furnishings, fixtures, computer equipment and leasehold improvements and are recorded at cost. Depreciation and amortization is calculated using the straight-line method over the estimated useful lives of the assets. Expenses for maintenance and repairs are charged to operations as incurred. Property and equipment is also reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of the asset may not be recoverable. Recoverability of assets to be held and used is measured by a comparison of the carrying amount of the asset to estimated undiscounted future cash flows expected to be generated by the asset. If the carrying amount of the asset exceeds its estimated future cash flows, then an impairment charge is recognized in the amount by which the carrying amount of the asset exceeds the fair value of the asset.

Description		Estimated useful life

Equipment		5 - 7 years
Computer equipment & software		3 years
Office furniture & fixtures		3 - 7 years
Equipment under capitalized lease		Over the life of the lease
Leasehold improvements		Shorter of the estimated useful life or lease term

(g) Foreign Exchange Gains and Losses

The Company has invested in certain certificates of deposit and has maintained cash accounts that are denominated in British pounds sterling, Euros and Australian dollars. These amounts are included in cash, cash equivalents, restricted cash and marketable securities on the accompanying consolidated balance sheets. Such positions may result in realized and unrealized foreign exchange gains or losses from exchange rate fluctuations, which are included in “foreign exchange gain (loss)” in the accompanying consolidated statements of operations.

(h) Concentration of Credit Risk

Financial instruments that potentially subject the Company to concentration of credit risk consist principally of cash balances and trade receivables. The Company invests its excess cash in money market funds and does not believe that it is exposed to any significant risks related to its cash accounts.

The table below shows the percentage of the Company’s revenues derived from customers whose revenues accounted for at least 10% of the Company’s consolidated revenues for at least one of the periods indicated:

	Twelve months ended April 30,
	2019			2018

Eni S.p.A.		54	%		33	%
Mitsui Engineering & Shipbuilding		0	%		43	%
Premier Oil UK Limited		33	%		10	%
Office of Naval Research		0	%		14	%
Other		13	%		0	%
		100	%		100	%

The loss of, or a significant reduction in revenues from a current customer could significantly impact the Company’s financial position or results of operations. The Company does not require its customers to maintain collateral.

(i) Warrant Accounting

The Company accounts for warrants issued in connection with its public offerings in accordance with the guidance on “Accounting for Certain Financial Instruments with Characteristics of Both Liabilities and Equity” in Topic 480 which provides that warrants meeting the classification of a liability award are recorded as a liability at its fair value. The warrant liabilities are subject to re-measurement at each balance sheet date using the Black-Scholes option pricing model. The Company recognizes any change in fair value in its consolidated statements of operations within “Gain due to the change in fair value of warrant liabilities”. The Company will continue to adjust the carrying value of the warrants for changes in the estimated fair value until such time as these instruments are exercised or expire. At that time, the liabilities will be reclassified to “Additional paid-in capital”, a component of “Stockholders’ equity” on the Consolidated Balance Sheets. The warrants issued in connection with the Company’s public offerings in June and July 2016 met the criteria of a liability award and were classified in warrant liabilities. The pre-funded and common warrants issued in the Company’s April 8, 2019 public offering did not meet the criteria to be classified as a liability award and therefore were treated as an equity award.

(j) Net Loss per Common Share

Basic and diluted net loss per share for all periods presented is computed by dividing net loss by the weighted average number of shares of common stock and common stock equivalents outstanding during the period. The pre-funded warrants were determined to be common stock equivalents and have been included in the weighted average number of shares outstanding for calculation of the basic earnings per share number. Due to the Company’s net losses, potentially dilutive securities, consisting of options to purchase shares of common stock, warrants on common stock and non-vested restricted stock issued to employees and non-employee directors, were excluded from the diluted loss per share calculation due to their anti-dilutive effect.

In computing diluted net loss per share, options to purchase shares of common stock, warrants on common stock and non-vested restricted stock issued to employees and non-employee directors, totaling 5,013,981 and 45,503 for the years ended April 30, 2019 and 2018, respectively, were excluded from each of the computations as the effect would be anti-dilutive due to the Company’s losses.

(k) Share-Based Compensation

Costs resulting from all share-based payment transactions are recognized in the consolidated financial statements at their fair values. The aggregate share-based compensation expense recorded in the consolidated statements of operations for the years ended April 30, 2019 and 2018 was approximately $0.3 million and $0.3 million, respectively. The following table summarizes share-based compensation related to the Company’s share-based plans by expense category for the years ended April 30, 2019 and 2018:

	Twelve months ended April 30,
	2019		2018
	(in thousands)

Product development	$	29	$	24
Selling, general and administrative		266		305
Total share-based compensation expense	$	295	$	329

Valuation Assumptions for Restricted Stock and Options Granted During the Years Ended April 30, 2019 and 2018

Options

The fair value of each stock option granted, for both service-based and performance-based vesting requirements during the year ended April 30, 2019, was estimated at the date of grant using the Black-Scholes option pricing model, assuming no dividends, and using the weighted average valuation assumptions noted in the below table. The risk-free rate is based on the U.S. Treasury yield curve in effect at the time of grant. The expected life (estimated period of time outstanding) of the stock options granted was estimated using the “simplified” method as permitted by the SEC’s Staff Accounting Bulletin No. 110, Share-Based Payment. Expected volatility was based on the Company’s historical volatility during the twelve months ended April 30, 2019.

	Twelve months ended April 30,
	2019			2018

Risk-free interest rate		2.7	%		2.1	%
Expected dividend yield		0.0	%		0.0	%
Expected life (in years)		5.5			5.5
Expected volatility		126.4	%		128.2	%

The above assumptions were used to determine the weighted average per share fair value of $7.15 and $23.40 for stock options granted during the years ended April 30, 2019 and 2018, respectively.

Restricted Stock

Compensation expense for non-vested restricted stock is recorded based on its market value on the date of grant and recognized ratably over the associated service and performance period. During the twelve months ended April 30, 2019, the Company granted 943 shares subject to service-based vesting requirements.

(l) Deferred Rent

On March 31, 2017, the Company signed a new 7-year lease for approximately 56,000 square feet in Monroe Township, New Jersey that will be used as warehouse/production space and the Company’s principal offices and corporate headquarters. The lease was classified as an operating lease. Rent payments relating to the Monroe premises are subject to annual increases. The minimum monthly payments will vary over the 7-year term of the lease. The Company will record rent expense on a straight-line basis over the 7-year term of the lease. The difference between rent expense and the monthly lease payment will go to a deferred rent/prepaid rent account. The Landlord has provided the Company a tenant improvement allowance in an amount up to, but not exceeding, $137,563 to be applied to the cost of tenant improvement work. The Company collected the full amount of the tenant improvement allowance in May 2018. The Company recorded lease incentive liability to deferred rent. With the Company’s adoption of ASU No. 2016-02 on May 1, 2019, the balances in lease incentive liability and deferred rent will be included in the value of the right of use asset.

(m) Income Taxes

Income taxes are accounted for under the asset and liability method. Deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases and operating loss and tax credit carry forwards. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences and operating loss and tax credit carry forwards are expected to be recovered, settled or utilized. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in income in the period that includes the enactment date.

The Company recognizes the effect of income tax positions only if those positions are more likely than not of being sustained upon examination. Recognized income tax positions are measured at the largest amount that is greater than 50% likely of being realized. Changes in recognition or measurement are reflected in the period in which the change in judgment occurs. The Company records interest related to unrecognized tax benefits in interest expense and penalties in selling, general, and administrative expenses, to the extent incurred.

(n) Accumulated Other Comprehensive Loss

The functional currency for the Company’s foreign operations is the applicable local currency. The translation from the applicable foreign currencies to U.S. dollars is performed for balance sheet accounts using the exchange rates in effect at the balance sheet date and for revenue and expense accounts using an average exchange rate during the period. The unrealized gains or losses resulting from such translation are included in accumulated other comprehensive loss within stockholders’ equity.

(o) Recently Issued Accounting Standards

In May 2014, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2014-09, “Revenue from Contracts with Customers (Topic 606).” ASU 2014-09 outlines a new, single comprehensive model for entities to use in accounting for revenue arising from contracts with customers and supersedes most current revenue recognition guidance, including industry-specific guidance. This new revenue recognition model provides a five-step analysis in determining when and how revenue is recognized. The new model will require revenue recognition to depict the transfer of promised goods or services to customers in an amount that reflects the consideration a company expects to receive in exchange for those goods or services. The FASB subsequently issued additional clarifying standards to address issues arising from implementation of the new revenue standard, including a one-year deferral of the effective date for the new revenue standard. Public companies should now apply the guidance in ASU 2014-09 to annual reporting periods beginning after December 15, 2017 and interim periods within those annual periods. Earlier application is permitted only as of annual reporting periods beginning after December 15, 2016, including interim periods within that annual period. Companies may use either a full retrospective or a modified retrospective approach to adopt ASU 2014-09. Under the full retrospective method, the standard would be applied to each prior reporting period presented and the cumulative effect of applying the standard would be recognized at the earliest period shown. Under the modified retrospective method, the cumulative effect of applying the standard would be recognized at the date of application. Effective May 1, 2018, the Company adopted the requirements of ASU 2014-09 using the modified retrospective method. As a practical expedient, the Company adopted the new standard only for existing contracts as of May 1, 2018, the date of adoption. Any contracts that had expired prior to May 1, 2018 were not evaluated against the new standard. The Company adopted ASU 2014-09 and the adoption did not have a material impact on the Company’s consolidated financial position, results of operations or cash flows.

In February 2016, the FASB issued ASU No. 2016-02, “Leases (Topic 842)” which amends the existing guidance on accounting for leases. Topic 842 was further clarified and amended within ASU 2017-13, ASU 2018-01, ASU 2018-10, ASU 2018-11 and ASU 2018-20. The new standard establishes a right-of-use (ROU) model that requires a lessee to record a ROU asset and a lease liability on the balance sheet for all leases with terms longer than twelve months or leases that contain a purchase option that is reasonably certain to be exercised. Leases will be classified as either finance or operating, with classification affecting the pattern of expense recognition in the income statement. ASU 2016-02 is effective for annual periods beginning after December 15, 2018, including interim periods within those annual periods, with early adoption permitted. The company will adopt Topic 842 during the first quarter of 2019 using the modified retrospective method. The new guidance will be applied to leases that exist or are entered into on or after May 1, 2019 without adjusting comparative periods in the financial statements. The company expects to utilize the package of practical expedients in ASC 842-10-65-1(f) that, upon adoption of Topic 842, allows entities to (1) not reassess whether any expired or existing contracts are or contain leases, (2) retain the classification of leases (e.g., operating or finance lease) existing as of the date of adoption and (3) not reassess initial direct costs for any existing leases. Based on the most recent assessment of existing leases, the Company expects to record a right-of-use asset and lease liability in the range of $1.0 to $2.0 million that will be included on the balance sheet as of May 1, 2019. The Company does not expect the adoption of Topic 842 to have a material impact on the company’s results of operations or cash flows.

In August 2016, the FASB issued ASU 2016-15, “Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments”, providing additional guidance on eight specific cash flow classification issues. The goal of the ASU is to reduce diversity in practice of classifying certain items. The amendments in the ASU are effective for fiscal years beginning after December 15, 2017, and interim periods within those fiscal years and early adoption is permitted. The Company adopted the standard on May 1, 2018 and determined the standard had no impact on its financial position, results of operation or cash flows.

In May 2017, the FASB issued ASU 2017-09, “Compensation — Stock Compensation (ASC Topic 718): Scope of Modification Accounting,” which clarifies when changes to the terms or conditions of a share-based payment award must be accounted for as a modification. Entities should apply the modification accounting guidance if the value, vesting conditions or classification of the award changes. The amendments in the ASU are effective for fiscal years beginning after December 15, 2017, and interim periods within those fiscal years and early adoption is permitted. The Company adopted the standard on May 1, 2018 and determined the standard had no impact on its financial position, results of operations or cash flows.

In August 2018, the FASB issued ASU No. 2018-13, “Fair Value Measurement (Topic 820).” The ASU modifies, removes and adds several disclosure requirements on fair value measurements in Topic 820, Fair Value Measurement. ASU 2018-13 is effective for all entities for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2019. The amendments on changes in unrealized gains and losses, the range and weighted average of significant unobservable inputs used to develop Level 3 fair value measurements, and the narrative description of measurement uncertainty should be applied prospectively for only the most recent interim or annual period presented in the initial fiscal year of adoption. All other amendments should be applied retrospectively to all periods presented upon their effective date. Early adoption is permitted upon issuance of ASU 2018-13. An entity is permitted to early adopt any removed or modified disclosures upon issuance of ASU 2018-13 and delay adoption of the additional disclosures until their effective date. The Company is evaluating the effect ASU 2018-13 will have on its consolidated financial statements and disclosures and has not yet determined the effect of the standard on its ongoing financial reporting at this time.

In August 2018, the FASB issued ASU No. 2018-15, “Intangibles — Goodwill and Other — Internal-Use Software (Subtopic 350-40).” The ASU provides for the recognition of an intangible asset for the costs of internal-use software licenses included in a cloud computing arrangement. Costs of arrangements that do not include a software license should be accounted for as a service contract and expensed as incurred. This ASU is effective for fiscal years beginning after December 15, 2019, with early adoption permitted. The ASU permits two methods of adoption: prospectively to all implementation costs incurred after the date of adoption, or retrospectively to each prior reporting period presented. The Company is evaluating the effect ASU 2018-15 will have on its consolidated financial statements and disclosures and has not yet determined the effect of the standard on its ongoing financial reporting at this time.

Account Receivable, Contract Assets, and Contract Liabilities

12 Months Ended

Apr. 30, 2019

Account Receivable Contract Assets And Contract Liabilities

Account Receivable, Contract Assets, and Contract Liabilities

(3) Account Receivable, Contract Assets, and Contract Liabilities

The following provides further details on the balance sheet accounts of accounts receivable, contract assets, and contract liabilities.

Accounts Receivable

The Company grants credit to its customers, generally without collateral, under normal payment terms (typically 30 to 60 days after invoicing). Generally, invoicing occurs after the related services are performed or control of good has transferred to the customer. Accounts receivable represents an unconditional right to consideration arising from the Company’s performance under contracts with customers. The carrying value of such receivables represent their estimated realizable value. Accounts receivable consisted of the following at April 30, 2019 and April 30, 2018.

	April 30, 2019			April 30, 2018
	(in thousands)

Opening balance	$	171		$	48
Amount invoiced to customer		857			754
Collections		(965	)		(631	)
Ending balance	$	63		$	171

Contract Assets and Contract Liabilities

Contract assets (previously referred to as unbilled receivables). Contract assets include unbilled amounts typically resulting from arrangements whereby the right to payment is conditioned on completing additional tasks or services for a performance obligation. On May 1, 2018, the day of adoption of ASC 2014-09, the Company reclassified $71,000 of unbilled receivables to contract assets.

Contract liabilities (previously referred to as unearned revenue). Contract liabilities consist of amounts invoiced to customers in excess of revenue recognized. On May 1, 2018, the day of adoption of ASC 2014-09, the Company reclassified $18,000 of unearned revenue to contract liabilities.

A summary of the contract assets and contract liabilities is as follows:

	April 30, 2019			April 30, 2018
	(in thousands)

Contract assets	$	15		$	-
Contract liabilities		(188	)		-
Contract (liability)/assets, net	$	(173	)	$	-

The increase in contract assets is primarily a result of services performed but unbilled during the twelve months ended April 30, 2019. The increase in contract liabilities is primarily a result of additional amounts invoiced to customers in excess of revenue recognized during the twelve months ended April 30, 2019. During the twelve months ended April 30, 2019, the Company recognized $18,000 of revenue that was included in contract liabilities at May 1, 2018. During the twelve months ended April 30, 2019, the Company recognized revenue of $145,000 related to performance obligations that were partially satisfied in previous periods.

Property and Equipment

12 Months Ended

Apr. 30, 2019

Property, Plant and Equipment [Abstract]

Property and Equipment

(4) Property and Equipment

The components of property and equipment as of April 30, 2019 and 2018 consisted of the following:

	April 30, 2019			April 30, 2018
	(in thousands)

Equipment	$	339		$	394
Computer Equipment & Software		558			614
Office Furniture & Equipment		341			338
Leasehold improvements		474			473
Equipment under capitalized lease		103			103
Construction in process		15			0
	$	1,830		$	1,922
Less: accumulated depreciation		(1,238	)		(1,210	)
	$	592		$	712

Depreciation expense was $0.2 million and $0.1 million for the years ended April 30, 2019 and 2018, respectively.

As of April 30, 2019 and 2018, computer equipment and software under capital leases was $103 thousand and $103 thousand, respectively. The terms of the leases are for 36 months. The leases for computer equipment and software under capital leases have ended and there no future minimum lease payments under capital leases as of April 30, 2019.

Accrued Expenses

12 Months Ended

Apr. 30, 2019

Payables and Accruals [Abstract]

Accrued Expenses

(5) Accrued Expenses

Accrued expenses consist of the following at April 30, 2019 and April 30, 2018.

	April 30, 2019		April 30, 2018
	(in thousands)

Project costs	$	9	$	57
Contract loss reserve		211		395
Employee incentive payments		580		761
Accrued salary and benefits		500		442
Legal and accounting fees		273		246
Accrued taxes payable		177		179
Other		188		181
	$	1,938	$	2,261

Deferred Credits Payable

12 Months Ended

Apr. 30, 2019

Deferred Credits Payable

(6) Deferred Credits Payable

During the year ended April 30, 2001, in connection with the sale of Common Stock to an investor, the Company received $0.6 million from the investor in exchange for an option to purchase up to 500,000 metric tons of carbon emissions credits generated by the Company during the years 2008 through 2012, at a 30% discount from the then-prevailing market rate. If the Company received emission credits under applicable laws and failed to sell to the investor the credits up to the full amount of emission credits covered by the option, the investor was entitled to liquidated damages equal to 30% of the aggregate market value of the shortfall in emission credits (subject to a limit on the market price of emission credits). Under the terms of the agreement, if the Company did not become entitled under applicable laws to the full amount of emission credits covered by the option by December 31, 2012, the Company was obligated to return the option fee of $0.6 million, less the aggregate discount on any emission credits sold to the investor prior to such date. In December 2012, the Company and the investor agreed to extend the period for the sale of emission credits until December 31, 2017. The Company did not generate any emissions credits eligible for purchase under the agreement and it was agreed by the investor and the Company that the Company return the option fee of $0.6 million, which was completed as of August 31, 2018. As a result, this matter is completely resolved, and no additional amounts are owed by the Company to the investor.

Warrants

12 Months Ended

Apr. 30, 2019

Warrants and Rights Note Disclosure [Abstract]

Warrants

(7) Warrants

Liability Classified Warrants

On June 2, 2016, the Company entered into a securities purchase agreement, which was amended on June 7, 2016 (as amended, the “June Purchase Agreement”) with certain institutional purchasers (the “June Purchasers”). Pursuant to the terms of the June Purchase Agreement, the Company sold an aggregate of 20,850 shares of Common Stock together with warrants to purchase up to an aggregate of 7,298 shares of Common Stock. Each share of Common Stock was sold together with a warrant to purchase 0.35 of a share of Common Stock at a combined purchase price of $92.00. The warrants have an exercise price of $121.60 per share, became exercisable on December 3, 2016 (“Initial Exercise Date”), and will expire five years following the Initial Exercise Date. As of April 30, 2019, none of the warrants have been exercised.

On July 22, 2016, the Company entered into a Second Amendment to the Purchase Agreement (the “Second Amended Purchase Agreement”) with certain institutional purchasers (the “July Purchasers”). Pursuant to the terms of the Second Amended Purchase Agreement, the Company sold an aggregate of 29,750 shares of Common Stock together with warrants to purchase up to an aggregate of 8,925 shares of Common Stock. Each share of Common Stock was sold together with a warrant to purchase 0.30 of a share of Common Stock at a combined purchase price of $135.00. The Warrants were exercisable immediately at an exercise price of $187.20 per share. The Warrants will expire on the fifth (5th) anniversary of the initial date of issuance. As of April 30, 2019, none of the warrants have been exercised.

Equity Classified Warrants

On April 8, 2019, the Company entered into a securities purchase agreement (the “April Purchase Agreement”) with certain institutional purchasers. Pursuant to the terms of the April Purchase Agreement, the Company issued and sold 1,542,000 shares of common stock and pre-funded warrants to purchase up to 3,385,680 shares of common stock and common warrants to purchase up to 4,927,680 shares of our common stock in an underwritten public offering. The public offering price for the pre-funded warrants was equal to the public offering price of the common stock, less the $0.01 per share exercise price of each warrant. The pre-funded warrants have no expiration date. As of April 30, 2019, 753,560 of the pre-funded warrants have not been exercised. In connection with the public offering, the Company issued common warrants to purchase up to 4,927,680 shares of our common stock. The common stock warrants have an exercise price of $3.85 per share and expire five years from the issuance date. As of April 30, 2019, none of the common stock warrants have been exercised.

The Company accounts for warrants issued in connection with its public offerings in accordance with the guidance on “Accounting for Certain Financial Instruments with Characteristics of Both Liabilities and Equity” in Topic 480 which provides that the Company classify the warrant instruments as a liability at its fair value. The warrant liabilities are subject to re-measurement at each balance sheet date using the Black-Scholes option pricing model. The June and July 2016 warrants contain a feature whereby they could require the transfer of assets and therefore are classified as a liability award in accordance with the guidance Topic 480. As such, the warrants have a value of $6,000 at April 30, 2019 and $0.2 million at April 30, 2018 and are reflected within “Warrant liabilities” in the consolidated balance sheets. The pre-funded and common warrants issued in the Company’s April 8, 2019 public offering did not meet the criteria to be classified as a liability award and therefore were treated as an equity award and recorded as a component of stockholders’ equity in the consolidated balance sheets.

An unrealized gain of $0.2 million and $0.1 million, were included within “Gain due to change in fair value of warrant liabilities” in the consolidated statements of operations for the year ended April 30, 2019 and 2018, respectively. The Company determined the fair value using the Black-Scholes option pricing model with the following assumptions for the period ended April 30, 2019 and April 30, 2018:

	April 30, 2019			April 30, 2018

Dividend rate		0.0	%		0.0	%
Risk-free rate		2.2% - 2.3	%		2.7% - 2.8	%
Expected life (years)		2.2 - 2.6			3.2 - 3.6
Expected volatility		110.0% - 153.4	%		132.9% - 142.7	%

Preferred Stock

12 Months Ended

Apr. 30, 2019

Equity [Abstract]

Preferred Stock

(8) Preferred Stock

The Company has authorized 5,000,000 shares of undesignated preferred stock with a par value of $0.001 per share. As of April 30, 2019, and 2018, no shares of preferred stock had been issued.

Common Stock

12 Months Ended

Apr. 30, 2019

Equity [Abstract]

Common Stock

(9) Common Stock

As of April 30, 2019, the Company has 100,000,000 shares authorized with a par value of $0.001 per share and 5,425,517 shares issued.

On January 7, 2019, the Company entered into an At the Market Offering Agreement (“2019 ATM Facility”) with A.G.P./Alliance Global Partners (“AGP”), under which the Company may issue and sell to or through A.G.P./Alliance Global Partners, acting as agent and/or principal, shares of the Company’s common stock having an aggregate offering price of up to $25 million. As of April 30, 2019, under the 2019 ATM Facility the Company had issued and sold 151,561 shares of its common stock with an aggregate market value of $958,229 at an average price of $6.32 per share and paid AGP a sales commission of approximately $33,469 related to those shares.

On April 8, 2019, the Company sold 1,542,000 shares of common stock, which includes the sale of 642,000 shares of the Company’s common stock sold by the Company pursuant to the exercise, in full, of the over-allotment option by the underwriters in a public offering, prefunded warrants to purchase up to 3,385,680 shares of common stock and common warrants to purchase up to 4,927,680 shares of our common stock in an underwritten public offering. The net proceeds to the Company from the offering were approximately $15.7 million, after deducting underwriter’s fees and offering expenses payable by the Company.

Treasury Shares

12 Months Ended

Apr. 30, 2019

Equity [Abstract]

Treasury Shares

10) Treasury Shares

During the years ended April 30, 2019 and 2018, 89 and 1,298 shares of Common Stock, respectively, were purchased by the Company from employees to pay taxes related to the vesting of restricted stock.

Share-Based Compensation Plans

12 Months Ended

Apr. 30, 2019

Share-based Payment Arrangement [Abstract]

Share-Based Compensation Plans

(11) Share-Based Compensation Plans

2015 Omnibus Incentive Plan

In 2015, upon approval by the Company’s stockholders, the Company’s 2015 Omnibus Incentive Plan (the “2015 Plan”) became effective. A total of 12,036 shares were authorized for issuance under the 2015 Omnibus Incentive Plan, including shares available for awards under the 2006 Stock Incentive Plan remaining at the time that plan terminated, or that were subject to awards under the 2006 Stock Incentive Plan that thereafter terminated by reason of expiration, forfeiture, cancellation or otherwise. On October 21, 2016, upon approval by the Company’s stockholders, the Company increased the number of shares authorized for issuance to 32,036. If any award under the 2006 Stock Incentive Plan or 2015 Plan expires, is cancelled, terminates unexercised or is forfeited, those shares become again available for grant under the 2015 Plan. As of April 30, 2019, the Company has 58,555 shares available for future issuance under the 2015 Plan.

The 2015 Plan provides for the grant of stock options, SARs, restricted stock awards, stock unit awards and unrestricted stock awards, dividend equivalent rights, performance share awards or other performance-based awards, other equity-based awards or cash to eligible employees, officers and non-employee directors of the Company or any affiliate of the Company, or any consultant or adviser to the Company. The maximum number of shares of stock subject to Awards that can be granted under the 2015 Plan in any one calendar year to any person, other than a non-employee director, is 3,750. However, incentive stock options may only be granted to employees. The limitation on the amount of shares of stock issuable under the 2015 Plan is subject to adjustment in the event of certain changes in the Company’s capital stock, such as recapitalizations, reclassifications, stock splits, reverse stock splits, spin-offs, combinations of our stock, exchanges of the Company’s stock and other increases or decreases in the Company’s stock without receipt of consideration.

The 2015 Plan will terminate ten years after its effective date, in October 2025, but is subject to earlier termination as provided in the 2015 Plan.

Except in connection with a corporate transaction in which the Company is involved, without obtaining stockholder approval, the 2015 Plan may not be amended to reduce the exercise price of such outstanding options or SARs, cancel outstanding options or SARs in exchange for or in substitution of options or SARs with an exercise price that is less than the exercise price of the original options or SARs, or cancel outstanding options or SARs with an exercise price above the current stock price in exchange for cash or other securities.

2018 Employment Inducement Incentive Award Plan

On January 18, 2018, the Company’s Board of Directors adopted the Company’s Employment Inducement Incentive Award Plan (the “2018 Inducement Plan”) pursuant to which the Company reserved 25,000 shares of common stock for issuance under the Inducement Plan. In accordance with Rule 5635(c)(4) and Rule 5635(c)(3) of the Nasdaq Listing Rules, awards under the Inducement Plan may only be made to individuals not previously employees of the Company (or following such individuals’ bona fide period of non-employment with the Company), as an inducement material to the individuals’ entry into employment with the Company. An award is any right to receive the Company’s common stock pursuant to the 2018 Inducement Plan, consisting of a performance share award, restricted stock award, a restricted stock unit award or a stock payment award. As of April 30, 2019, there were no shares outstanding and 25,000 shares available for grant under the 2018 Inducement Plan.

(a) Stock Options

A summary of stock options under the plans described above is as follows:

						Weighted
						Average
				Weighted		Remaining
	Shares			Average		Contractual
	Underlying			Exercise		Term
	Options			Price		(In Years)
Outstanding as of April 30, 2018		19,427		$	123.00		7.4
Granted		49,750		$	8.20
Exercised		-		$	-
Cancelled/forfeited		(3,605	)	$	392.80
Outstanding as of April 30, 2019		65,572		$	21.08		8.9
Exercisable as of April 30, 2019		17,822		$	55.60		7.1

As of April 30, 2019, the total intrinsic value of outstanding and exercisable options was approximately zero. As of April 30, 2019, approximately 42,343 additional options were unvested, which options had no intrinsic value and a weighted-average remaining contractual term of 9.6 years. There was approximately $0.2 million and $0.2 million of total recognized compensation cost related to employees for stock options during the years ended April 30, 2019 and 2018, respectively. As of April 30, 2019, there was approximately $0.2 million of total unrecognized compensation cost related to non-vested stock options granted under the plans. This cost is expected to be recognized over a weighted-average period of 0.6 years. The Company typically issues newly authorized but unissued shares to satisfy option exercises under these plans.

(b) Restricted Stock

Compensation expense for non- vested restricted stock is generally recorded based on its market value on the date of grant and recognized ratably over the associated service and performance period. During fiscal 2019, the Company granted 943 shares subject to service-based vesting requirements and no shares subject to performance-based vesting requirements.

A summary of unvested restricted stock under the plans described above is as follows:

				Weighted
	Number			Average Price per
	of Shares			Share

Issued and unvested at April 30, 2018		9,854		$	27.00
Granted		943		$	22.80
Vested		(258	)	$	64.40
Cancelled/forfeited		(6,033	)	$	22.51
Issued and unvested at April 30, 2019		4,506		$	30.08

There was approximately $0.1 million and $0.1 million of total recognized compensation cost relating to restricted stock granted to employees during the years ended April 30, 2019 and 2018, respectively. As of April 30, 2019, there was $9,000 of total unrecognized compensation cost related to unvested restricted stock granted under the plans. This cost is expected to be recognized over a weighted-average period of 0.3 years.

Fair Value Measurements

12 Months Ended

Apr. 30, 2019

Fair Value Disclosures [Abstract]

Fair Value Measurements

(12) Fair Value Measurements

The Company measures and reports certain financial and non-financial assets and liabilities on a fair value basis. Fair value is the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date (exit price). GAAP specifies a three-level hierarchy that is used when measuring and disclosing fair value. The fair value hierarchy gives the highest priority to quoted prices available in active markets (i.e., observable inputs) and the lowest priority to data lacking transparency (i.e., unobservable inputs). An instrument’s categorization within the fair value hierarchy is based on the lowest level of significant input to its valuation. The following is a description of the three hierarchy levels.

Level 1	Unadjusted quoted prices in active markets that are accessible at the measurement date for identical, unrestricted assets or liabilities. Active markets are considered to be those in which transactions for the assets or liabilities occur in sufficient frequency and volume to provide pricing information on an ongoing basis.

Level 2	Quoted prices in markets that are not active, or inputs which are observable, either directly or indirectly, for substantially the full term of the asset or liability. This category includes quoted prices for similar assets or liabilities in active markets and quoted prices for identical or similar assets or liabilities in inactive markets.

Level 3	Unobservable inputs are not corroborated by market data. This category is comprised of financial and non-financial assets and liabilities whose fair value is estimated based on internally developed models or methodologies using significant inputs that are generally less readily observable from objective sources.

Transfers into or out of any hierarchy level are recognized at the end of the reporting period in which the transfers occurred. There were no transfers between any levels during the year ended April 30, 2019 and 2018.

The following information is provided to help readers gain an understanding of the relationship between amounts reported in the accompanying consolidated financial statements and the related market or fair value. The disclosures include financial instruments and derivative financial instruments, other than investment in affiliates.

Following are descriptions of the valuation methodologies used to measure material assets and liabilities at fair value and details of the valuation models, key inputs to those models and significant assumptions utilized.

Warrant Liabilities

The fair value of the Company’s warrant liabilities (refer to Note 7) recorded in the Company’s financial statements is determined using the Black-Scholes option pricing model and the quoted price of the Company’s common stock in an active market, volatility and expected life, is a Level 3 measurement. Volatility is based on the actual market activity of the Company’s stock. The expected life is based on the remaining contractual term of the warrants and the risk-free interest rate is based on the implied yield available on U.S. Treasury Securities with a maturity equivalent to the warrants’ expected life.

The following table presents financial assets and liabilities measured at fair value on a recurring basis as of April 30, 2019:

	Total Carrying Value in Consolidated Balance Sheet		Quoted prices in active markets for identical assets or liabilities (Level 1)		Significant other observable inputs (Level 2)		Significant unobservable inputs (Level 3)
	(in thousands)

Warrant liabilities	$	6	$	-	$	-	$	6

The following table presents financial assets and liabilities measured at fair value on a recurring basis as of April 30, 2018:

	Total Carrying Value in Consolidated Balance Sheet		Quoted prices in active markets for identical assets or liabilities (Level 1)		Significant other observable inputs (Level 2)		Significant unobservable inputs (Level 3)
	(in thousands)

Warrant liabilities	$	201	$	-	$	-	$	201

The following table provides a summary of changes in the fair value of the warrant liabilities during the year ended April 30, 2019;

Fair Value Measurement Using Significant Unobservable Inputs (Level 3)

	Total
	Warrant
	Liability
		(in thousands)

Fair value – April 30, 2017	$	323
Issuance		-
Transfers		-
Change in fair value		(122	)
Fair value – April 30, 2018	$	201

Change in fair value		(195	)
Fair value – April 30, 2019	$	6

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Income Taxes

12 Months Ended

Apr. 30, 2019

Income Tax Disclosure [Abstract]

Income Taxes

(13) Income Taxes-

Loss before income taxes for the years ended April 30, 2019 and 2018 consisted of the following components:

	April 30, 2019			April 30, 2018
	(in thousands)

Domestic	$	(12,860	)	$	(11,004	)
Foreign		(236	)		(272	)
Total loss before income taxes	$	(13,096	)	$	(11,276	)

The income tax benefit for the years ended April 30, 2019 and 2018 consist of state income tax benefits of $0.9 million and $1.1 million, respectively, from the sale of New Jersey net operating losses and research and development credits.

Tax Rate Reconciliation

The effective income tax rate differed from the percentages computed by applying the US federal income tax rate for the periods ended April 30, 2019 and 2018 to loss before income taxes as a result of the following:

	April 30, 2019			April 30, 2018

Computed expected tax (benefit)		-21.0	%		-29.7	%
Increase(reduction) in income taxes resulting from:
State income taxes, net of federal (benefit)		0.8	%		3.0	%
Federal research and development tax credits		-1.5	%		-1.5	%
Foreign rate differential		0.2	%		0.3	%
Other non-deductible expenses		0.1	%		0.4	%
Proceeds of sale of New Jersey tax (benefits)		-6.5	%		-9.9	%
U.S. tax reform effects		0.0	%		162.2	%
Other		0.6	%		5.1	%
Increase in valuation allowance		20.8	%		-139.4	%
Income tax (benefit)		-6.5	%		-9.5	%

Significant Components of Deferred Taxes

The tax effects of temporary differences and carry forwards that give rise to the Company’s deferred tax assets and deferred tax liabilities are presented below.

	April 30, 2019			April 30, 2018
	(in thousands)

Deferred tax assets:
Federal net operating loss carryforwards	$	32,025		$	29,329
Foreign net operating loss carryforwards		3,641			3,852
State operating loss carryforwards		1,653			1,460
Federal and New Jersey research and development tax credits		3,315			3,143
Stock compensation		486			645
Unrealized foreign exchange loss		5			12
Accrued expenses		145			487
Other		438			330
Net deferred tax assets before valuation allowance		41,708			39,258
Valuation allowance		(41,708	)		(39,258	)
Net deferred tax assets	$	-		$	-

In assessing the realizability of deferred tax assets, management considers whether it is more likely than not that some portion or all of the deferred tax assets will not be realized. The ultimate realization of deferred tax assets is dependent upon the generation of future taxable income during the periods in which those temporary differences and carry forwards become deductible or are utilized. As of April 30, 2019 and 2018, based upon the level of historical taxable losses, valuation allowances of $41.7 million and $39.3 million, respectively, were recorded to fully offset deferred tax assets. The valuation allowance increased $2.5 million during the year ended April 30, 2019 and decreased $15.4 million during the year ended 2018 respectively.

As of April 30, 2019, the Company had net operating loss carry forwards for federal income tax purposes of approximately $152.5 million, which begin to expire in fiscal 2019. The Company also had federal research and development tax credit carry forwards of approximately $3.2 million as of April 30, 2019, which begins to expire in 2019. The Tax Reform Act of 1986 contains provisions that limit the utilization of net operating loss and tax credit carry forwards if there has been an ownership change, as defined. The Company has determined that such an ownership change, as described in Section 382 of the Internal Revenue Code, occurred in conjunction with the Company’s U.S. initial public offering in April 2007. The Company’s annual Section 382 limitation is approximately $3.3 million. The Section 382 limitation is cumulative from year to year, and thus, to the extent net operating loss or other credit carry forwards are not utilized up to the amount of the available annual limitation, the limitation is carried forward and added to the following year’s available limitation. Such limitation only applies to net operating losses incurred in periods prior to the ownership change. The Company has not performed additional analysis on ownership changes that may have occurred subsequently to further limit the ability to utilize net tax attributes. As of April 30, 2019, the Company had state net operating loss carry forwards of approximately $23.3 million which begin to expire in 2037, which also may be limited to utilization limitations. As of April 30, 2019, the Company had foreign net operating loss carry forwards of approximately $16.9 million. The ability to utilize these carry forwards may also be limited in the event of a significant change to ownership.

New Jersey Net Operating Loss

During the years ended April 30, 2019 and 2018, the Company sold New Jersey State net operating losses and research and development credits in the amount of $9.1 million and $11.5 million, respectively, resulting in the recognition of income tax benefits of $0.9 million and $1.1 million, respectively, recorded in the Company’s Statement of Operations.

Uncertain Tax Positions

The Company applies the guidance issued by the FASB for the accounting and reporting of uncertain tax positions. The guidance requires the Company to recognize in its consolidated financial statements the impact of a tax position if that position is more likely than not to be sustained upon examination, based on the technical merits of the position. The Company is currently undergoing an income tax audit in Spain for the period from 2008 to 2014, when the Company’s Spanish branch was closed (see Note 15 to the Consolidated Financial Statements) . At April 30, 2019 and 2018, the Company had no other unrecognized tax positions. The Company does not expect any material increase or decrease in its income tax expense in the next twelve months, related to examinations or uncertain tax positions. U.S. federal and state income tax returns were audited through fiscal 2014 and fiscal 2010 respectively. Net operating loss and credit carry forwards since inception remain open to examination by taxing authorities and will continue to remain open for a period of time after utilization.

The Company does not have any interest or penalties accrued related to uncertain tax positions as it does not have any unrecognized tax benefits.

Commitments and Contingencies

12 Months Ended

Apr. 30, 2019

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies

(14) Commitments and Contingencies

(a) Operating Lease Commitments

The Company leases office, laboratory, manufacturing and other space in Monroe Township, New Jersey under an operating lease that expires on October 31, 2024. The lease commencement date is November 1, 2017, with lease payments beginning the same month. The lease expiration date is seven years from the rent commencement date. The Company provided a cash security deposit of approximately $154,000. The Lease contains a tenant improvement allowance of up to $138,000 and annual escalations, as such, the Company accounts for rent expense on a straight-line basis. Rent expense under operating leases was approximately $0.5 million and $0.4 million for the years ended April 30, 2019 and 2018, respectively.

Future minimum lease payments under operating leases as of April 30, 2019 are as follows:

	April 30, 2019
		(in thousands)

2020		322
2021		331
2022		341
2023		352
2024		362
Thereafter		184
	$	1,892

Shareholder Litigation

The Company and certain of its current and former directors and officers were identified as defendants in a derivative lawsuit filed on March 18, 2015 in the United States District Court for the District of New Jersey captioned Labare v. Dunleavy, et. al., Case No. 3:15-cv-01980-FLW-LHG. The derivative complaint alleged claims for breach of fiduciary duty, abuse of control, gross mismanagement and unjust enrichment relating to the now terminated agreement between Victorian Wave Partners Pty. Ltd. (VWP) and the Australian Renewable Energy Agency (ARENA) for the development of a wave power station. The derivative complaint sought unspecified monetary damages and other relief.

On July 10, 2015, a second derivative lawsuit, captioned Rywolt v. Dunleavy, et al., Case No. 3:15-cv-05469, was filed by another shareholder against the same defendants in the United States District Court for the District of New Jersey alleging similar claims for breach of fiduciary duty, gross mismanagement, abuse of control, and unjust enrichment relating to the now terminated agreement between VWP and ARENA. The Rywolt complaint also seeks unspecified monetary damages and other relief.

On April 21, 2016, a third derivative lawsuit, captioned LaCalamito v. Dunleavy, et al., Case No. 3:16-cv-02249, was filed by another shareholder against certain current and former directors and officers of the Company in the United States District Court for the District of New Jersey alleging similar claims for breach of fiduciary duty relating to the now terminated agreement between VWP and ARENA. The LaCalamito complaint sought unspecified monetary damages and other relief.

On June 9, 2016, a fourth derivative lawsuit, captioned Pucillo v. Dunleavy, et al., was filed by another shareholder against certain current and former directors and officers of the Company in the United States District Court for the District of New Jersey alleging similar claims for breach of fiduciary duty, unjust enrichment, and abuse of control relating to the now terminated agreement between VWP and ARENA. The Pucillo complaint seeks unspecified monetary damages and other relief.

On October 25, 2016, the Court approved and entered a Stipulation and Order that, among other things, (i) consolidated the LaBare, Rywolt, LaCalamito and Pucillo derivative actions; (ii) identified plaintiff Pucillo as the lead plaintiff in the consolidated actions; and (iii) stayed the consolidated actions pending the November 14, 2016 settlement hearing in the now-settled securities class action and further order of the Court.

On October 23, 2017, the parties entered into a Stipulation and Agreement of Settlement to resolve the four consolidated derivative lawsuits. The settlement provided for, among other things, the Company to implement certain corporate governance changes, a $350,000 payment to the plaintiffs’ attorneys for attorneys’ fees and costs that will be made by the Company’s insurance carrier, dismissal of the derivative lawsuits, and certain releases. On November 21, 2017, the plaintiffs filed an unopposed motion seeking preliminary approval of the settlement, which the Court granted on March 9, 2018. On May14, 2018, the Court held a final settlement approval hearing at which the Court stated that it was approving the settlement. On June 13, 2018, the Court issued a Final Order and Judgment, approving the Stipulation and Agreement of Settlement. The Company had accrued $350,000 related to this matter as a probable and reasonably estimable loss contingency during the twelve months ended April 30, 2018. The Company also recorded a receivable of $350,000 from its insurance carrier with the offset to the statement of operations. The Company’s insurance carrier made a payment of $350,000 to the plaintiffs’ attorneys on May 3, 2018. As a result, the consolidated derivatives lawsuits are now completely resolved, the releases are operative, and the matter is closed.

Employment Arbitration

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 shareholder litigation. The securities class action was resolved in November 2017 and the 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-member 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 in Princeton, New Jersey. As of April 30, 2019, the Company has not accrued any provision related to this matter since it cannot reasonably estimate the loss contingency.

Tide Runner Marine, Inc. Lawsuit

On June 13, 2018, Tide Runner Marine, Inc. (“Tide Runner”) filed a lawsuit in the United States District Court for the District of New Jersey captioned Tide Runner Marine, Inc. v. Ocean Power Technologies, Inc., Case No. 1:18-cv-10496. The complaint names the Company as defendant and alleges claims for breach of contract, unjust enrichment, conversion, and fraud, negligent and/or reckless misrepresentation all as associated with the removal of a Company mooring system off the coast of New Jersey that was completed in May 2017. The complaint seeks damages in the amount of $2,825,130 together with interest, costs, attorney’s fees, punitive damages and such other relief as may be appropriate under the circumstances. On July 27, 2018, the Company filed an answer denying the claims in the complaint, asserted various affirmative defenses, and asserted a counter-claim for damages in the amount of $15,000 for Tide Runner’s failure to pay the Company for certain portions of the mooring system that were recovered. On August 2, 2018, Tide Runner filed its answer to and denied the Company’s counterclaim and asserted various affirmative defenses. During the initial scheduling conference held on September 13, 2018, the parties agreed to engage in mediation in an effort to resolve this matter and also agreed to include Tide Runner’s subcontractor, Wittich Bros. Marine Inc. (“Wittich”) in the mediation process. The parties participated in mediation on November 15, 2018 but were unable to reach an agreement. However, the parties agreed to continue the mediation process and on February 11, 2019 reached a settlement agreement. On February 22, 2019, the parties executed a Settlement Agreement and Release (“Settlement”). Under the Settlement, the Company will pay to Wittich (i) $50,000 within 10 days after the final execution of the Settlement and (ii) another $150,000 on or before May 1, 2019. Subsequently, the parties filed a stipulation of dismissal of both Tide Runner’s complaint and the Company’s counterclaim with prejudice and without costs, and the Court granted the dismissal and terminated the case. The parties have also provided mutual releases for the matters in dispute in the litigation and will indemnify each other for future similar claims. As of April 30, 2019, the Company made the two required payments to Wittich.

Nasdaq Compliance

On August 9, 2018, the Company received written notification from Nasdaq indicating that the closing bid price of the Company’s common stock had been below $1.00 per share for a period of 30 consecutive trading days, and as a result, the Company was not in compliance with the minimum bid price requirement for continued listing. Under the Nasdaq Listing Rules, the Company was provided with a grace period of 180 calendar days, or until February 5, 2019, 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 the grace period. If the Company did not regain compliance before February 5, 2019, Nasdaq stated that it would provide the Company with written notice that its securities are subject to delisting. At that time, the Company could appeal Nasdaq’s determination to a Nasdaq Listing Qualifications Panel, which would stay any further delisting action by Nasdaq pending a final decision by the panel. Alternatively, the Company could have been eligible for an additional 180 calendar day grace period if it met the continued listing standards, with the exception of bid price, for the Nasdaq Capital Market, and if the Company stated its intent to affect a reverse split, if necessary, to cure such deficiency.

On February 11, 2019, the Company received another written notification from Nasdaq indicating that the Company had not regained compliance with the minimum bid price requirement and that the Company’s stockholders’ equity, as reported in the Company’s Quarterly Report on Form 10-Q for the quarter ended October 31, 2018, did not qualify the Company for an additional 180 calendar day extension period for compliance. On February 19, 2019, the Company appealed Nasdaq’s determination to a Hearings Panel (the “Panel”), pursuant to the procedures set forth in the Nasdaq Listing Rule 5800 Series. The appeal stayed the suspension of the Company’s securities pending the Panel’s decision, during which time the Company’s common stock will continue to be listed on Nasdaq, and the Company’s common stock will continue to trade under the symbol “OPTT”.

On March 14, 2019, the Company received another written notification from Nasdaq indicating that the Company did not comply with the minimum stockholders’ equity requirement for continued listing. The earlier-filed appeal of the minimum bid price requirement was sufficient to encompass the minimum stockholder’s equity requirement, and the stay of suspension continued pending the Panel hearing and decision.

The Panel held its hearing on March 28, 2019. On April 4, 2019, the Panel issued the following two decisions: (i) the Panel concluded that the Company was in compliance with the minimum bid price rule; and (ii) the Panel granted the Company’s request to cure its stockholder equity deficiency by conducting a public offering that was estimated to raise $10 million by no later than April 30, 2019. On April 24, 2019, the Company provided the Panel with an update following a public offering that raised approximately $15.7 million (after deducting underwriter fees, commissions and other offering expenses) and closed on April 8, 2019. The update included revised projections of stockholder equity based upon the actual amount of proceeds raised during the public offering, which in the Company’s opinion was sufficient to cure the stockholder equity deficiency.

On May 20, 2019 the Company received a letter from Nasdaq confirming that the Company has regained compliance with the minimum shareholders’ equity rule, as required by the Panel’s decision dated April 4, 2019, and is in compliance with other applicable requirements as set forth in the decision and required for listing on Nasdaq. Accordingly, the Panel has determined to continue the listing of the Company’s securities on Nasdaq and closed the matter.

FINRA Review

On April 4, 2019, FINRA notified the Company that it was conducting a routine review of the Company’s stock associated with two public announcements and asked several questions regarding: (i) an April 3, 2019 announcement that the Company had won a contract with a leading oil and gas operator; and (ii) an April 4, 2019 announcement of the pricing of an underwritten public offering. The Company provided its response to the FINRA questions on Tuesday, April 9, 2019. As of July 22, 2019, FINRA has not provided any follow-up.

Spain Income Tax Audit

The Company is currently undergoing an income tax audit in Spain for the period from 2008 to 2014, when our Spanish branch was closed. The branch reported net operating losses for each of the years reported that the Spanish tax inspector claims should have been capitalized on the balance sheet instead of charged as an expense in the Statement of Operations. As of April 30, 2017, the Company had recorded a penalty of $132,000 to Selling, general and administrative costs in the Statement of Operations. The Spanish tax inspector has recently closed its discussion relating to the capitalization of expenses and as of April 30, 2018 the Company reversed the penalty. However, during the fiscal year ended April 30, 2018 the Spanish tax inspector raised questions with respect to the Company’s recognition of funds received in 2011 to 2014 from a governmental grant from the European Commission in connection with the Waveport project. It is anticipated that we 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, 2019 and 2018 has recorded the penalty in Accrued expenses in the Consolidated Balance Sheet.

Operating Segments and Geographic Information

12 Months Ended

Apr. 30, 2019

Segment Reporting [Abstract]

Operating Segments and Geographic Information

(15) Operating Segments and Geographic Information

The Company’s business consists of one segment as this represents management’s view of the Company’s operations. The Company operates on a worldwide basis with one operating company in the US and operating subsidiaries in the UK and in Australia. Revenues and expenses are generally attributed to the operating unit that bills the customers. Geographic information is as follows:

	Year Ended April 30, 2019
	North						Asia and
	America			Europe			Australia			Total
	(in thousands)

Revenues from external customers	$	632		$	-		$	-		$	632
Operating loss		(13,045	)		(204	)		(22	)		(13,271	)
Long-lived assets		592			-			-			592
Total assets		18,028			49			289			18,366

	Year Ended April 30, 2018
	North						Asia and
	America			Europe			Australia			Total
	(in thousands)

Revenues from external customers	$	511		$	-		$	-		$	511
Operating loss		(11,282	)		(243	)		(35	)		(11,560	)
Long-lived assets		712			-			-			712
Total assets		13,762			22			337			14,121

Adoption of Revenue Recognition Guidance

12 Months Ended

Apr. 30, 2019

Accounting Changes and Error Corrections [Abstract]

Adoption of Revenue Recognition Guidance

(16) Adoption of Revenue Recognition Guidance

The Company adopted the new revenue recognition guidance effective May 1, 2018, using the modified retrospective method. The primary impact of the new guidance was a change in the timing of revenue recognition on certain long-term contracts. The new guidance does not change the total sales or operating income on the related customer contracts, only the timing of when sales and operating income are recognized. The Company uses the expected cost plus a margin approach and lease accounting literature for revenue recognition on customer contracts. The impact of the adoption for the twelve months ended April 30, 2019 was an increase of $118,000 to net loss. Further, as the Company’s adoption of the guidance decelerated the timing of revenue recognition on the Company’s contracts, the adoption resulted in an $118,000 increase in the Company’s remaining performance obligations, also referred to as backlog, as of April 30, 2019.

The following tables present how the adoption of the new revenue recognition standard affected certain line items in the Company’s condensed statement of operations for the twelve months ended April 30, 2019.

	Twelve months ended April 30, 2019
							Amounts Excluding
	As Reported			Effect of Adoption			Effect of Adoption

Revenues	$	632		$	(118	)	$	750
Operating loss		(13,271	)		(118	)		(13,153	)
Net loss	$	(12,246	)	$	(118	)	$	(12,128	)
Basic and diluted net loss per share	$	(9.52	)	$	(0.09	)	$	(9.43	)
Weighted average shares used to compute basic and diluted net loss per share		1,286,727			1,286,727			1,286,727

The following tables present how the adoption of the new revenue recognition standard affected certain line items in the Company’s statement of comprehensive loss for the twelve months ended April 30, 2019.

	Twelve months ended April 30, 2019
							Amounts Excluding
	As Reported			Effect of Adoption			Effect of Adoption

Net loss	$	(12,246	)	$	(118	)	$	(12,128	)
Foreign currency translation adjustment		(11	)		-			(11	)
Total comprehensive loss	$	(12,257	)	$	(118	)	$	(12,139	)

The following tables present how the adoption of the new revenue recognition standard affected certain line items in the Company’s consolidated balance sheet as of April 30, 2019.

	As of April 30, 2019
							Amounts Excluding
	As Reported			Effect of Adoption			Effect of Adoption

ASSETS
Contract assets	$	15		$	(70	)	$	85
Total assets	$	18,366		$	(70	)	$	18,436

LIABILITIES AND STOCKHOLDERS’ EQUITY
Contract liability	$	188		$	48		$	140
Accumulated deficit		(209,784	)		(118	)		(209,666	)
Total stockholders’ equity	$	15,775		$	(70	)	$	15,845
Total liabilities and stockholders’ equity	$	18,366		$	(70	)	$	18,436

The following tables present how the adoption of the new revenue recognition standard affected certain line items in the Company’s consolidated statement of cash flows for the twelve months ended April 30, 2019.

	Twelve months ended April 30, 2019
							Amounts Excluding
	As Reported			Effect of Adoption			Effect of Adoption

Net loss	$	(12,246	)	$	(118	)	$	(12,128	)
Contract assets		(15	)		70			(85	)
Contract liability		188			48			140
Net cash used in operating activities	$	(12,140	)	$	-		$	(12,140	)
Net increase in cash, cash equivalents and restricted cash	$	4,934		$	-		$	4,934
Cash, cash equivalents and restricted cash, end of period	$	17,159		$	-		$	17,159

Summary of Significant Accounting Policies (Policies)

12 Months Ended

Apr. 30, 2019

Accounting Policies [Abstract]

Consolidation

(a) Consolidation

Use of Estimates

(b) Use of Estimates

Revenue Recognition

(c) Revenue Recognition

Cash and Cash Equivalents, Restricted Cash and Security Agreements

(d) Cash and Cash Equivalents, Restricted Cash and Security Agreements

Cash and Cash Equivalents

	April 30, 2019		April 30, 2018
	(in thousands)

Checking and savings accounts	$	860	$	1,332
Money market account		15,800		10,167
	$	16,660	$	11,499

Restricted Cash and Security Agreements

A portion of the Company’s cash is restricted under the terms of two security agreements.

	April 30, 2019		April 30, 2018
	(in thousands)

Barclay’s Bank Agreement	$	344	$	372
Santander Bank		155		354
	$	499	$	726

	April 30, 2019		April 30, 2018
	(in thousands)

Cash and cash equivalents	$	16,660	$	11,499
Restricted cash- short term		344		572
Restricted cash- long term		155		154
	$	17,159	$	12,225

Marketable Securities

(e) Marketable Securities

Property and Equipment

(f) Property and Equipment

Description		Estimated useful life

Equipment		5 - 7 years
Computer equipment & software		3 years
Office furniture & fixtures		3 - 7 years
Equipment under capitalized lease		Over the life of the lease
Leasehold improvements		Shorter of the estimated useful life or lease term

Foreign Exchange Gains and Losses

(g) Foreign Exchange Gains and Losses

Concentration of Credit Risk

(h) Concentration of Credit Risk

	Twelve months ended April 30,
	2019			2018

Eni S.p.A.		54	%		33	%
Mitsui Engineering & Shipbuilding		0	%		43	%
Premier Oil UK Limited		33	%		10	%
Office of Naval Research		0	%		14	%
Other		13	%		0	%
		100	%		100	%

Warrant Accounting

(i) Warrant Accounting

Net Loss Per Common Share

(j) Net Loss per Common Share

Share-Based Compensation

(k) Share-Based Compensation

	Twelve months ended April 30,
	2019		2018
	(in thousands)

Product development	$	29	$	24
Selling, general and administrative		266		305
Total share-based compensation expense	$	295	$	329

Valuation Assumptions for Restricted Stock and Options Granted During the Years Ended April 30, 2019 and 2018

Options

	Twelve months ended April 30,
	2019			2018

Risk-free interest rate		2.7	%		2.1	%
Expected dividend yield		0.0	%		0.0	%
Expected life (in years)		5.5			5.5
Expected volatility		126.4	%		128.2	%

The above assumptions were used to determine the weighted average per share fair value of $7.15 and $23.40 for stock options granted during the years ended April 30, 2019 and 2018, respectively.

Restricted Stock

Deferred Rent

(l) Deferred Rent

Income Taxes

(m) Income Taxes

Accumulated Other Comprehensive Loss

(n) Accumulated Other Comprehensive Loss

Recently Issued Accounting Standards

(o) Recently Issued Accounting Standards

Summary of Significant Accounting Policies (Tables)

12 Months Ended

Apr. 30, 2019

Schedule of Cash and Cash Equivalents

The following table summarizes cash and cash equivalents for the years ended April 30, 2019 and 2018:

	April 30, 2019		April 30, 2018
	(in thousands)

Checking and savings accounts	$	860	$	1,332
Money market account		15,800		10,167
	$	16,660	$	11,499

Schedule of Cash and Cash Equivalents and Restricted Cash

	April 30, 2019		April 30, 2018
	(in thousands)

Cash and cash equivalents	$	16,660	$	11,499
Restricted cash- short term		344		572
Restricted cash- long term		155		154
	$	17,159	$	12,225

Schedule of Property, Plant and Equipment, Useful Life

Description		Estimated useful life

Equipment		5 - 7 years
Computer equipment & software		3 years
Office furniture & fixtures		3 - 7 years
Equipment under capitalized lease		Over the life of the lease
Leasehold improvements		Shorter of the estimated useful life or lease term

Schedule of Revenue by Major Customers by Reporting Segments

	Twelve months ended April 30,
	2019			2018

Eni S.p.A.		54	%		33	%
Mitsui Engineering & Shipbuilding		0	%		43	%
Premier Oil UK Limited		33	%		10	%
Office of Naval Research		0	%		14	%
Other		13	%		0	%
		100	%		100	%

Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs

The following table summarizes share-based compensation related to the Company’s share-based plans by expense category for the years ended April 30, 2019 and 2018:

	Twelve months ended April 30,
	2019		2018
	(in thousands)

Product development	$	29	$	24
Selling, general and administrative		266		305
Total share-based compensation expense	$	295	$	329

Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions

	Twelve months ended April 30,
	2019			2018

Risk-free interest rate		2.7	%		2.1	%
Expected dividend yield		0.0	%		0.0	%
Expected life (in years)		5.5			5.5
Expected volatility		126.4	%		128.2	%

Restricted Cash [Member]

Schedule of Cash and Cash Equivalents and Restricted Cash

The following table summarizes restricted cash for the years ended April 30, 2019 and 2018:

	April 30, 2019		April 30, 2018
	(in thousands)

Barclay’s Bank Agreement	$	344	$	372
Santander Bank		155		354
	$	499	$	726

Account Receivable, Contract Assets, and Contract Liabilities (Tables)

12 Months Ended

Apr. 30, 2019

Account Receivable Contract Assets And Contract Liabilities

Schedule of Accounts Receivable

Accounts receivable consisted of the following at April 30, 2019 and April 30, 2018.

	April 30, 2019			April 30, 2018
	(in thousands)

Opening balance	$	171		$	48
Amount invoiced to customer		857			754
Collections		(965	)		(631	)
Ending balance	$	63		$	171

Schedule of Contract Assets and Contract Liabilities

A summary of the contract assets and contract liabilities is as follows:

	April 30, 2019			April 30, 2018
	(in thousands)

Contract assets	$	15		$	-
Contract liabilities		(188	)		-
Contract (liability)/assets, net	$	(173	)	$	-

Property and Equipment (Tables)

12 Months Ended

Apr. 30, 2019

Property, Plant and Equipment [Abstract]

Schedule of Components of Property and Equipment

The components of property and equipment as of April 30, 2019 and 2018 consisted of the following:

	April 30, 2019			April 30, 2018
	(in thousands)

Equipment	$	339		$	394
Computer Equipment & Software		558			614
Office Furniture & Equipment		341			338
Leasehold improvements		474			473
Equipment under capitalized lease		103			103
Construction in process		15			0
	$	1,830		$	1,922
Less: accumulated depreciation		(1,238	)		(1,210	)
	$	592		$	712

Accrued Expenses (Tables)

12 Months Ended

Apr. 30, 2019

Payables and Accruals [Abstract]

Schedule of Accrued Expenses

Accrued expenses consist of the following at April 30, 2019 and April 30, 2018.

	April 30, 2019		April 30, 2018
	(in thousands)

Project costs	$	9	$	57
Contract loss reserve		211		395
Employee incentive payments		580		761
Accrued salary and benefits		500		442
Legal and accounting fees		273		246
Accrued taxes payable		177		179
Other		188		181
	$	1,938	$	2,261

Warrants (Tables)

12 Months Ended

Apr. 30, 2019

Warrant [Member]

Schedule of Fair Value Assumptions Used

The Company determined the fair value using the Black-Scholes option pricing model with the following assumptions for the period ended April 30, 2019 and April 30, 2018:

	April 30, 2019			April 30, 2018

Dividend rate		0.0	%		0.0	%
Risk-free rate		2.2% - 2.3	%		2.7% - 2.8	%
Expected life (years)		2.2 - 2.6			3.2 - 3.6
Expected volatility		110.0% - 153.4	%		132.9% - 142.7	%

Share-Based Compensation Plans (Tables)

12 Months Ended

Apr. 30, 2019

Share-based Payment Arrangement [Abstract]

Schedule of Stock Option Activity

A summary of stock options under the plans described above is as follows:

						Weighted
						Average
				Weighted		Remaining
	Shares			Average		Contractual
	Underlying			Exercise		Term
	Options			Price		(In Years)
Outstanding as of April 30, 2018		19,427		$	123.00		7.4
Granted		49,750		$	8.20
Exercised		-		$	-
Cancelled/forfeited		(3,605	)	$	392.80
Outstanding as of April 30, 2019		65,572		$	21.08		8.9
Exercisable as of April 30, 2019		17,822		$	55.60		7.1

Schedule of Non-vested Restricted Stock Activity

A summary of unvested restricted stock under the plans described above is as follows:

				Weighted
	Number			Average Price per
	of Shares			Share

Issued and unvested at April 30, 2018		9,854		$	27.00
Granted		943		$	22.80
Vested		(258	)	$	64.40
Cancelled/forfeited		(6,033	)	$	22.51
Issued and unvested at April 30, 2019		4,506		$	30.08

Fair Value Measurements (Tables)

12 Months Ended

Apr. 30, 2019

Fair Value Disclosures [Abstract]

Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis

The following table presents financial assets and liabilities measured at fair value on a recurring basis as of April 30, 2019:

	Total Carrying Value in Consolidated Balance Sheet		Quoted prices in active markets for identical assets or liabilities (Level 1)		Significant other observable inputs (Level 2)		Significant unobservable inputs (Level 3)
	(in thousands)

Warrant liabilities	$	6	$	-	$	-	$	6

The following table presents financial assets and liabilities measured at fair value on a recurring basis as of April 30, 2018:

	Total Carrying Value in Consolidated Balance Sheet		Quoted prices in active markets for identical assets or liabilities (Level 1)		Significant other observable inputs (Level 2)		Significant unobservable inputs (Level 3)
	(in thousands)

Warrant liabilities	$	201	$	-	$	-	$	201

Summary of Changes on Value of Warrant Liability Using Significant Unobservable Inputs

The following table provides a summary of changes in the fair value of the warrant liabilities during the year ended April 30, 2019;

Fair Value Measurement Using Significant Unobservable Inputs (Level 3)

	Total
	Warrant
	Liability
		(in thousands)

Fair value – April 30, 2017	$	323
Issuance		-
Transfers		-
Change in fair value		(122	)
Fair value – April 30, 2018	$	201

Change in fair value		(195	)
Fair value – April 30, 2019	$	6

Income Taxes (Tables)

12 Months Ended

Apr. 30, 2019

Income Tax Disclosure [Abstract]

Schedule of Components of Loss Before Income Taxes

Loss before income taxes for the years ended April 30, 2019 and 2018 consisted of the following components:

	April 30, 2019			April 30, 2018
	(in thousands)

Domestic	$	(12,860	)	$	(11,004	)
Foreign		(236	)		(272	)
Total loss before income taxes	$	(13,096	)	$	(11,276	)

Schedule of Effective Income Tax Rate Reconciliation

	April 30, 2019			April 30, 2018

Computed expected tax (benefit)		-21.0	%		-29.7	%
Increase(reduction) in income taxes resulting from:
State income taxes, net of federal (benefit)		0.8	%		3.0	%
Federal research and development tax credits		-1.5	%		-1.5	%
Foreign rate differential		0.2	%		0.3	%
Other non-deductible expenses		0.1	%		0.4	%
Proceeds of sale of New Jersey tax (benefits)		-6.5	%		-9.9	%
U.S. tax reform effects		0.0	%		162.2	%
Other		0.6	%		5.1	%
Increase in valuation allowance		20.8	%		-139.4	%
Income tax (benefit)		-6.5	%		-9.5	%

Schedule of Deferred Tax Assets and Liabilities

The tax effects of temporary differences and carry forwards that give rise to the Company’s deferred tax assets and deferred tax liabilities are presented below.

	April 30, 2019			April 30, 2018
	(in thousands)

Deferred tax assets:
Federal net operating loss carryforwards	$	32,025		$	29,329
Foreign net operating loss carryforwards		3,641			3,852
State operating loss carryforwards		1,653			1,460
Federal and New Jersey research and development tax credits		3,315			3,143
Stock compensation		486			645
Unrealized foreign exchange loss		5			12
Accrued expenses		145			487
Other		438			330
Net deferred tax assets before valuation allowance		41,708			39,258
Valuation allowance		(41,708	)		(39,258	)
Net deferred tax assets	$	-		$	-

Commitments and Contingencies (Tables)

12 Months Ended

Apr. 30, 2019

Commitments and Contingencies Disclosure [Abstract]

Schedule of Future Minimum Payments for Operating Leases

Future minimum lease payments under operating leases as of April 30, 2019 are as follows:

	April 30, 2019
		(in thousands)

2020		322
2021		331
2022		341
2023		352
2024		362
Thereafter		184
	$	1,892

Operating Segments and Geographic Information (Tables)

12 Months Ended

Apr. 30, 2019

Segment Reporting [Abstract]

Schedule of Revenue from External Customers and Long-Lived Assets, by Geographical Areas

Geographic information is as follows:

	Year Ended April 30, 2019
	North						Asia and
	America			Europe			Australia			Total
	(in thousands)

Revenues from external customers	$	632		$	-		$	-		$	632
Operating loss		(13,045	)		(204	)		(22	)		(13,271	)
Long-lived assets		592			-			-			592
Total assets		18,028			49			289			18,366

	Year Ended April 30, 2018
	North						Asia and
	America			Europe			Australia			Total
	(in thousands)

Revenues from external customers	$	511		$	-		$	-		$	511
Operating loss		(11,282	)		(243	)		(35	)		(11,560	)
Long-lived assets		712			-			-			712
Total assets		13,762			22			337			14,121

Adoption of Revenue Recognition Guidance (Tables)

12 Months Ended

Apr. 30, 2019

Accounting Changes and Error Corrections [Abstract]

Schedule of Condensed Consolidated Financial Statements

	Twelve months ended April 30, 2019
							Amounts Excluding
	As Reported			Effect of Adoption			Effect of Adoption

Revenues	$	632		$	(118	)	$	750
Operating loss		(13,271	)		(118	)		(13,153	)
Net loss	$	(12,246	)	$	(118	)	$	(12,128	)
Basic and diluted net loss per share	$	(9.52	)	$	(0.09	)	$	(9.43	)
Weighted average shares used to compute basic and diluted net loss per share		1,286,727			1,286,727			1,286,727

	Twelve months ended April 30, 2019
							Amounts Excluding
	As Reported			Effect of Adoption			Effect of Adoption

Net loss	$	(12,246	)	$	(118	)	$	(12,128	)
Foreign currency translation adjustment		(11	)		-			(11	)
Total comprehensive loss	$	(12,257	)	$	(118	)	$	(12,139	)

The following tables present how the adoption of the new revenue recognition standard affected certain line items in the Company’s consolidated balance sheet as of April 30, 2019.

	As of April 30, 2019
							Amounts Excluding
	As Reported			Effect of Adoption			Effect of Adoption

ASSETS
Contract assets	$	15		$	(70	)	$	85
Total assets	$	18,366		$	(70	)	$	18,436

LIABILITIES AND STOCKHOLDERS’ EQUITY
Contract liability	$	188		$	48		$	140
Accumulated deficit		(209,784	)		(118	)		(209,666	)
Total stockholders’ equity	$	15,775		$	(70	)	$	15,845
Total liabilities and stockholders’ equity	$	18,366		$	(70	)	$	18,436

	Twelve months ended April 30, 2019
							Amounts Excluding
	As Reported			Effect of Adoption			Effect of Adoption

Net loss	$	(12,246	)	$	(118	)	$	(12,128	)
Contract assets		(15	)		70			(85	)
Contract liability		188			48			140
Net cash used in operating activities	$	(12,140	)	$	-		$	(12,140	)
Net increase in cash, cash equivalents and restricted cash	$	4,934		$	-		$	4,934
Cash, cash equivalents and restricted cash, end of period	$	17,159		$	-		$	17,159

Background and Liquidity (Details Narrative)									12 Months Ended
Background and Liquidity (Details Narrative)	Apr. 08, 2019 USD ($) $ / shares shares	Jan. 07, 2019 USD ($)	Aug. 13, 2018 USD ($) shares	Oct. 23, 2017 USD ($) $ / shares shares	May 02, 2017 USD ($) $ / shares shares	Oct. 19, 2016 USD ($) $ / shares shares	Jul. 22, 2016 USD ($) $ / shares shares	Jun. 02, 2016 USD ($) $ / shares shares	Apr. 30, 2019 USD ($) Integer $ / shares shares	Apr. 30, 2018 USD ($)
Accumulated deficit \| $									$ 209,784,000	$ 197,538,000
Cash, cash equivalents and restricted cash, at carrying value \| $									17,159,000	12,225,000
Revenues \| $									$ 632,000	$ 511,000
Number of financing agreements closed \| Integer									5
Number of common stock shares sold \| shares	1,542,000			286,972	309,638	138,000
Warrant to purchase shares common stock \| shares	4,927,680
Combined purchase price per share \| $ / shares				$ 28.40	$ 26.00	$ 55.00
Proceeds from issuance or sale of equity, net of issuance costs \| $				$ 7,400,000	$ 7,200,000	$ 6,900,000
Aggregate offering price \| $	$ 15,700,000
Over-Allotment Option [Member]
Number of common stock shares sold \| shares	642,000				40,388
Common Shares [Member]
Number of common stock shares sold \| shares						18,000
Pre-funded Warrants [Member]
Warrant to purchase shares common stock \| shares	3,385,680
Securities Purchase Agreement [Member]
Number of common stock shares sold \| shares								20,850
Warrant to purchase shares common stock \| shares	4,927,680							7,298	4,927,680
Class of warrant or right, number of securities called by each warrant or right \| shares								0.35
Combined purchase price per share \| $ / shares								$ 92.00
Proceeds from issuance or sale of equity, net of issuance costs \| $								$ 1,700,000
Class of warrant or right, exercise price of warrants or rights \| $ / shares	$ 3.85							$ 121.60	$ 3.85
Class of warrant or right, expiration period								5 years
Securities Purchase Agreement [Member] \| Pre-funded Warrants [Member]
Warrant to purchase shares common stock \| shares	3,385,680
Class of warrant or right, exercise price of warrants or rights \| $ / shares	$ 0.01
Securities Purchase Agreement [Member] \| Placement Agents [Member] \| Placement Agent Fees [Member]
Payments of stock issuance costs \| $								$ 100,000
Securities Purchase Agreement [Member] \| Placement Agents [Member] \| Pocket and Legal Expenses [Member]
Payments of stock issuance costs \| $								$ 35,000
Second Amended Purchase Agreement [Member]
Number of common stock shares sold \| shares							29,750
Warrant to purchase shares common stock \| shares							8,925
Class of warrant or right, number of securities called by each warrant or right \| shares							0.30
Combined purchase price per share \| $ / shares							$ 135.00
Proceeds from issuance or sale of equity, net of issuance costs \| $							$ 3,600,000
Class of warrant or right, exercise price of warrants or rights \| $ / shares							$ 187.20
Stock Purchase Agreement [Member] \| Aspire Capital Fund, LLC [Member]
Number of common stock shares sold \| shares									162,162
Combined purchase price per share \| $ / shares									$ 5.85
Proceeds from issuance or sale of equity, net of issuance costs \| $									$ 949,259
Aggregate purchase of common stock \| $			$ 10,000,000
Common stock issued for commitment fee \| shares			21,429
Stock Purchase Agreement [Member] \| Aspire Capital Fund, LLC [Member] \| Maximum [Member]
Percentage of outstanding common stock			19.99%
2019 ATM Facility [Member]
Proceeds from issuance or sale of equity, net of issuance costs \| $	$ 882,000
2019 ATM Facility [Member] \| Alliance Global Partners [Member]
Number of common stock shares sold \| shares									151,561
Combined purchase price per share \| $ / shares									$ 6.32
Proceeds from issuance or sale of equity, net of issuance costs \| $									$ 958,229
Aggregate offering price \| $		$ 25,000,000
Payment of sales commission \| $									$ 33,469

Summary of Significant Accounting Policies (Details Narrative)		12 Months Ended
	Mar. 31, 2017 USD ($) ft²	Apr. 30, 2019 USD ($) $ / shares shares	Apr. 30, 2018 USD ($) $ / shares shares	Apr. 30, 2019 EUR (€)
Revenue remaining performance obligation		$ 900,000
Revenue remaining performance obligation, percentage		81.00%
Performance obligation revenue of next twelve months		$ 700,000
Additional performance obligation revenue of next twelve months		19.00%
Marketable securities			$ 25,000
Antidilutive securities excluded from computation of earnings per share, shares \| shares		5,013,981	45,503
Share-based compensation expense		$ 300,000	$ 300,000
Fair value of weighted average price per shares \| $ / shares		$ 7.15	$ 23.40
Share based compensation restricted stock granted \| shares		943
Monore Township [Member]
Term of lease	7 years
Area of land \| ft²	56,000
Tenant improvement work	$ 137,563
Minimum [Member]
Concentration risk percentage		10.00%
Right-of-use asset		$ 1,000,000
Right-of-use lease liability		1,000,000
Maximum [Member]
Right-of-use asset		2,000,000
Right-of-use lease liability		2,000,000
One Agreement [Member] \| Barclays Bank [Member]
Long-term line of credit		$ 300,000
Line of credit facility, commitment fee percentage		1.00%
Letters of credit outstanding, amount		$ 300,000
One Agreement [Member] \| Barclays Bank [Member] \| Euro [Member]
Long-term line of credit \| €				€ 300,000
Letters of credit outstanding, amount \| €				€ 300,000

Summary of Significant Accounting Policies - Schedule of Cash and Cash Equivalents (Details) - USD ($) $ in Thousands	Apr. 30, 2019	Apr. 30, 2018
Cash and cash equivalents	$ 16,660	$ 11,499
Checking and Savings Accounts [Member]
Cash and cash equivalents	860	1,332
Money Market Account [Member]
Cash and cash equivalents	$ 15,800	$ 10,167

Summary of Significant Accounting Policies - Schedule of Cash and Cash Equivalents and Restricted Cash (Details) - USD ($)	Apr. 30, 2019	Apr. 30, 2018
Restricted Cash	$ 499,000	$ 726,000
Cash and Cash Equivalents	16,660,000	11,499,000
Restricted cash- short term	344,000	572,000
Restricted cash- long term	155,000	154,000
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	17,159,000	12,225,000
Barclay's Bank Agreement [Member]
Restricted Cash	344,000	372,000
Santander Bank [Member]
Restricted Cash	$ 155,000	$ 354,000

Summary of Significant Accounting Policies - Schedule of Property, Plant and Equipment, Useful Life (Details)	12 Months Ended
	Apr. 30, 2019
Equipment [Member] \| Minimum [Member]
Property and equipment, useful life (Year)	5 years
Equipment [Member] \| Maximum [Member]
Property and equipment, useful life (Year)	7 years
Computer Equipment & Software [Member]
Property and equipment, useful life (Year)	3 years
Office Furniture & Fixtures [Member] \| Minimum [Member]
Property and equipment, useful life (Year)	3 years
Office Furniture & Fixtures [Member] \| Maximum [Member]
Property and equipment, useful life (Year)	7 years
Equipment Under Capitalized Lease [Member]
Property and equipment, useful life	Over the life of the lease
Leasehold Improvements [Member]
Property and equipment, useful life	Shorter of the estimated useful life or lease term

Summary of Significant Accounting Policies - Schedule of Revenue by Major Customers by Reporting Segments (Details) - Sales Revenue, Net [Member] - Customer Concentration Risk [Member]	12 Months Ended
	Apr. 30, 2019	Apr. 30, 2018
Revenues, percentage	100.00%	100.00%
Eni S.p.A [Member]
Revenues, percentage	54.00%	33.00%
Mitsui Engineering & Shipbuilding [Member]
Revenues, percentage	0.00%	43.00%
Premier Oil UK Limited [Member]
Revenues, percentage	33.00%	10.00%
Office of Naval Research [Member]
Revenues, percentage	0.00%	14.00%
Other [Member]
Revenues, percentage	13.00%	0.00%

Summary of Significant Accounting Policies - Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs (Details) - USD ($) $ in Thousands	12 Months Ended
	Apr. 30, 2019	Apr. 30, 2018
Total share-based compensation expense	$ 295	$ 329
Product Development [Member]
Total share-based compensation expense	29	24
Selling, General and Administrative [Member]
Total share-based compensation expense	$ 266	$ 305

Summary of Significant Accounting Policies - Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions (Details)	12 Months Ended
	Apr. 30, 2019	Apr. 30, 2018
Accounting Policies [Abstract]
Risk-free interest rate	2.70%	2.10%
Expected dividend yield	0.00%	0.00%
Expected life (in years)	5 years 6 months	5 years 6 months
Expected volatility	126.40%	128.20%

Account Receivable, Contract Assets, and Contract Liabilities (Details Narrative) - USD ($) $ in Thousands	12 Months Ended
	Apr. 30, 2019	May 02, 2018	Apr. 30, 2018
Account Receivable Contract Assets And Contract Liabilities
Contract assets	$ 15	$ 71
Contract liabilities	188	$ 18
Revenue recognized	18
Revenue related to performance obligations	$ 145

Account Receivable, Contract Assets, and Contract Liabilities - Schedule of Accounts Receivable (Details) - USD ($) $ in Thousands	12 Months Ended
	Apr. 30, 2019	Apr. 30, 2018
Account Receivable Contract Assets And Contract Liabilities
Opening balance	$ 171	$ 48
Amount invoiced to customer	857	754
Collections	(965)	(631)
Ending balance	$ 63	$ 171

Account Receivable, Contract Assets, and Contract Liabilities - Schedule of Contract Assets and Contract Liabilities (Details) - USD ($) $ in Thousands	Apr. 30, 2019	May 02, 2018
Account Receivable Contract Assets And Contract Liabilities
Contract assets	$ 15	$ 71
Contract liabilities	(188)	$ (18)
Contract (liability)/assets, net	$ (173)

Property and Equipment (Details Narrative) - USD ($) $ in Thousands	12 Months Ended
	Apr. 30, 2019	Apr. 30, 2018
Depreciation	$ 200	$ 100
Capital lease, term	36 months	36 months
Computer Equipment & Software [Member]
Capital leased assets, gross	$ 103	$ 103

Property and Equipment - Schedule of Components of Property and Equipment (Details) - USD ($) $ in Thousands	Apr. 30, 2019	Apr. 30, 2018
Property and equipment, gross	$ 1,830	$ 1,922
Less: accumulated depreciation	(1,238)	(1,210)
Property and equipment, net	592	712
Equipment [Member]
Property and equipment, gross	339	394
Computer Equipment & Software [Member]
Property and equipment, gross	558	614
Office Furniture & Equipment [Member]
Property and equipment, gross	341	338
Leasehold Improvements [Member]
Property and equipment, gross	474	473
Equipment Under Capitalized Lease [Member]
Property and equipment, gross	103	103
Construction in Process [Member]
Property and equipment, gross	$ 15	$ 0

Accrued Expenses - Schedule of Accrued Expenses (Details) - USD ($) $ in Thousands	Apr. 30, 2019	Apr. 30, 2018
Payables and Accruals [Abstract]
Project costs	$ 9	$ 57
Contract loss reserve	211	395
Employee incentive payments	580	761
Accrued salary and benefits	500	442
Legal and accounting fees	273	246
Accrued taxes payable	177	179
Other	188	181
Accrued expenses total	$ 1,938	$ 2,261

Deferred Credits Payable (Details Narrative) $ in Thousands	Aug. 31, 2018 USD ($)	Apr. 30, 2001 USD ($) t
Compensation Related Costs [Abstract]
Customer advances or deposits, noncurrent		$ 600
Deferred credits payable option details \| t		500,000
Deferred credits payable market discount rate		30.00%
Deferred credits payable market liquidated damages rate		30.00%
Option fee amount	$ 600	$ 600

Warrants (Details Narrative) - USD ($) $ / shares in Units, $ in Thousands				12 Months Ended
	Apr. 08, 2019	Jul. 22, 2016	Jun. 02, 2016	Apr. 30, 2019	Apr. 30, 2018
Warrant to purchase shares common stock	4,927,680
Warrant liabilities				$ 6	$ 201
Unrealized gain on warrants				$ 200	$ 100
Pre-funded Warrants [Member]
Warrant to purchase shares common stock	3,385,680
Securities Purchase Agreement [Member]
Number of common stock shares sold	1,542,000		20,850
Warrant to purchase shares common stock	4,927,680		7,298	4,927,680
Class of warrant or right, number of securities called by each warrant or right			0.35
Combined purchase price per share			$ 92.00
Warrant exercise price per share	$ 3.85		$ 121.60	$ 3.85
Class of warrant or right, expiration period	5 years		5 years	5 years
Securities Purchase Agreement [Member] \| Pre-funded Warrants [Member]
Warrant to purchase shares common stock	3,385,680
Warrant exercise price per share	$ 0.01
Unexercised warrants				753,560
Second Amended Purchase Agreement [Member]
Number of common stock shares sold		29,750
Warrant to purchase shares common stock		8,925
Class of warrant or right, number of securities called by each warrant or right		0.30
Combined purchase price per share		$ 135.00
Warrant exercise price per share		$ 187.20
Class of warrant or right, expiration period		5 years

Warrants - Schedule of Fair Value Assumptions Used (Details) - Warrant [Member]	Apr. 30, 2019	Apr. 30, 2018
Dividend Rate [Member]
Fair value measurement percent	0.000	0.000
Risk Free Interest Rate [Member] \| Minimum [Member]
Fair value measurement percent	0.022	0.027
Risk Free Interest Rate [Member] \| Maximum [Member]
Fair value measurement percent	0.023	0.028
Expected Life (Years) [Member] \| Minimum [Member]
Fair value measurement expected life	2 years 2 months 12 days	3 years 2 months 12 days
Expected Life (Years) [Member] \| Maximum [Member]
Fair value measurement expected life	2 years 7 months 6 days	3 years 7 months 6 days
Expected Volatility [Member] \| Minimum [Member]
Fair value measurement percent	1.100	1.329
Expected Volatility [Member] \| Maximum [Member]
Fair value measurement percent	1.534	1.427

Preferred Stock (Details Narrative) - $ / shares	Apr. 30, 2019	Apr. 30, 2018
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares issued
Undesignated Preferred Stock [Member]
Preferred stock, shares authorized	5,000,000
Preferred stock, par value	$ 0.001

Common Stock (Details Narrative) - USD ($)							12 Months Ended
Common Stock (Details Narrative) - USD ($)	Apr. 08, 2019	Jan. 07, 2019	Aug. 13, 2018	Oct. 23, 2017	May 02, 2017	Oct. 19, 2016	Apr. 30, 2019	Apr. 30, 2018
Common stock, shares authorized							100,000,000	100,000,000
Common stock, par value							$ 0.001	$ 0.001
Common stock, shares issued							5,425,517	921,247
Number of common stock shares sold	1,542,000			286,972	309,638	138,000
Sale of stock, price per share				$ 28.40	$ 26.00	$ 55.00
Value of common stock shares sold, net of issuance costs				$ 7,400,000	$ 7,200,000	$ 6,900,000
Aggregate offering price	$ 15,700,000
Warrant to purchase shares common stock	4,927,680
Pre-funded Warrants [Member]
Warrant to purchase shares common stock	3,385,680
Stock Purchase Agreement [Member] \| Aspire Capital Fund, LLC [Member]
Number of common stock shares sold							162,162
Sale of stock, price per share							$ 5.85
Value of common stock shares sold, net of issuance costs							$ 949,259
Aggregate purchase of common stock			$ 10,000,000
Common stock issued for commitment fee			21,429
Stock Purchase Agreement [Member] \| Aspire Capital Fund, LLC [Member] \| Maximum [Member]
Percentage of outstanding common stock limit for shareholder approval			19.99%
2019 ATM Facility [Member]
Value of common stock shares sold, net of issuance costs	$ 882,000
2019 ATM Facility [Member] \| Alliance Global Partners [Member]
Number of common stock shares sold							151,561
Sale of stock, price per share							$ 6.32
Value of common stock shares sold, net of issuance costs							$ 958,229
Aggregate offering price		$ 25,000,000
Payment of sales commission							$ 33,469
Over-Allotment Option [Member]
Number of common stock shares sold	642,000				40,388

Treasury Shares (Details Narrative) - shares	12 Months Ended
Treasury Shares (Details Narrative) - shares	Apr. 30, 2019	Apr. 30, 2018
Equity [Abstract]
Treasury stock, shares, acquired	89	1,298

Share-Based Compensation Plans (Details Narrative) - USD ($)	12 Months Ended
	Apr. 30, 2019	Apr. 30, 2018	Jan. 18, 2018	Oct. 21, 2016	Dec. 31, 2015
Share-based compensation expense	$ 300,000	$ 300,000
Employee Stock Option [Member]
Number of shares outstanding during period	65,572	19,427
Share-based compensation intrinsic value of outstanding	$ 0
Share-based compensation options, exercisable intrinsic value	$ 0
Share-based compensation unvested shares of stock options	42,343
Share-based compensation weighted average remaining contractual term	9 years 7 months 6 days
Share-based compensation expense	$ 200,000	$ 200,000
Unrecognized compensation cost related to non-vested stock options	$ 200,000
Share-based compensation cost expected to recognize weighted-average term	7 months 6 days
Restricted Stock [Member]
Share-based compensation expense	$ 100,000	$ 100,000
Share-based compensation cost expected to recognize weighted-average term	3 months 19 days
Number of restricted shares granted	943
Unrecognized compensation cost related to unvested restricted stock	$ 9,000
2015 Omnibus Incentive Plan [Member]
Share-based compensation arrangement by share-based payment award, number of shares authorized				32,036	12,036
Stock based compensation shares, available for grant	58,555
Maximum number of shares that can be granted to participant in calendar year	3,750
2018 Inducement Plan [Member]
Stock based compensation shares, available for grant	25,000		25,000
Number of shares outstanding during period

Share-Based Compensation Plans - Schedule of Stock Option Activity (Details) - $ / shares	12 Months Ended
	Apr. 30, 2019	Apr. 30, 2018
Weighted Average Exercise Price, Granted	$ 7.15	$ 23.40
Employee Stock Option [Member]
Shares Underlying Options Outstanding, Beginning	19,427
Shares Underlying Options Outstanding, Granted	49,750
Shares Underlying Options Outstanding, Exercised
Shares Underlying Options Outstanding, Cancelled/forfeited	(3,605)
Shares Underlying Options Outstanding, Ending	65,572	19,427
Shares Underlying Options Outstanding, Exercisable at Ending	17,822
Weighted Average Exercise Price, Beginning Balance	$ 123.00
Weighted Average Exercise Price, Granted	8.20
Weighted Average Exercise Price, Exercised
Weighted Average Exercise Price, Cancelled/forfeited	392.80
Weighted Average Exercise Price, Ending Balance	21.08	$ 123.00
Weighted Average Exercise Price, Exercisable at Ending	$ 55.60
Weighted Average Remaining Contractual Term (In Years), Beginning	7 years 4 months 24 days
Weighted Average Remaining Contractual Term (In Years), Ending	8 years 10 months 25 days
Weighted Average Remaining Contractual Term (In Years), Exercisable at Ending	7 years 1 month 6 days

Share-Based Compensation Plans - Schedule of Non-vested Restricted Stock Activity (Details)	12 Months Ended
	Apr. 30, 2019 $ / shares shares
Number of Shares, Granted	943
Non-Vested Restricted Stock [Member]
Number of Shares, Issued and unvested, Beginning	9,854
Number of Shares, Granted	943
Number of Shares, Vested	(258)
Number of Shares, Cancelled/forfeited	(6,033)
Number of Shares, Issued and Unvested, Ending	4,506
Weighted Average Price per Share, Issued and Unvested, Beginning \| $ / shares	$ 27.00
Weighted Average Price per Share, Granted \| $ / shares	22.80
Weighted Average Price per Share, Vested \| $ / shares	64.40
Weighted Average Price per Share, Cancelled/forfeited \| $ / shares	22.51
Weighted Average Price per Share, Issued and Unvested, Ending \| $ / shares	$ 30.08

Fair Value Measurements - Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis (Details) - USD ($) $ in Thousands	Apr. 30, 2019	Apr. 30, 2018
Warrant liabilities	$ 6	$ 201
Fair Value, Measurements, Recurring [Member]
Warrant liabilities	6	201
Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member]
Warrant liabilities
Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member]
Warrant liabilities
Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member]
Warrant liabilities	$ 6	$ 201

Fair Value Measurements - Summary of Changes on Value of Warrant Liability Using Significant Unobservable Inputs (Details) - Warrant Liability [Member] - USD ($) $ in Thousands	12 Months Ended
	Apr. 30, 2019	Apr. 30, 2018
Fair value, beginning	$ 201	$ 323
Issuance
Transfers
Change in fair value	(195)	(122)
Fair value, ending	$ 6	$ 201

Income Taxes (Details Narrative) - USD ($) $ in Thousands	12 Months Ended
Income Taxes (Details Narrative) - USD ($) $ in Thousands	Apr. 30, 2019	Apr. 30, 2018
Income tax (expense) benefit	$ 850	$ 1,119
Deferred tax assets, valuation allowance	41,708	39,258
Valuation allowance, deferred tax asset, increase (decrease), amount	2,500	15,400
Operating loss carryforwards	152,500
Deferred tax assets, tax credit carryforwards, research and development	$ 3,315	3,143
Income tax description	Begins to expire in 2019
Operating loss carryforwards, limitation	$ 3,300
Foreign net operating loss carry forwards	16,900
State and Local Jurisdiction [Member]
Operating loss carryforwards	$ 23,300
Income tax description	Begin to expire in 2037
Foreign Tax Authority [Member]
Operating loss carryforwards	$ 16,900
New Jersey Division of Taxation [Member]
Income tax (expense) benefit	(900)	(1,100)
Proceed from sale of loss carryforwards and tax credits	$ 9,100	$ 11,500

Income Taxes - Schedule of Components of Loss Before Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Apr. 30, 2019	Apr. 30, 2018
Income Tax Disclosure [Abstract]
Domestic	$ (12,860)	$ (11,004)
Foreign	(236)	(272)
Total loss before income taxes	$ (13,096)	$ (11,276)

Income Taxes - Schedule of Effective Income Tax Rate Reconciliation (Details)	12 Months Ended
	Apr. 30, 2019	Apr. 30, 2018
Income Tax Disclosure [Abstract]
Computed expected tax (benefit)	(21.00%)	(29.70%)
State income taxes, net of federal (benefit)	0.80%	3.00%
Federal research and development tax credits	(1.50%)	(1.50%)
Foreign rate differential	0.20%	0.30%
Other non-deductible expenses	0.10%	0.40%
Proceeds of sale of New Jersey tax (benefits)	(6.50%)	(9.90%)
U.S. tax reform effects	0.00%	162.20%
Other	0.60%	5.10%
Increase in valuation allowance	20.80%	(139.40%)
Income tax (benefit)	(6.50%)	(9.50%)

Income Taxes - Schedule of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Apr. 30, 2019	Apr. 30, 2018
Income Tax Disclosure [Abstract]
Federal net operating loss carryforwards	$ 32,025	$ 29,329
Foreign net operating loss carryforwards	3,641	3,852
State operating loss carryforwards	1,653	1,460
Federal and New Jersey research and development tax credits	3,315	3,143
Stock compensation	486	645
Unrealized foreign exchange loss	5	12
Accrued expenses	145	487
Other	438	330
Net deferred tax assets before valuation allowance	41,708	39,258
Valuation allowance	(41,708)	(39,258)
Net deferred tax assets

Commitments and Contingencies (Details Narrative) - USD ($)									12 Months Ended
	May 02, 2019	Feb. 22, 2019	Aug. 28, 2018	Aug. 09, 2018	Jul. 27, 2018	Jun. 13, 2018	May 03, 2018	Oct. 23, 2017	Apr. 30, 2019	Apr. 30, 2018	Apr. 30, 2017
Lease expiration									Oct. 31, 2024
Lease term									7 years
Security deposit									$ 154,000
Operating leases, tenant improvement allowance, maximum									138,000
Operating leases, rent expense									500,000	$ 400,000
Litigation settlement, amount awarded to other party							$ 350,000
Loss Contingency Accrual										350,000
Loss contingency, receivable									350,000
Stock price per share				$ 1.00
Debt description				The Company's common stock had been below $1.00 per share for a period of 30 consecutive trading days, and as a result, the Company was not in compliance with the minimum bid price requirement for continued listing. Under the Nasdaq Listing Rules, the Company was provided with a grace period of 180 calendar days, or until February 5, 2019, 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 the grace period. If the Company did not regain compliance before February 5, 2019,
Selling, General and Administrative [Member] \| Tax Authority, Spain [Member]
Income tax examination, penalties and interest accrued									$ 177,000	$ 177,000	$ 132,000
Tide Runner Marine, Inc. [Member]
Damages sought value					$ 15,000	$ 2,825,130
Charles F. Dunleavy [Member]
Damages sought value			$ 5,000,000
Wittich [Member] \| Settlement [Member]
Litigation settlement, amount awarded to other party	$ 150,000	$ 50,000
Stipulation [Member]
Litigation settlement, amount awarded to other party								$ 350,000

Commitments and Contingencies - Schedule of Future Minimum Payments for Operating Leases (Details) $ in Thousands	Apr. 30, 2019 USD ($)
Commitments and Contingencies Disclosure [Abstract]
2020	$ 322
2021	331
2022	341
2023	352
2024	362
Thereafter	184
Total	$ 1,892

Operating Segments and Geographic Information (Details Narrative)	12 Months Ended
	Apr. 30, 2019 segments
Segment Reporting [Abstract]
Number of reportable segments	1

Operating Segments and Geographic Information - Schedule of Revenue from External Customers and Long-Lived Assets, by Geographical Areas (Details) - USD ($) $ in Thousands	12 Months Ended
	Apr. 30, 2019	Apr. 30, 2018
Revenues from external customers	$ 632	$ 511
Operating loss	(13,271)	(11,560)
Long-lived assets	592	712
Total assets	18,366	14,121
North America [Member]
Revenues from external customers	632	511
Operating loss	(13,045)	(11,282)
Long-lived assets	592	712
Total assets	18,028	13,762
Europe [Member]
Revenues from external customers
Operating loss	(204)	(243)
Long-lived assets
Total assets	49	22
Asia and Australia [Member]
Revenues from external customers
Operating loss	(22)	(35)
Long-lived assets
Total assets	$ 289	$ 337

Adoption of Revenue Recognition Guidance (Details Narrative) - USD ($) $ in Thousands	12 Months Ended
	Apr. 30, 2019	Apr. 30, 2018
Net loss	$ (12,246)	$ (10,157)
Effect of Adoption [Member]
Net loss	(118)
Increase in revenue remaining performance obligation	$ 118

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References + Details

Adoption of Revenue Recognition Guidance - Schedule of Condensed Consolidated Financial Statements (Details) - USD ($)	12 Months Ended
	Apr. 30, 2019	Apr. 30, 2018	May 02, 2018	Apr. 30, 2017
Revenues	$ 632,000	$ 511,000
Operating loss	(13,271,000)	(11,560,000)
Net loss	$ (12,246,000)	$ (10,157,000)
Basic and diluted net loss per share	$ (9.52)	$ (13.24)
Weighted average shares used to compute basic and diluted net loss per share	1,286,727	767,330
Foreign currency translation adjustment	$ (11,000)
Total comprehensive loss	(12,257,000)	(10,157,000)
Contract assets	15,000		$ 71,000
Total assets	18,366,000	14,121,000
Contract liability	188,000		$ 18,000
Accumulated deficit	(209,784,000)	(197,538,000)
Stockholders' equity	15,775,000	10,236,000		$ 5,447,000
Total liabilities and stockholders' equity	18,366,000	14,121,000
Contract assets	(15,000)
Contract liability	188,000
Net cash used in operating activities	(12,140,000)	(10,696,000)
Net increase in cash, cash equivalents and restricted cash	4,934,000	$ 3,316,000
Cash, cash equivalents and restricted cash, end of period	17,159,000
Effect of Adoption [Member]
Revenues	(118,000)
Operating loss	(118,000)
Net loss	$ (118,000)
Basic and diluted net loss per share	$ (0.09)
Weighted average shares used to compute basic and diluted net loss per share	1,286,727
Foreign currency translation adjustment
Total comprehensive loss	(118,000)
Contract assets	(70,000)
Total assets	(70,000)
Contract liability	48,000
Accumulated deficit	(118,000)
Stockholders' equity	(70,000)
Total liabilities and stockholders' equity	(70,000)
Contract assets	70,000
Contract liability	48,000
Net cash used in operating activities
Net increase in cash, cash equivalents and restricted cash
Cash, cash equivalents and restricted cash, end of period
Amounts Excluding Effect of Adoption [Member]
Revenues	750,000
Operating loss	(13,153,000)
Net loss	$ (12,128,000)
Basic and diluted net loss per share	$ (9.43)
Weighted average shares used to compute basic and diluted net loss per share	1,286,727
Foreign currency translation adjustment	$ (11,000)
Total comprehensive loss	(12,139,000)
Contract assets	85,000
Total assets	18,436,000
Contract liability	140,000
Accumulated deficit	(209,666,000)
Stockholders' equity	15,845,000
Total liabilities and stockholders' equity	18,436,000
Contract assets	(85,000)
Contract liability	140,000
Net cash used in operating activities	(12,140,000)
Net increase in cash, cash equivalents and restricted cash	4,934,000
Cash, cash equivalents and restricted cash, end of period	$ 17,159,000