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Document And Entity Information - USD ($) $ in Millions	12 Months Ended
Document And Entity Information - USD ($) $ in Millions	Apr. 30, 2017	Jul. 10, 2017	Oct. 31, 2016
Document Information [Line Items]
Entity Registrant Name	Ocean Power Technologies, Inc.
Entity Central Index Key	0001378140
Trading Symbol	optt
Current Fiscal Year End Date	--04-30
Entity Filer Category	Smaller Reporting Company
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Well-known Seasoned Issuer	No
Entity Common Stock, Shares Outstanding (in shares)		12,573,265
Entity Public Float			$ 14.6
Document Type	10-K
Document Period End Date	Apr. 30, 2017
Document Fiscal Year Focus	2017
Document Fiscal Period Focus	FY
Amendment Flag	false

Consolidated Balance Sheets - USD ($) $ in Thousands	Apr. 30, 2017	Apr. 30, 2016
ASSETS
Cash and cash equivalents	$ 8,421	$ 6,730
Marketable securities	25	75
Restricted cash- short-term	334	300
Accounts Receivable	48
Unbilled receivables	296	37
Litigation receivable		2,500
Other current assets	622	117
Total current assets	9,746	9,759
Property and equipment, net	170	273
Restricted cash- long-term	154
Other noncurrent assets	3	319
Total assets	10,073	10,351
LIABILITIES AND STOCKHOLDERS' EQUITY
Accounts payable	586	373
Accrued expenses	3,059	2,675
Litigation payable		3,000
Unearned revenue		39
Warrant liabilities	323
Current portion of long-term debt and capital lease obligations	35	81
Deferred credits payable current	600
Total current liabilities	4,603	6,168
Long-term debt and capital lease obligations	23	55
Deferred credits payable non-current		600
Total liabilities	4,626	6,823
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 50,000,000 shares, issued 6,313,996 and 2,352,100 shares, respectively	6	2
Treasury stock, at cost; 48,065 and 6,894 shares, respectively	(263)	(138)
Additional paid-in capital	193,234	181,670
Accumulated deficit	(187,370)	(177,884)
Accumulated other comprehensive loss	(160)	(122)
Total stockholders' equity	5,447	3,528
Total liabilities and stockholders’ equity	$ 10,073	$ 10,351

Consolidated Balance Sheets (Parentheticals) - $ / shares	Apr. 30, 2017	Apr. 30, 2016
Preferred stock par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized (in shares)	5,000,000	5,000,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	50,000,000	50,000,000
Common stock, shares issued (in shares)	6,313,996	2,352,100
Treasury stock (in shares)	48,065	6,894

Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Apr. 30, 2017	Apr. 30, 2016
Revenues	$ 843	$ 705
Cost of revenues	938	668
Gross profit (loss)	(95)	37
Operating expenses:
Product development costs	5,029	7,051
Selling, general and administrative costs	6,563	6,747
Litigation settlement		1,097
Total operating expenses	11,592	14,895
Operating loss	(11,687)	(14,858)
Change in fair value of warrant liabilities	1,491	0
Interest income, net	28	8
Other income		241
Foreign exchange gain (loss)	(16)	(149)
Loss before income taxes	(10,184)	(14,758)
Income tax benefit	698	1,674
Net loss	(9,486)	(13,084)
Less: Net profit attributable to the non-controlling interest in Ocean Power Technologies (Australasia) Pty Ltd.		(45)
Net loss attributable to Ocean Power Technologies, Inc.	$ (9,486)	$ (13,129)
Basic and diluted net loss per share (in dollars per share)	$ (2.23)	$ (7.25)
Weighted average shares used to compute basic and diluted net loss per share (in shares)	4,259,172	1,810,173

Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Apr. 30, 2017	Apr. 30, 2016
Net loss	$ (9,486)	$ (13,084)
Foreign currency translation adjustment	(38)	135
Total comprehensive loss	(9,524)	(12,949)
Comprehensive income attributable to the non-controlling interest in Ocean Power Technologies (Australasia) Pty Ltd.		(73)
Comprehensive loss attributable to Ocean Power Technologies, Inc.	$ (9,524)	$ (13,022)

Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Common Stock [Member]	Treasury Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	AOCI Attributable to Parent [Member]	Parent [Member]	Noncontrolling Interest [Member]	Total
Balance (in shares) at Apr. 30, 2015	1,838,720	(3,865)
Balance at Apr. 30, 2015	$ 2	$ (132)	$ 180,803	$ (164,755)	$ (230)	$ 15,688	$ (427)	$ 15,261
Net loss				(13,129)		(13,129)	45	(13,084)
Stock based compensation			142			142		142
Issuance of restricted stock, net (in shares)	(11,191)
Issuance of restricted stock, net			194			194		194
Sale of stock (in shares)	144,571
Sale of stock			289			289		$ 289
Acquisition of treasury stock (in shares)		(3,029)						(3,029)
Acquisition of treasury stock		$ (6)				(6)		$ (6)
Additional investment in subsidiary			(354)			(354)	354
Legal settlement (in shares)	380,000
Legal settlement			596			596		596
Other comprehensive loss					108	108	28	136
Balance (in shares) at Apr. 30, 2016	2,352,100	(6,894)
Balance at Apr. 30, 2016	$ 2	$ (138)	181,670	(177,884)	(122)	3,528		3,528
Net loss				(9,486)		(9,486)		(9,486)
Stock based compensation			278			278		278
Issuance of restricted stock, net (in shares)	189,896
Issuance of restricted stock, net			954			954		954
Sale of stock (in shares)	3,772,000
Sale of stock	$ 4		10,332			10,336		$ 10,336
Acquisition of treasury stock (in shares)		(41,171)						(41,171)
Acquisition of treasury stock		$ (125)				(125)		$ (125)
Other comprehensive loss					(38)	(38)		(38)
Balance (in shares) at Apr. 30, 2017	6,313,996	(48,065)
Balance at Apr. 30, 2017	$ 6	$ (263)	$ 193,234	$ (187,370)	$ (160)	$ 5,447		$ 5,447

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Apr. 30, 2017	Apr. 30, 2016
Cash flows from operating activities:
Net loss	$ (9,486)	$ (13,084)
Adjustments to reconcile net loss to net cash used in operating activities:
Foreign exchange loss	16	149
Depreciation and amortization	140	112
Loss on disposal of property, plant and equipment		2
Compensation expense related to stock option grants and restricted stock	1,232	336
Change in fair value of warrant liabilities	(1,491)	0
Common Stock issuance in settlement of lawsuit		597
Changes in operating assets and liabilities:
Accounts receivable	(48)	103
Unbilled receivable	(258)	44
Other assets	(212)	75
Accounts payable	213	22
Accrued expenses	395	175
Litigation payable	(500)	500
Unearned revenues	(39)	39
Net cash used in operating activities	(10,038)	(10,930)
Cash flows from investing activities:
Maturities of marketable securities	50
Restricted cash	(189)	139
Purchases of equipment	(37)	(24)
Net cash (used in) provided by investing activities	(176)	115
Cash flows from financing activities:
Proceeds from issuance of common stock, net of costs		289
Proceeds from issuance of common stock and related warrants, net of costs	12,150
Payment of capital lease obligations	(28)	(63)
Payment of debt	(50)
Acquisition of treasury stock	(125)	(6)
Net cash provided by financing activities	11,947	220
Effect of exchange rate changes on cash and cash equivalents	(42)	(11)
Net increase (decrease) in cash and cash equivalents	1,691	(10,606)
Cash and cash equivalents, beginning of period	6,730	17,336
Cash and cash equivalents, end of period	8,421	6,730
Supplemental schedule of cash flows information:
Cash paid for interest	6
Supplemental disclosure of noncash investing activities:
Acquisition of equipment pursuant to capital leases	$ 4	$ 99

Note 1 - Background and Liquidity

12 Months Ended

Apr. 30, 2017

Notes to Financial Statements

Business Description and Basis of Presentation [Text Block]

(

)

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. The Company’s goal is that an increased portion of its revenues be from the sale or lease of products and maintenance services, as compared to revenue to support its product development efforts. As the Company continues to advance its proprietary technologies, it expects to continue to have a net decrease in cash from operating activities unless and until it achieves positive cash flow from the planned commercialization of its 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

$187.4

million at

April 30, 2017.

April 30, 2017,

the Company had approximately

$8.4

million in cash on hand. The Company generated revenues of only

$0.8

million and

$0.7

million during the years ended

April 30, 2017

and

2016,

respectively. Based on the Company’s cash and cash equivalents and marketable securities balances as of

April 30, 2017,

and including the proceeds received from our

May 2017

financing transaction in which we received aggregate net proceeds to us of approximately

$7.2

million, the Company believes that it will be able to finance its capital requirements and operations into the quarter ending

July 31, 2018.

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

assurance that any of these future-funding efforts will be successful.

In fiscal

2017

and

2016,

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

four

equity financing arrangements during the year ended

April 30, 2017

and subsequently on

May 2, 2017.

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, 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.

Historically, the Company has funded its operations principally through public and private sales of our equity. In

October 2015,

the Company entered into an At the Market Offering Agreement (

“2015

ATM Agreement”) with H.C. Wainwright & Co., LLC (“Manager”), under which the Company offered from time to time in an at the market offering (the

“2015

ATM Facility”) shares of our Common Stock under the Form S-

and under a subsequent shelf registration statement on Form S-

(the

“2016

Form S-

3”

) filed with the SEC in

February 2016

and declared effective by the SEC in

April 2016.

The

2016

Form S-

registers for sale up to

$15

million in securities by the Company in a public offering, although the Company is limited by Instruction

I.B.6

in the amount that we

may

sell under Form S-

in any

calendar month period to

one

third

of our public float. Under the

2015

ATM Facility, between

October 2015

and

April 2016,

the Company issued and sold

144,571

shares of its Common Stock with an aggregate market value of

$293,343

under the

2015

ATM Agreement at an average price of

$2.03

per share and paid the Manager of the

2015

ATM Facility a sales commission of approximately

$4,400

related to those shares. The

2015

ATM Agreement was terminated on

June 2, 2016,

effective immediately, and the

2015

ATM Facility is

longer available for use by the Company.

Form S-

limits the aggregate market value of securities that the Company is permitted to offer in any

-month period under its

2013

Form S-

Shelf, whether under the ATM Agreement, the Underwriting Agreement or otherwise, to

one

third

of its public float. In

2014,

the Company fully utilized its available transaction capacity to sell securities using the

2013

Form S-

Shelf in the ATM offering. However, the Company regained the ability to utilize the

2013

Form S-

Shelf as the Company entered fiscal

2016.

Under the SEC’s regulations, the securities registered under its

2013

Form S-

Shelf

may

only be offered and sold if

not

more than

three

years have elapsed from the initial effective date of the Form S-

except that if a new shelf registration statement is filed then the Company is permitted to continue to offer and sell securities under the Form S-

until the earlier of the effective date of the new shelf registration statement or

180

days after the

third

anniversary of the initial effective date.

February 12, 2016,

the Company filed a new Form S-

shelf registration statement (the

“2016

Form S-

3”

) to register the offering and sale of up to

$15

million in securities. The

2016

Form S-

registration was declared effective by the SEC on

April 26, 2016.

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

417,000

shares of Common Stock together with warrants to purchase up to an aggregate of

145,952

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

$4.60.

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

$6.08

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

$0.1

million as placement agent fees in connection with the sale of securities in the offering. The Company also reimbursed the placement agents

$35

thousand for their out of pocket and legal expenses in connection with the offering.

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

595,000

shares of Common Stock together with warrants to purchase up to an aggregate of

178,500

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

$6.75.

The net proceeds to the Company from the offering were approximately

$3.6

$9.36

per share. The Warrants will expire on the

fifth

(

5th

) anniversary of the initial date of issuance.

October 19, 2016,

the Company sold

2,760,000

shares of common stock at a price of

$2.75

per share, which includes the sale of

360,000

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 placement agent fees and offering expenses payable by the Company.

May 2, 2017,

the Company sold

6,192,750

shares of common stock at a price of

$1.30

per share, which includes the sale of

807,750

$7.2

million, after deducting placement agent 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.

Stock Split

At the annual meeting of stockholders on

October 22, 2015,

the Company’s stockholders approved a proposal to amend the Certificate of Incorporation of the Company to effect a reverse split of its Common Stock, at a ratio to be determined by the Company’s Board of Directors within a specific range and a reduction in the authorized number of shares of its Common Stock. See also the discussion in Part I, Item

“Legal Proceedings” of the accompanying Annual Report and Note

“Commitments and Contingencies- Shareholder Litigation and Demand” in these consolidated financial statements for the fiscal year ended

April 30, 2017.

October 27, 2015,

the Company filed a Certificate of Amendment to its Certificate of Incorporation to affect a

one

-for-

reverse stock split of its Common Stock and to decrease the number of authorized shares of its Common Stock to

50,000,000

shares (the “Reverse Stock Split”). As a result of the Reverse Stock Split, as of the effective date of the Reverse Stock Split, every

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.

fractional shares were issued in connection with the Reverse Stock Split. Total cash payments made by the Company to stockholders in lieu of fractional shares were

not

material. The Common Stock began trading on a reverse stock split-adjusted basis on the NASDAQ Stock Market (“NASDAQ”) on

October 29, 2015.

November 12, 2015,

NASDAQ notified the Company that it’s Common Stock had regained compliance with the NASDAQ listed company closing bid price requirement.

Note 2 - Summary of Significant Accounting Policies

12 Months Ended

Apr. 30, 2017

Notes to Financial Statements

Significant Accounting Policies [Text Block]

(

)

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. Participation of stockholders other than the Company in the net assets and in the earnings or losses of a consolidated subsidiary is reflected as a non-controlling interest in the Company's Consolidated Balance Sheets and Statements of Operations, which adjusts the Company's consolidated results of operations to reflect only the Company's share of the earnings or losses of the consolidated subsidiary

September 2015,

the Company re-purchased the non-controlling interest (consisting of

11.8%

) of the Company's Australian subsidiary, Ocean Power Technologies (Australasia) Pty. Ltd. (“OPTA”) for nominal consideration and now has

100%

ownership of OPTA. OPTA owns

100%

of Victorian Wave Partners Pty. Ltd. (“VWP”), which is also organized under the laws of Australia. As of

April 30, 2017

and

2016,

there were

such entities.

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, 2016,

there were

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 the recoverability of the carrying amount of property and equipment; fair value of warrant liabilities; valuation allowances for receivables and deferred income tax assets; 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

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.

Generally, revenue under fixed price or cost plus contracts is recognized using the cost to cost percentage-of-completion method, measured by the ratio of costs incurred to total estimated costs at completion. In certain circumstances, revenue under contracts that have specified milestones or other performance criteria

may

be recognized only when the customer acknowledges that such criteria have been satisfied. If an arrangement involves multiple deliverables, the delivered items are considered separate units of accounting if the items have value on a stand-alone basis. Amounts allocated to each element are based on its objectively determined fair value, such as the sales price for the product or service when it is sold separately or competitor prices for similar products or services.

In addition, recognition of revenue (and the related costs)

may

be deferred for fixed price contracts until contract completion if the Company is unable to reasonably estimate the total costs of the project prior to completion. These contracts are subject to interpretation and management

may

make a judgment as to the amount of revenue earned and recorded. Because the Company has a small number of contracts, revisions to the percentage-of-completion determination, management interpretation or delays in meeting performance and

contractual criteria or in completing projects

may

have a significant effect on revenue for the periods involved. Upon anticipating a loss on a contract, the Company recognizes the full amount of the anticipated loss in the current period.

Unbilled receivables represent expenditures on contracts, plus applicable profit margin,

not

yet billed. Unbilled receivables are normally billed and collected within

one

year. Billings made on contracts are recorded as a reduction of unbilled receivables, and to the extent that such billings and cash collections exceed costs incurred plus applicable profit margin, they are recorded as unearned revenues.

(d)	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 an overnight U.S. government securities repurchase bank account and a money market account. In accordance with the terms of the repurchase agreement, the Company does

not

take possession of the related securities. The agreement contains provisions to ensure that the market value of the underlying assets remain sufficient to protect the Company in the event of default by the bank by requiring that the underlying securities have a total market value of at least

100%

of the bank’s total obligations under the agreement. The following table summarizes cash and cash equivalents for the years ended

April 30, 2017

and

2016:

	April 30, 2017		April 30, 2016
	(in thousands)

Checking and savings accounts	$	4,241	$	4,535
Overnight repurchase account		4,180		2,195
	$	8,421	$	6,730

(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, 2017

and,

2016,

all of the Company’s investments were classified as held-to-maturity.

(f)	Restricted Cash and Credit Facility

As of

April 30, 2017

and

2016,

a portion of the Company’s cash was restricted under the terms of

three

security agreements.

One agreement was between the Company and Barclays Bank. Under this agreement, the cash was on deposit at Barclays Bank and served as security for letters of credit and bank guarantees that were 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

€0.3million

(

$0.3

million) and carries a fee of

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 both

April 30, 2017

and

2016,

there was

€0.3

million (

$0.3

million) in letters of credit outstanding under this agreement.

The

second

agreement is between the Company and Santander Bank. Under this 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,

but is cancelable at the discretion of the bank.

The

third

agreement was between the Company and the New Jersey Board of Public Utilities (“NJBPU”). The Company received a

$0.5

million recoverable grant award from the NJBPU, repayable over a

five

-year period beginning in

November 2011.

The agreement also required the Company to annually assign to the NJBPU a certificate of deposit in an amount equal to the outstanding grant balance. As of

April 30, 2017,

the grant was fully repaid and therefore there was

certificate of deposit.

The following table summarizes restricted cash for the years ended

April 30, 2017

and

2016:

	April 30, 2017		April 30, 2016
	(in thousands)

Barclay's Bank Agreement	$	334	$	250
Santander Bank		154		-
NJBPU agreement		-		50
	$	488	$	300

(g)	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 (years)

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

(h)	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.

(i)

Patents

External costs related to the filing of patents, including legal and filing fees, are capitalized if expenses related to the filing of a patent are significant. The Company continually re-assesses the remaining useful lives of its long-lived assets and costs are expensed when it is

longer probable that such technology will be utilized. Patents are also reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of the patent

may

not

be recoverable.

new patents were granted in fiscal years

2017

and

2016.

There was

amortization of patents recorded during the years ended

April 30, 2017

and

2016,

as the patents are fully amortized.

(j)	Concentration of Credit Risk

Financial instruments that potentially subject the Company to concentration of credit risk consist principally of cash balances, bank certificates of deposit and trade receivables. The Company invests its excess cash in highly liquid investments (principally, short-term bank deposits, Treasury bills, Treasury notes and money market funds) and does

not

believe that it is exposed to any significant risks related to its cash accounts, money market funds or certificates of deposit.

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:

	2017			2016

Mitsui Engineering & Shipbuilding		80	%		14	%
U.S. Department of Defense Office of Naval Research		20	%		0	%
U.S. Department of Energy		0	%		28	%
EU (WavePort Project)		0	%		58	%
		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.

(k)	Warrant Liabilities

The Company's warrants to purchase shares of its common stock are classified as warrant liabilities and are recorded at fair value. The warrant liabilities are subject to re-measurement at each balance sheet date and the Company recognizes any change in fair value in its consolidated statements of operations within “(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.

(l)	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 outstanding during the period. Due to the Company's net losses, potentially dilutive securities, consisting of outstanding stock options and non-vested performance-based shares, 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

657,078

and

129,311

for the years ended

April

30,

2017

and

2016,

respectively, were excluded from each of the computations as the effect would be anti-dilutive due to the Company's losses.

(m)	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,

2017

and

2016

was approximately

$1.2

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, 2017

and

2016:

	Year ended April 30,
	2017		2016
	(in thousands)

Product development	$	525	$	131
Selling, general and administratvie		707		206
Total share-based compensation expense	$	1,232	$	337

Valuation Assumptions for Restricted Stock and Options Granted During the Years Ended

April

30,

2017

and

201

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. If the vesting requirement of performance-based grants is tied to the Company's total shareholder return (TSR) relative to the total shareholder return of alternative energy Exchange Traded Funds as measured over a specific performance period then the compensation expense for these awards with market-based vesting is calculated based on the estimated fair value as of the grant date utilizing a Monte Carlo simulation model and is recognized over the service period on a straight-line basis.

Options

The fair value of each stock option granted, for both service-based and performance-based vesting requirements during the year ended

April 30 2017,

was estimated at the date of grant using the Black-Scholes option pricing model, assuming

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, 2017.

	Twelve months ended April 30,
	2017			2016

Risk-free interest rate		1.3	%		1.6	%
Expected dividend yield		0.0	%		0.0	%
Expected life (in years)		5.50			5.5
Expected volatility		96.2	%		85.7	%

The above assumptions were used to determine the weighted average per share fair value of

$2.52

and

0.58

for stock options granted during the years ended

April

30,

2017

and

2016,

respectively.

(n)	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.

(o)	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.

(p)	Recently Issued Accounting Standards

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

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

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.

The Company has

not

yet completed its final review of the impact of this guidance; however the Company anticipates applying the modified retrospective method upon adoption of ASU

2014

May 1, 2018.

The impact to the Company could be affected by the nature and terms of potential future contracts with customers, as those contracts

may

have terms that differ from the company’s current contracts.

August 2014,

the FASB issued ASU

2014

15,

“Disclosure of Uncertainties about an Entity’s Ability

to Continue as a Going Concern”,

which describes how an entity should assess its ability to meet obligations and sets rules for how this information should be disclosed in the financial statements. The standard provides accounting guidance that will be used along with existing auditing standards. The new standard applies to all entities for the

first

annual period ending after

December 15, 2016,

and interim periods thereafter. Early application is permitted. The Company adopted ASU

2014

for the fiscal year

2017.

The Company’s addition of the standard did

not

have a material impact on its disclosures.

See section (b) “Liquidity/Going Concern” within Note (

) “Background and Liquidity” of these financial statements for further discussion on the Company’s ability to continue as a going concern.

January 2016,

the FASB issued ASU

No.

2016

01,

“Recognition and Measurement of Financial Assets and Financial Liabilities”,

which makes limited amendments to the guidance in U.S. GAAP on the classification and measurement of financial instruments. The update significantly revises an entity's accounting related to the classification and measurement of investments in equity securities and the presentation of certain fair value changes for financial liabilities measured at fair value. It also amends certain disclosure requirements associated with the fair value of financial instruments. The update will take effect for public companies for fiscal years beginning after

December 15, 2017,

including interim periods within those fiscal years. The Company will evaluate the effect of ASU

2016

for future periods as applicable.

February 2016,

the FASB issued ASU

No.

2016

02,

“Leases (Topic

842

).” 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

months. Leases will be classified as either finance or operating, with classification affecting the pattern of expense recognition in the income statement. ASU

2016

is effective for annual periods beginning after

December

15,

2018,

including interim periods within those annual periods, with early adoption permitted. A modified retrospective transition approach is required for lessees for capital and operating leases existing at, or entered into after, the beginning of the earliest comparative period presented in the financial statements, with certain practical expedients available. The Company is evaluating the effect ASU

2016

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.

March 2016,

the FASB issued ASU

No.

2016

09,

“Compensation - Stock Compensation (Topic

718

)

”

The amendments of ASU

No.

2016

were issued as part of the FASB's Simplification initiative focused on improving areas of GAAP for which cost and complexity

may

be reduced while maintaining or improving the usefulness of information disclosed within the financial statements. The amendments focused on simplification specifically with regard to share-based payment transactions, including income tax consequences, classification of awards as equity or liabilities and classification on the statement of cash flows. The guidance in ASU

No.

2016

is effective for fiscal years beginning after

December 15, 2016,

and interim periods within those annual periods. Early adoption is permitted. The Company will evaluate the effect of ASU

2016

for future periods as applicable.

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 is evaluating the effect ASU

2016

will have on its consolidated financial statements and disclosures and has determined the standard will have

impact on its ongoing financial reporting at this time.

November 2016,

the FASB issued ASU

2016

18,

“Statement of Cash Flows (Topic

230

): Restricted

Cash”,

providing additional guidance on specific restricted cash flow classification on the cash flow statement. Cash flow should include restricted cash in total cash, and an entity is required to provide a disclosure indicating the reconciliation of all cash accounts. 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 is evaluating the effect ASU

2016

will have on its consolidated financial statements and disclosures and believes the effect of the standard on its ongoing financial reporting will

not

have a material impact.

January 2017,

the FASB issued ASU

2017

03,

“Accounting Changes and Error Corrections (Topic

250

) and Investments- Equity Method and Joint Ventures (Topic

323

)”, providing guidance on how a company should evaluate ASUs that have

not

yet been adopted to determine the appropriate financial statement disclosures about the potential material effects of those ASUs on the financial statements when adopted.

The Company is currently evaluating the effect ASU

2017

will have on its consolidated financial statements and disclosures.

Note 3 - Marketable Securities

12 Months Ended

Apr. 30, 2017

Notes to Financial Statements

Investments in Debt and Marketable Equity Securities (and Certain Trading Assets) Disclosure [Text Block]

(

)

Marketable Securities

Marketable securities with initial maturities greater than

three

months but that mature within

one

year from the balance sheet date are classified as current assets and are summarized as follows:

	April 30, 2017		April 30, 2016
	(in thousands)

Certificate of Deposit	$	25	$	75

Note 4 - Property and Equipment

12 Months Ended

Apr. 30, 2017

Notes to Financial Statements

Property, Plant and Equipment Disclosure [Text Block]

(

)

Property and Equipment

The components of property and equipment as of

April 30, 2017

and

2016

consisted of the following:

	April 30, 2017			April 30, 2016
	(in thousands)

Equipment	$	715		$	711
Computer Equipment & Software		556			630
Office Furniture & Equipment		250			250
Leasehold improvements		182			182
Equipment under capitalized lease		103			0
	$	1,806		$	1,773
Less: accumulated depreciation		(1,636	)		(1,500	)
	$	170		$	273

Depreciation expense was

$0.1

million and

$0.1

million for the years ended

April

30,

2017

and

2016,

respectively.

As of

April 30, 2017

and

2016,

computer equipment and software under capital leases was

$103

thousand and

$99

thousand, respectively. The terms of the leases are for

months. Future minimum lease payments under capital leases together with the present value of the net minimum lease payments as of

April 30, 2017

are as follows:

	April 30, 2017
	(in thousands)

2018	$	35
2019		23
Total net future minimum lease payments	$	58
Less; Amount representing interest		(4	)
Present value of net minimum lease payments	$	54

Note 5 - Accrued Expenses

12 Months Ended

Apr. 30, 2017

Notes to Financial Statements

Supplemental Balance Sheet Disclosures [Text Block]

(

)

Accrued Expenses

	April 30, 2017		April 30, 2016
	(in thousands)

Project costs	$	898	$	818
Contract loss reserve		238		199
Employee incentive payments		643		688
Accrued salary and benefits		484		456
Legal and accounting fees		478		240
Accrued taxes payable		132		-
Other		186		274
	$	3,059	$	2,675

Note 6 - Related Party Transactions

12 Months Ended

Apr. 30, 2017

Notes to Financial Statements

(

)

Related Party Transactions

April 2014,

the Company entered into an Executive Transition Agreement with George W. Taylor, who was formerly employed by the Company as Executive Vice Chairman and served on the Company’s Board of Directors prior to that date. Under this agreement, Dr. Taylor received

fifteen

months of consulting fees at a monthly rate of

$20,000.

During fiscal

2016,

the Company recorded

$53

thousand in expense relating to this agreement, which was recorded in “selling, general and administrative expense” in the consolidated statements of operations. There were

such amounts recorded during the year ended

April 30, 2017.

Note 7 - Debt

12 Months Ended

Apr. 30, 2017

Notes to Financial Statements

Debt Disclosure [Text Block]

(

)

Debt

The Company was awarded a recoverable grant totaling

$0.5

million, between

April 2009

and

June 2010,

from the NJBPU under the Renewable Energy Business Venture Assistance Program. Under the terms of this agreement, the amount to be repaid is a fixed monthly amount of principal only, repayable over a

five

-year period beginning in

November 2011.

The terms also required the Company to annually assign to the NJBPU a certificate of deposit in an amount equal to the outstanding grant balance. As of

April 30, 2016

the Company had

$50

thousand outstanding and the respective

$50

thousand certificate of deposit was recorded within “Restricted cash” on the balance sheet. As of

April 30, 2017,

the grant was fully repaid, and therefore, there is

balance outstanding and

respective certificate of deposit assigned to restricted cash. See Note

(f) “Summary of Significant Accounting Policies - Restricted Cash and Credit Facility” for more information regarding the certificate of deposit.

Note 8 - Deferred Credits Payable

12 Months Ended

Apr. 30, 2017

Notes to Financial Statements

Customer Advances and Deposits Disclosure [Text Block]

(

)

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.

As of

April 30, 2017,

the Company has

not

generated any emissions credits eligible for purchase under the agreement. The

$0.6

million is reflected on the balance sheet within “Deferred credits payable current” and “Deferred credits payable non-current” as of

April 30, 2017

and

2016,

respectively.

Note 9 - Warrants

12 Months Ended

Apr. 30, 2017

Notes to Financial Statements

Warrant Disclosure [Text Block]

(

)

Warrants

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

417,000

shares of Common Stock together with warrants to purchase up to an aggregate of

145,952

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

$4.60.

The warrants have an exercise price of

$6.08

per share, became exercisable on

December 3, 2016 (

“Initial Exercise Date”), and will expire

five

years following the Initial Exercise Date.

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

595,000

shares of Common Stock together with warrants to purchase up to an aggregate of

178,500

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

$6.75.

The Warrants were exercisable immediately at an exercise price of

$9.36

per share. The Warrants will expire on the

fifth

(

5th

) anniversary of the initial date of issuance.

The warrants contain a feature whereby they could require the transfer of assets and therefore are classified as a liability in accordance with ASC

480.

As such, the warrants with a value of

$0.3

million at

April 30, 2017

are reflected within “warrant liabilities” in the consolidated balance sheets. There were

such amounts at

April 30, 2016.

An unrealized (loss)/gain of

$1.5

million, was included within “ Change in fair value of warrant liabilities” in the consolidated statements of operations for the year ended

April 30, 2017,

respectively. There were

unrealized gains or losses during the

twelve

months ended

April 30, 2016.

The Company determined the fair value using the Black-Scholes option pricing model with the following assumptions:

	April 30, 2017

Dividend rate			0.0%
Risk-free rate			1.81%
Expected life (years)		4.2	-	4.6
Expected volatility		131.7%	-	141.3%

Note 10 - Common Stock

12 Months Ended

Apr. 30, 2017

Notes to Financial Statements

Stockholders' Equity Note Disclosure [Text Block]

(

)

Common Stock

October 2015,

the Company’s stockholders approved and the Board of Directors authorized a reverse stock split in which every

shares of issued and outstanding Common Stock were combined into

one

issued and outstanding share of Common Stock, with

fractional shares being issued. All shares and per-share information has been retroactively restated to give effect to the reverse stock split for all periods presented.

Note 11 - Preferred Stock

12 Months Ended

Apr. 30, 2017

Notes to Financial Statements

Preferred Stock [Text Block]

(

)

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,

2017,

and

2016,

shares of preferred stock had been issued.

Note 12 - Share-based Compensation Plans

12 Months Ended

Apr. 30, 2017

Notes to Financial Statements

Disclosure of Compensation Related Costs, Share-based Payments [Text Block]

(

)

Share-Based Compensation Plans

2001,

the Company approved the

2001

Stock Plan, which provides for the grant of incentive stock options and nonqualified stock options. A total of

100,000

shares were authorized for issuance under the

2001

Stock Plan. As of

April

30,

2017,

the Company had

shares outstanding under the

2001

Stock Plan.

2007,

the Company's

2006

Stock Incentive Plan became effective. A total of

80,321

shares were authorized for issuance under the

2006

Stock Incentive Plan. In

2009,

an amendment to the

2006

Stock Incentive Plan was approved by the Company’s stockholders, increasing the aggregate number of shares authorized for issuance by

85,000

shares to

165,321.

October 2, 2013,

a further amendment to the

2006

Stock Incentive Plan was approved by the Company’s stockholders, increasing the aggregate number of shares authorized for issuance by an additional

80,000

shares to

245,321.

The Company's employees, officers, directors, consultants and advisors were eligible to receive awards under the

2006

Stock Incentive Plan; however, incentive stock options

may

only be granted to employees. The maximum number of shares of Common Stock with respect to which awards

may

be granted to any participant under the

2006

Stock Incentive Plan was

20,000

per calendar year. Vesting provisions of stock options are determined by the board of directors. The contractual term of these stock options is up to

ten

years. The

2006

Stock Incentive Plan was administered by the Company's board of directors, who were authorized to delegate authority to

one

or more committees or subcommittees of the board of directors or to the Company's officers. The

2006

Stock Incentive Plan was terminated in

December 2015

and unused shares in that Plan were transferred to the

2015

Omnibus Incentive Plan.

2015,

upon approval by the Company’s stockholders, the Company’s

2015

Omnibus Incentive Plan (the

“2015

Plan”) became effective. A total of

240,703

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

640,703.

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, 2017,

the Company has

322,305

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

75,000.

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.

A dividend equivalent right is an award entitling the recipient to receive credits based on cash distributions that would have been paid to the recipient on the shares of Common Stock specified in the dividend equivalent right if such shares had been issued to and held by the recipient of the dividend equivalent right as of the record date. A dividend equivalent right

may

be granted to any grantee under the

2015

Plan, but

may

not

be granted in connection with or related to an award of options or SARs under the

2015

Plan. The terms and conditions of any dividend equivalent right shall be as set forth in the award agreement relating to such right. Unless the committee administering the

2015

Plan otherwise provides in an award agreement, a grantee’s rights in all dividend equivalent rights will automatically terminate upon the grantee’s termination of service with the Company.

Performance-based awards

may

be granted by the committee administering the

2015

Plan in such amounts and upon such terms as the committee administering the

2015

Plan determines. Generally, performance-based awards will have an actual or target number of shares of Common Stock or initial value that is set by the committee at the time of grant. The committee administering the

2015

Plan has the discretion to set performance goals which, depending on the extent to which they are achieved, will determine the value and/or the number of shares of Common stock subject to a performance-based award that will be paid out to the grantee. The right of a grantee to exercise or receive a grant or settlement of any performance-based award, and the timing thereof, will be subject to the performance conditions specified by the committee, and will entitle the grantee to receive cash or shares of our Common Stock upon the attainment of the specified performance goals over a specified performance period.

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.

(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, 2016		89,303		$	42.90		3.6
Forfeited		(23,838	)	$	30.38
Exercised		-		$	-
Granted		171,749		$	2.12
Outstanding as of April 30, 2017		237,214		$	14.64		7.6
Exercisable as of April 30, 2017		134,381		$	23.55		6.2

As of

April 30, 2017,

the total intrinsic value of outstanding and exercisable options was approximately

thousand and

thousand, respectively. As of

April

30,

2017,

approximately

101,262

additional options were unvested, which options had

intrinsic value and a weighted-average remaining contractual term of

9.4

years. There was approximately

$0.3

million and

$0.1

million of total recognized compensation cost related to employees for stock options during the years ended

April

30,

2017

and

2016,

respectively. As of

April

30,

2017,

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

0.5

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

2017,

the Company granted

223,662

shares subject to service-based vesting requirements and

shares subject to performance-based vesting requirements. The achievement or vesting requirement of the performance-based grants is tied to the Company’s total shareholder return (TSR) relative to the total shareholder return of

three

alternative energy Exchange Traded Funds as measured over a specific performance period.

vesting of the relevant shares will occur in instances where the Company’s TSR for the relevant period is below

80%

of the peer group. However, additional opportunities to vest some or all of a portion of the shares in a subsequent period

may

occur. Compensation expense for these awards with market-based vesting is calculated based on the estimated fair value as of the grant date utilizing a Monte Carlo simulation model and is recognized over the service period on a straight-line basis.

January 2016,

the Board of Directors authorized a modification to certain outstanding restricted stock grants, which converted certain grants with performance-based grants to service based grants. The modification of the restricted stock grants did

not

have a material impact on the Company’s statement of operations for the fiscal year ended

April 30, 2017.

Restricted stock issued and unvested at

April 30, 2017

included

12,000

shares of unvested restricted stock subjected 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, 2016		44,008		$	6.35
Granted		223,662		$	3.94
Forfeited		(28,266	)	$	3.98
Vested		(135,992	)	$	4.68
Issued and unvested at April 30, 2017		103,412		$	3.99

There was approximately

$0.9

million and

$0.1

million of total recognized compensation cost relating to restricted stock granted to employees during the years ended

April 30, 2017

and

2016,

respectively. As of

April 30, 2017,

there was

$27

thousand 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

0.5

years.

(c)

Treasury Stock

During the years ended

April

30,

2017

and

2016,

41,171

and

3,029

shares of Common Stock, respectively, were purchased by the Company from employees to pay taxes related to the vesting of restricted stock.

Note 13 - Fair Value Measurements

12 Months Ended

Apr. 30, 2017

Notes to Financial Statements

Fair Value Disclosures [Text Block]

(

) 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

transfers between any levels during the year ended

April 30, 2017

and

2016.

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

) 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

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, 2017:

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

Warrant liabilities	$	323	$	-	$	-	$	323

The following table provides a summary of changes in the fair value of the warrant liabilities during the year ended

April 30, 2017;

Fair Value Measurement Using Significant Unobservable Inputs ( Level 3)

	Total
	Warrant
	Liability
	(in thousands)

Fair value – April 30, 2016	$	-
Issuance		1,814
Transfers		-
Change in fair value		(1,491	)
Fair value – April 30, 2017	$	323

- 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

Note 14 - Income Taxes

12 Months Ended

Apr. 30, 2017

Notes to Financial Statements

Income Tax Disclosure [Text Block]

(

)

Income Taxes

Loss before income taxes for the years ended

April 30, 2017

and

2016

consisted of the following components:

	April 30, 2017			April 30, 2016
	(in thousands)

Domestic	$	(9,805	)	$	(14,223	)
Foreign		(379	)		(535	)
Total loss before income taxes	$	(10,184	)	$	(14,758	)

The income tax benefit for the years ended

April 30, 2017

and

2016

consist of state income tax benefits of

$0.7

million and

$1.7

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 of

34%

to loss before income taxes as a result of the following:

	April 30, 2017			April 30, 2016

Computed expected tax benefit		-34.0	%		-34.0	%
Increase(reduction) in income taxes resulting from:
State income taxes, net of federal benefit		2.3	%		6.0	%
Federal research and development tax credits		-1.7	%		-3.0	%
Foreign rate differential		0.3	%		1.0	%
Other non-deductible expenses		0.1	%		5.0	%
Proceeds of sale of New Jersey tax benefits		-6.9	%		-11.0	%
Other		11.7	%		13.0	%
Increase in valuation allowance		25.9	%		12.0	%
Income tax benefit		2.3	%		-11.0	%

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, 2017			April 30, 2016
	(in thousands)

Deferred tax assets:
Federal net operating loss carryforwards	$	44,355		$	40,540
Foreign net operating loss carryforwards		3,761			4,393
State operating loss carryforwards		1,281			1,375
Federal and New Jersey research and development tax credits		2,996			2,708
Stock compensation		1,096			732
Unrealized foreign exchange loss		17			536
Accrued expenses		576			1,324
Other		627			945
Net deferred tax assets before valuation allowance		54,709			52,553
Valuation allowance		(54,709	)		(52,553	)
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,

2017

and

2016,

based upon the level of historical taxable losses, valuation allowances of

$54.7

million and

$52.6

million, respectively, were recorded to fully offset deferred tax assets. The valuation allowance increased

$2.1

million and

$1.8

during the years ended

April

30,

2017

and

2016,

respectively.

As of

April

30,

2017,

the Company had net operating loss carry forwards for federal income tax purposes of approximately

$130.5

million, which begin to expire in fiscal

2019.

The Company also had federal research and development tax credit carry forwards of approximately

$2.8

million as of

April

30,

2017,

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,

2017,

the Company had state net operating loss carry forwards of approximately

$21.6

million which begin to expire in

2019,

which also

may

be limited to utilization limitations. As of

April

30,

2017,

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.

During the years ended

April 30, 2017

and

2016,

the Company sold New Jersey State net operating losses in the amount of

$7.8

million and

$19.7

million, respectively, resulting in the recognition of income tax benefits of

$0.7

million and

$1.7

million, respectively, recorded in the Company’s Statement of Operations.

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. We are currently undergoing an income tax audit in Spain for the period from

2008

2014,

when our Spanish branch was closed. The branch reported net operating losses for each of the years reported. It is anticipated that we will be assessed a penalty relating to these tax years for these losses. We have estimated this penalty to be

$132

thousand, and as such, for the period ended

April 30, 2017,

we have recorded

$132

thousand for this penalty to Selling, general and administrative costs in the Statement of Operations. At

April

30,

2017

and

2016,

the Company had

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.

Note 15 - Commitments and Contingencies

12 Months Ended

Apr. 30, 2017

Notes to Financial Statements

Commitments and Contingencies Disclosure [Text Block]

(

) Commitments and Contingencies

(a)

Operating Lease Commitments

The Company leases office, laboratory, manufacturing and other space in Pennington, New Jersey under an operating lease that expires on

December 31, 2017.

March 31, 2017

the company entered into a lease for approximately

56,000

square feet in Monroe Township, New Jersey (the “Monroe Lease”) that will be used as warehouse/production space and Company’s principal offices and corporate headquarters. The lease commencement date is

October 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 Monroe 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. The Company expects to relocate to the new location by the end of

2017.

Rent expense under operating leases was approximately

$0.3

million and

$0.3

million for the years ended

April

30,

2017

and

2016,

respectively.

Future minimum lease payments under operating leases as of

April 30, 2016

are as follows:

	April 30, 2017
	(in thousands)

2018	$	348
2019		313
2020		323
2021		332
2022		342
Thereafter		869
	$	2,527

Shareholder Litigation and Demands

The Company and its former Chief Executive Officer Charles Dunleavy were named as defendants in consolidated securities class action lawsuits that were pending in the United States District Court for the District of New Jersey captioned

In Re: Ocean Power Technologies, Inc. Securities Litigation,

Civil Action

No.

3799

(FLW) (LHG).

May 5, 2016,

the parties entered into a Stipulation and Agreement of Class Settlement (“Stipulation”) in which they agreed to a settlement of the consolidated securities class action lawsuits, subject to Court approval. The Stipulation provides, among other things, for a settlement payment by or on behalf of the Company of

$3.0

million in cash, of which the Company would pay

$0.5

million and the Company’s insurer would pay

$2.5

million, and the issuance by the Company of

380,000

shares (valued at

$0.6

million on the date the Stipulation was signed by the parties) of its Common Stock to the class members. The Stipulation also provided for mutual releases. The amounts agreed in the Stipulation, including the amount to be contributed by our insurance carrier, were reflected in the Company’s Consolidated Financial Statements as of

April 30, 2016.

July 2016,

the Company paid the

$0.5

million portion of the settlement and the remaining balance of

$2.5

million was paid by the Company’s insurer in

August 2016.

November 14, 2016,

the Court held its previously scheduled Settlement Hearing to consider whether to grant final approval of the settlement, and on

November 15, 2016,

the Court issued its Final Judgment approving the settlement and dismissing the proceeding with prejudice.

The

380,000

shares of common stock were issued on

November 22, 2016.

The time to file an appeal from the Final Judgment has expired without any appeal being filed.

The Company and certain of its current and former directors and officers are 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 alleges 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 seeks unspecified monetary damages and other relief.

July 10, 2015,

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.

February 8, 2016,

the Court issued an order consolidating the

Labare

and

Rywolt

actions, appointing co-lead plaintiffs and lead counsel, and ordering a consolidated amended complaint to be filed within

days of the order. On

March 9, 2016,

the co-lead plaintiffs filed an amended complaint consolidating their claims and seeking unspecified monetary damages and other relief.

April 21, 2016,

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 seeks unspecified monetary damages and other relief. The Company has

not

been formally served and has

not

yet responded to the complaint.

June 9, 2016,

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

August 2, 2016,

the parties in the

Pucillo

lawsuit filed a Stipulation and Proposed Order pursuant to which: (i) the defendants agreed to accept service of the

Pucillo

complaint; (ii) the parties agreed to stay the

Pucillo

action pending the filing and resolution of a motion to consolidate the

Pucillo

action with the

Labar

e and

Rywolt

actions; and (iii) the parties agreed that the defendants shall

not

be required to respond to the

Pucillo

complaint during the pendency of the stay. The Court approved the Stipulation on

August 3, 2016.

October 25, 2016,

the Court approved and entered a Stipulation and Order that, among other things, (i) consolidated the

four

derivative actions; (ii) identified plaintiff Pucillo as the lead plaintiff in the consolidated actions; and (iii) stayed the consolidated actions pending the settlement hearing scheduled for

November 14, 2016

in the securities class action and further order of the Court. Defendants have

not

responded to the consolidated derivative actions because the actions remain stayed pending further order from the Court.

The Company and certain of its current directors are defendants in a lawsuit filed by an alleged shareholder in the Superior Court of New Jersey, Mercer County Chancery Division on

January 25, 2016,

captioned

Stern v. Ocean Power Technologies, Inc., et al.,

Civil Action

No.

C-

16.

The complaint alleges that certain provisions of the Company’s Certificate of Incorporation and By-laws providing that the Company’s directors

may

be removed only for cause and only by an affirmative vote of at least

75%

of the votes which all the stockholders would be entitled to cast in any annual election of directors are invalid under Section

141

(k) of the Delaware General Corporation Law. The Complaint asserts a breach of fiduciary claim against the director defendants and a declaratory judgment claim against all defendants seeking, among other things, to invalidate the challenged provisions and declare that the Company’s directors

may

be removed and replaced without cause and by a simple majority vote. The Complaint sought declaratory and injunctive relief as well as unspecified costs and attorneys’ fees. By Unanimous Written Consent dated

June 17, 2016,

the Company’s Board of Directors amended the Company’s By-laws to delete the “only for cause” requirement, thereby allowing for removal of directors with or without cause by the Company’s stockholders. In addition, the Board proposed, subject to approval by the Company’s stockholders at the next annual general meeting of stockholders, a similar amendment to the director removal provision in the Company’s Certificate of Incorporation. On

June 30, 2016,

the Court approved a Stipulation and Proposed Order Staying Proceedings that, among other things, stayed the case pending the stockholder vote on the proposed amendment to the Company’s Certificate of Incorporation; On

September 2, 2016,

the Company filed a definitive proxy statement with the SEC which included the proposed amendment of the director removal rovision in the Company’s Certificate of Incorporation. At the annual shareholder meeting on

October 21, 2016,

the proposal was

not

approved because an insufficient number of votes were cast to satisfy the requirement that the proposal be approved by the holders of at least

75%

of the outstanding shares of common stock entitled to vote at the meeting. However, stockholders approved an amendment to the Company’s Certificate of Incorporation to add a provision which requires that any provision of the Certificate of Incorporation that is contrary to a requirement of the Delaware General Corporate Law shall be read in conformity with the applicable requirement of the Delaware General Corporate Law

. On

April 12, 2017,

the parties in the

Stern

lawsuit executed a settlement that required the Company to file a Form

-K (which was filed on

April 17, 2017)

with the U.S. Securities and Exchange Commission announcing that the Company will follow its By-Laws as opposed to its Certificate of Incorporation as regards the director removal provisions; and (

) to pay the

Stern

plaintiff an amount equal to

$22,500

to compensate the plaintiff for the legal costs of bringing the lawsuit. Also on

April 17, 2017,

the parties executed a Stipulation of Dismissal that was subsequently filed with the court. The Company paid the plaintiff’s counsel the amount required by the settlement agreement within the time period required by the settlement agreement.

May 26, 2017,

an attorney claiming to represent

two

stockholders sent the Company’s Board of Directors a Stockholder Litigation Demand letter (“Stockholder Demand”). The Stockholder Demand alleges that the voting of shares for the

-for-

reverse stock split at the

2015

annual meeting of stockholders held on

October 22, 2015

was

not

properly counted, and further alleges that, although the Company reported the reverse stock split as having been passed, if the vote was properly counted the reverse stock split would

not

have been approved. The Stockholder Demand requests the Board of Directors either to deem the reverse stock split as ineffective and disclose the same or to seek a proper and effective stockholder ratification of the reverse stock split. In addition, the Stockholder Demand requests the Board of Directors to adopt and implement adequate internal controls and systems to prevent the alleged improper voting from recurring. On

June 23, 2017,

the Company responded to the Stockholder Demand, explained the procedures that were followed for the

2015

annual meeting of stockholders and provided the Oath of the Inspector of Elections and the Certificate of the Inspector of Elections that certified as accurate the results of the voting at the meeting including voting on the reverse stock split proposal. On

June 26, 2017,

the attorney representing the alleged stockholders replied to the Company’s response, further alleged that the proxy statement underlying the

2015

annual meeting provided voting instructions that misled the stockholders regarding whether their brokers could vote on the reverse stock split proposal, and renewed their requests of the Board.

The Company is evaluating further the Stockholder Demand and the reply letter and will respond in due course.

Employment Litigation

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. The Company and Mr. Dunleavy have agreed to suspend his alleged employment claims pending resolution of the shareholder litigation, and have since agreed to continue to the suspension pending resolution of the derivatives litigation.

Except for the Stipulation agreement noted previously, we have

not

established any provision for losses relating to these claims and pending litigation. Due to the stages of these proceedings, and considering the inherent uncertainty of these claims and litigation, at this time we are

not

able to predict or reasonably estimate whether we have any possible loss exposure or the ultimate outcome of these claims.

(b) Regulatory Matters

SEC Investigation

February 4, 2015,

the Company received a subpoena from the SEC requesting information related to the VWP Project. The Company has provided information to the SEC in response to that subpoena. As part of the same investigation, on

July 12, 2016,

the SEC issued

second

subpoena requesting information related to the Company’s

April 4, 2014

public offering. The Company has provided information to the SEC in response to that subpoena. The SEC investigation is ongoing and the Company continues to cooperate with the SEC in its investigation. We are unable to predict what action, if any, might be taken by the SEC or its staff as a result of this investigation or what impact, if any, the cost of responding to the SEC’s investigation or its ultimate outcome might have on our financial position, results of operations or liquidity. We have

not

established any provision for losses relating to this matter.

Spain IVA (sales tax)

June 2012,

the Company received notice that the Spanish tax authorities are inquiring into its

2010

IVA (value-added tax) filing for which the Company benefitted from the offset of approximately

$0.3

million of input tax. The Company believed that the tax credit was properly claimed and, therefore,

liability was recorded. The Company issued

two

letters of credit totaling

€0.3

million (

$0.3

million) at the request of the Spanish tax authorities. On

January 31, 2017

the Company received

$0.2

million from the Spanish tax authorities as a result of the conclusion of the inquiry. In addition, during

February 2017,

the Spanish tax authorities approved of the release of the

two

outstanding letters of credit.

Spain Income Tax Audit

We are currently undergoing an income tax audit in Spain for the period from

2008

2014,

$132

thousand, and as such, for the period ended

April 30, 2017,

we have recorded

$132

thousand for this penalty to Selling, general and administrative costs in the Statement of Operations.

Note 16 - Operating Segments and Geographic Information

12 Months Ended

Apr. 30, 2017

Notes to Financial Statements

Segment Reporting Disclosure [Text Block]

(

) 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, 2017

	North						Asia and
	America			Europe			Australia			Total
	(in thousands)

Revenues from external customers	$	843		$	-		$	-		$	843
Operating loss		(11,270	)		(389	)		(28	)		(11,687	)
Long-lived assets		170			-			-			170
Total assets		9,498			209			366			10,073

	Year Ended April 30, 2016

	North						Asia and
	America			Europe			Australia			Total
	(in thousands)

Revenues from external customers	$	705		$	-		$	-		$	705
Operating loss		(14,402	)		(295	)		(161	)		(14,858	)
Long-lived assets		273			-			-			273
Total assets		9,553			395			403			10,351

Note 17 - Subsequent Event	12 Months Ended
Note 17 - Subsequent Event	Apr. 30, 2017
Notes to Financial Statements
Subsequent Events [Text Block]	( 1 7 ) Subsequent Event On May 2, 2017, the Company sold 6,192,750 shares of common stock at a price of $1.30 per share, which includes the sale of 807,750 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 placement agent fees and offering expenses payable by the Company.

Significant Accounting Policies (Policies)

12 Months Ended

Apr. 30, 2017

Accounting Policies [Abstract]

Basis of Accounting, Policy [Policy Text Block]

(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.

1997.

The Company markets its PowerBuoys in the United States and internationally.

Since fiscal

2002,

Liquidity, Policy [Policy Text Block]

(b)

Liquidity/Going Concern

$187.4

million at

April 30, 2017.

April 30, 2017,

the Company had approximately

$8.4

million in cash on hand. The Company generated revenues of only

$0.8

million and

$0.7

million during the years ended

April 30, 2017

and

2016,

respectively. Based on the Company’s cash and cash equivalents and marketable securities balances as of

April 30, 2017,

and including the proceeds received from our

May 2017

financing transaction in which we received aggregate net proceeds to us of approximately

$7.2

million, the Company believes that it will be able to finance its capital requirements and operations into the quarter ending

July 31, 2018.

not

Management is evaluating different strategies to obtain the required additional funding for future operations. These strategies

may

include, but are

not

assurance that any of these future-funding efforts will be successful.

In fiscal

2017

and

2016,

not

four

equity financing arrangements during the year ended

April 30, 2017

and subsequently on

May 2, 2017.

The Company does

not

obtained when needed, the Company

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.

Historically, the Company has funded its operations principally through public and private sales of our equity. In

October 2015,

the Company entered into an At the Market Offering Agreement (

“2015

ATM Agreement”) with H.C. Wainwright & Co., LLC (“Manager”), under which the Company offered from time to time in an at the market offering (the

“2015

ATM Facility”) shares of our Common Stock under the Form S-

and under a subsequent shelf registration statement on Form S-

(the

“2016

Form S-

3”

) filed with the SEC in

February 2016

and declared effective by the SEC in

April 2016.

The

2016

Form S-

registers for sale up to

$15

million in securities by the Company in a public offering, although the Company is limited by Instruction

I.B.6

in the amount that we

may

sell under Form S-

in any

calendar month period to

one

third

of our public float. Under the

2015

ATM Facility, between

October 2015

and

April 2016,

the Company issued and sold

144,571

shares of its Common Stock with an aggregate market value of

$293,343

under the

2015

ATM Agreement at an average price of

$2.03

per share and paid the Manager of the

2015

ATM Facility a sales commission of approximately

$4,400

related to those shares. The

2015

ATM Agreement was terminated on

June 2, 2016,

effective immediately, and the

2015

ATM Facility is

longer available for use by the Company.

Form S-

limits the aggregate market value of securities that the Company is permitted to offer in any

-month period under its

2013

Form S-

Shelf, whether under the ATM Agreement, the Underwriting Agreement or otherwise, to

one

third

of its public float. In

2014,

the Company fully utilized its available transaction capacity to sell securities using the

2013

Form S-

Shelf in the ATM offering. However, the Company regained the ability to utilize the

2013

Form S-

Shelf as the Company entered fiscal

2016.

Under the SEC’s regulations, the securities registered under its

2013

Form S-

Shelf

may

only be offered and sold if

not

more than

three

years have elapsed from the initial effective date of the Form S-

except that if a new shelf registration statement is filed then the Company is permitted to continue to offer and sell securities under the Form S-

until the earlier of the effective date of the new shelf registration statement or

180

days after the

third

anniversary of the initial effective date.

February 12, 2016,

the Company filed a new Form S-

shelf registration statement (the

“2016

Form S-

3”

) to register the offering and sale of up to

$15

million in securities. The

2016

Form S-

registration was declared effective by the SEC on

April 26, 2016.

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

417,000

shares of Common Stock together with warrants to purchase up to an aggregate of

145,952

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

$4.60.

The net proceeds to the Company from the offering were approximately

$1.7

$6.08

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

$0.1

million as placement agent fees in connection with the sale of securities in the offering. The Company also reimbursed the placement agents

$35

thousand for their out of pocket and legal expenses in connection with the offering.

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

595,000

shares of Common Stock together with warrants to purchase up to an aggregate of

178,500

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

$6.75.

The net proceeds to the Company from the offering were approximately

$3.6

$9.36

per share. The Warrants will expire on the

fifth

(

5th

) anniversary of the initial date of issuance.

October 19, 2016,

the Company sold

2,760,000

shares of common stock at a price of

$2.75

per share, which includes the sale of

360,000

$6.9

million, after deducting placement agent fees and offering expenses payable by the Company.

May 2, 2017,

the Company sold

6,192,750

shares of common stock at a price of

$1.30

per share, which includes the sale of

807,750

$7.2

million, after deducting placement agent fees and offering expenses payable by the Company.

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 forced to cease operations.

Common Stock, Policy [Policy Text Block]

Stock Split

At the annual meeting of stockholders on

October 22, 2015,

“Legal Proceedings” of the accompanying Annual Report and Note

“Commitments and Contingencies- Shareholder Litigation and Demand” in these consolidated financial statements for the fiscal year ended

April 30, 2017.

October 27, 2015,

the Company filed a Certificate of Amendment to its Certificate of Incorporation to affect a

one

-for-

reverse stock split of its Common Stock and to decrease the number of authorized shares of its Common Stock to

50,000,000

shares (the “Reverse Stock Split”). As a result of the Reverse Stock Split, as of the effective date of the Reverse Stock Split, every

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.

fractional shares were issued in connection with the Reverse Stock Split. Total cash payments made by the Company to stockholders in lieu of fractional shares were

not

material. The Common Stock began trading on a reverse stock split-adjusted basis on the NASDAQ Stock Market (“NASDAQ”) on

October 29, 2015.

November 12, 2015,

NASDAQ notified the Company that it’s Common Stock had regained compliance with the NASDAQ listed company closing bid price requirement.

Consolidation, Policy [Policy Text Block]

(a)

Consolidation

September 2015,

the Company re-purchased the non-controlling interest (consisting of

11.8%

) of the Company's Australian subsidiary, Ocean Power Technologies (Australasia) Pty. Ltd. (“OPTA”) for nominal consideration and now has

100%

ownership of OPTA. OPTA owns

100%

of Victorian Wave Partners Pty. Ltd. (“VWP”), which is also organized under the laws of Australia. As of

April 30, 2017

and

2016,

there were

such entities.

April 30, 2016,

there were

such entities.

Use of Estimates, Policy [Policy Text Block]

(b)	Use of Estimates

Revenue Recognition, Policy [Policy Text Block]

(c)	Revenue Recognition

The Company has

two

may

In addition, recognition of revenue (and the related costs)

may

contractual criteria or in completing projects

may

have a significant effect on revenue for the periods involved. Upon anticipating a loss on a contract, the Company recognizes the full amount of the anticipated loss in the current period.

Unbilled receivables represent expenditures on contracts, plus applicable profit margin,

not

yet billed. Unbilled receivables are normally billed and collected within

one

Cash and Cash Equivalents, Policy [Policy Text Block]

(d)	Cash and Cash Equivalents

The Company considers all highly liquid investments with a maturity of

three

not

100%

of the bank’s total obligations under the agreement. The following table summarizes cash and cash equivalents for the years ended

April 30, 2017

and

2016:

	April 30, 2017		April 30, 2016
	(in thousands)

Checking and savings accounts	$	4,241	$	4,535
Overnight repurchase account		4,180		2,195
	$	8,421	$	6,730

Marketable Securities, Policy [Policy Text Block]

(e)	Marketable Securities

Marketable securities with original maturities longer than

three

months but that mature in less than

one

April 30, 2017

and,

2016,

all of the Company’s investments were classified as held-to-maturity.

Cash and Cash Equivalents, Restricted Cash and Cash Equivalents, Policy [Policy Text Block]

(f)	Restricted Cash and Credit Facility

As of

April 30, 2017

and

2016,

a portion of the Company’s cash was restricted under the terms of

three

security agreements.

one

of the Company's subsidiaries, under a credit facility established by Barclays Bank for OPT LTD. The credit facility is approximately

€0.3million

(

$0.3

million) and carries a fee of

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 both

April 30, 2017

and

2016,

there was

€0.3

million (

$0.3

million) in letters of credit outstanding under this agreement.

The

second

January 31, 2025,

but is cancelable at the discretion of the bank.

The

third

agreement was between the Company and the New Jersey Board of Public Utilities (“NJBPU”). The Company received a

$0.5

million recoverable grant award from the NJBPU, repayable over a

five

-year period beginning in

November 2011.

The agreement also required the Company to annually assign to the NJBPU a certificate of deposit in an amount equal to the outstanding grant balance. As of

April 30, 2017,

the grant was fully repaid and therefore there was

certificate of deposit.

The following table summarizes restricted cash for the years ended

April 30, 2017

and

2016:

	April 30, 2017		April 30, 2016
	(in thousands)

Barclay's Bank Agreement	$	334	$	250
Santander Bank		154		-
NJBPU agreement		-		50
	$	488	$	300

Property, Plant and Equipment, Policy [Policy Text Block]

(g)	Property and Equipment

may

not

Description	Estimated useful life (years)

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

Foreign Currency Transactions and Translations Policy [Policy Text Block]

(h)	Foreign Exchange Gains and Losses

may

Intangible Assets, Finite-Lived, Policy [Policy Text Block]

(i)

Patents

longer probable that such technology will be utilized. Patents are also reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of the patent

may

not

be recoverable.

new patents were granted in fiscal years

2017

and

2016.

There was

amortization of patents recorded during the years ended

April 30, 2017

and

2016,

as the patents are fully amortized.

Concentration Risk, Credit Risk, Policy [Policy Text Block]

(j)	Concentration of Credit Risk

not

believe that it is exposed to any significant risks related to its cash accounts, money market funds or certificates of deposit.

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:

	2017			2016

Mitsui Engineering & Shipbuilding		80	%		14	%
U.S. Department of Defense Office of Naval Research		20	%		0	%
U.S. Department of Energy		0	%		28	%
EU (WavePort Project)		0	%		58	%
		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.

Warrant Liability, Policy [Policy Text Block]

(k)	Warrant Liabilities

Earnings Per Share, Policy [Policy Text Block]

(l)	Net Loss per Common Share

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

657,078

and

129,311

for the years ended

April

30,

2017

and

2016,

respectively, were excluded from each of the computations as the effect would be anti-dilutive due to the Company's losses.

Share-based Compensation, Option and Incentive Plans Policy [Policy Text Block]

(m)	Share-Based Compensation

April

30,

2017

and

2016

was approximately

$1.2

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, 2017

and

2016:

	Year ended April 30,
	2017		2016
	(in thousands)

Product development	$	525	$	131
Selling, general and administratvie		707		206
Total share-based compensation expense	$	1,232	$	337

Valuation Assumptions for Restricted Stock and Options Granted During the Years Ended

April

30,

2017

and

201

Restricted Stock

Options

The fair value of each stock option granted, for both service-based and performance-based vesting requirements during the year ended

April 30 2017,

was estimated at the date of grant using the Black-Scholes option pricing model, assuming

No.

110,

Share-Based Payment.

Expected volatility was based on the Company’s historical volatility during the

twelve

months ended

April 30, 2017.

	Twelve months ended April 30,
	2017			2016

Risk-free interest rate		1.3	%		1.6	%
Expected dividend yield		0.0	%		0.0	%
Expected life (in years)		5.50			5.5
Expected volatility		96.2	%		85.7	%

The above assumptions were used to determine the weighted average per share fair value of

$2.52

and

0.58

for stock options granted during the years ended

April

30,

2017

and

2016,

respectively.

Income Tax, Policy [Policy Text Block]

(n)	Income Taxes

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%

Comprehensive Income, Policy [Policy Text Block]

(o)	Accumulated Other Comprehensive Loss

New Accounting Pronouncements, Policy [Policy Text Block]

(p)	Recently Issued Accounting Standards

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

five

one

-year deferral of the effective date for the new revenue standard. Public companies should now apply the guidance in ASU

2014

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.

The Company has

not

yet completed its final review of the impact of this guidance; however the Company anticipates applying the modified retrospective method upon adoption of ASU

2014

May 1, 2018.

The impact to the Company could be affected by the nature and terms of potential future contracts with customers, as those contracts

may

have terms that differ from the company’s current contracts.

August 2014,

the FASB issued ASU

2014

15,

“Disclosure of Uncertainties about an Entity’s Ability

to Continue as a Going Concern”,

first

annual period ending after

December 15, 2016,

and interim periods thereafter. Early application is permitted. The Company adopted ASU

2014

for the fiscal year

2017.

The Company’s addition of the standard did

not

have a material impact on its disclosures.

See section (b) “Liquidity/Going Concern” within Note (

) “Background and Liquidity” of these financial statements for further discussion on the Company’s ability to continue as a going concern.

January 2016,

the FASB issued ASU

No.

2016

01,

“Recognition and Measurement of Financial Assets and Financial Liabilities”,

December 15, 2017,

including interim periods within those fiscal years. The Company will evaluate the effect of ASU

2016

for future periods as applicable.

February 2016,

the FASB issued ASU

No.

2016

02,

“Leases (Topic

842

).” 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

months. Leases will be classified as either finance or operating, with classification affecting the pattern of expense recognition in the income statement. ASU

2016

is effective for annual periods beginning after

December

15,

2018,

2016

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.

March 2016,

the FASB issued ASU

No.

2016

09,

“Compensation - Stock Compensation (Topic

718

)

”

The amendments of ASU

No.

2016

were issued as part of the FASB's Simplification initiative focused on improving areas of GAAP for which cost and complexity

may

No.

2016

is effective for fiscal years beginning after

December 15, 2016,

and interim periods within those annual periods. Early adoption is permitted. The Company will evaluate the effect of ASU

2016

for future periods as applicable.

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 is evaluating the effect ASU

2016

will have on its consolidated financial statements and disclosures and has determined the standard will have

impact on its ongoing financial reporting at this time.

November 2016,

the FASB issued ASU

2016

18,

“Statement of Cash Flows (Topic

230

): Restricted

Cash”,

fiscal years beginning after

December 15, 2017,

and interim periods within those fiscal years and early adoption is permitted. The Company is evaluating the effect ASU

2016

will have on its consolidated financial statements and disclosures and believes the effect of the standard on its ongoing financial reporting will

not

have a material impact.

January 2017,

the FASB issued ASU

2017

03,

“Accounting Changes and Error Corrections (Topic

250

) and Investments- Equity Method and Joint Ventures (Topic

323

)”, providing guidance on how a company should evaluate ASUs that have

not

yet been adopted to determine the appropriate financial statement disclosures about the potential material effects of those ASUs on the financial statements when adopted.

The Company is currently evaluating the effect ASU

2017

will have on its consolidated financial statements and disclosures.

Note 2 - Summary of Significant Accounting Policies (Tables)

12 Months Ended

Apr. 30, 2017

Notes Tables

Schedule of Cash and Cash Equivalents [Table Text Block]

	April 30, 2017		April 30, 2016
	(in thousands)

Checking and savings accounts	$	4,241	$	4,535
Overnight repurchase account		4,180		2,195
	$	8,421	$	6,730

Restrictions on Cash and Cash Equivalents [Table Text Block]

	April 30, 2017		April 30, 2016
	(in thousands)

Barclay's Bank Agreement	$	334	$	250
Santander Bank		154		-
NJBPU agreement		-		50
	$	488	$	300

Property, Plant and Equipment, Useful Life [Table Text Block]

Description	Estimated useful life (years)

Equipment		5	-	7
Computer equipment & software			3
Office furniture & fixtures		3	-	7
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 [Table Text Block]

	2017			2016

Mitsui Engineering & Shipbuilding		80	%		14	%
U.S. Department of Defense Office of Naval Research		20	%		0	%
U.S. Department of Energy		0	%		28	%
EU (WavePort Project)		0	%		58	%
		100	%		100	%

Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Table Text Block]

	Year ended April 30,
	2017		2016
	(in thousands)

Product development	$	525	$	131
Selling, general and administratvie		707		206
Total share-based compensation expense	$	1,232	$	337

Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block]

	Twelve months ended April 30,
	2017			2016

Risk-free interest rate		1.3	%		1.6	%
Expected dividend yield		0.0	%		0.0	%
Expected life (in years)		5.50			5.5
Expected volatility		96.2	%		85.7	%

Note 3 - Marketable Securities (Tables)

12 Months Ended

Apr. 30, 2017

Current [Member]

Notes Tables

Marketable Securities [Table Text Block]

	April 30, 2017		April 30, 2016
	(in thousands)

Certificate of Deposit	$	25	$	75

Note 4 - Property and Equipment (Tables)

12 Months Ended

Apr. 30, 2017

Notes Tables

Property, Plant and Equipment [Table Text Block]

	April 30, 2017			April 30, 2016
	(in thousands)

Equipment	$	715		$	711
Computer Equipment & Software		556			630
Office Furniture & Equipment		250			250
Leasehold improvements		182			182
Equipment under capitalized lease		103			0
	$	1,806		$	1,773
Less: accumulated depreciation		(1,636	)		(1,500	)
	$	170		$	273

Schedule of Future Minimum Lease Payments for Capital Leases [Table Text Block]

	April 30, 2017
	(in thousands)

2018	$	35
2019		23
Total net future minimum lease payments	$	58
Less; Amount representing interest		(4	)
Present value of net minimum lease payments	$	54

Note 5 - Accrued Expenses (Tables)

12 Months Ended

Apr. 30, 2017

Notes Tables

Schedule of Other Assets and Other Liabilities [Table Text Block]

	April 30, 2017		April 30, 2016
	(in thousands)

Project costs	$	898	$	818
Contract loss reserve		238		199
Employee incentive payments		643		688
Accrued salary and benefits		484		456
Legal and accounting fees		478		240
Accrued taxes payable		132		-
Other		186		274
	$	3,059	$	2,675

Note 9 - Warrants (Tables)

12 Months Ended

Apr. 30, 2017

Notes Tables

Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Table Text Block]

	April 30, 2017

Dividend rate			0.0%
Risk-free rate			1.81%
Expected life (years)		4.2	-	4.6
Expected volatility		131.7%	-	141.3%

Note 12 - Share-based Compensation Plans (Tables)

12 Months Ended

Apr. 30, 2017

Notes Tables

Share-based Compensation, Activity [Table Text Block]

						Weighted
						Average
				Weighted		Remaining
	Shares			Average		Contractual
	Underlying			Exercise		Term
	Options			Price		(In Years)
Outstanding as of April 30, 2016		89,303		$	42.90		3.6
Forfeited		(23,838	)	$	30.38
Exercised		-		$	-
Granted		171,749		$	2.12
Outstanding as of April 30, 2017		237,214		$	14.64		7.6
Exercisable as of April 30, 2017		134,381		$	23.55		6.2

Schedule of Share-based Compensation, Restricted Stock Units Award Activity [Table Text Block]

				Weighted
	Number			Average Price per
	of Shares			Share

Issued and unvested at April 30, 2016		44,008		$	6.35
Granted		223,662		$	3.94
Forfeited		(28,266	)	$	3.98
Vested		(135,992	)	$	4.68
Issued and unvested at April 30, 2017		103,412		$	3.99

Note 13 - Fair Value Measurements (Tables)

12 Months Ended

Apr. 30, 2017

Notes Tables

Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block]

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

Warrant liabilities	$	323	$	-	$	-	$	323

Changes on Value of Warrant Liability [Table Text Block]

Fair Value Measurement Using Significant Unobservable Inputs ( Level 3)

	Total
	Warrant
	Liability
	(in thousands)

Fair value – April 30, 2016	$	-
Issuance		1,814
Transfers		-
Change in fair value		(1,491	)
Fair value – April 30, 2017	$	323

Note 14 - Income Taxes (Tables)

12 Months Ended

Apr. 30, 2017

Notes Tables

Schedule of Components of Loss Before Income Taxes [Table Text Block]

<div style="display: inline; font-family: times new roman; font-size: 10pt"><table style="FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman, Times, serif; WIDTH: 85%; MARGIN-LEFT: 36pt; MARGIN-RIGHT: 15%; TEXT-INDENT: 0px;" cellspacing="0" cellpadding="0" border="0"> <tr> <td style="FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman, Times, serif"><div style="display: inline; font-weight: bold;"> </div></td> <td style="FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman, Times, serif"><div style="display: inline; font-weight: bold;"> </div></td> <td style="FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman, Times, serif; VERTICAL-ALIGN: bottom; BORDER-BOTTOM: #000000 1px solid; TEXT-ALIGN: center" colspan="2"> <div style=" MARGIN-BOTTOM: 0pt; TEXT-ALIGN: center; MARGIN-TOP: 0pt; LINE-HEIGHT: 1.25"><div style="display: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman, Times, serif"><div style="display: inline; font-weight: bold;">April 30, 2017</div></div></div></td> <td style="FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman, Times, serif; PADDING-BOTTOM: 1px"><div style="display: inline; font-weight: bold;"> </div></td> <td style="FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman, Times, serif"><div style="display: inline; font-weight: bold;"> </div></td> <td style="FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman, Times, serif; VERTICAL-ALIGN: bottom; BORDER-BOTTOM: #000000 1px solid; TEXT-ALIGN: center" colspan="2"> <div style=" MARGIN-BOTTOM: 0pt; TEXT-ALIGN: center; MARGIN-TOP: 0pt; LINE-HEIGHT: 1.25"><div style="display: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman, Times, serif"><div style="display: inline; font-weight: bold;">April 30, 2016</div></div></div></td> <td style="FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman, Times, serif; PADDING-BOTTOM: 1px"><div style="display: inline; font-weight: bold;"> </div></td> </tr> <tr> <td style="FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman, Times, serif"> </td> <td style="FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman, Times, serif"> </td> <td style="FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman, Times, serif; VERTICAL-ALIGN: bottom; TEXT-ALIGN: center" colspan="6"> <div style=" MARGIN-BOTTOM: 0pt; TEXT-ALIGN: center; MARGIN-TOP: 0pt; LINE-HEIGHT: 1.25"><div style="display: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman, Times, serif">(in thousands)</div></div></td> <td style="FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman, Times, serif"> </td> </tr> <tr> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> </tr> <tr style="BACKGROUND-COLOR: #cceeff"> <td style="FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman, Times, serif; WIDTH: 64%; VERTICAL-ALIGN: bottom; BACKGROUND-COLOR: #cceeff"> <div style=" MARGIN-BOTTOM: 0pt; MARGIN-TOP: 0pt; LINE-HEIGHT: 1.25"><div style="display: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman, Times, serif">Domestic</div></div></td> <td style="FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman, Times, serif; WIDTH: 1%; VERTICAL-ALIGN: bottom; BACKGROUND-COLOR: #cceeff"> </td> <td style="FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman, Times, serif; WIDTH: 1%; VERTICAL-ALIGN: bottom; BACKGROUND-COLOR: #cceeff">$</td> <td style="FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman, Times, serif; WIDTH: 15%; VERTICAL-ALIGN: bottom; TEXT-ALIGN: right; BACKGROUND-COLOR: #cceeff"><div style="display: inline; font-style: italic; font-weight: inherit; font-style: normal;">(9,805</div></td> <td style="FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman, Times, serif; WIDTH: 1%; VERTICAL-ALIGN: bottom; MARGIN-LEFT: 0pt; BACKGROUND-COLOR: #cceeff" nowrap="nowrap">)</td> <td style="FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman, Times, serif; WIDTH: 1%; VERTICAL-ALIGN: bottom; BACKGROUND-COLOR: #cceeff"> </td> <td style="FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman, Times, serif; WIDTH: 1%; VERTICAL-ALIGN: bottom; BACKGROUND-COLOR: #cceeff">$</td> <td style="FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman, Times, serif; WIDTH: 15%; VERTICAL-ALIGN: bottom; TEXT-ALIGN: right; BACKGROUND-COLOR: #cceeff"><div style="display: inline; font-style: italic; font-weight: inherit; font-style: normal;">(14,223</div></td> <td style="FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman, Times, serif; WIDTH: 1%; VERTICAL-ALIGN: bottom; MARGIN-LEFT: 0pt; BACKGROUND-COLOR: #cceeff" nowrap="nowrap">)</td> </tr> <tr style="BACKGROUND-COLOR: #ffffff"> <td style="FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman, Times, serif; VERTICAL-ALIGN: bottom; BACKGROUND-COLOR: #ffffff"> <div style=" MARGIN-BOTTOM: 0pt; MARGIN-TOP: 0pt; LINE-HEIGHT: 1.25"><div style="display: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman, Times, serif">Foreign</div></div></td> <td style="FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman, Times, serif; WIDTH: 1%; VERTICAL-ALIGN: bottom; BACKGROUND-COLOR: #ffffff"> </td> <td style="FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman, Times, serif; WIDTH: 1%; VERTICAL-ALIGN: bottom; BORDER-BOTTOM: #000000 1px solid; BACKGROUND-COLOR: #ffffff"> </td> <td style="FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman, Times, serif; WIDTH: 15%; VERTICAL-ALIGN: bottom; BORDER-BOTTOM: #000000 1px solid; TEXT-ALIGN: right; BACKGROUND-COLOR: #ffffff"><div style="display: inline; font-style: italic; font-weight: inherit; font-style: normal;">(379</div></td> <td style="FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman, Times, serif; WIDTH: 1%; VERTICAL-ALIGN: bottom; BORDER-BOTTOM: medium none; PADDING-BOTTOM: 1px; MARGIN-LEFT: 0pt; BACKGROUND-COLOR: #ffffff" nowrap="nowrap">)</td> <td style="FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman, Times, serif; WIDTH: 1%; VERTICAL-ALIGN: bottom; BACKGROUND-COLOR: #ffffff"> </td> <td style="FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman, Times, serif; WIDTH: 1%; VERTICAL-ALIGN: bottom; BORDER-BOTTOM: #000000 1px solid; BACKGROUND-COLOR: #ffffff"> </td> <td style="FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman, Times, serif; WIDTH: 15%; VERTICAL-ALIGN: bottom; BORDER-BOTTOM: #000000 1px solid; TEXT-ALIGN: right; BACKGROUND-COLOR: #ffffff"><div style="display: inline; font-style: italic; font-weight: inherit; font-style: normal;">(535</div></td> <td style="FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman, Times, serif; WIDTH: 1%; VERTICAL-ALIGN: bottom; BORDER-BOTTOM: medium none; PADDING-BOTTOM: 1px; MARGIN-LEFT: 0pt; BACKGROUND-COLOR: #ffffff" nowrap="nowrap">)</td> </tr> <tr style="BACKGROUND-COLOR: #cceeff"> <td style="FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman, Times, serif; VERTICAL-ALIGN: bottom; PADDING-LEFT: 9pt; BACKGROUND-COLOR: #cceeff"> <div style=" MARGIN-BOTTOM: 0pt; MARGIN-TOP: 0pt; LINE-HEIGHT: 1.25"><div style="display: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman, Times, serif">Total loss before income taxes</div></div></td> <td style="FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman, Times, serif; WIDTH: 1%; VERTICAL-ALIGN: bottom; BACKGROUND-COLOR: #cceeff"> </td> <td style="FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman, Times, serif; WIDTH: 1%; VERTICAL-ALIGN: bottom; BORDER-BOTTOM: #000000 3px double; BACKGROUND-COLOR: #cceeff">$</td> <td style="FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman, Times, serif; WIDTH: 15%; VERTICAL-ALIGN: bottom; BORDER-BOTTOM: #000000 3px double; TEXT-ALIGN: right; BACKGROUND-COLOR: #cceeff"><div style="display: inline; font-style: italic; font-weight: inherit; font-style: normal;">(10,184</div></td> <td style="FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman, Times, serif; WIDTH: 1%; VERTICAL-ALIGN: bottom; PADDING-BOTTOM: 3px; MARGIN-LEFT: 0pt; BACKGROUND-COLOR: #cceeff" nowrap="nowrap">)</td> <td style="FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman, Times, serif; WIDTH: 1%; VERTICAL-ALIGN: bottom; BACKGROUND-COLOR: #cceeff"> </td> <td style="FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman, Times, serif; WIDTH: 1%; VERTICAL-ALIGN: bottom; BORDER-BOTTOM: #000000 3px double; BACKGROUND-COLOR: #cceeff">$</td> <td style="FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman, Times, serif; WIDTH: 15%; VERTICAL-ALIGN: bottom; BORDER-BOTTOM: #000000 3px double; TEXT-ALIGN: right; BACKGROUND-COLOR: #cceeff"><div style="display: inline; font-style: italic; font-weight: inherit; font-style: normal;">(14,758</div></td> <td style="FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman, Times, serif; WIDTH: 1%; VERTICAL-ALIGN: bottom; PADDING-BOTTOM: 3px; MARGIN-LEFT: 0pt; BACKGROUND-COLOR: #cceeff" nowrap="nowrap">)</td> </tr> </table></div>

Schedule of Effective Income Tax Rate Reconciliation [Table Text Block]

	April 30, 2017			April 30, 2016

Computed expected tax benefit		-34.0	%		-34.0	%
Increase(reduction) in income taxes resulting from:
State income taxes, net of federal benefit		2.3	%		6.0	%
Federal research and development tax credits		-1.7	%		-3.0	%
Foreign rate differential		0.3	%		1.0	%
Other non-deductible expenses		0.1	%		5.0	%
Proceeds of sale of New Jersey tax benefits		-6.9	%		-11.0	%
Other		11.7	%		13.0	%
Increase in valuation allowance		25.9	%		12.0	%
Income tax benefit		2.3	%		-11.0	%

Schedule of Deferred Tax Assets and Liabilities [Table Text Block]

	April 30, 2017			April 30, 2016
	(in thousands)

Deferred tax assets:
Federal net operating loss carryforwards	$	44,355		$	40,540
Foreign net operating loss carryforwards		3,761			4,393
State operating loss carryforwards		1,281			1,375
Federal and New Jersey research and development tax credits		2,996			2,708
Stock compensation		1,096			732
Unrealized foreign exchange loss		17			536
Accrued expenses		576			1,324
Other		627			945
Net deferred tax assets before valuation allowance		54,709			52,553
Valuation allowance		(54,709	)		(52,553	)
Net deferred tax assets	$	-		$	-

Note 15 - Commitments and Contingencies (Tables)

12 Months Ended

Apr. 30, 2017

Notes Tables

Lessee, Operating Lease, Disclosure [Table Text Block]

	April 30, 2017
	(in thousands)

2018	$	348
2019		313
2020		323
2021		332
2022		342
Thereafter		869
	$	2,527

Note 16 - Operating Segments and Geographic Information (Tables)

12 Months Ended

Apr. 30, 2017

Notes Tables

Schedule of Revenue from External Customers and Long-Lived Assets, by Geographical Areas [Table Text Block]

	Year Ended April 30, 2017

	North						Asia and
	America			Europe			Australia			Total
	(in thousands)

Revenues from external customers	$	843		$	-		$	-		$	843
Operating loss		(11,270	)		(389	)		(28	)		(11,687	)
Long-lived assets		170			-			-			170
Total assets		9,498			209			366			10,073

	Year Ended April 30, 2016

	North						Asia and
	America			Europe			Australia			Total
	(in thousands)

Revenues from external customers	$	705		$	-		$	-		$	705
Operating loss		(14,402	)		(295	)		(161	)		(14,858	)
Long-lived assets		273			-			-			273
Total assets		9,553			395			403			10,351

Note 1 - Background and Liquidity (Details Textual)							7 Months Ended	12 Months Ended
Note 1 - Background and Liquidity (Details Textual)	May 02, 2017 USD ($) $ / shares shares	Oct. 19, 2016 USD ($) $ / shares shares	Jul. 22, 2016 USD ($) $ / shares shares	Jun. 02, 2016 USD ($) $ / shares shares	Oct. 27, 2015 shares	Oct. 22, 2015	Apr. 30, 2016 USD ($) $ / shares shares	Apr. 30, 2017 USD ($) shares	Apr. 30, 2016 USD ($) $ / shares shares	Feb. 12, 2016 USD ($)	Apr. 30, 2015 USD ($)
Retained Earnings (Accumulated Deficit)							$ (177,884,000)	$ (187,370,000)	$ (177,884,000)
Cash and Cash Equivalents, at Carrying Value							$ 6,730,000	8,421,000	6,730,000		$ 17,336,000
Revenues								843,000	705,000
Proceeds from Issuance or Sale of Equity								$ 12,150,000
Common Stock, Shares Authorized \| shares					50,000,000		50,000,000	50,000,000	50,000,000
Reverse Stock Split [Member]
Stockholders' Equity Note, Stock Split, Conversion Ratio					10	10
Offering Agreement [Member]
Aggregate Market Value, Common Stock							$ 293,343		$ 293,343
Share Price \| $ / shares		$ 2.75					$ 2.03		$ 2.03
Stock Issued During Period, Shares, New Issues \| shares		2,760,000					144,571
Payments of Stock Issuance Costs							$ 4,400
Shelf Registration Amount Of Securities To Offer And Sale										$ 15,000,000
Purchase Agreement [Member]
Stock Issued During Period, Shares, New Issues \| shares			595,000	417,000
Class of Warrant or Right, Number of Securities Called by Warrants or Rights \| shares			178,500	145,952
Class of Warrant or Right, Number of Securities Called by Each Warrant or Right \| shares			0.3	0.35
Price Per Common Stock and Warrant \| $ / shares			$ 6.75	$ 4.60
Proceeds from Issuance or Sale of Equity			$ 3,600,000	$ 1,700,000
Class of Warrant or Right, Exercise Price of Warrants or Rights \| $ / shares			$ 9.36	$ 6.08
Class of Warrant or Right, Expiration Period			5 years	5 years
Purchase Agreement [Member] \| Placement Agents [Member] \| Placement Agent Fees [Member]
Payments of Stock Issuance Costs				$ 100,000
Purchase Agreement [Member] \| Placement Agents [Member] \| Reimbursement of Out of Pocket and Legal Expenses [Member]
Payments of Stock Issuance Costs				$ 35,000
Over-Allotment Option [Member]
Stock Issued During Period, Shares, New Issues \| shares		360,000
Proceeds from Issuance or Sale of Equity		$ 6,900,000
Subsequent Event [Member]
Share Price \| $ / shares	$ 1.30
Stock Issued During Period, Shares, New Issues \| shares	6,192,750
Proceeds from Issuance or Sale of Equity	$ 7,200,000
Subsequent Event [Member] \| Over-Allotment Option [Member]
Stock Issued During Period, Shares, New Issues \| shares	807,750

Note 2 - Summary of Significant Accounting Policies (Details Textual) $ / shares in Units, $ in Thousands, € in Millions	12 Months Ended
	Apr. 30, 2017 USD ($) $ / shares shares	Apr. 30, 2016 USD ($) $ / shares shares	Apr. 30, 2017 EUR (€)	Apr. 30, 2016 EUR (€)	Sep. 30, 2015	Nov. 30, 2011 USD ($)
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount \| shares	657,078	129,311
Allocated Share-based Compensation Expense	$ 1,232	$ 337
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value \| $ / shares	$ 2.52	$ 0.58
Barclays Bank [Member]
Line of Credit Facility, Commitment Fee Percentage	1.00%
Long-term Line of Credit	$ 300	$ 300	€ 0.3	€ 0.3
New Jersey Board of Public Utilities 1 [Member]
Restricted Cash and Cash Equivalents						$ 500
OPTA [Member]
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners					11.80%
Ownership Percentage					100.00%

Note 2 - Summary of Significant Accounting Policies - Cash and Cash Equivalents (Details) - USD ($) $ in Thousands	Apr. 30, 2017	Apr. 30, 2016	Apr. 30, 2015
Cash and cash equivalents	$ 8,421	$ 6,730	$ 17,336
Checking and Savings Accounts [Member]
Cash and cash equivalents	4,241	4,535
Overnight Repurchase Account [Member]
Cash and cash equivalents	$ 4,180	$ 2,195

Note 2 - Summary of Significant Accounting Policies - Cash Restricted Under Security Agreements (Details) - USD ($) $ in Thousands	Apr. 30, 2017	Apr. 30, 2016
Restricted cash	$ 488	$ 300
Barclays Bank Agreement [Member]
Restricted cash	334	250
Santander Bank [Member]
Restricted cash	154
NJBPU Agreement [Member]
Restricted cash		$ 50

Note 2 - Summary of Significant Accounting Policies - Property and Equipment Useful Lives (Details)	12 Months Ended
	Apr. 30, 2017
Equipment [Member] \| Minimum [Member]
Property and equipment, useful life (Year)	5 years
Equipment [Member] \| Maximum [Member]
Property and equipment, useful life (Year)	7 years
Computers and Software [Member]
Property and equipment, useful life (Year)	3 years
Office Furniture and Equipment [Member] \| Minimum [Member]
Property and equipment, useful life (Year)	3 years
Office Furniture and Equipment [Member] \| Maximum [Member]
Property and equipment, useful life (Year)	7 years
Assets Held under Capital Leases [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

Note 2 - Summary of Significant Accounting Policies - Revenues by Major Customers (Details) - Customer Concentration Risk [Member] - Sales Revenue, Net [Member]	12 Months Ended
	Apr. 30, 2017	Apr. 30, 2016
Revenues, percentage	100.00%	100.00%
Mitsui Engineering and Ship Building [Member]
Revenues, percentage	80.00%	14.00%
U.S. Department of Defense Office of Naval Research [Member]
Revenues, percentage	20.00%	0.00%
US Department of Energy [Member]
Revenues, percentage	0.00%	28.00%
European Union Waver Port Project [Member]
Revenues, percentage	0.00%	58.00%

Note 2 - Summary of Significant Accounting Policies - Share-based Compensation (Details) - USD ($) $ in Thousands	12 Months Ended
	Apr. 30, 2017	Apr. 30, 2016
Allocated Share-based Compensation Expense	$ 1,232	$ 337
Product Development [Member]
Allocated Share-based Compensation Expense	525	131
Selling, General and Administrative Expenses [Member]
Allocated Share-based Compensation Expense	$ 707	$ 206

Note 2 - Summary of Significant Accounting Policies - Weighted Average Fair Value Assumptions for Stock-based Compensation (Details)	12 Months Ended
	Apr. 30, 2017	Apr. 30, 2016
Risk-free interest rate	1.30%	1.60%
Expected dividend yield	0.00%	0.00%
Expected life (in years) (Year)	5 years 182 days	5 years 182 days
Expected volatility	96.20%	85.70%

Note 3 - Marketable Securities - Marketable Securities That Mature Within One Year (Details) - USD ($) $ in Thousands	Apr. 30, 2017	Apr. 30, 2016
Marketable securities	$ 25	$ 75

Note 4 - Property and Equipment (Details Textual) - USD ($) $ in Thousands	12 Months Ended
	Apr. 30, 2017	Apr. 30, 2016
Depreciation	$ 100	$ 100
Capital Lease, Term	3 years	3 years
Computers and Software [Member]
Capital Leased Assets, Gross	$ 103	$ 99

Note 4 - Property and Equipment - Components of Property and Equipment (Details) - USD ($) $ in Thousands	Apr. 30, 2017	Apr. 30, 2016
Property and equipment, gross	$ 1,806	$ 1,773
Less: accumulated depreciation	(1,636)	(1,500)
Property and equipment, net	170	273
Equipment [Member]
Property and equipment, gross	715	711
Computers and Software [Member]
Property and equipment, gross	556	630
Office Furniture and Equipment [Member]
Property and equipment, gross	250	250
Leasehold Improvements [Member]
Property and equipment, gross	182	182
Assets Held under Capital Leases [Member]
Property and equipment, gross	$ 103	$ 0

Note 4 - Property and Equipment - Capital Lease Commitments (Details) $ in Thousands	Apr. 30, 2017 USD ($)
2018	$ 35
2019	23
Total net future minimum lease payments	58
Less; Amount representing interest	(4)
Present value of net minimum lease payments	$ 54

Note 5 - Accrued Expenses - Accrued Expenses (Details) - USD ($) $ in Thousands	Apr. 30, 2017	Apr. 30, 2016
Project costs	$ 898	$ 818
Contract loss reserve	238	199
Employee incentive payments	643	688
Accrued salary and benefits	484	456
Legal and accounting fees	478	240
Accrued taxes payable	132
Other	186	274
Accrued expenses total	$ 3,059	$ 2,675

Note 6 - Related Party Transactions (Details Textual) - George W. Taylor [Member] - USD ($)	1 Months Ended	12 Months Ended
	Apr. 30, 2014	Apr. 30, 2017	Apr. 30, 2016
Related Party Transaction Term of Agreement	1 year 90 days
Related Party Transaction Monthly Consulting Fee	$ 20,000
Selling, General and Administrative Expenses [Member]
Related Party Transaction, Expenses from Transactions with Related Party		$ 0	$ 53,000

Note 7 - Debt (Details Textual) - USD ($) $ in Thousands	1 Months Ended
Note 7 - Debt (Details Textual) - USD ($) $ in Thousands	Nov. 30, 2011	Apr. 30, 2017	Apr. 30, 2016	Jun. 30, 2010
Other Assets, Current		$ 622	$ 117
New Jersey Board of Public Utilities 1 [Member]
Long-term Debt		0	50
Long-term Debt Payment Terms	5 years
New Jersey Board of Public Utilities 1 [Member] \| Certificates of Deposit [Member]
Other Assets, Current		$ 0	$ 50
Corporation [Member]
Long-term Debt				$ 500

Note 8 - Deferred Credits Payable (Details Textual) $ in Millions	Apr. 30, 2017 USD ($)	Apr. 30, 2016 USD ($)	Apr. 30, 2001 USD ($) T Rate
Deferred Credits Payable Market Discount Rate \| Rate			30.00%
Deferred Credits Payable Market Liquidated Damages Rate \| Rate			30.00%
Customer Advances or Deposits, Noncurrent \| $		$ 0.6	$ 0.6
Deferred Credits Payable Option Details \| T			500,000
Customer Advances and Deposits, Current \| $	$ 0.6

Note 9 - Warrants (Details Textual) - USD ($) $ / shares in Units, $ in Thousands			12 Months Ended
	Jul. 22, 2016	Jun. 02, 2016	Apr. 30, 2017	Apr. 30, 2016
Fair Value Adjustment of Warrants			$ (1,491)	$ 0
Warrant [Member]
Derivative Liability, Current			$ 300	$ 0
Purchase Agreement [Member]
Price Per Common Stock and Warrant	$ 6.75	$ 4.60
Class of Warrant or Right, Exercise Price of Warrants or Rights	$ 9.36	$ 6.08
Class of Warrant or Right, Expiration Period	5 years	5 years
Stock Issued During Period, Shares, New Issues	595,000	417,000
Class of Warrant or Right, Number of Securities Called by Warrants or Rights	178,500	145,952
Class of Warrant or Right, Number of Securities Called by Each Warrant or Right	0.3	0.35

Note 9 - Warrants - Fair Value Assumptions for Warrants (Details) - Warrant [Member]	12 Months Ended
	Apr. 30, 2017
Dividend rate	0.00%
Risk-free rate	1.81%
Minimum [Member]
Expected life (years) (Year)	4 years 73 days
Expected volatility	131.70%
Maximum [Member]
Expected life (years) (Year)	4 years 219 days
Expected volatility	141.30%

Note 10 - Common Stock (Details Textual)	Oct. 27, 2015	Oct. 22, 2015
Reverse Stock Split [Member]
Stockholders' Equity Note, Stock Split, Conversion Ratio	10	10

Note 11 - Preferred Stock (Details Textual) - $ / shares	Apr. 30, 2017	Apr. 30, 2016
Preferred Stock, Shares Authorized	5,000,000	5,000,000
Preferred Stock, Par or Stated Value Per Share	$ 0.001	$ 0.001
Preferred Stock, Shares Issued	0	0

Note 12 - Share-based Compensation Plans (Details Textual) - USD ($)			12 Months Ended
	Oct. 02, 2013	Oct. 02, 2009	Apr. 30, 2017	Apr. 30, 2016	Oct. 21, 2016	Apr. 30, 2015	Apr. 30, 2007	Apr. 30, 2001
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value			$ 5,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Intrinsic Value			$ 4,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Number of Shares			101,262
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Weighted Average Remaining Contractual Term			9 years 146 days
Allocated Share-based Compensation Expense			$ 1,232,000	$ 337,000
Treasury Stock, Shares, Acquired			41,171	3,029
Employee Stock Option [Member]
Allocated Share-based Compensation Expense			$ 300,000	$ 100,000
Employee Service Share-based Compensation, Nonvested Awards, Compensation Not yet Recognized, Stock Options			$ 200,000
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition			182 days
Restricted Stock [Member]
Allocated Share-based Compensation Expense			$ 900,000	$ 100,000
Employee Service Share-based Compensation, Nonvested Awards, Compensation Not yet Recognized, Share-based Awards Other than Options			$ 27
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition			182 days
Restricted Stock [Member] \| Service-based Vesting [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period			223,662
Restricted Stock [Member] \| Performance-based vesting [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period			0
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number			12,000
Stock Plan 2001 [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant			0
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized								100,000
Stock Incentive Plan 2006 [Member]
Share Based Compensation Arrangement By Share Based Payment Award Maximum Number of Shares Grants Per Participant			20,000
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized	245,321	165,321					80,321
Share-based Compensation Arrangement by Share-based Payment Award, Number of Additional Shares Authorized	80,000	85,000
Stock Incentive Plan 2006 [Member] \| Maximum [Member]
Sharebased Compensation Arrangement By Sharebased Payment Award Options Outstanding Contractual Term			10 years
Stock Incentive Plan 2015 [Member]
Common Stock, Capital Shares Reserved for Future Issuance			322,305
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized					640,703	240,703
Share-based Compensation Arrangement by Share-based Payment Award, Plan Effective Period			10 years
Stock Incentive Plan 2015 [Member] \| Stock Appreciation Rights (SARs) [Member]
Share Based Compensation Arrangement By Share Based Payment Award Maximum Number of Shares Grants Per Participant			75,000

Note 12 - Share-based Compensation Plans - Stock Options Under the Plans (Details) - $ / shares	12 Months Ended
	Apr. 30, 2017	Apr. 30, 2016
Beginning Balance, shares underlying options (in shares)	89,303
Beginning Balance, weighted average exercise price (in dollars per share)	$ 42.90
Ending Balance, weighted average exercise price (in dollars per share)	$ 14.64	$ 42.90
Balance, weighted average remaining contractual term (Year)	7 years 219 days	3 years 219 days
Forfeited (in shares)	(23,838)
Forfeited (in dollars per share)	$ 30.38
Exercised (in shares)
Exercised (in dollars per share)
Exercisable, shares underlying options (in shares)	134,381
Exercisable, weighted average exercise price (in dollars per share)	$ 23.55
Exercisable, weighted average remaining contractual term (Year)	6 years 73 days
Granted (in shares)	171,749
Granted (in dollars per share)	$ 2.12
Ending Balance, shares underlying options (in shares)	237,214	89,303

Note 12 - Share-based Compensation Plans - Non-vested Restricted Stock Under the Plans (Details) - Non-vested Restricted Stock [Member]	12 Months Ended
	Apr. 30, 2017 $ / shares shares
Beginning Balance, issued and unvested (in shares) \| shares	44,008
Beginning Balance, issued and unvested (in dollars per share) \| $ / shares	$ 6.35
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period \| shares	223,662
Granted (in dollars per share) \| $ / shares	$ 3.94
Forfeited (in shares) \| shares	(28,266)
Forfeited (in dollars per share) \| $ / shares	$ 3.98
Vested (in shares) \| shares	(135,992)
Vested (in dollars per share) \| $ / shares	$ 4.68
Ending Balance, issued and unvested (in shares) \| shares	103,412
Ending Balance, issued and unvested (in dollars per share) \| $ / shares	$ 3.99

Note 13 - Fair Value Measurements - Financial Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	Apr. 30, 2017	Apr. 30, 2016
Warrant liabilities	$ 323
Warrant [Member] \| Fair Value, Measurements, Recurring [Member] \| Reported Value Measurement [Member]
Warrant liabilities	323
Warrant [Member] \| Fair Value, Measurements, Recurring [Member] \| Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 1 [Member]
Warrant liabilities
Warrant [Member] \| Fair Value, Measurements, Recurring [Member] \| Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 2 [Member]
Warrant liabilities
Warrant [Member] \| Fair Value, Measurements, Recurring [Member] \| Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 3 [Member]
Warrant liabilities	$ 323

Note 13 - Fair Value Measurements - Changes on Value of Warrant Liability (Details) - Warrant [Member] $ in Thousands	12 Months Ended
	Apr. 30, 2017 USD ($)
Fair value – April 30, 2016
Issuance	1,814
Transfers
Change in fair value	(1,491)
Fair value – April 30, 2017	$ 323

Note 14 - Income Taxes (Details Textual) - USD ($) $ in Thousands	12 Months Ended
	Apr. 30, 2017	Apr. 30, 2016
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent	34.00%	34.00%
Deferred Tax Assets, Valuation Allowance	$ 54,709	$ 52,553
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount	2,100	1,800
Deferred Tax Assets, Tax Credit Carryforwards, Research	2,996	2,708
Operating Loss Carryforwards, Limitation	3,300
Income Tax Expense (Benefit)	(698)	(1,674)
Unrecognized Tax Benefits	0	0
Income Tax Examination, Penalties and Interest Accrued	0
New Jersey Division of Taxation [Member]
Proceed from Sale of Loss Carryforwards and Tax Credits	7,800	$ 19,700
Domestic Tax Authority [Member]
Deferred Tax Assets, Tax Credit Carryforwards, Research	2,800
Operating Loss Carryforwards	130,500
State and Local Jurisdiction [Member]
Operating Loss Carryforwards	21,600
Foreign Tax Authority [Member]
Operating Loss Carryforwards	16,900
Foreign Tax Authority [Member] \| Tax Authority, Spain [Member] \| Selling, General and Administrative Expenses [Member]
Income Tax Examination, Penalties Expense	$ 132

Note 14 - Income Taxes - Components of Loss Before Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Apr. 30, 2017	Apr. 30, 2016
Domestic	$ (9,805)	$ (14,223)
Foreign	(379)	(535)
Loss before income taxes	$ (10,184)	$ (14,758)

Note 14 - Income Taxes - Effective Income Tax Rate Reconciliation (Details)	12 Months Ended
	Apr. 30, 2017	Apr. 30, 2016
Computed expected tax benefit	34.00%	34.00%
Increase(reduction) in income taxes resulting from:
State income taxes, net of federal benefit	2.30%	6.00%
Federal research and development tax credits	1.70%	3.00%
Foreign rate differential	0.30%	1.00%
Other non-deductible expenses	0.10%	5.00%
Proceeds of sale of New Jersey tax benefits	6.90%	11.00%
Other	11.70%	13.00%
Increase in valuation allowance	25.90%	12.00%
Income tax benefit	2.30%	11.00%

Note 14 - Income Taxes - Deferred Tax Assets and Deferred Tax Liabilities (Details) - USD ($) $ in Thousands	Apr. 30, 2017	Apr. 30, 2016
Federal net operating loss carryforwards	$ 44,355	$ 40,540
Foreign net operating loss carryforwards	3,761	4,393
State operating loss carryforwards	1,281	1,375
Federal and New Jersey research and development tax credits	2,996	2,708
Stock compensation	1,096	732
Unrealized foreign exchange loss	17	536
Accrued expenses	576	1,324
Other	627	945
Net deferred tax assets before valuation allowance	54,709	52,553
Valuation allowance	(54,709)	(52,553)
Net deferred tax assets

Note 15 - Commitments and Contingencies (Details Textual) € in Millions						1 Months Ended				12 Months Ended
	Apr. 12, 2017 USD ($)	Mar. 31, 2017 USD ($) ft²	Nov. 14, 2016 USD ($)	Oct. 27, 2015	Oct. 22, 2015	Dec. 15, 2016 USD ($) shares	Aug. 31, 2016 USD ($)	Jul. 31, 2016 USD ($)	Jun. 30, 2012 USD ($)	Apr. 30, 2017 USD ($)	Apr. 30, 2016 USD ($)	Jan. 31, 2017 USD ($)	Jan. 25, 2016	Jun. 30, 2012 EUR (€)
Operating Leases, Rent Expense										$ 300,000	$ 300,000
Stock Issued During Period, Value, Litigation Settlement											$ 596,000
Tax Authority, Spain [Member] \| Foreign Tax Authority [Member]
Input Tax									$ 300,000
Letters of Credit Outstanding, Amount									$ 300,000					€ 0.3
Foreign Tax Examination Refund												$ (200,000)
Tax Authority, Spain [Member] \| Foreign Tax Authority [Member] \| Selling, General and Administrative Expenses [Member]
Income Tax Examination, Penalties Expense										$ 132,000
Reverse Stock Split [Member]
Stockholders' Equity Note, Stock Split, Conversion Ratio				10	10
Stipulation [Member]
Litigation Settlement, Amount Awarded to Other Party			$ 3,000,000
Stock Issued During Period, Shares, Litigation Settlement \| shares						380,000
Stock Issued During Period, Value, Litigation Settlement						$ 600,000
Payments for Legal Settlements								$ 500,000
Litigation Settlement, Amount Paid by Insurer							$ 2,500,000
Stern Lawsuit [Member]
Affirmative Vote Percentage By Stockholders													75.00%
Payments for Legal Settlements	$ 22,500
Monroe Lease [Member]
Area of Real Estate Property \| ft²		56,000
Lessee, Operating Lease, Term of Contract		7 years
Security Deposit		$ 154,000
Operating Leases, Tenant Improvement Allowance, Maximum		$ 138,000

Note 15 - Commitments and Contingencies - Operating Lease Commitments (Details) $ in Thousands	Apr. 30, 2017 USD ($)
2018	$ 348
2019	313
2020	323
2021	332
2022	342
Thereafter	869
Total	$ 2,527

Note 16 - Operating Segments and Geographic Information (Details Textual)	12 Months Ended
	Apr. 30, 2017
Number of Operating Segments	1

Note 16 - Operating Segments and Geographic Information - Geographic Segment Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Apr. 30, 2017	Apr. 30, 2016
Long-lived assets	$ 170	$ 273
Total assets	10,073	10,351
Revenues	843	705
Operating loss	(11,687)	(14,858)
North America [Member]
Long-lived assets	170	273
Total assets	9,498	9,553
Revenues	843	705
Operating loss	(11,270)	(14,402)
Asia and Australia [Member]
Long-lived assets
Total assets	366	403
Revenues
Operating loss	(28)	(161)
Europe [Member]
Long-lived assets
Total assets	209	395
Operating loss	$ (389)	$ (295)

Note 17 - Subsequent Event (Details Textual) - USD ($)			12 Months Ended
Note 17 - Subsequent Event (Details Textual) - USD ($)	May 02, 2017	Oct. 19, 2016	Apr. 30, 2017	Apr. 30, 2016
Proceeds from Issuance or Sale of Equity			$ 12,150,000
Over-Allotment Option [Member]
Stock Issued During Period, Shares, New Issues		360,000
Proceeds from Issuance or Sale of Equity		$ 6,900,000
Subsequent Event [Member]
Share Price	$ 1.30
Stock Issued During Period, Shares, New Issues	6,192,750
Proceeds from Issuance or Sale of Equity	$ 7,200,000
Subsequent Event [Member] \| Over-Allotment Option [Member]
Stock Issued During Period, Shares, New Issues	807,750