P10 Industries (PIOE) 10-K 27 Feb 15 2014 FY Annual report Financial data

Document_and_Entity_Informatio

Document and Entity Information (USD $)	12 Months Ended
In Millions, except Share data, unless otherwise specified	Dec. 31, 2014	Feb. 25, 2015	Jun. 30, 2014
Document and Entity Information [Abstract]
Entity Registrant Name	ACTIVE POWER INC
Entity Central Index Key	1044435
Current Fiscal Year End Date	-19
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Accelerated Filer
Entity Public Float			$53.70
Entity Common Stock, Shares Outstanding		23,157,509
Document Fiscal Year Focus	2014
Document Fiscal Period Focus	FY
Document Type	10-K
Amendment Flag	FALSE
Document Period End Date	31-Dec-14

Consolidated_Balance_Sheets

Consolidated Balance Sheets (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Current assets:
Cash and cash equivalents	$14,824	$12,261
Restricted cash	40	520
Accounts receivable, net of allowance for doubtful accounts of $212 and $313 at December 31, 2014 and December 31, 2013, respectively	11,222	9,075
Inventories, net	6,845	12,020
Prepaid expenses and other	800	680
Total current assets	33,731	34,556
Property and equipment, net	2,076	3,056
Deposits and other	291	295
Total assets	36,098	37,907
Current liabilities:
Accounts payable	4,044	2,993
Accrued expenses	4,134	5,583
Deferred revenue	2,771	2,749
Revolving line of credit	5,535	5,535
Total current liabilities	16,484	16,860
Long-term liabilities	821	741
Commitments and contingencies
Stockholders' equity:
Preferred stock - $0.001 par value; 2,000 shares authorized	0	0
Common stock - $0.001 par value; 40,000 and 30,000 shares authorized; 23,162 and 19,452 issued and 23,094 and 19,388 outstanding at December 31, 2014 and 2013, respectively	23	19
Treasury stock	-231	-215
Additional paid-in capital	302,667	290,964
Accumulated deficit	-283,995	-271,168
Other accumulated comprehensive income	329	706
Total stockholders' equity	18,793	20,306
Total liabilities and stockholders' equity	$36,098	$37,907

Consolidated_Balance_Sheets_Pa

Consolidated Balance Sheets (Parenthetical) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, except Per Share data, unless otherwise specified
Current assets:
Accounts receivable, allowance for doubtful accounts	$212	$313
Stockholders' equity:
Preferred Stock, par value (in dollars per share)	$0.00	$0.00
Preferred stock authorized (in shares)	2,000	2,000
Common Stock, par value (in dollars per share)	$0.00	$0.00
Common Stock, shares authorized (in shares)	40,000	30,000
Common Stock, shares issued (in shares)	23,162	19,452
Common Stock, shares outstanding (in shares)	23,094	19,388

Consolidated_Statement_of_Oper

Consolidated Statement of Operations and Comprehensive Loss (USD $)	12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Revenues:
Product revenue	$36,211	$44,158	$62,031
Service and other revenue	12,925	17,541	14,284
Total revenue	49,136	61,699	76,315
Cost of goods sold:
Cost of product revenue	29,182	32,825	42,510
Cost of service and other revenue	7,302	9,478	9,091
Total cost of goods sold	36,484	42,303	51,601
Gross profit	12,652	19,396	24,714
Operating expenses:
Research and development	6,689	7,430	5,440
Selling and marketing	11,940	12,032	14,139
General and administrative	6,043	7,551	6,861
Total operating expenses	24,672	27,013	26,440
Loss from Operations	-12,020	-7,617	-1,726
Interest expense, net	-395	-370	-327
Other income (expense), net	-160	-364	131
Loss before income taxes	-12,575	-8,351	-1,922
Income tax expense	-252	0	0
Net Loss	-12,827	-8,351	-1,922
Net Loss per share, basic and diluted (in dollars per share)	($0.57)	($0.43)	($0.10)
Shares used in computing net loss per share, basic and diluted (in shares)	22,494	19,329	18,584
Comprehensive loss:
Net Loss	-12,827	-8,351	-1,922
Translation gain (loss) on subsidiaries denominated in foreign currencies	-377	384	123
Comprehensive loss	($13,204)	($7,967)	($1,799)

Consolidated_Statement_of_Stoc

Consolidated Statement of Stockholders' Equity (USD $)	Common Stock [Member]	Treasury Stock [Member]	Additional Paid-In Capital [Member]	Accumulated Deficit [Member]	Other Accumulated Comprehensive Income (Loss) [Member]	Total
In Thousands, except Share data, unless otherwise specified
Balance at Dec. 31, 2011	$16	($115)	$277,087	($260,895)	$199	$16,292
Balance (in shares) at Dec. 31, 2011	16,116,000	28,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Employee stock option exercises	0	0	562	0	0	562
Employee stock option exercises (in shares)	155,000	0
Sale of common stock, less issuance costs	3	0	9,560	0	0	9,563
Sale of common stock, less issuance costs (in shares)	2,868,000	0
Release of Restricted Stock	0	0	0	0	0	0
Release of Restricted Stock (in shares)	32,000	0
Shares held in treasury	0	-29	0	0	0	-29
Shares held in treasury (in shares)	0	5,000
Net translation gain (loss) on foreign subsidiaries	0	0	0	0	123	123
Stock-based compensation	0	0	1,410	0	0	1,410
Net Loss	0	0	0	-1,922	0	-1,922
Balance at Dec. 31, 2012	19	-144	288,619	-262,817	322	25,999
Balance (in shares) at Dec. 31, 2012	19,171,000	33,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Employee stock option exercises	0	0	711	0	0	711
Employee stock option exercises (in shares)	200,000	0
Release of Restricted Stock	0		4	0	0	4
Release of Restricted Stock (in shares)	81,000
Shares held in treasury	0	-71	0	0	0	-71
Shares held in treasury (in shares)	0	18,000
Net translation gain (loss) on foreign subsidiaries	0	0	0	0	384	384
Stock-based compensation	0	0	1,689	0	0	1,689
Issuance costs, shelf registration			-59		0	-59
Net Loss	0	0	0	-8,351	0	-8,351
Balance at Dec. 31, 2013	19	-215	290,964	-271,168	706	20,306
Balance (in shares) at Dec. 31, 2013	19,452,000	51,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Employee stock option exercises	0	0	129	0	0	129
Employee stock option exercises (in shares)	43,000	0
Sale of common stock, less issuance costs	4		10,434			10,438
Sale of common stock, less issuance costs (in shares)	3,651,000
Release of Restricted Stock	0			0	0	0
Release of Restricted Stock (in shares)	16,000
Shares held in treasury		-16	0	0	0	-16
Shares held in treasury (in shares)		5,000
Net translation gain (loss) on foreign subsidiaries	0	0	0	0	-377	-377
Stock-based compensation	0	0	1,140	0	0	1,140
Net Loss	0	0	0	-12,827	0	-12,827
Balance at Dec. 31, 2014	$23	($231)	$302,667	($283,995)	$329	$18,793
Balance (in shares) at Dec. 31, 2014	23,162,000	56,000

Consolidated_Statement_of_Cash

Consolidated Statement of Cash Flows (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Operating activities
Net Loss	($12,827)	($8,351)	($1,922)
Adjustments to reconcile net loss to cash used in operating activities:
Depreciation expense	1,220	1,084	1,282
Change to allowance for doubtful accounts	-101	-175	151
Loss (gain) on disposal of fixed assets	4	30	-35
Impairment on fixed assets	57	69	218
Stock-based compensation	1,140	1,700	1,410
Changes in operating assets and liabilities:
Restricted cash	480	-520	389
Accounts receivable	-2,046	8,962	-6,850
Inventories	5,257	-1,796	-1,640
Prepaid expenses and other assets	-116	-99	-58
Accounts payable	1,051	-1,043	-721
Accrued expenses	-1,449	623	-403
Deferred revenue	22	-1,819	2,202
Long term liabilities	80	28	-13
Net cash used in operating activities	-7,228	-1,307	-5,990
Investing activities
Purchases of property and equipment	-343	-996	-1,274
Proceeds from sale of fixed assets	19	71	212
Net cash used in investing activities	-324	-925	-1,062
Financing activities
Proceeds from public offering of common stock, net of issuance costs	10,438	0	0
Proceeds from private placement of common stock	0	0	9,750
Issuance costs of private placement	0	0	-187
Proceeds from draw on revolving line of credit	0	0	2,017
Payments on revolving line of credit	0	0	-2,017
Proceeds from employee stock option exercises	129	711	562
Issuance costs, shelf registration		-59	0
Taxes paid related to the net share settlement of equity awards	-16	-67	-29
Net cash provided by financing activities	10,551	585	10,096
Effects of exchange rates on cash	-436	384	123
Change in cash and cash equivalents	2,563	-1,263	3,167
Cash and cash equivalents, beginning of period	12,261	13,524	10,357
Cash and cash equivalents, end of period	14,824	12,261	13,524
Supplemental Cash Flow Information:
Interest Paid	401	380	335
Income Tax Paid	$252	$0	$0

Summary_of_Significant_Account

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2014
Summary of Significant Accounting Policies [Abstract]
Summary of Significant Accounting Policies	1. Summary of Significant Accounting Policies
	Description of Business
	Active Power, Inc. and its subsidiaries (collectively, “we”, “us”, “Active Power” or “Company”) design, manufacture, sell and service flywheel-based uninterruptible power supply (“UPS”) products that use kinetic energy to provide short-term power as a cleaner alternative to conventional electro-chemical battery-based energy storage. We also design, manufacture, sell, and service modular infrastructure solutions (“MIS”) that integrate critical power components into a pre-packaged, purpose built enclosure that may include our UPS products as a component. Our products and solutions are based on our patented flywheel and power electronics technology and are designed to ensure continuity for data centers and other mission critical operations in the event of power disturbances.
	Our products and solutions are designed to deliver continuous conditioned power during power disturbances such as voltage sags and surges, and to provide ride-through power in the event of a brief utility failure, supporting operations until utility power is restored or a longer term alternative power source, such as a diesel generator, is started. We sell our products globally through our direct sales force, manufacturer’s representatives, distributors, Original Equipment Manufacturer (“OEM”) channel, and IT partners in the Americas, in Europe, Middle East, and Africa (“EMEA”), and in the Asia Pacific region (“APAC”).
	We also offer services, including hardware and software maintenance, on all Active Power products, and other professional services such as assessment and implementation, for our customers’ infrastructure projects.
	We were founded as a Texas Corporation in 1992 and reincorporated in Delaware in 2000. Our headquarters are in Austin, Texas with international offices in the United Kingdom, Germany and China.
	The accompanying consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (“US GAAP”) and include the accounts of the Company and its consolidated subsidiaries. All intercompany transactions and balances have been eliminated upon consolidation.
	The accompanying consolidated financial statements have also been prepared on the assumption that the Company will continue to operate as a going concern. Accordingly, assets and liabilities are recorded on the basis that the Company will be able to realize its assets and discharge its liabilities in the normal course of business. The Company’s history of operating losses and use of cash, in the absence of other factors, may cause uncertainty as to its ability to continue as a going concern. We have reviewed the current and prospective sources of liquidity, significant conditions and events and forecast financial results and concluded that we have adequate resources to continue to operate as a going concern. Our business plan and our assumptions around the adequacy of our liquidity are based on estimates regarding expected revenues and future costs. However, our revenues may not meet our projections or our costs may exceed our estimates. Further, our estimates may change and future events or developments may also affect our estimates. Any of these factors may change our expectation of cash usage in 2015 or significantly affect our level of liquidity, which may require us to seek additional financing or take other measures to reduce our operating costs in order to continue operating. These financial statements do not include any adjustments that might result from the Company not being able to continue as a going concern.
	All common stock information and related share prices included in these notes to financial statements have been adjusted to reflect the five for one reverse stock split that occurred on December 21, 2012.
	Use of Estimates
	The preparation of financial statements in conformity with US GAAP requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. Actual results could differ from those estimates. Changes in the estimates or assumptions used by management could have a material impact upon reported amounts and our results of operations.
	Revenue Recognition
	In general, we recognize revenue when four criteria are met: (i) persuasive evidence that an arrangement exists; (ii) delivery has occurred or services have been rendered; (iii) the sales price is fixed or determinable; and (iv) collectability is reasonably assured. In general, revenue is recognized when revenue-generating transactions generally fall into one of the following categories of revenue recognition:
		·	We recognize product revenue at the time of shipment for a significant portion of all products sold directly to customers and through distributors because title and risk of loss pass on delivery to the common carrier. Our customers and distributors do not have the right to return products. If title and risk of loss pass at some other point in time, we recognize such revenue for our customers when the product is delivered to the customer and title and risk of loss has passed. We may enter into bill-and-hold arrangements and when this happens delivery may not occur, but other criteria are reviewed to determine proper timing of revenue recognition.
		·	We recognize installation, service and maintenance revenue at the time the service is performed.
		·	We recognize revenue associated with extended maintenance agreements (“EMAs”) over the life of the contracts using the straight-line method, which approximates the expected timing in which applicable services are performed. Amounts collected in advance of revenue recognition are recorded as a current liability in the deferred revenue line of the consolidated balance sheet or long-term liability based on the time from the balance sheet date to the future date of revenue recognition.
		·	We recognize revenue on certain rental programs over the life of the rental agreement using the straight-line method. Amounts collected in advance of revenue recognition are recorded as a current or long-term liability based on the time from the balance sheet date to the future date of revenue recognition.
	When collectability is not reasonably assured, we defer revenue and will recognize revenue as payments are received.
	Multiple element arrangements (“MEAs”) are arrangements to sell products to customers that frequently include multiple deliverables. Our most significant MEAs include the sale of one or more of our CleanSource UPS or CleanSource PowerHouse products, combined with one or more of the following products: design services, project management, commissioning and installation services, spare parts or consumables, and EMA’s. Delivery of the various products or performance of services within the arrangement may or may not coincide. Certain services related to design and consulting may occur prior to product delivery.  Commissioning and installation typically take place within six months of product delivery, depending upon customer requirements. EMAs, consumables, and repair, maintenance or consulting services are generally delivered over a period of one to five years. In certain arrangements revenue recognized is limited to the amount invoiced or received that is not contingent on the delivery of future products and services.
	When arrangements include multiple elements, we allocate revenue to each element based on the relative selling price and recognize revenue when the elements have standalone value and the four criteria for revenue recognition have been met. We establish the selling price of each element based on Vendor Specific Objective Evidence (“VSOE”) if available, Third Party Evidence (“TPE”) if VSOE is not available, or best estimate of selling price (“BESP”) if neither VSOE nor TPE is available. We generally determine selling price based on amounts charged separately for the delivered and undelivered elements to similar customers in standalone sales of the specific elements. When arrangements include an EMA, we recognize revenue related to the EMA at the stated contractual price on a straight-line basis over the life of the agreement.
	Any taxes imposed by governmental authorities on our revenue-producing transactions with customers are shown in our consolidated statements of operations on a net-basis; that is, excluded from our reported revenues.
	Shipping and Handling Costs
	We classify shipping and handling costs related to product sales as cost of revenue, and any payments from customers for shipping and handling are categorized in revenue. We classify shipping and handling costs associated with receiving production inventory as cost of product revenue. Any materials received or shipped which are related to our engineering, sales, marketing and administrative functions are classified as operating expenses.
	Cash and Cash Equivalents
	Investments with a contractual maturity of three months or less when purchased are classified as cash equivalents.
	Fair Value of Financial Instruments
	Fair value is measured based on an exit price, representing the amount that would be received to sell an asset or paid to satisfy a liability in an orderly transaction between market participants. Fair value is a market-based measurement that should be determined based on assumptions that market participants would use in pricing an asset or liability. As a basis for considering such assumptions, a fair value hierarchy is established, which categorizes the inputs used in measuring fair value as follows:
	Level 1—Quoted prices in active markets for identical assets or liabilities.
	Level 2—Significant observable inputs other than quoted prices in Level 1, such as quoted prices for similar assets and liabilities in active markets; quoted prices for identical or similar assets and liabilities in markets that are not active; or other inputs that are observable or can be corroborated by observable market data.
	Level 3—One or more significant inputs that are unobservable and supported by little or no market data.
	Highest priority is given for Level 1 input and lower propriety to Level 3 inputs.  A financial instruments level is based on the lowest level of any input that is significant to the fair value measurement.  No changes were made to our methodology.
	Our Level 1 assets consist of cash equivalents, which are primarily invested in money-market funds. These assets are classified as Level 1 because they are valued using quoted prices in active markets and other relevant information generated by market transactions involving identical assets and liabilities. The fair value was $3.1 million as of December 31, 2014 and 2013.
	For cash and cash equivalents, accounts receivable, accounts payable and our revolving line of credit, the carrying amount approximates fair value because of the relative short maturity of those instruments.
	Allowance for Doubtful Accounts
	We estimate an allowance for doubtful accounts based on factors related to the credit risk of each customer. Historically, credit losses were minimal, primarily because the majority of our revenues were generated from large customers, primarily Caterpillar, Inc. (“Caterpillar”) and Hewlett Packard Corporation (“HP”). We perform credit evaluations of new customers and often require deposits, prepayments or use of bank instruments such as trade letters of credit to mitigate our credit risk. We write off uncollectable trade receivables, and record any recoveries of previous write offs against the allowance. Our standard terms are net 30 days; however we may have agreements with our larger customers and certain distributors, OEM customers, and IT channel that allow for more extended terms at or above net 60 days.
	The following table summarizes the annual changes in our allowance for doubtful accounts (in thousands):
	Balance at December 31, 2011		$	337
	Change in provision charged to expense			151
	Write-off of uncollectible accounts, net of recoveries			-
	Balance at December 31, 2012		$	488
	Change in provision charged to expense			(139	)
	Write-off of uncollectible accounts, net of recoveries			(36	)
	Balance at December 31, 2013		$	313
	Change in provision charged to expense			(67	)
	Write-off of uncollectible accounts, net of recoveries			(34	)
	Balance at December 31, 2014		$	212
	Inventories, net
	Inventories, net are stated at the lower of cost or market, using the first-in-first-out method, and consisted of the following at December 31 (in thousands, net of allowances):
			2014			2013
	Raw materials		$	5,440		$	4,521
	Work in progress			473			2,429
	Finished goods			932			5,070
			$	6,845		$	12,020
	Property and Equipment
	Property and equipment is stated at cost and is depreciated using the straight-line method over the estimated useful lives of the assets, as follows (in years):
	Equipment			10-Feb
	Demonstration units			5-Mar
	Computers and purchased software			3-Feb
	Furnitures and fixtures			5-Feb
	Leasehold improvements are depreciated over the shorter of the life of the improvement or the remainder of the property lease term, including renewal options, generally three to five years. Repairs and maintenance is expensed as incurred.
	Long-Lived Assets
	Long-lived assets held and used by the Company are reviewed for impairment whenever events or changes in circumstances indicate that their net book value may not be recoverable. When such factors and circumstances exist, we compare the projected undiscounted future cash flows associated with the related asset or group of assets over their estimated useful lives against their respective carrying amounts. Impairment, if any, is based on the excess of the carrying amount over the fair value of those assets and is recorded in the period in which the determination was made.
	Accrued Expenses
	Accrued expenses consist of the following at December 31 (in thousands):
		2014			2013
Compensation, severance and benefits		$	1,296		$	2,685
Warranty liability			475			529
Taxes, other than income			1,080			483
Professional fees			463			759
Other			820			1,127
		$	4,134		$	5,583
Warranty Liability
Generally, the warranty period for our power quality products is 12 months from the date of commissioning or 18 months from the date of shipment from Active Power, whichever period is shorter. Occasionally we offer longer warranty periods to certain customers. The warranty period for products sold to our primary OEM customer, Caterpillar, is 12 months from the date of shipment to the end-user, or up to 36 months from shipment from Active Power. This is dependent upon Caterpillar complying with our storage requirements for our products in order to preserve this warranty period beyond the standard 18-month limit. We provide for the estimated cost of product warranties at the time revenue is recognized and this accrual is included in accrued expenses and long term liabilities on the accompanying consolidated balance sheet.
Changes in the Company’s warranty liability are as follows (in thousands):
Balance at December 31, 2011		$	613
Warranty expense			1,294
Payments			(1,152	)
Balance at December 31, 2012		$	755
Warranty expense			589
Payments			(782	)
Balance at December 31, 2013		$	562
Warranty expense			660
Payments			(695	)
Balance at December 31, 2014		$	527
Warranty liability included in accrued expenses		$	475
Long term warranty liability			52
Balance at December 31, 2014		$	527
Long-Term Liabilities
Long term liabilities consisted of the following at December 31 (in thousands):
		2014			2013
Deferred revenue		$	751		$	601
Technology licensing agreement			-			88
Warranty liability			52			33
Sublease deposits			18			19
		$	821		$	741
Stock-Based Compensation Expense
We account for our stock-based compensation using the Black Scholes option valuation model. Stock-based compensation cost is estimated at the grant date based on the fair-value of the award and is recognized as expense ratably over the requisite service period of the award, generally four years. We develop our estimates of expected life and forfeitures based on historical data. We estimate stock price volatility based on historical volatilities. The risk-free rates are based on the U.S. Treasury yield in effect at the time of grant. Details of our stock-based compensation include the following (in thousands):
		2014			2013			2012
Stock-based compensation expense by caption:
Cost of product revenue		$	110		$	254		$	216
Cost of service and other revenue			111			116			70
Research and development			207			204			153
Selling and marketing			370			587			484
General and administrative			342			539			486
		$	1,140		$	1,700		$	1,409
Stock-based compensation expense by type of award:
Stock options		$	1,068		$	1,488		$	1,213
Restricted stock awards			72			212			196
		$	1,140		$	1,700		$	1,409
Assumptions used in the Black-Scholes model for our stock plans are presented below:
		2014			2013			2012
Weighted average expected life in years		6.27 years			6.35 years			6.83 years
Weighted average expected volatility			75	%		76	%		77	%
Volatility Range			73%-76	%		75%-76	%		75%-78	%
Risk-free interest rate range			1.96%-2.12	%		1.13%-2.38	%		0.63%-1.00	%
Weighted average forfeiture rate			29.7	%		18.9	%		17	%
Income Taxes
We account for income taxes using the liability method of accounting for income taxes. Under the liability method, deferred taxes are determined based on the differences between the financial statement and tax basis of assets and liabilities using enacted tax rates in effect in the years in which the differences are expected to reverse. A valuation allowance is recorded to reduce the carrying amounts of deferred tax assets if it is more likely than not such assets will not be realized. Deferred income taxes reflect the net tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes.
We recognize the financial statement benefit of a tax position that does not meet the more-likely-than-not threshold only after the statute of limitations expire of the relevant tax authority sustains the Company’s position following an audit. For tax positions meeting the more likely-than-not threshold, the amount recognized in the financial statements is the largest benefit that has a greater than 50 percent likelihood of being realized upon the ultimate settlement with the relevant tax authority. At December 31, 2014 and 2013, the Company had no material unrecognized tax benefits.
The Company recognizes interest and penalties related to uncertain tax positions in income tax expense. As of December 31, 2014, the Company had no accrued or expensed interest or penalties related to uncertain tax positions.
Segment Reporting
Active Power’s chief operating decision makers allocate resources and assess the performance of its power management product development and sales activities as one segment.
Concentration of Credit Risk
Financial instruments which potentially subject Active Power to concentrations of credit risk consist of cash and cash equivalents, investments and accounts receivable. Active Power’s cash and cash equivalents and investments are placed with high credit quality financial institutions and issuers. From time to time, we may have amounts on deposit with financial institutions that are in excess of the federally insured limit. We have not experienced any losses on deposits of cash and cash equivalents.
Active Power performs credit evaluations of its customers’ financial condition prior to entering into commercial transactions. We generally require letters of credit or prepayments from higher-risk customers as deemed necessary to ensure collection. Our allowance for doubtful accounts is estimated based on factors related to the credit risk of each customer. Individual receivables are written off after they have been deemed uncollectible. We also purchase several components from sole source or limited source suppliers.
Economic Dependence
We are significantly dependent on our relationships with HP and Caterpillar. If these relationships are unsuccessful or discontinue, our business and revenue may suffer. The loss of, or a significant reduction in, orders from HP or Caterpillar, or the failure to provide adequate service and support to the end-users of our products by HP or Caterpillar, could significantly reduce our revenue. Our operating results in the foreseeable future will continue to depend on the sales made by a relatively small number of customers, including HP and Caterpillar.
The following customers accounted for a significant percentage of Active Power’s total revenue during each of the years ended December 31:
		2014			2013			2012
Caterpillar			18	%		14	%		13	%
HP			1	%		22	%		35	%
European based IT Customer			-			-			12	%
No other customer represented more than 10% of our revenues in any of the years reported. Caterpillar represented 18% and 23% of our outstanding accounts receivable at December 31, 2014 and 2013, respectively. HP represented 22% of our outstanding receivables at December 31, 2013.
Advertising Costs
We expense advertising costs as incurred. These expenses were immaterial in 2014, 2013, and 2012, respectively.
Net Loss Per Share
The following table sets forth the computation of basic and diluted net loss per share (in thousands) for the years ended December 31:
		2014			2013			2012
Net loss		$	(12,827	)	$	(8,351	)	$	(1,922	)
Basic and diluted:
Weighted-average shares of common stock outstanding used in computing basic and diluted net loss per share			22,494			19,329			18,584
Basic and diluted net loss per share		$	(0.57	)	$	(0.43	)	$	(0.10	)
The calculation of diluted net loss per share excludes 2,399,890, 2,407,664, and 1,882,584 shares of common stock issuable upon exercise of employee stock options as of December 31, 2014, 2013, and 2012, respectively, and 21,994, 53,038, and 200,071 non-vested shares of common stock issuable upon exercise of restricted stock awards as of December 31, 2014, 2013, and 2012, respectively, because their inclusion in the calculation would be anti-dilutive.
Recent Accounting Pronouncements
In August 2014, the Financial Accounting Standards Board (the “FASB”) issued Accounting Standards Update (“ASU”) No. 2014-15, (“ASU 2014-15”), “Disclosure of Uncertainties About an Entity’s Ability to Continue as a Going Concern”. ASU 2014-15 requires management to perform interim and annual assessments of an entity’s ability to continue as a going concern within one year of the date the financial statements are issued and provides guidance on determining when and how to disclose going concern uncertainties in the financial statements. Certain disclosures will be required if conditions give rise to substantial doubt about an entity’s ability to continue as a going concern. ASU 2014-15 applies to all entities and is effective for annual and interim reporting periods ending after December 15, 2016, with early adoption permitted. The Company does not expect that the adoption of this standard will have a material effect on its financial statements.
In May 2014, the FASB issued ASU 2014-09, “Revenue from Contracts with Customers”, “Topic 606”. This ASU will supersede the revenue recognition requirements in Topic 605, Revenue Recognition, and most industry-specific guidance, and creates a Topic 606 Revenue from Contracts with Customers. The core principle of the guidance is that an entity should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. The Company will adopt this guidance January 1, 2017 as required. We are evaluating the new guidelines to see if they will have a significant impact on our consolidated results of operation, financial condition or cash flows.

Property_and_Equipment

Property and Equipment	12 Months Ended
	Dec. 31, 2014
Property and Equipment [Abstract]
Property and Equipment	2. Property and Equipment
	Property and equipment consists of the following at December 31 (in thousands):
		2014			2013
	Equipment	$	9,122		$	9,168
	Demonstration units		1,836			1,470
	Computers and purchased software		3,321			3,273
	Furnitures and fixtures		366			380
	Leasehold improvements		7,225			7,216
	Construction in progress		19			458
			21,889			21,965
	Accumulated depreciation		(19,813	)		(18,909	)
		$	2,076		$	3,056
	In 2014, we reclassified $44,000 of inventory into demonstration units. In 2013, we reclassified $0.9 million of inventory into equipment related to test units for our latest generation UPS product.

Stockholders_Equity

Stockholders' Equity	12 Months Ended
	Dec. 31, 2014
Stockholders' Equity [Abstract]
Stockholders' Equity	3. Stockholders’ Equity
	Common Stock
	Common stock reserved for future issuance at December 31, 2014 consisted of 3,461,909 shares of common stock reserved under our 2010 Stock Incentive Plan, of which 2,409,590 shares were subject to outstanding options and restricted shares and 1,052,319 shares were available for future grants of awards.
	On May 28, 2014, our stockholders approved an amendment to the Company’s Restated Certificate of Incorporation to increase the number of authorized shares of common stock from 30 million shares to 40 million shares.
	In March 2014, we sold approximately 3.7 million shares of common stock at a purchase price of $3.15 per share in a public underwritten offering made under a shelf registration statement that we had filed with the SEC and that had been declared effective in June 2013. This offering resulted in proceeds, net of expenses including underwriting discounts, commissions and fees of $0.8 million and professional service expenses of $0.2 million, of approximately $10.4 million. The proceeds from this offering will be used by us to help fund our working capital requirements and for general corporate purposes.
	In May 2012, our Board of Directors approved the addition of 1.7 million shares of our common stock to be issued in accordance with our 2010 Equity Incentive Plan, and such addition was subsequently approved by our stockholders. Options are subject to terms and conditions as determined by the Compensation Committee of our Board of Directors.
	In March 2012, we sold approximately 2.9 million shares of common stock at a purchase price of $3.40 per share, for proceeds, net of fees and expenses, of approximately $9.6 million, in an offering made under a shelf registration statement that we filed with the Securities and Exchange Commission and that had been declared effective in December 2009. The proceeds from this offering were used by us to help fund our working capital requirements and for general corporate purposes.
	Stock Option Plan
	Since its inception, we have authorized 5,682,296 shares of common stock for issuance under our 2000 and 2010 Stock Incentive Plans, however, we are only issuing new shares of common stock under our 2010 Stock Incentive Plan. We grant options under these plans that vest over periods of up to four years. The term of each option is no more than ten years from the date of grant. Our policy is to issue new shares when required to issue shares upon option exercises. The total fair value of options vested in the year was $1.8 million, $1.4 million, and $1.7 million in 2014, 2013, and 2012, respectively.
	A summary of common stock option activity is as follows:
		Number of			Weighted-		Weighted-		Aggregate
		Shares			Average		Average		Intrinsic Value
					Exercise		Contractual Life		(whole dollars)
					Price		(in years)
	Outstanding at December 31, 2013		2,407,664		$	5.27
	Granted		993,725			3.01
	Exercised		(42,600	)		3.03
	Canceled		(958,899	)		5.44
	Outstanding at December 31, 2014		2,399,890		$	4.3		7.57	$	2,000
	Vested and expected to vest at December 31, 2014		1,901,476		$	4.63		7.18	$	1,000
	Exercisable at December 31, 2014		1,028,618		$	5.83		5.64	$	-
	The weighted average grant date fair value per share of options granted during 2014, 2013, and 2012 was $2.03, $2.60, and $2.60, respectively.  The total intrinsic value of options exercised (which is the amount by which the stock price exceeded the exercise price of the options at the date of exercise) during the years ended December 31, 2014, 2013, and 2012 was $14,000, $0.1 million, and $0.1 million, respectively.
	As of December 31, 2014, there was $2.6 million of total unrecognized compensation cost, related to non-vested stock options, that is expected to be recognized over a weighted-average vesting period of 2.8 years.
	Restricted (non-vested) Shares
	In 2013 and 2012, we issued approximately 6,000 and 248,000 restricted shares, respectively, to directors and employees of the Company. The restrictions lapse as the shares vest in equal quarterly installments over a four year period from the date of issuance. We recorded stock compensation expense related to restricted share units of $0.1 million in 2014. A summary of our restricted, non-vested, shares is as follows:
		Number of			Weighted-
		Shares			Average
					Grant Date
					Fair Value
	Outstanding at December 31, 2013		53,038		$	4
	Granted		-			-
	Vested		(18,681	)		4
	Canceled		(12,363	)		4
	Outstanding at December 31, 2014		21,994		$	4
	As of December 31, 2014, there was $0.1 million of total unrecognized compensation cost related to restricted shares that is expected to be recognized over a weighted-average vesting period of 1.1 years. The total fair value of restricted share units vested in 2014 and 2013 was $0.1 million and $0.3 million, respectively.

Income_Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2014
Income Taxes [Abstract]
Income Taxes	4. Income Taxes
	The Company’s pretax loss for the three years ended December 31, 2014, 2013, and 2012 were allocated between domestic and foreign operations as follows:
		Year Ended December 31,
		2014			2013			2012
	Domestic	$	(15,909	)	$	(9,105	)	$	(1,642	)
	Foreign		3,334			754			(280	)
	Total	$	(12,575	)	$	(8,351	)	$	(1,922	)
	In September 2014, we settled a tax examination of our German subsidiary for years 2007 through 2011.  In the settlement, we agreed to transfer pricing adjustments for the period under examination resulting in a reduction of loss carryovers and a deemed distribution subject to withholding taxes under German law.  We recorded a provision for foreign income taxes of $0.3 million in the quarter ended September 30, 2014 related to the settlement of the German tax examination.
	As of December 31, 2014, the Company had federal net operating loss carry-forwards of approximately $232.0 million and research and development credit carry-forwards of approximately $4.0 million. The net operating loss and credit carry-forwards will expire beginning in 2018, if not utilized. The Company is currently in the process of analyzing potential limitations on the future utilization of the net operating losses and credit carry-forwards due to the “change of ownership” provisions of the Internal Revenue Code of 1986. Any annual limitation may result in the expiration of net operating losses and credit carry-forwards before utilization.
	Deferred income taxes reflect the net tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. Significant components of the Company’s deferred taxes as of December 31 are as follows (in thousands):
		2014			2013
	Deferred tax assets:
	Current deferred tax assets
	Reserves and allowances	$	751		$	1,177
	Deferred Rent		45			55
	Deferred revenue		255			328
	Valuation allowance for current deferred tax assets		(1,049	)		(1,558	)
	Net current deferred tax assets	$	2		$	2
	Noncurrent deferred tax assets
	Acquired technology		571			695
	Capital expenses		1,652			1,624
	Stock compensation		594			699
	Net operating loss and tax credit carryforwards		84,047			84,356
	Valuation allowance for noncurrent deferred tax assets		(86,687	)		(87,263	)
	Net noncurrent deferred tax assets	$	177		$	111
	Deferred tax liabilities:
	Current deferred tax liabilities
	Prepaid expenses		(179	)		(113	)
	Total current deferred tax liabilities	$	(179	)	$	(113	)
	Total net deferred taxes	$	-		$	-
	The Company has established a valuation allowance equal to the net deferred tax asset due to uncertainties regarding the realization of deferred tax assets based on the Company’s lack of earnings history. The valuation allowance decreased by approximately $1.1 million during 2014.
	The Company’s provision for income taxes differs from the expected tax expense (benefit) amount computed by applying the statutory federal income tax rate of 34% to income before taxes due to the following:
		Year Ended December 31,
		2014			2013			2012
	Federal statutory rate		(34.0	)%		(34.0	)%		(34.0	)%
	State taxes, net of federal benefit		(1.0	)		(13.5	)		7.2
	R&D credits		(1.8	)		(5.6	)		1.3
	Stock compensation		3.8			6.2			14.5
	Effect of current foreign operations		5.5			(20.5	)		157.3
	Expiration and adjustment of net operating losses		26.7			-			63.2
	Foreign tax audit settlement		2			-			-
	Loss carryforward adjustments due to tax audit methodologies		9.1			-			-
	Permanent items and other		0.3			(1.9	)		6.8
	Change in valuation allowance		(8.6	)		69.3			(216.3	)
			2	%		-	%		-	%
	The Company recognized no material adjustment in the liability for unrecognized income tax benefits. The reconciliation of the Company’s unrecognized tax benefits at the beginning and end of the year is as follows:
	Balance at January 1, 2014	$	1,990
	Additions based on tax positions related to the current year		257
	Additions for tax positions of prior years		24
	Balance at December 31, 2014	$	2,271
	Due to the existence of the valuation allowance, future changes in our unrecognized tax benefits will not materially impact the Company’s effective tax rate. The Company's assessment of its unrecognized tax benefits is subject to change as a function of the Company's financial statement audit.
	The Company recognizes interest and penalties related to uncertain tax positions in income tax expense. As of December 31, 2014, the Company had no accrued interest or penalties related to uncertain tax positions.
	The tax years 2009 through 2014 remain open to examination by the major taxing jurisdictions to which the Company is subject.

Commitments

Commitments	12 Months Ended
	Dec. 31, 2014
Commitments [Abstract]
Commitments	5. Commitments
	We lease our office, manufacturing and engineering facilities and our foreign sales offices under operating lease agreements. These facilities’ leases are non-cancelable and obligate us to pay taxes and maintenance costs.  In addition, we lease certain equipment such as copiers and phone systems under non-cancelable leases. Our leases expire at various dates through 2018. Rent expense for leases with escalating or de-escalating rent payments are recorded on a straight-line basis over the period of the lease. Net deferred rent on the consolidated balance sheet as of December 31, 2014 and 2013 was $0.1 million and $0.1 million, respectively. There was no deferred rent in 2012. Rent expense was $1.5 million, $1.7 million, and $1.7 million for the years ended December 31, 2014, 2013, and 2012, respectively.
	Future minimum payments under these leases at December 31, 2014 are as follows (in thousands):
		Rental
		payments
	2015	$	1,260
	2016		1,073
	2017		116
	2018		72
	Total future minimum lease payments	$	2,521
	We enter into certain commitments to purchase inventory and other items in the course of normal operations. At December 31, 2014, the total of these commitments was $6.1 million, of which $5.8 million, $0.2 million, and $45,000 will mature in 2015, 2016, and 2017, respectively.
	We have entered into Severance Benefits Agreements with our Chief Executive Officer (“CEO”) and Chief Financial Officer (“CFO”) and with each of our other executive officers. These agreements generally provide that, if within 12 months following a change in control the executive officer’s employment is terminated for reasons other than for cause (as defined in the agreement) or by the executive for good reason, including a significant reduction in the role and/or responsibility of the executive within 12 months of the change in corporate control, then all outstanding stock options or restricted shares held by the executive would vest as of the date of the termination and certain severance payments would be payable. In the case of our CEO and CFO, in the event of termination by the Company for reasons other than for cause or by him for good reason, he would be entitled to a severance payment equal to 12 months of salary and be entitled to receive health benefits for 12 additional months after termination. In the case of our other executive officer, in the event of a termination by the Company for reasons other than for cause or by the officer for good reason, he would be entitled to a severance payment equivalent to six months of salary and be entitled to receive health benefits for six additional months after termination.

Contingencies

Contingencies	12 Months Ended
	Dec. 31, 2014
Contingencies [Abstract]
Contingencies	6. Contingencies
	The Company may be involved, either as plaintiff or defendant, in a variety of ongoing claims, demands, suits, investigations, tax matters and proceedings that arise from time to time in the ordinary course of its business.  In evaluating whether a contingency should be disclosed, the Company considers if there is at least a reasonable possibility that a loss or an additional loss may have been incurred, and either an accrual is not made because any of the conditions, or an exposure to loss exists in excess of the amount accrued.  The Company evaluated all potentially significant litigation, government investigations, claims or assessments in which the Company is involved and determined there were no contingent losses, either accrued or reasonably possible of loss that could materially affect its results of operations, financial condition, or cash flows.
	The Company records an accrual with respect to a claim, suit, investigation or proceeding when it is reasonably probable that a liability has been incurred and the amount of the loss can be reasonably estimated. Any recorded liabilities, including any changes to such liabilities for the year ended December 31, 2014, were not material to the Consolidated Financial Statements.
	The following is a summary of the significant legal matters involving the Company.
	SEC Inquiry
	By letter dated September 30, 2013, the SEC Division of Enforcement notified us that it is conducting an investigation regarding us, including matters relating to our public statements regarding Digital China Information Services Company Limited (“Digital China”) and our distribution relationships in China. We have been and intend to continue cooperating fully with the SEC. As of the date of this filing, we believe we have provided all requested material to the SEC.
	Stockholder Litigation
	Class action complaint
	On September 10, 2013, a purported class action complaint was filed in the United States District Court for the Western District of Texas against us and certain of our former executives. The case is captioned Don Lee v. Active Power, Inc., et. al. (Civil Action No. 1:13-cv-00797-SS). As amended, the complaint alleges that on February 19, 2013, we reported that we had begun working with an unnamed Chinese distributor partner, and that on April 30, 2013, we announced in press releases and conference calls that we had entered into a strategic distribution partnership with Digital China. However, on September 5, 2013, after the close of trading, we disclosed that our partnership was with Qiyuan Network System Limited, which is neither an affiliate nor a subsidiary of Digital China. The amended complaint asserts claims under Sections 10(b) and 20(a) of the Securities Exchange Act of 1934, as amended, and Rule 10b-5 promulgated thereunder, and seeks unspecified damages on behalf of all stockholders who purchased common stock between February 19 and September 5, 2013.  On March 7, 2014, we filed a motion to dismiss the class action complaint.  Our motion was denied by the Court on July 2, 2014.  On August 11, 2014, we filed an answer to the class action complaint, and on September 2, 2014, the Court declined to certify its order of July 2, 2014 for an interlocutory appeal to the United States Court of Appeals for the Fifth Circuit.
	On September 23, 2014, we reached an agreement in principle and entered into a memorandum of understanding to settle the class action complaint.  The parties to the class action signed a definitive settlement agreement on December 2, 2014, which was granted preliminary approval by the Court on January 7, 2015. The proposed settlement would resolve for all defendants all of the issues that are pending in the class action complaint.  If completed, the class action settlement would result in a payment of $1.5 million to the settlement class, inclusive of fees and expenses.  We anticipate that the total settlement amount and related expenses would be paid from insurance proceeds.  The proposed settlement is not yet consummated, and is subject to a number of conditions.  The proposed settlement is also subject to final approval by the Court at a hearing scheduled for May 15, 2015.
	Derivative actions
	On September 13, 2013 and October 14, 2013, two separate stockholders filed complaints in the District Court of Travis County, Texas, purporting to bring derivative actions on behalf of us against certain current and former officers and directors of the Company. The first derivative action is captioned Okumura v. Almgren, et. al. (Cause No. D-1-GN-13-003230), and the second derivative action is captioned Shaev v. Milner, et. al. (Cause No. D-1-GN-13-003557). The allegations of each derivative complaint mirror those of the class action complaint, and they assert claims for breach of fiduciary duty, unjust enrichment, and/or abuse of control and seek damages on our behalf.  These derivative actions were stayed by agreement pending resolution of the motion to dismiss the securities class action. The stay was lifted and on August 4, 2014, the parties filed a joint motion to consolidate the two derivative cases.  On September 18, 2014, the District Court appointed lead counsel in the consolidated derivative action.
	On September 23, 2014, we reached an agreement in principle and entered into a memorandum of understanding to settle the consolidated derivative actions.  The parties to the consolidated derivative actions signed a definitive settlement agreement on January 30, 2015. The proposed settlement would resolve for all defendants all of the issues that are pending in the consolidated derivative actions.  The proposed consolidated derivative settlement includes, among other things, certain governance improvements by us. We anticipate that the settlement fees and related expenses would be paid entirely from insurance proceeds.  The proposed settlement is not yet consummated, and is subject to a number of conditions.  The proposed settlement is also subject to approval by the Court following completion of a fairness hearing. The initial Court hearing is scheduled for March 10, 2015.

Employee_Benefit_Plan

Employee Benefit Plan	12 Months Ended
	Dec. 31, 2014
Employee Benefit Plan [Abstract]
Employee Benefit Plan	7. Employee Benefit Plan
	We maintain a 401(k) Plan that covers substantially all full-time employees. Company contributions to the plan are determined at the discretion of the Board of Directors and vest ratably over five years of service starting after the first year of employment. We did not contribute to this plan in 2014, 2013, or 2012.

Geographic_Information

Geographic Information	12 Months Ended
	Dec. 31, 2014
Geographic Information [Abstract]
Geographic Information	8. Geographic Information
	Revenues for the year ended December 31 were as follows (in thousands):
		2014		2013		2012
	Americas	$	31,495	$	50,365	$	48,190
	Europe, Middle East and Africa		13,998		6,941		21,917
	Asia		3,643		4,393		6,208
	Total	$	49,136	$	61,699	$	76,315
	Revenues from foreign countries above represented shipments to customers located in 38 countries during 2014. We often ship to areas that are outside of the jurisdiction in which revenue is recognized. Substantially all of our property, plant and equipment are located in the United States. Net assets of operations in foreign countries (excluding intercompany receivables and payables eliminated in consolidation) were $2.8 million at December 31, 2014 and were mostly located in the UK, Germany, and China.

Guarantees

Guarantees	12 Months Ended
	Dec. 31, 2014
Guarantees [Abstract]
Guarantees	9. Guarantees
	In certain geographical regions, particularly Europe, we are sometimes required to issue performance guarantees to our customers as a condition of sale. These guarantees usually provide financial protection to our customers in the event that we fail to fulfill our delivery or warranty obligations. We secure these guarantees with standby letters of credit through our bank. At December 31, 2014 we had a $6,000 deposit guarantee for our building lease in the United Kingdom, which expires in April 2015 and a $34,000 performance guarantee to a customer that was secured with a letter of credit, which expires in June 2017. At December 31, 2013, we had a $0.5 million performance guarantee outstanding to a customer that was secured with a letter of credit. There is no foreseeable risk that we will not be able to meet the performance obligations. Our restricted cash, as shown on the balance sheet, is related to these guarantees.

Revolving_Credit_Facility

Revolving Credit Facility	12 Months Ended
	Dec. 31, 2014
Revolving Credit Facility [Abstract]
Revolving Credit Facility	10. Revolving Credit Facility
	In August 2010, we entered into a Second Amended and Restated Loan and Security Agreement (the “Loan Agreement”) with Silicon Valley Bank (“SVB”) which increased the total line of credit available to $12.5 million subject to certain borrowing bases. This facility expanded our ability to borrow funds from U.S. receivables to include qualifying receivables from our UK operations as well, increased our ability to use inventory as collateral, and also added an ability to borrow against purchase orders. These additional bases of borrowing were designed to allow us to use the credit facility to fund inventory purchases in the event we received large or multiple sales orders that would require a major investment in inventory and work in progress such as our MIS products, to help fund our business and to manage our working capital requirements.
	This loan facility provides for a secured revolving line of credit in an aggregate amount of up to eighty percent (80%) of the facility amount of $15.625 million, or $12.5 million, subject to certain borrowing bases. In the event we have maintained unrestricted cash and cash equivalents of at least $6.25 million with SVB for at least 30 consecutive days, which is referred to as being in a “Streamline Period”, the borrowing base formula is based on eligible accounts receivable, eligible purchase orders and eligible inventory, subject to a sublimit of $5.0 million for U.K. accounts receivable, $3.5 million for inventory and $1.5 million for purchase orders. When we are not in a Streamline Period, our borrowings are limited based on accounts receivable and purchase orders that SVB has specifically agreed to finance and a borrowing base for eligible inventory. We may also request that SVB issue letters of credit on our behalf, of up to $1.5 million, as a portion of our total loan facility.
	In August 2012, we entered into the Second Amendment to Second Amended and Restated Loan and Security Agreement with SVB (“Second Amendment”) which amends the Second Amended and Restated Loan and Security Agreement, dated as of August 5, 2010, by and between us and SVB. Pursuant to the Second Amendment, the maturity date of the loan facility was extended by two years, to August 5, 2014, unless earlier terminated by us, subject to any then applicable early termination fee. The Second Amendment further provides for, among other things, (i) adding a $1.5 million sublimit under the borrowing base formula for 91-120 day aged accounts receivable, (ii) removing eligible purchase orders from the borrowing base formula, and (iii) removing sublimits providing for the issuance of letters of credit and cash management services. Additionally, pursuant to the Second Amendment, the definition of “Streamline Period” was amended such that the Company will be deemed to be in a Streamline Period in the event that it has a liquidity ratio of greater than or equal to 1.75:1.00 at all times for at least 60 consecutive days; provided that a Streamline Period will automatically be in effect if we achieve such liquidity ratio as a result of the sale of our equity securities.
	Further, the Second Amendment provides for, among other things, (i) amending the finance charge on each eligible account financed by SVB to a per annum rate equal to SVB’s prime rate, subject to a minimum prime rate of four percent (4.00%), plus (a) one and one-quarter percent (1.25%) when we are in a Streamline Period or (b) one and three-quarters percent (1.75%) for eligible accounts (other than eligible 91-120 day aged accounts) and two percent (2.00%) for eligible 91 to 120 day aged accounts when we are not in a Streamline Period, and (ii) reducing the interest rate upon which each inventory advance accrues interest such that each advance based upon inventory accrues interest at a per annum rate equal to SVB’s prime rate, subject to a minimum prime rate of four percent (4.00%), plus (a) one and one-quarter percent (1.25%) when we are in a Streamline Period or (b) three and one half percent (3.50%) when we are not in a Streamline Period.
	On July 28, 2014, we entered into a Third Amendment to Second Amended and Restated Loan and Security Agreement with SVB (“Third Amendment”). The amended three-year loan facility provides for a secured revolving line of credit in an aggregate amount of up to eighty percent (80%) of the facility amount of $18.8 million, or $15.0 million, and increases our inventory and purchase order availability from $3.5 million to $7.0 million subject to certain borrowing bases. Purchase orders and eligible inventory are subject to a sublimit of $4.0 million and accounts receivable for UK and Germany have a $5.0 million sublimit.  If we maintain our Liquidity Ratio of 2.50:1.00 for the immediately preceding reconciliation periods the sublimit will be uncapped. We are currently in compliance with all loan covenants under the Loan Agreement. Further, the Third Amendment extends the maturity date to August 5, 2017 and reduces the finance charge to a per annum rate equal to Silicon Valley Bank's prime rate, subject to a minimum prime rate of 4.00%, plus (a) 0.50% for eligible accounts, inventory and purchase orders when we are Borrowing Base Eligible (as defined in the Loan Agreement), or (b) 1.20% for eligible accounts when we are not Borrowing Base Eligible.
	The revolving loans made to us under this loan facility are secured by a lien on substantially all of our assets, including the assets of Active Power Solutions Limited, our wholly-owned United Kingdom subsidiary, and the assets of Active Power (Germany) GmbH, our indirect wholly-owned German subsidiary. The only direct or indirect subsidiaries of Active Power, Inc. that are not guarantors under the Loan Agreement are Active Power China (Beijing) Co. Ltd. and immaterial subsidiaries that are not operating companies.  There are no restrictions on the ability of any of the subsidiary guarantors to transfer funds to Active Power, Inc. in the form of loans, advances or dividends, except as provided by applicable law.
	The Loan Agreement includes customary affirmative covenants for a credit facility of this size and type, including delivery of financial statements, compliance with laws, maintenance of insurance, and protection of intellectual property rights. Further, the Loan Agreement contains customary negative covenants for a credit facility of this size and type, including covenants that limit or restrict our ability, among other things, to dispose of assets, change our business, change our CEO or CFO without replacing such person within 120 days, have a change in control, make acquisitions, be acquired, incur indebtedness, grant liens, make investments, make distributions, repurchase stock, and enter into certain transactions with affiliates.
	The Loan Agreement contains customary events of default that include, among other things, non-payment defaults, covenant defaults, material adverse change defaults, insolvency defaults, material judgment defaults and inaccuracy of representations and warranty defaults. The occurrence of an event of default could result in the acceleration of obligations under the Loan Agreement, in which case we must repay all loans and related charges, fees and amounts then due and payable, and our subsidiary may be required to pay any such amounts under the Guarantee and Debenture. At the election of SVB, upon the occurrence and during the continuance of an event of default, finance charges or interest rates, as applicable, will increase an additional five percentage points (5.00%) per annum above the rate that is otherwise applicable thereto upon the occurrence of such event of default, and the collateral handling fees will increase by one-half percent (0.50%).
	During 2012, we borrowed amounts under this credit facility based on our short term liquidity requirements. As of December 31, 2014, we had outstanding borrowings of $5.5 million under this loan facility. Based on the borrowing base formula subsequent to the amendment, the additional amount available for use at December 31, 2014 was approximately $4.6 million.

Selected_Quarterly_Consolidate

Selected Quarterly Consolidated Financial Data (unaudited)	12 Months Ended
	Dec. 31, 2014
Selected Quarterly Consolidated Financial Data (unaudited) [Abstract]
Selected Quarterly Consolidated Financial Data (unaudited)	11. Selected Quarterly Consolidated Financial Data (unaudited)
	The following tables present selected unaudited consolidated statement of operations information for each of the quarters in the years ended December 31, 2014 and 2013 (in thousands, except per share data):
		For the Quarter Ended
	Year Ended December 31, 2014	31-Dec			30-Sep			30-Jun			31-Mar
	Selected consolidated statement of operations information:
	Total revenue	$	15,352		$	12,692		$	10,154		$	10,938
	Total cost of goods sold	$	11,303		$	8,932		$	8,239		$	8,010
	Gross profit	$	4,049		$	3,760		$	1,915		$	2,928
	Operating expenses	$	6,015		$	5,862		$	6,221		$	6,574
	Operating loss	$	(1,966	)	$	(2,102	)	$	(4,306	)	$	(3,646	)
	Net loss	$	(2,044	)	$	(2,496	)	$	(4,413	)	$	(3,874	)
	Basic and diluted net loss per share	$	(0.09	)	$	(0.11	)	$	(0.19	)	$	(0.19	)
	Selected consolidated balance sheet information:
	Current assets	$	33,731		$	34,711		$	36,427		$	42,070
	Total assets	$	36,098		$	37,341		$	39,350		$	45,164
	Current liabilities	$	16,484		$	15,720		$	15,529		$	17,069
	Working capital	$	17,247		$	18,991		$	20,898		$	25,001
	Long term obligations	$	821		$	852		$	697		$	746
	Stockholders' equity	$	18,793		$	20,769		$	23,124		$	27,349
		For the Quarter Ended
	Year Ended December 31, 2013	31-Dec			30-Sep			30-Jun			31-Mar
	Selected consolidated statement of operations information:
	Total revenue	$	13,926		$	13,154		$	20,195		$	14,424
	Total cost of goods sold	$	9,750		$	9,210		$	13,273		$	10,070
	Gross profit	$	4,176		$	3,944		$	6,922		$	4,354
	Operating expenses	$	7,990		$	6,909		$	6,412		$	5,702
	Operating profit (loss)	$	(3,814	)	$	(2,965	)	$	510		$	(1,348	)
	Net income (loss)	$	(4,127	)	$	(3,135	)	$	332		$	(1,421	)
	Basic and diluted new income (loss) per share	$	(0.21	)	$	(0.16	)	$	0.02		$	(0.07	)
	Selected consolidated balance sheet information:
	Current assets	$	34,556		$	39,110		$	45,722		$	42,019
	Total assets	$	37,907		$	42,263		$	49,052		$	44,748
	Current liabilities	$	16,860		$	18,194		$	22,758		$	19,208
	Working capital	$	17,696		$	20,916		$	22,964		$	22,811
	Long term obligations	$	741		$	737		$	689		$	774
	Stockholders' equity	$	20,306		$	23,332		$	25,605		$	24,766

Summary_of_Significant_Account1

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2014
Summary of Significant Accounting Policies [Abstract]
Description of Business	Description of Business
	Active Power, Inc. and its subsidiaries (collectively, “we”, “us”, “Active Power” or “Company”) design, manufacture, sell and service flywheel-based uninterruptible power supply (“UPS”) products that use kinetic energy to provide short-term power as a cleaner alternative to conventional electro-chemical battery-based energy storage. We also design, manufacture, sell, and service modular infrastructure solutions (“MIS”) that integrate critical power components into a pre-packaged, purpose built enclosure that may include our UPS products as a component. Our products and solutions are based on our patented flywheel and power electronics technology and are designed to ensure continuity for data centers and other mission critical operations in the event of power disturbances.
	Our products and solutions are designed to deliver continuous conditioned power during power disturbances such as voltage sags and surges, and to provide ride-through power in the event of a brief utility failure, supporting operations until utility power is restored or a longer term alternative power source, such as a diesel generator, is started. We sell our products globally through our direct sales force, manufacturer’s representatives, distributors, Original Equipment Manufacturer (“OEM”) channel, and IT partners in the Americas, in Europe, Middle East, and Africa (“EMEA”), and in the Asia Pacific region (“APAC”).
	We also offer services, including hardware and software maintenance, on all Active Power products, and other professional services such as assessment and implementation, for our customers’ infrastructure projects.
	We were founded as a Texas Corporation in 1992 and reincorporated in Delaware in 2000. Our headquarters are in Austin, Texas with international offices in the United Kingdom, Germany and China.
	The accompanying consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (“US GAAP”) and include the accounts of the Company and its consolidated subsidiaries. All intercompany transactions and balances have been eliminated upon consolidation.
	The accompanying consolidated financial statements have also been prepared on the assumption that the Company will continue to operate as a going concern. Accordingly, assets and liabilities are recorded on the basis that the Company will be able to realize its assets and discharge its liabilities in the normal course of business. The Company’s history of operating losses and use of cash, in the absence of other factors, may cause uncertainty as to its ability to continue as a going concern. We have reviewed the current and prospective sources of liquidity, significant conditions and events and forecast financial results and concluded that we have adequate resources to continue to operate as a going concern. Our business plan and our assumptions around the adequacy of our liquidity are based on estimates regarding expected revenues and future costs. However, our revenues may not meet our projections or our costs may exceed our estimates. Further, our estimates may change and future events or developments may also affect our estimates. Any of these factors may change our expectation of cash usage in 2015 or significantly affect our level of liquidity, which may require us to seek additional financing or take other measures to reduce our operating costs in order to continue operating. These financial statements do not include any adjustments that might result from the Company not being able to continue as a going concern.
	All common stock information and related share prices included in these notes to financial statements have been adjusted to reflect the five for one reverse stock split that occurred on December 21, 2012.
Use of Estimates	Use of Estimates
	The preparation of financial statements in conformity with US GAAP requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. Actual results could differ from those estimates. Changes in the estimates or assumptions used by management could have a material impact upon reported amounts and our results of operations.
Revenue Recognition	Revenue Recognition
	In general, we recognize revenue when four criteria are met: (i) persuasive evidence that an arrangement exists; (ii) delivery has occurred or services have been rendered; (iii) the sales price is fixed or determinable; and (iv) collectability is reasonably assured. In general, revenue is recognized when revenue-generating transactions generally fall into one of the following categories of revenue recognition:
		·	We recognize product revenue at the time of shipment for a significant portion of all products sold directly to customers and through distributors because title and risk of loss pass on delivery to the common carrier. Our customers and distributors do not have the right to return products. If title and risk of loss pass at some other point in time, we recognize such revenue for our customers when the product is delivered to the customer and title and risk of loss has passed. We may enter into bill-and-hold arrangements and when this happens delivery may not occur, but other criteria are reviewed to determine proper timing of revenue recognition.
		·	We recognize installation, service and maintenance revenue at the time the service is performed.
		·	We recognize revenue associated with extended maintenance agreements (“EMAs”) over the life of the contracts using the straight-line method, which approximates the expected timing in which applicable services are performed. Amounts collected in advance of revenue recognition are recorded as a current liability in the deferred revenue line of the consolidated balance sheet or long-term liability based on the time from the balance sheet date to the future date of revenue recognition.
		·	We recognize revenue on certain rental programs over the life of the rental agreement using the straight-line method. Amounts collected in advance of revenue recognition are recorded as a current or long-term liability based on the time from the balance sheet date to the future date of revenue recognition.
	When collectability is not reasonably assured, we defer revenue and will recognize revenue as payments are received.
	Multiple element arrangements (“MEAs”) are arrangements to sell products to customers that frequently include multiple deliverables. Our most significant MEAs include the sale of one or more of our CleanSource UPS or CleanSource PowerHouse products, combined with one or more of the following products: design services, project management, commissioning and installation services, spare parts or consumables, and EMA’s. Delivery of the various products or performance of services within the arrangement may or may not coincide. Certain services related to design and consulting may occur prior to product delivery.  Commissioning and installation typically take place within six months of product delivery, depending upon customer requirements. EMAs, consumables, and repair, maintenance or consulting services are generally delivered over a period of one to five years. In certain arrangements revenue recognized is limited to the amount invoiced or received that is not contingent on the delivery of future products and services.
	When arrangements include multiple elements, we allocate revenue to each element based on the relative selling price and recognize revenue when the elements have standalone value and the four criteria for revenue recognition have been met. We establish the selling price of each element based on Vendor Specific Objective Evidence (“VSOE”) if available, Third Party Evidence (“TPE”) if VSOE is not available, or best estimate of selling price (“BESP”) if neither VSOE nor TPE is available. We generally determine selling price based on amounts charged separately for the delivered and undelivered elements to similar customers in standalone sales of the specific elements. When arrangements include an EMA, we recognize revenue related to the EMA at the stated contractual price on a straight-line basis over the life of the agreement.
	Any taxes imposed by governmental authorities on our revenue-producing transactions with customers are shown in our consolidated statements of operations on a net-basis; that is, excluded from our reported revenues.
Shipping and Handling Costs	Shipping and Handling Costs
	We classify shipping and handling costs related to product sales as cost of revenue, and any payments from customers for shipping and handling are categorized in revenue. We classify shipping and handling costs associated with receiving production inventory as cost of product revenue. Any materials received or shipped which are related to our engineering, sales, marketing and administrative functions are classified as operating expenses.
Cash and Cash Equivalents	Cash and Cash Equivalents
	Investments with a contractual maturity of three months or less when purchased are classified as cash equivalents.
Fair Value of Financial Instruments	Fair Value of Financial Instruments
	Fair value is measured based on an exit price, representing the amount that would be received to sell an asset or paid to satisfy a liability in an orderly transaction between market participants. Fair value is a market-based measurement that should be determined based on assumptions that market participants would use in pricing an asset or liability. As a basis for considering such assumptions, a fair value hierarchy is established, which categorizes the inputs used in measuring fair value as follows:
	Level 1—Quoted prices in active markets for identical assets or liabilities.
	Level 2—Significant observable inputs other than quoted prices in Level 1, such as quoted prices for similar assets and liabilities in active markets; quoted prices for identical or similar assets and liabilities in markets that are not active; or other inputs that are observable or can be corroborated by observable market data.
	Level 3—One or more significant inputs that are unobservable and supported by little or no market data.
	Highest priority is given for Level 1 input and lower propriety to Level 3 inputs.  A financial instruments level is based on the lowest level of any input that is significant to the fair value measurement.  No changes were made to our methodology.
	Our Level 1 assets consist of cash equivalents, which are primarily invested in money-market funds. These assets are classified as Level 1 because they are valued using quoted prices in active markets and other relevant information generated by market transactions involving identical assets and liabilities. The fair value was $3.1 million as of December 31, 2014 and 2013.
	For cash and cash equivalents, accounts receivable, accounts payable and our revolving line of credit, the carrying amount approximates fair value because of the relative short maturity of those instruments.
Allowance for Doubtful Accounts	Allowance for Doubtful Accounts
	We estimate an allowance for doubtful accounts based on factors related to the credit risk of each customer. Historically, credit losses were minimal, primarily because the majority of our revenues were generated from large customers, primarily Caterpillar, Inc. (“Caterpillar”) and Hewlett Packard Corporation (“HP”). We perform credit evaluations of new customers and often require deposits, prepayments or use of bank instruments such as trade letters of credit to mitigate our credit risk. We write off uncollectable trade receivables, and record any recoveries of previous write offs against the allowance. Our standard terms are net 30 days; however we may have agreements with our larger customers and certain distributors, OEM customers, and IT channel that allow for more extended terms at or above net 60 days.
	The following table summarizes the annual changes in our allowance for doubtful accounts (in thousands):
	Balance at December 31, 2011		$	337
	Change in provision charged to expense			151
	Write-off of uncollectible accounts, net of recoveries			-
	Balance at December 31, 2012		$	488
	Change in provision charged to expense			(139	)
	Write-off of uncollectible accounts, net of recoveries			(36	)
	Balance at December 31, 2013		$	313
	Change in provision charged to expense			(67	)
	Write-off of uncollectible accounts, net of recoveries			(34	)
	Balance at December 31, 2014		$	212
Inventories, net	Inventories, net
	Inventories, net are stated at the lower of cost or market, using the first-in-first-out method, and consisted of the following at December 31 (in thousands, net of allowances):
			2014			2013
	Raw materials		$	5,440		$	4,521
	Work in progress			473			2,429
	Finished goods			932			5,070
			$	6,845		$	12,020
Property and Equipment	Property and Equipment
	Property and equipment is stated at cost and is depreciated using the straight-line method over the estimated useful lives of the assets, as follows (in years):
	Equipment			10-Feb
	Demonstration units			5-Mar
	Computers and purchased software			3-Feb
	Furnitures and fixtures			5-Feb
	Leasehold improvements are depreciated over the shorter of the life of the improvement or the remainder of the property lease term, including renewal options, generally three to five years. Repairs and maintenance is expensed as incurred.
Long-Lived Assets	Long-Lived Assets
	Long-lived assets held and used by the Company are reviewed for impairment whenever events or changes in circumstances indicate that their net book value may not be recoverable. When such factors and circumstances exist, we compare the projected undiscounted future cash flows associated with the related asset or group of assets over their estimated useful lives against their respective carrying amounts. Impairment, if any, is based on the excess of the carrying amount over the fair value of those assets and is recorded in the period in which the determination was made.
Accrued Expenses	Accrued Expenses
	Accrued expenses consist of the following at December 31 (in thousands):
			2014			2013
	Compensation, severance and benefits		$	1,296		$	2,685
	Warranty liability			475			529
	Taxes, other than income			1,080			483
	Professional fees			463			759
	Other			820			1,127
			$	4,134		$	5,583
Warranty Liability	Warranty Liability
	Generally, the warranty period for our power quality products is 12 months from the date of commissioning or 18 months from the date of shipment from Active Power, whichever period is shorter. Occasionally we offer longer warranty periods to certain customers. The warranty period for products sold to our primary OEM customer, Caterpillar, is 12 months from the date of shipment to the end-user, or up to 36 months from shipment from Active Power. This is dependent upon Caterpillar complying with our storage requirements for our products in order to preserve this warranty period beyond the standard 18-month limit. We provide for the estimated cost of product warranties at the time revenue is recognized and this accrual is included in accrued expenses and long term liabilities on the accompanying consolidated balance sheet.
	Changes in the Company’s warranty liability are as follows (in thousands):
	Balance at December 31, 2011		$	613
	Warranty expense			1,294
	Payments			(1,152	)
	Balance at December 31, 2012		$	755
	Warranty expense			589
	Payments			(782	)
	Balance at December 31, 2013		$	562
	Warranty expense			660
	Payments			(695	)
	Balance at December 31, 2014		$	527
	Warranty liability included in accrued expenses		$	475
	Long term warranty liability			52
	Balance at December 31, 2014		$	527
Long-Term Liabilities	Long-Term Liabilities
	Long term liabilities consisted of the following at December 31 (in thousands):
			2014			2013
	Deferred revenue		$	751		$	601
	Technology licensing agreement			-			88
	Warranty liability			52			33
	Sublease deposits			18			19
			$	821		$	741
Stock-Based Compensation Expense	Stock-Based Compensation Expense
	We account for our stock-based compensation using the Black Scholes option valuation model. Stock-based compensation cost is estimated at the grant date based on the fair-value of the award and is recognized as expense ratably over the requisite service period of the award, generally four years. We develop our estimates of expected life and forfeitures based on historical data. We estimate stock price volatility based on historical volatilities. The risk-free rates are based on the U.S. Treasury yield in effect at the time of grant. Details of our stock-based compensation include the following (in thousands):
			2014			2013			2012
	Stock-based compensation expense by caption:
	Cost of product revenue		$	110		$	254		$	216
	Cost of service and other revenue			111			116			70
	Research and development			207			204			153
	Selling and marketing			370			587			484
	General and administrative			342			539			486
			$	1,140		$	1,700		$	1,409
	Stock-based compensation expense by type of award:
	Stock options		$	1,068		$	1,488		$	1,213
	Restricted stock awards			72			212			196
			$	1,140		$	1,700		$	1,409
	Assumptions used in the Black-Scholes model for our stock plans are presented below:
			2014			2013			2012
	Weighted average expected life in years		6.27 years			6.35 years			6.83 years
	Weighted average expected volatility			75	%		76	%		77	%
	Volatility Range			73%-76	%		75%-76	%		75%-78	%
	Risk-free interest rate range			1.96%-2.12	%		1.13%-2.38	%		0.63%-1.00	%
	Weighted average forfeiture rate			29.7	%		18.9	%		17	%
Income Taxes	Income Taxes
	We account for income taxes using the liability method of accounting for income taxes. Under the liability method, deferred taxes are determined based on the differences between the financial statement and tax basis of assets and liabilities using enacted tax rates in effect in the years in which the differences are expected to reverse. A valuation allowance is recorded to reduce the carrying amounts of deferred tax assets if it is more likely than not such assets will not be realized. Deferred income taxes reflect the net tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes.
	We recognize the financial statement benefit of a tax position that does not meet the more-likely-than-not threshold only after the statute of limitations expire of the relevant tax authority sustains the Company’s position following an audit. For tax positions meeting the more likely-than-not threshold, the amount recognized in the financial statements is the largest benefit that has a greater than 50 percent likelihood of being realized upon the ultimate settlement with the relevant tax authority. At December 31, 2014 and 2013, the Company had no material unrecognized tax benefits.
	The Company recognizes interest and penalties related to uncertain tax positions in income tax expense. As of December 31, 2014, the Company had no accrued or expensed interest or penalties related to uncertain tax positions.
Segment Reporting	Segment Reporting
	Active Power’s chief operating decision makers allocate resources and assess the performance of its power management product development and sales activities as one segment.
Concentration of Credit Risk	Concentration of Credit Risk
	Financial instruments which potentially subject Active Power to concentrations of credit risk consist of cash and cash equivalents, investments and accounts receivable. Active Power’s cash and cash equivalents and investments are placed with high credit quality financial institutions and issuers. From time to time, we may have amounts on deposit with financial institutions that are in excess of the federally insured limit. We have not experienced any losses on deposits of cash and cash equivalents.
	Active Power performs credit evaluations of its customers’ financial condition prior to entering into commercial transactions. We generally require letters of credit or prepayments from higher-risk customers as deemed necessary to ensure collection. Our allowance for doubtful accounts is estimated based on factors related to the credit risk of each customer. Individual receivables are written off after they have been deemed uncollectible. We also purchase several components from sole source or limited source suppliers.
Economic Dependence	Economic Dependence
	We are significantly dependent on our relationships with HP and Caterpillar. If these relationships are unsuccessful or discontinue, our business and revenue may suffer. The loss of, or a significant reduction in, orders from HP or Caterpillar, or the failure to provide adequate service and support to the end-users of our products by HP or Caterpillar, could significantly reduce our revenue. Our operating results in the foreseeable future will continue to depend on the sales made by a relatively small number of customers, including HP and Caterpillar.
	The following customers accounted for a significant percentage of Active Power’s total revenue during each of the years ended December 31:
			2014			2013			2012
	Caterpillar			18	%		14	%		13	%
	HP			1	%		22	%		35	%
	European based IT Customer			-			-			12	%
	No other customer represented more than 10% of our revenues in any of the years reported. Caterpillar represented 18% and 23% of our outstanding accounts receivable at December 31, 2014 and 2013, respectively. HP represented 22% of our outstanding receivables at December 31, 2013.
Advertising Costs	Advertising Costs
	We expense advertising costs as incurred. These expenses were immaterial in 2014, 2013, and 2012, respectively.
Net (Loss) Per Share	Net Loss Per Share
	The following table sets forth the computation of basic and diluted net loss per share (in thousands) for the years ended December 31:
			2014			2013			2012
	Net loss		$	(12,827	)	$	(8,351	)	$	(1,922	)
	Basic and diluted:
	Weighted-average shares of common stock outstanding used in computing basic and diluted net loss per share			22,494			19,329			18,584
	Basic and diluted net loss per share		$	(0.57	)	$	(0.43	)	$	(0.10	)
	The calculation of diluted net loss per share excludes 2,399,890, 2,407,664, and 1,882,584 shares of common stock issuable upon exercise of employee stock options as of December 31, 2014, 2013, and 2012, respectively, and 21,994, 53,038, and 200,071 non-vested shares of common stock issuable upon exercise of restricted stock awards as of December 31, 2014, 2013, and 2012, respectively, because their inclusion in the calculation would be anti-dilutive.
Recent Accounting Pronouncements	Recent Accounting Pronouncements
	In August 2014, the Financial Accounting Standards Board (the “FASB”) issued Accounting Standards Update (“ASU”) No. 2014-15, (“ASU 2014-15”), “Disclosure of Uncertainties About an Entity’s Ability to Continue as a Going Concern”. ASU 2014-15 requires management to perform interim and annual assessments of an entity’s ability to continue as a going concern within one year of the date the financial statements are issued and provides guidance on determining when and how to disclose going concern uncertainties in the financial statements. Certain disclosures will be required if conditions give rise to substantial doubt about an entity’s ability to continue as a going concern. ASU 2014-15 applies to all entities and is effective for annual and interim reporting periods ending after December 15, 2016, with early adoption permitted. The Company does not expect that the adoption of this standard will have a material effect on its financial statements.
	In May 2014, the FASB issued ASU 2014-09, “Revenue from Contracts with Customers”, “Topic 606”. This ASU will supersede the revenue recognition requirements in Topic 605, Revenue Recognition, and most industry-specific guidance, and creates a Topic 606 Revenue from Contracts with Customers. The core principle of the guidance is that an entity should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. The Company will adopt this guidance January 1, 2017 as required. We are evaluating the new guidelines to see if they will have a significant impact on our consolidated results of operation, financial condition or cash flows.

Summary_of_Significant_Account2

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2014
Summary of Significant Accounting Policies [Abstract]
Summary of the annual changes in allowance for doubtful accounts	The following table summarizes the annual changes in our allowance for doubtful accounts (in thousands):
	Balance at December 31, 2011	$	337
	Change in provision charged to expense		151
	Write-off of uncollectible accounts, net of recoveries		-
	Balance at December 31, 2012	$	488
	Change in provision charged to expense		(139	)
	Write-off of uncollectible accounts, net of recoveries		(36	)
	Balance at December 31, 2013	$	313
	Change in provision charged to expense		(67	)
	Write-off of uncollectible accounts, net of recoveries		(34	)
	Balance at December 31, 2014	$	212
Schedule of inventory	Inventories, net are stated at the lower of cost or market, using the first-in-first-out method, and consisted of the following at December 31 (in thousands, net of allowances):
		2014			2013
	Raw materials	$	5,440		$	4,521
	Work in progress		473			2,429
	Finished goods		932			5,070
		$	6,845		$	12,020
Summary of depreciation period of property and equipment	Property and equipment is stated at cost and is depreciated using the straight-line method over the estimated useful lives of the assets, as follows (in years):
	Equipment		10-Feb
	Demonstration units		5-Mar
	Computers and purchased software		3-Feb
	Furnitures and fixtures		5-Feb
Schedule of accrued liabilities	Accrued expenses consist of the following at December 31 (in thousands):
		2014			2013
	Compensation, severance and benefits	$	1,296		$	2,685
	Warranty liability		475			529
	Taxes, other than income		1,080			483
	Professional fees		463			759
	Other		820			1,127
		$	4,134		$	5,583
Changes in the company's warranty liability	Changes in the Company’s warranty liability are as follows (in thousands):
	Balance at December 31, 2011	$	613
	Warranty expense		1,294
	Payments		(1,152	)
	Balance at December 31, 2012	$	755
	Warranty expense		589
	Payments		(782	)
	Balance at December 31, 2013	$	562
	Warranty expense		660
	Payments		(695	)
	Balance at December 31, 2014	$	527
	Warranty liability included in accrued expenses	$	475
	Long term warranty liability		52
	Balance at December 31, 2014	$	527
Summary of long term liabilities	Long term liabilities consisted of the following at December 31 (in thousands):
		2014			2013
	Deferred revenue	$	751		$	601
	Technology licensing agreement		-			88
	Warranty liability		52			33
	Sublease deposits		18			19
		$	821		$	741
Details of stock-based compensation	Details of our stock-based compensation include the following (in thousands):
		2014			2013			2012
	Stock-based compensation expense by caption:
	Cost of product revenue	$	110		$	254		$	216
	Cost of service and other revenue		111			116			70
	Research and development		207			204			153
	Selling and marketing		370			587			484
	General and administrative		342			539			486
		$	1,140		$	1,700		$	1,409
	Stock-based compensation expense by type of award:
	Stock options	$	1,068		$	1,488		$	1,213
	Restricted stock awards		72			212			196
		$	1,140		$	1,700		$	1,409
Assumption used in Black Scholes model	Assumptions used in the Black-Scholes model for our stock plans are presented below:
		2014			2013			2012
	Weighted average expected life in years	6.27 years			6.35 years			6.83 years
	Weighted average expected volatility		75	%		76	%		77	%
	Volatility Range		73%-76	%		75%-76	%		75%-78	%
	Risk-free interest rate range		1.96%-2.12	%		1.13%-2.38	%		0.63%-1.00	%
	Weighted average forfeiture rate		29.7	%		18.9	%		17	%
Customer concentration risk revenue percentages	The following customers accounted for a significant percentage of Active Power’s total revenue during each of the years ended December 31:
		2014			2013			2012
	Caterpillar		18	%		14	%		13	%
	HP		1	%		22	%		35	%
	European based IT Customer		-			-			12	%
Basic and diluted net loss per share	The following table sets forth the computation of basic and diluted net loss per share (in thousands) for the years ended December 31:
		2014			2013			2012
	Net loss	$	(12,827	)	$	(8,351	)	$	(1,922	)
	Basic and diluted:
	Weighted-average shares of common stock outstanding used in computing basic and diluted net loss per share		22,494			19,329			18,584
	Basic and diluted net loss per share	$	(0.57	)	$	(0.43	)	$	(0.10	)

Property_and_Equipment_Tables

Property and Equipment (Tables)	12 Months Ended
	Dec. 31, 2014
Property and Equipment [Abstract]
Summary of property and equipment	Property and equipment consists of the following at December 31 (in thousands):
		2014			2013
	Equipment	$	9,122		$	9,168
	Demonstration units		1,836			1,470
	Computers and purchased software		3,321			3,273
	Furnitures and fixtures		366			380
	Leasehold improvements		7,225			7,216
	Construction in progress		19			458
			21,889			21,965
	Accumulated depreciation		(19,813	)		(18,909	)
		$	2,076		$	3,056

Stockholders_Equity_Tables

Stockholders' Equity (Tables)	12 Months Ended
	Dec. 31, 2014
Stockholders' Equity [Abstract]
Summary of common stock option activity	A summary of common stock option activity is as follows:
		Number of			Weighted-		Weighted-		Aggregate
		Shares			Average		Average		Intrinsic Value
					Exercise		Contractual Life		(whole dollars)
					Price		(in years)
	Outstanding at December 31, 2013		2,407,664		$	5.27
	Granted		993,725			3.01
	Exercised		(42,600	)		3.03
	Canceled		(958,899	)		5.44
	Outstanding at December 31, 2014		2,399,890		$	4.3		7.57	$	2,000
	Vested and expected to vest at December 31, 2014		1,901,476		$	4.63		7.18	$	1,000
	Exercisable at December 31, 2014		1,028,618		$	5.83		5.64	$	-
Summary of activity of restricted stock during the period	A summary of our restricted, non-vested, shares is as follows:
		Number of			Weighted-
		Shares			Average
					Grant Date
					Fair Value
	Outstanding at December 31, 2013		53,038		$	4
	Granted		-			-
	Vested		(18,681	)		4
	Canceled		(12,363	)		4
	Outstanding at December 31, 2014		21,994		$	4

Income_Taxes_Tables

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2014
Income Taxes [Abstract]
Schedule of pre-tax loss allocated between domestic and foreign operations	The Company’s pretax loss for the three years ended December 31, 2014, 2013, and 2012 were allocated between domestic and foreign operations as follows:
		Year Ended December 31,
		2014			2013			2012
	Domestic	$	(15,909	)	$	(9,105	)	$	(1,642	)
	Foreign		3,334			754			(280	)
	Total	$	(12,575	)	$	(8,351	)	$	(1,922	)
Significant components of deferred taxes	Significant components of the Company’s deferred taxes as of December 31 are as follows (in thousands):
		2014			2013
	Deferred tax assets:
	Current deferred tax assets
	Reserves and allowances	$	751		$	1,177
	Deferred Rent		45			55
	Deferred revenue		255			328
	Valuation allowance for current deferred tax assets		(1,049	)		(1,558	)
	Net current deferred tax assets	$	2		$	2
	Noncurrent deferred tax assets
	Acquired technology		571			695
	Capital expenses		1,652			1,624
	Stock compensation		594			699
	Net operating loss and tax credit carryforwards		84,047			84,356
	Valuation allowance for noncurrent deferred tax assets		(86,687	)		(87,263	)
	Net noncurrent deferred tax assets	$	177		$	111
	Deferred tax liabilities:
	Current deferred tax liabilities
	Prepaid expenses		(179	)		(113	)
	Total current deferred tax liabilities	$	(179	)	$	(113	)
	Total net deferred taxes	$	-		$	-
Income tax rate reconciliation	The Company’s provision for income taxes differs from the expected tax expense (benefit) amount computed by applying the statutory federal income tax rate of 34% to income before taxes due to the following:
		Year Ended December 31,
		2014			2013			2012
	Federal statutory rate		(34.0	)%		(34.0	)%		(34.0	)%
	State taxes, net of federal benefit		(1.0	)		(13.5	)		7.2
	R&D credits		(1.8	)		(5.6	)		1.3
	Stock compensation		3.8			6.2			14.5
	Effect of current foreign operations		5.5			(20.5	)		157.3
	Expiration and adjustment of net operating losses		26.7			-			63.2
	Foreign tax audit settlement		2			-			-
	Loss carryforward adjustments due to tax audit methodologies		9.1			-			-
	Permanent items and other		0.3			(1.9	)		6.8
	Change in valuation allowance		(8.6	)		69.3			(216.3	)
			2	%		-	%		-	%
Reconciliation of unrecognized tax benefits	The reconciliation of the Company’s unrecognized tax benefits at the beginning and end of the year is as follows:
	Balance at January 1, 2014	$	1,990
	Additions based on tax positions related to the current year		257
	Additions for tax positions of prior years		24
	Balance at December 31, 2014	$	2,271

Commitments_Tables

Commitments (Tables)	12 Months Ended
	Dec. 31, 2014
Commitments [Abstract]
Future minimum payments	Future minimum payments under these leases at December 31, 2014 are as follows (in thousands):
		Rental
		payments
	2015	$	1,260
	2016		1,073
	2017		116
	2018		72
	Total future minimum lease payments	$	2,521

Geographic_Information_Tables

Geographic Information (Tables)	12 Months Ended
	Dec. 31, 2014
Geographic Information [Abstract]
Revenues from foreign countries	Revenues for the year ended December 31 were as follows (in thousands):
		2014		2013		2012
	Americas	$	31,495	$	50,365	$	48,190
	Europe, Middle East and Africa		13,998		6,941		21,917
	Asia		3,643		4,393		6,208
	Total	$	49,136	$	61,699	$	76,315

Selected_Quarterly_Consolidate1

Selected Quarterly Consolidated Financial Data (unaudited) (Tables)	12 Months Ended
	Dec. 31, 2014
Selected Quarterly Consolidated Financial Data (unaudited) [Abstract]
Quarterly consolidated statement of operations	The following tables present selected unaudited consolidated statement of operations information for each of the quarters in the years ended December 31, 2014 and 2013 (in thousands, except per share data):
		For the Quarter Ended
	Year Ended December 31, 2014	31-Dec			30-Sep			30-Jun			31-Mar
	Selected consolidated statement of operations information:
	Total revenue	$	15,352		$	12,692		$	10,154		$	10,938
	Total cost of goods sold	$	11,303		$	8,932		$	8,239		$	8,010
	Gross profit	$	4,049		$	3,760		$	1,915		$	2,928
	Operating expenses	$	6,015		$	5,862		$	6,221		$	6,574
	Operating loss	$	(1,966	)	$	(2,102	)	$	(4,306	)	$	(3,646	)
	Net loss	$	(2,044	)	$	(2,496	)	$	(4,413	)	$	(3,874	)
	Basic and diluted net loss per share	$	(0.09	)	$	(0.11	)	$	(0.19	)	$	(0.19	)
	Selected consolidated balance sheet information:
	Current assets	$	33,731		$	34,711		$	36,427		$	42,070
	Total assets	$	36,098		$	37,341		$	39,350		$	45,164
	Current liabilities	$	16,484		$	15,720		$	15,529		$	17,069
	Working capital	$	17,247		$	18,991		$	20,898		$	25,001
	Long term obligations	$	821		$	852		$	697		$	746
	Stockholders' equity	$	18,793		$	20,769		$	23,124		$	27,349
		For the Quarter Ended
	Year Ended December 31, 2013	31-Dec			30-Sep			30-Jun			31-Mar
	Selected consolidated statement of operations information:
	Total revenue	$	13,926		$	13,154		$	20,195		$	14,424
	Total cost of goods sold	$	9,750		$	9,210		$	13,273		$	10,070
	Gross profit	$	4,176		$	3,944		$	6,922		$	4,354
	Operating expenses	$	7,990		$	6,909		$	6,412		$	5,702
	Operating profit (loss)	$	(3,814	)	$	(2,965	)	$	510		$	(1,348	)
	Net income (loss)	$	(4,127	)	$	(3,135	)	$	332		$	(1,421	)
	Basic and diluted new income (loss) per share	$	(0.21	)	$	(0.16	)	$	0.02		$	(0.07	)
	Selected consolidated balance sheet information:
	Current assets	$	34,556		$	39,110		$	45,722		$	42,019
	Total assets	$	37,907		$	42,263		$	49,052		$	44,748
	Current liabilities	$	16,860		$	18,194		$	22,758		$	19,208
	Working capital	$	17,696		$	20,916		$	22,964		$	22,811
	Long term obligations	$	741		$	737		$	689		$	774
	Stockholders' equity	$	20,306		$	23,332		$	25,605		$	24,766

Summary_of_Significant_Account3

Summary of Significant Accounting Policies (Details) (USD $)	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Summary of Significant Accounting Policies [Abstract]
Reverse stock split									five for one
Revenue Recognition [Abstract]
Duration period of product delivery related to certain services on design and consultation									6 months
Delivery period for EMAs, consumables, and repair, maintenance or consulting services, minimum									1 year
Delivery period for EMAs, consumables, and repair, maintenance or consulting services, maximum									5 years
Allowance for Doubtful Accounts [Abstract]
Allowance for doubtful accounts standard terms									30 days
Allowance for doubtful accounts standard terms, maximum									60 days
Annual changes in allowance for doubtful accounts [Roll Forward]
Balance at the beginning of the period				$313,000				$488,000	$313,000	$488,000	$337,000
Change in provision charged to expense									-67,000	-139,000	151,000
Write-off of uncollectible accounts, net of recoveries									-34,000	-36,000	0
Balance at the end of the period	212,000				313,000				212,000	313,000	488,000
Inventories, net [Abstract]
Raw materials	5,440,000				4,521,000				5,440,000	4,521,000
Work in progress	473,000				2,429,000				473,000	2,429,000
Finished goods	932,000				5,070,000				932,000	5,070,000
Inventories	6,845,000				12,020,000				6,845,000	12,020,000
Accrued Expenses [Abstract]
Compensation, severance and benefits	1,296,000				2,685,000				1,296,000	2,685,000
Warranty liability	475,000				529,000				475,000	529,000
Taxes, other than income	1,080,000				483,000				1,080,000	483,000
Professional fees	463,000				759,000				463,000	759,000
Other	820,000				1,127,000				820,000	1,127,000
Accrued expenses	4,134,000				5,583,000				4,134,000	5,583,000
Changes in the Company's warranty liability [Roll Forward]
Balance at beginning of period				562,000				755,000	562,000	755,000	613,000
Warranty expense									660,000	589,000	1,294,000
Payments									-695,000	-782,000	-1,152,000
Balance at ending of period	527,000				562,000				527,000	562,000	755,000
Warrant liability included in accrued expenses	475,000				529,000				475,000	529,000
Long term warranty liability	52,000				33,000				52,000	33,000
Warranty accrual at end of period	527,000								527,000
Long Term Liabilities [Abstract]
Deferred revenue	751,000				601,000				751,000	601,000
Technology licensing agreement	0				88,000				0	88,000
Warranty liability	52,000				33,000				52,000	33,000
Sublease deposits	18,000				19,000				18,000	19,000
Long-term liabilities	821,000	852,000	697,000	746,000	741,000	737,000	689,000	774,000	821,000	741,000
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Requisite Service period of award									4 years
Stock-based compensation expense									1,140,000	1,700,000	1,409,000
Fair value assumptions used in Black-Scholes model [Abstract]
Weighted average expected life in years									6 years 3 months 7 days	6 years 4 months 6 days	6 years 9 months 29 days
Weighted average expected volatility (in hundredths)									75.00%	76.00%	77.00%
Volatility range, minimum (in hundredths)									73.00%	75.00%	75.00%
Volatility range, maximum (in hundredths)									76.00%	76.00%	78.00%
Risk-free interest rate range, minimum (in hundredths)									1.96%	1.13%	0.63%
Risk-free interest rate range, maximum (in hundredths)									2.12%	2.38%	1.00%
Weighted average forfeiture rate (in hundredths)									29.70%	18.90%	17.00%
Income Taxes [Abstract]
Accrued interest and penalties	0								0
Net Income (Loss) Per Share [Abstract]
Net loss	-2,044,000	-2,496,000	-4,413,000	-3,874,000	-4,127,000	-3,135,000	332,000	-1,421,000	-12,827,000	-8,351,000	-1,922,000
Basic and diluted [Abstract]
Weighted-average shares of common stock outstanding used in computing basic and diluted net loss per share (in shares)									22,494,000	19,329,000	18,584,000
Basic and diluted net loss per share (in dollars per share)	($0.09)	($0.11)	($0.19)	($0.19)	($0.21)	($0.16)	$0.02	($0.07)	($0.57)	($0.43)	($0.10)
Stock Options [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive stock not included in net loss per share (in shares)									2,399,890	2,407,664	1,882,584
Restricted Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive stock not included in net loss per share (in shares)									21,994	53,038	200,071
Revenue [Member] | Customer Concentration Risk [Member] | Caterpillar [Member]
Concentration Risk [Line Items]
Concentration risk percentage (in hundredths)									18.00%	14.00%	13.00%
Revenue [Member] | Customer Concentration Risk [Member] | HP [Member]
Concentration Risk [Line Items]
Concentration risk percentage (in hundredths)									1.00%	22.00%	35.00%
Revenue [Member] | Customer Concentration Risk [Member] | European Based IT Customer [Member]
Concentration Risk [Line Items]
Concentration risk percentage (in hundredths)									0.00%	0.00%	12.00%
Outstanding Receivables [Member]
Concentration Risk [Line Items]
Benchmark description									18% of our accounts receivable	23% of our accounts receivable
Outstanding Receivables [Member] | Caterpillar [Member]
Concentration Risk [Line Items]
Concentration risk percentage (in hundredths)									18.00%	23.00%
Outstanding Receivables [Member] | HP [Member]
Concentration Risk [Line Items]
Concentration risk percentage (in hundredths)										22.00%
Stock Options [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense									1,068,000	1,488,000	1,213,000
Restricted Stock Awards [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense									72,000	212,000	196,000
Cost of Product Revenue [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense									110,000	254,000	216,000
Cost of Service and Other Revenue [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense									111,000	116,000	70,000
Research and Development Expense [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense									207,000	204,000	153,000
Selling and Marketing Expense [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense									370,000	587,000	484,000
General and Administrative Expense [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense									342,000	539,000	486,000
Power Quality Products [Member]
Warranty Liabilities [Line Items]
Warranty period from date of commissioning									12 months
Warranty period granted from date of shipment									18 months
Minimum [Member]
Property and Equipment [Line Items]
Leasehold improvements renewal options									3 years
Minimum [Member] | Caterpillar [Member]
Warranty Liabilities [Line Items]
Warranty period granted from date of shipment									12 months
Maximum [Member]
Property and Equipment [Line Items]
Leasehold improvements renewal options									5 years
Maximum [Member] | Caterpillar [Member]
Warranty Liabilities [Line Items]
Warranty period granted from date of shipment									36 months
Equipment [Member] | Minimum [Member]
Property and Equipment [Line Items]
Estimated useful lives of property and equipment									2 years
Equipment [Member] | Maximum [Member]
Property and Equipment [Line Items]
Estimated useful lives of property and equipment									10 years
Demonstration Units [Member] | Minimum [Member]
Property and Equipment [Line Items]
Estimated useful lives of property and equipment									3 years
Demonstration Units [Member] | Maximum [Member]
Property and Equipment [Line Items]
Estimated useful lives of property and equipment									5 years
Computers and Purchased Software [Member] | Minimum [Member]
Property and Equipment [Line Items]
Estimated useful lives of property and equipment									2 years
Computers and Purchased Software [Member] | Maximum [Member]
Property and Equipment [Line Items]
Estimated useful lives of property and equipment									3 years
Furnitures and Fixtures [Member] | Minimum [Member]
Property and Equipment [Line Items]
Estimated useful lives of property and equipment									2 years
Furnitures and Fixtures [Member] | Maximum [Member]
Property and Equipment [Line Items]
Estimated useful lives of property and equipment									5 years
Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	$3,100,000				$3,100,000				$3,100,000	$3,100,000

Property_and_Equipment_Details

Property and Equipment (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Property and Equipment [Line Items]
Property and equipment, gross	$21,889	$21,965
Accumulated depreciation	-19,813	-18,909
Property and equipment, net	2,076	3,056
Reclassification of inventory	44	900
Equipment [Member]
Property and Equipment [Line Items]
Property and equipment, gross	9,122	9,168
Demonstration Units [Member]
Property and Equipment [Line Items]
Property and equipment, gross	1,836	1,470
Computers and Purchased Software [Member]
Property and Equipment [Line Items]
Property and equipment, gross	3,321	3,273
Furnitures and Fixtures [Member]
Property and Equipment [Line Items]
Property and equipment, gross	366	380
Leasehold Improvements [Member]
Property and Equipment [Line Items]
Property and equipment, gross	7,225	7,216
Construction in Progress [Member]
Property and Equipment [Line Items]
Property and equipment, gross	$19	$458

Stockholders_Equity_Details

Stockholders' Equity (Details) (USD $)	0 Months Ended		12 Months Ended
	Mar. 31, 2014	Mar. 31, 2012	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	28-May-14	31-May-12
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for future grants of awards (in shares)			1,052,319
Common Stock, shares authorized (in shares)			40,000,000	30,000,000		30,000,000
Shares of common stock sold (in shares)	3,700,000	2,900,000	23,162,000	19,452,000
Purchase price per share (in dollars per share)	$3.15	$3.40
Commissions and fees related to issuance of stock	$800,000
Professional fees related to issuance of stock	200,000
Proceeds from private placement, net of fees and expenses	$10,400,000	$9,600,000	$0	$0	$9,750,000
2000 and 2010 Stock Incentive Plans [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Authorized shares of common stock for issuance (in shares)			5,682,296
Common Stock [Member] | Shares Added to 2010 Stock Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares reserved for future issuance (in shares)			3,461,909				1,700,000
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period			4 years
Term of awards			10 years
Restricted (Non-Vested) Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period				4 years
Shares offered to officers and/or employees (in shares)				6,000	248,000
Stock Options and Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares reserved for future issuance (in shares)			2,409,590

Stockholders_Equity_Stock_Opti

Stockholders' Equity, Stock Options Activity (Details) (Stock Options [Member], USD $)	12 Months Ended
In Thousands, except Share data, unless otherwise specified	Dec. 31, 2014
Stock Options [Member]
Share-based compensation options outstanding [Roll Forward]
Outstanding at the beginning of the period (in shares)	2,407,664
Granted (in shares)	993,725
Exercised (in shares)	-42,600
Canceled (in shares)	-958,899
Outstanding at the end of the period (in shares)	2,399,890
Vested and expected to vest at the end of the period (in shares)	1,901,476
Exercisable number of shares at the end of the period (in shares)	1,028,618
Share-based compensation options weighted average exercise price [Roll Forward]
Outstanding at the beginning of the period (in dollars per share)	$5.27
Granted (in dollars per share)	$3.01
Exercised (in dollars per share)	$3.03
Canceled (in dollars per share)	$5.44
Outstanding at the end of the period (in dollars per share)	$4.30
Weighted average exercise price vested and expected to vest (in dollars per share)	$4.63
Weighted average exercise price of shares exercisable at the end of the period (in dollars per share)	$5.83
Weighted average contractual term of shares outstanding	7 years 6 months 25 days
Weighted average contractual term of shares vested and expected to vest at end of the period	7 years 2 months 5 days
Weighted average contractual term of shares exercisable at the end of the period	5 years 7 months 20 days
Aggregate intrinsic value, outstanding, ending balance	$2,000
Aggregate intrinsic value, vested and expected to vest, ending balance	1,000
Aggregate intrinsic value, exercisable, ending balance	$0

Stockholders_Equity_Stock_Opti1

Stockholders' Equity, Stock Options, by Exercise Price Range (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Weighted average grant date fair value (in dollars per share)	$2.03	$2.60	$2.60
Intrinsic value of options exercised	$14,000	$100,000	$100,000

Stockholders_Equity_Restricted

Stockholders' Equity, Restricted (non-vested) Shares (Details) (USD $)	12 Months Ended
In Millions, except Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Restricted (Non-Vested) Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted Stock or Unit Expense	$0.10
Share-based Compensation other than options [Roll Forward]
Outstanding at the beginning of the period (in shares)	53,038
Granted (in shares)	0
Vested (in shares)	-18,681
Canceled (in shares)	-12,363
Outstanding at the end of the period (in shares)	21,994	53,038
Share-based compensation other than options grant date fair value [Roll Forward]
Weighted average grant date fair value at the beginning of the period (in dollars per share)	$4
Granted (in dollars per share)	$0
Vested (in dollars per share)	$4
Canceled (in dollars per share)	$4
Weighted average grant date fair value at the end of the period (in dollars per share)	$4	$4
Total unrecognized compensation cost	0.1
Unrecognized compensation cost, weighted-average vesting period	1 year 1 month 6 days
Fair value of restricted share units vested	0.1	0.3
Stock Options [Member]
Share-based compensation other than options grant date fair value [Roll Forward]
Total unrecognized compensation cost	2.6
Unrecognized compensation cost, weighted-average vesting period	2 years 9 months 18 days
Fair value of restricted share units vested	$1.80	$1.40	$1.70

Income_Taxes_Details

Income Taxes (Details) (USD $)	3 Months Ended	12 Months Ended
	Sep. 30, 2014	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Extraordinary Items, Noncontrolling Interest [Abstract]
Domestic		($15,909,000)	($9,105,000)	($1,642,000)
Foreign	300,000	3,334,000	754,000	-280,000
Total		-12,575,000	-8,351,000	-1,922,000
Federal net operating loss carryforwards		232,000,000
Current deferred tax assets [Abstract]
Reserves and allowances		751,000	1,177,000
Deferred Rent		45,000	55,000
Deferred revenue		255,000	328,000
Valuation allowance for current deferred tax assets		-1,049,000	-1,558,000
Net current deferred tax assets		2,000	2,000
Noncurrent deferred tax assets [Abstract]
Acquired technology		571,000	695,000
Capital expenses		1,652,000	1,624,000
Stock compensation		594,000	699,000
Net operating loss and tax credit carryforwards		84,047,000	84,356,000
Valuation allowance for noncurrent deferred tax assets		-86,687,000	-87,263,000
Net noncurrent deferred tax assets		177,000	111,000
Current deferred tax liabilities [Abstract]
Prepaid expenses		-179,000	-113,000
Total current deferred tax liabilities		-179,000	-113,000
Total net deferred taxes		0	0
Valuation Allowance [Line Items]
Change in valuation allowance		-1,100,000
Effective Income Tax Rate, Continuing Operations, Tax Rate Reconciliation [Abstract]
Federal statutory rate (in hundredths)		-34.00%	-34.00%	-34.00%
State taxes, net of federal benefit (in hundredths)		-1.00%	-13.50%	7.20%
R&D credits (in hundredths)		-1.80%	-5.60%	1.30%
Stock compensation (in hundredths)		3.80%	6.20%	14.50%
Effect of current foreign operations (in hundredths)		5.50%	-20.50%	157.30%
Expiration and adjustment of net operating losses (in hundredths)		26.70%	0.00%	63.20%
Foreign tax audit settlement (in hundredths)		2.00%	0.00%	0.00%
Loss carryforward adjustments due to tax audit methodologies (in hundredths)		9.10%	0.00%	0.00%
Permanent items and other (in hundredths)		0.30%	-1.90%	6.80%
Change in valuation allowance (in hundredths)		-8.60%	69.30%	-216.30%
Effective income tax rate (in hundredths)		2.00%	0.00%	0.00%
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance at beginning of period		1,990,000
Additions based on tax positions related to the current year		257,000
Additions for tax positions of prior years		24,000
Balance at end of period		2,271,000	1,990,000
Accrued interest and penalties		0
Research Tax Credit Carryforward [Member]
Tax Credit Carryforward [Line Items]
Tax credit carryforwards		$4,000,000

Commitments_Details

Commitments (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Real Estate Properties [Line Items]
Net deferred rent	$100,000	$100,000	$0
Net rent expense	1,500,000	1,700,000	1,700,000
Future minimum payments [Abstract]
2015	1,260,000
2016	1,073,000
2017	116,000
2018	72,000
Total future minimum lease payments	2,521,000
Commitments to purchase inventory and other items [Abstract]
2015	5,800,000
2016	200,000
2017	45,000
Total purchase commitments	$6,045,000
Severance Benefits Agreements [Abstract]
Duration period in change in executive officer's employment	12 months
Chief Executive Officer [Member]
Severance Benefits Agreements [Abstract]
Duration period of payment of salary and health benefits after termination	12 months
Other Executive Officer [Member]
Severance Benefits Agreements [Abstract]
Duration period of payment of salary and health benefits after termination	6 months

Contingencies_Details

Contingencies (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014
Contingencies [Abstract]
Cash settlement inclusive of fees and expenses	$1.50

Employee_Benefit_Plan_Details

Employee Benefit Plan (Details) (401 (k) Plan [Member])	12 Months Ended
	Dec. 31, 2014
401 (k) Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Vesting period	5 years

Geographic_Information_Details

Geographic Information (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
	Country
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	$49,136,000	$61,699,000	$76,315,000
Number of foreign countries from which revenue derived	38
Net assets	2,800,000
Reportable Geographical Components [Member] | Americas [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	31,495,000	50,365,000	48,190,000
Reportable Geographical Components [Member] | EMEA [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	13,998,000	6,941,000	21,917,000
Reportable Geographical Components [Member] | Asia [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	$3,643,000	$4,393,000	$6,208,000

Guarantees_Details

Guarantees (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
Guarantor Obligations [Line Items]
Deposit guarantees outstanding for building lease	$6,000
Performance Guarantee [Member]
Guarantor Obligations [Line Items]
Performance guarantees outstanding to customers	$34,000	$500,000

Revolving_Credit_Facility_Deta

Revolving Credit Facility (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2010
Line of Credit Facility Inventory Borrowing Rates [Line Items]
Borrowing base sublimits, U.K.(United Kingdom) and Germany accounts receivable	$5,000,000
Borrowing base sublimits, Inventory	3,500,000
Borrowing base sublimits, Purchase orders	1,500,000
Increase in rate on finance charges or interest rates, as applicable, in the event of default (in hundredths)	5.00%
Increase in rate on collateral handling fees in the event of default (in hundredths)	0.50%
Minimum [Member]
Line of Credit Facility Inventory Borrowing Rates [Line Items]
Repayment terms on purchase orders borrowings	91 days
Maximum [Member]
Line of Credit Facility Inventory Borrowing Rates [Line Items]
Borrowing base sublimits, Inventory	7,000,000
Repayment terms on purchase orders borrowings	120 days
SVB Streamline Period [Member]
Line of Credit Facility Inventory Borrowing Rates [Line Items]
Minimum prime interest rate (in hundredths)	4.00%
SVB Streamline Period [Member] | Inventory Borrowing Rates [Member]
Line of Credit Facility Inventory Borrowing Rates [Line Items]
Prime interest plus rate (in hundredths)	1.25%
SVB Streamline Period [Member] | Accounts Receivable Aged Borrowing Rates [Member]
Line of Credit Facility Inventory Borrowing Rates [Line Items]
Prime interest plus rate (in hundredths)	1.75%
SVB non Streamline Period [Member]
Line of Credit Facility Inventory Borrowing Rates [Line Items]
Minimum prime interest rate (in hundredths)	4.00%
SVB non Streamline Period [Member] | Inventory Borrowing Rates [Member]
Line of Credit Facility Inventory Borrowing Rates [Line Items]
Prime interest plus rate (in hundredths)	3.50%
SVB non Streamline Period [Member] | Accounts Receivable Aged Borrowing Rates [Member]
Line of Credit Facility Inventory Borrowing Rates [Line Items]
Prime interest plus rate (in hundredths)	2.00%
SVB Borrowing Base Eligible [Member] | Amended and Restated Loan and Security Agreement [Member]
Line of Credit Facility Inventory Borrowing Rates [Line Items]
Minimum prime interest rate (in hundredths)	4.00%
Prime interest plus rate (in hundredths)	0.50%
SVB Non Borrowing Base Eligible [Member] | Amended and Restated Loan and Security Agreement [Member]
Line of Credit Facility Inventory Borrowing Rates [Line Items]
Prime interest plus rate (in hundredths)	1.20%
Revolving Line of Credit [Member]
Line of Credit Facility Inventory Borrowing Rates [Line Items]
Current borrowing capacity			12,500,000
Aggregate percentage of the facility provision available during the "Streamline Period" (in hundredths)	80.00%
Maximum borrowing capacity	15,625,000
Line of credit facility outstanding	5,500,000	5,500,000
Loan facility term	2 years
Minimum liquidity ratio considered for steam line period	1.75:1
Minimum number of consecutive days required to maintain a liquidity ratio to be considered in a streamline period	60 days
Minimum restricted cash and cash equivalents required for the facility	6,250,000
Minimum duration period to maintain cash and cash equivalents	30 days
Additional borrowing base	4,600,000
Maturity date	5-Aug-14
Revolving Line of Credit [Member] | Amended and Restated Loan and Security Agreement [Member]
Line of Credit Facility Inventory Borrowing Rates [Line Items]
Current borrowing capacity	15,000,000
Aggregate percentage of the facility provision available during the "Streamline Period" (in hundredths)	80.00%
Maximum borrowing capacity	18,800,000
Borrowing base sublimits, U.K.(United Kingdom) and Germany accounts receivable	4,000,000
Loan facility term	3 years
Minimum liquidity ratio requirement	2.50:1
Letter of Credit [Member]
Line of Credit Facility Inventory Borrowing Rates [Line Items]
Maximum borrowing capacity	$1,500,000

Selected_Quarterly_Consolidate2

Selected Quarterly Consolidated Financial Data (unaudited) (Details) (USD $)	3 Months Ended								12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Selected consolidated statement of operations information [Abstract]
Total revenue	$15,352	$12,692	$10,154	$10,938	$13,926	$13,154	$20,195	$14,424	$49,136	$61,699	$76,315
Total cost of goods sold	11,303	8,932	8,239	8,010	9,750	9,210	13,273	10,070	36,484	42,303	51,601
Gross profit	4,049	3,760	1,915	2,928	4,176	3,944	6,922	4,354	12,652	19,396	24,714
Operating expenses	6,015	5,862	6,221	6,574	7,990	6,909	6,412	5,702	24,672	27,013	26,440
Operating profit (loss)	-1,966	-2,102	-4,306	-3,646	-3,814	-2,965	510	-1,348	-12,020	-7,617	-1,726
Net income (loss)	-2,044	-2,496	-4,413	-3,874	-4,127	-3,135	332	-1,421	-12,827	-8,351	-1,922
Basic and diluted net income (loss) per share (in dollars per share)	($0.09)	($0.11)	($0.19)	($0.19)	($0.21)	($0.16)	$0.02	($0.07)	($0.57)	($0.43)	($0.10)
Selected consolidated balance sheet information [Abstract]
Current assets	33,731	34,711	36,427	42,070	34,556	39,110	45,722	42,019	33,731	34,556
Total assets	36,098	37,341	39,350	45,164	37,907	42,263	49,052	44,748	36,098	37,907
Current liabilities	16,484	15,720	15,529	17,069	16,860	18,194	22,758	19,208	16,484	16,860
Working capital	17,247	18,991	20,898	25,001	17,696	20,916	22,964	22,811	17,247	17,696
Long term obligations	821	852	697	746	741	737	689	774	821	741
Stockholders' equity	$18,793	$20,769	$23,124	$27,349	$20,306	$23,332	$25,605	$24,766	$18,793	$20,306	$25,999	$16,292