Annual report pursuant to Section 13 and 15(d)

Summary of Significant Accounting Policies (Details)

v2.4.0.6
Summary of Significant Accounting Policies (Details) (USD $)
12 Months Ended
Mar. 31, 2013
Mar. 31, 2012
Mar. 31, 2011
Restricted Cash      
Additional security maintained with Wells Fargo for line of credit     $ 1,300,000
Restricted cash released by Wells Fargo   (1,250,000) 1,250,000
Long-Lived Assets      
Impairment 0    
Revenue      
Term for advance payment from shipment of sales 90 days    
Research and Development ("R&D")      
Total offsets to R&D expenses 1,700,000 800,000 900,000
Risk Concentrations      
Aggregate uninsured balances 38,600,000    
Bad debt expense 276,000 2,256,000 231,000
Net Loss Per Common Share      
Outstanding stock options (in shares) 11,800,000 10,000,000 10,100,000
Outstanding restricted stock units (in shares) 1,500,000 1,100,000 1,500,000
Number of warrants excluded from diluted net loss per common share computations 26,500,000 26,500,000 21,700,000
Revenue | Customer concentrations | BPC
     
Risk Concentrations      
Concentration percentage 11.00% 26.00% 23.00%
Revenue | Customer concentrations | Horizon
     
Risk Concentrations      
Concentration percentage 27.00% 19.00% 18.00%
Net accounts receivable | Credit concentration | BPC
     
Risk Concentrations      
Concentration percentage 35.00% 44.00%  
Net accounts receivable | Credit concentration | Regatta Solutions, Inc.
     
Risk Concentrations      
Concentration percentage 11.00%    
CPS
     
Depreciation and Amortization      
Capacity of microturbine (in kW) 100    
DOE
     
Risk Concentrations      
Other receivables under grants awarded $ 300,000 $ 100,000  
Minimum
     
Depreciation and Amortization      
Estimated Useful Life 2 years    
Maximum
     
Depreciation and Amortization      
Estimated Useful Life 10 years    
Warranty      
Warranty period 18 months