Annual report pursuant to Section 13 and 15(d)

Stockholders' equity - Stock-Based Compensation (Details)

v3.23.1
Stockholders' equity - Stock-Based Compensation (Details) - USD ($)
12 Months Ended
Dec. 31, 2022
Dec. 31, 2021
Jun. 09, 2022
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Options granted, exercise price range, lower limit (usd per share) $ 1.00    
Options granted, exercise price range, upper limit (usd per share) $ 1.41 $ 10.33  
Historical forfeiture rate (percent) 15.00%    
Tecogen      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Options granted 1,036,650 258,000  
Shares of common stock granted (in shares) 761,650    
Options granted, exercise price range, lower limit (usd per share) $ 1.10 $ 1.75  
Options granted, exercise price range, upper limit (usd per share) $ 1.20    
Award vesting period 4 years 4 years  
Award expiration period   10 years  
Fair value of options issued $ 321,910 $ 166,474  
Weighted-average grant date fair value of options granted $ 0.42 $ 0.65  
Recognized stock-based compensation $ 334,149 $ 202,431  
Compensation cost related to unvested restricted stock awards and stock option awards not yet recognized $ 500,059 $ 470,063  
Compensation cost not yet recognized, weighted average period of recognition 1 year 6 months 29 days    
Tecogen | Director      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Options granted 275,000    
Options granted, exercise price range, lower limit (usd per share) $ 1.00    
Options granted, exercise price range, upper limit (usd per share) $ 1.41    
Award expiration period   10 years  
Fair value of options issued $ 145,600    
Weighted-average grant date fair value of options granted $ 0.53    
Tecogen | Amended Plan | Stock Options      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Shares of common stock reserved for future issuance 3,838,750    
Number of shares remaining available for future issuance 146,393 764,768  
Tecogen | 2022 Stock Incentive Plan | Stock Options      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Shares of common stock reserved for future issuance 3,600,000   3,800,000