Annual report pursuant to Section 13 and 15(d)

Stockholders' equity - Stock Option Activity (Details)

v3.23.1
Stockholders' equity - Stock Option Activity (Details) - USD ($)
12 Months Ended
Dec. 31, 2022
Dec. 31, 2021
Exercise Price Per Share [Abstract]    
Outstanding, Exercise Price Lower Range Limit (usd per share) $ 0.71 $ 0.71
Outstanding, Exercise Price Upper Range Limit (usd per share) 10.33  
Granted, Exercise Price Lower Range Limit (usd per share) 1.00  
Granted, Exercise Price Upper Range Limit (usd per share) 1.41 $ 10.33
Canceled and Forfeited, Exercise Price Lower Range Limit (usd per share) 1.00  
Canceled and Forfeited, Exercise Price Upper Range Limit (usd per share) $ 6.74  
Tecogen    
Stock Options Outstanding [Roll Forward]    
Beginning (shares) 2,386,842  
Granted (shares) 1,036,650 258,000
Canceled and forfeited (shares) (219,195)  
Ending (shares) 3,204,297 2,386,842
Exercisable (shares) 1,421,147  
Vested and expected to vest (shares) 2,936,825  
Weighted Average Exercise Price [Roll Forward]    
Beginning (usd per share) $ 1.81  
Granted (usd per share) 1.14  
Canceled and forfeited (usd per share) 1.58  
Ending (usd per share) 1.61 $ 1.81
Vested and expected to vest (usd per share) 1.66  
Exercisable (usd per share) $ 2.32  
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Additional Disclosures [Abstract]    
Outstanding, Aggregate Intrinsic Value $ 882,074 $ 697,935
Exercisable, Aggregate Intrinsic Value 391,257  
Vested and expected to vest, Aggregate Intrinsic Value $ 808,252  
Exercise Price Per Share [Abstract]    
Granted, Exercise Price Lower Range Limit (usd per share) $ 1.10 $ 1.75
Granted, Exercise Price Upper Range Limit (usd per share) $ 1.20  
Stock Options | Tecogen    
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Additional Disclosures [Abstract]    
Outstanding, Weighted Average Remaining Life 7 years 3 months 18 days 7 years 6 months 21 days