100 amp service, 200 amp panel. 20 amp solar breaker or 40?

[ACV987]

My incoming service and main breaker is 100 amp but I have a 200 amp busbar. Does the 120% rule apply to the actual service or the panel?

 

[mnd]

Or use a line side tap and avoid the 120% rule entirely?

 

[ACV987]

seems more advanced than id like to venture

 

[RCinFLA]

120% rule you can inject a maximum 240 amps into 200A rated bus. Since you have a 100 amps grid main input breaker it means there is 240-100A = 140A max remaining margin meaning you could go up to 140A of GT injection.

Main Grid breaker | panel rating | 120% margin for PV GT injection

200A | 200A | 40A
150A | 200A | 90A
100A | 200A | 140A

There is likely a maximum branch breaker amperage allowed for given manuf. box. You could likely put two separate 70A breakers inputs for two GT PV inverter inputs. Usually branch breakers are limited to less than or equal 100A. I have seen some box branch breaker limit as low as 60A.

 

[ACV987]

120% rule you can inject a maximum 240 amps into 200A rated bus. Since you have a 100 amps grid main input breaker it means there is 240-100A = 140A max remaining margin meaning you could go up to 140A of GT injection.

Main Grid breaker | panel rating | 120% margin for PV GT injection

200A | 200A | 40A
150A | 200A | 90A
100A | 200A | 140A

There is likely a maximum branch breaker amperage allowed for given manuf. box. You could likely put two separate 70A breakers inputs for two GT PV inverter inputs. Usually branch breakers are limited to less than or equal 100A. I have seen some box branch breaker limit as low as 60A.

thanks! so the main breaker isnt what matters its the busbar.