What is your largest inverter size?

Example:

Busbar = 200A

Main = 200A

What is your largest inverter size?

                                 200A X 1.2 = 240A

                                 240A – 200A = 40A

                                  40A / 1.25 = 32A

Largest inverter is 32A

You can multiply by the ac voltage to get the power!

705.12(D)(2)(3)(C): SOLAR + LOAD BREAKER METHOD

Load and supply breakers do not exceed the main breaker (this also works for subpanels).

New in the 2014 NEC, 705.12(D)(2)(3)(c) allows us to add up the load and supply breakers and as long as they don’t exceed the rating of the main supply breaker (or the busbar rating) then we are good.

                                  Solar + Load ≤ Main

Note that for the solar + load breaker accounting method, we do not use

125% of the inverter current, we use the size of the breaker. This is easy and convenient when combining inverters with an ac combiner subpanel.