Solar backfeed clarity

[Eros]

I have an outbuilding that a solar array is being installed on with the inverter located in the same building. I want to install the solar back feed breaker in the sub panel in the outbuilding. Two scenarios : 1, the sub panel has a main in it as well as a breaker in the House panel that is feeding it. 2 : the sub panel is a main lug that is being fed from a breaker in the House panel. Question - what is classified as the "true" back feed breaker and how is the calculation done (code articles would help) ? I am dealing with a very confused inspector
Thank you

 

[jaggedben]

If you are on the 2014 or 2017 code the breaker doesn't matter anymore. The backfeed is 125% of inverter output.

705.12(D) in 2014, 705.12(B) in 2017.

The 2011 code had language that clarified that it was the breaker closest to the inverter(s), but that was no longer needed when the stopped using breaker ratings for busbar calculations.

 

[jaggedben]

By the way, the sub in the outbuilding should probably have a main. Disconnecting means are required for feeders to outbuildings. It needs a main unless the loads are six handles or less.