I'm working with a solar contractor who asked me to install a 100 amp subpanel so he could backfeed several strings of panels with micro inverters. The subpanel will also have circuits for a PV monitor and a heat pump. I placed the 100 amp subpanel breaker in the furthest slots away from the main breaker. His engineer says this arrangement is not code compliant. Is this true? Could someone give me the code reference.
The panel is a 200 Amp panelboard with a 200 Amp breaker.
A load side connection, via a backfed breaker in the sub-panel, would not be code compliant.
The continuous current of the X22 microverters is 1.33 amps.
1.33 amps x 26 microinverters= 34.58 amps
34.58 amps x 1.25= 43.23 amps
The maximum allowable backfeed if the main is a 200 A with 200 A main breaker is 40 amps.
I would have to draw this as a "supply side connection" with an additional sub-panel for PV combining.