So I purchased a Eaton BRN115A1CS breaker which supports AFCI and GFCI functions. Not quite what you are using but should be representative of what you have. Will be running some tests with my 18KPV to see how it reacts. On another thought and something you can try in the mean time. I suppose that it could be possible that there could be some type of interference with one of the loads you have connected. To make sure that this is not the case. First pick a breaker that tends to exhibit the issue most often. Then turn off all other load breakers and run with just the one breaker. Does it still trip? If so, remove the load connections (Hot & Neutral) to this test breaker. Reset breaker and try again. Does it still trip on it's own? Also, make sure that your loads neutral connection is from the breaker and not the neutral buss bar connection in the breaker box. These breakers must monitor the currents through the neutral wire through the breaker to operate properly. I'm assuming that you also have the white neutral pig tail wire that comes out of the breaker, is connected to the neutral buss bar connection in the breaker box. One other note. On your ground neutral bonding. This should only take place at one location. Usually at the service entrance, so when you are running from the grid (extension cord), this bonding has already occurred in the buildings entry wiring. So you don't want to have a secondary bonding in your setup in this case. The reverse of this is when you are running solely with the inverter (no extension cord), In which case, you will need to provide bonding in your local PV AC panel disconnect. So this could be an issue if you are trying to switch between the two sources of power, i.e having remote grid power provide the bonding or having to add local bonding when when running on the inverter only and grid power connection is removed.
