I have a 3 phase off grid system with 3x 2000W Compact Phoenix Inverters (same as Multis, just there is no Ac input). I don't have installed ESS but PV inverter assistant. I would like to add some PV AC coupled with Fronius 3 phase inverter on the AC output. According to the 1.0 rule, I could add 6kW Fronius Symo inverter which can have a maximum current on one phase 13.5A (arround 3kW on a 230V system). But I am concerned with possible overload in the case of high load on one phase.
Example:
Fronius is producing 4kW from PVs which is equally divided charging the batteries through the three Victron inverters. If I switch on a 3kW load on a one phase what is happening?
1) Fronius is giving 3kW to the load, and the remaining 1kW will go through the remaining two inverters and charge the battery?
2) Or every phase will get 1/3 (1.33kW), and the rest of 1.7kW for the load will be supplied through the Victron inverter from the battery. In that case Two inverters would be charging and one would be discharging the battery.
I suppose that answer number 1) is correct. In that case, when the load is disconnected, will the Victron inverter on this phase have to absorb all the 3kW power and be overloaded (exceeding 1.0 rule) or the Fronius will manage to balance load through the other phases?
Then maybe it would be better to couple three 2kW grid tie inverters, one on the each phase.
