I wasn't able to find the answer on the forum and in the manuals or Victron unlimited.
I'm planing for a 3 phase completely offgrid situation with 3 units of MP 10k. Will be adding a Fronius 20kw 3 phase PV inverter (or 3*MP2-15kva+1 Fronius ECO 27kw)
As it would be disconnected for the grid, I suspect the MP are going to do frequency shifting (instead of Modbus communication). That's ok (not ideal, but ok).
All the house/shop will be on AC-OUT. If the batteries are full, the MP's will increase freq to stop the Fronius (in all 3 phases).
What's going to happen if L1 has a load? As the frequency shifting applies to the PV inverter, all 3 phases will be shut down. If L1 has a load, the idea scenario will do that the Fronius deliver power to that load (L1 1500W, L2 0W, L3 0W). But I've no idea if it works like that (specially if the communication is via freq. Shifting instead of Modbus).
I suspect (hope I'm wrong) that the MP on phase 1 is going to invert from the battery, and as the battery gets drained, the frequency shifting will decrease, starting again the Fronius, to recharge the battery (AC-DC). In this case, is not ideal, the battery will be most of the time playing between 100% to whatever takes to restart the Fronius.
Cheers