I would like to connect a Delta Solivia 11 with a 3-phase output to the output of my Delta Solivia 11 multiplus.
In summer I work as an offgrid without distribution and in winter with distribution.
Is it possible to connect this ongrid inverter to the multiplus output or are only certain inverters such as Fronius, SMA reserved for it?
Your first sentence isn't very clear, but yes, you can connect an AC-coupled inverter to the output of a MultiPlus.
If you are off-grid in the summer, you can't connect it to the MultiPlus input, because the inverter won't turn on in that case due to loss of mains. So it needs to be connected to the AC-out of the multiplus.
If your PV output will exceed your battery capacity and self consumption, and you are off-grid, there is nowhere the PV power can go to. I believe (but not sure) VenusOS (eg. cerbo) can somewhat control the output of Fronius inverters by playing with the frequency.
For other inverter types it could mean that the inverter will simply shutdown when there is excess energy that can't go anywhere. That's not necessarily bad, but not ideal.
