I want to connect the AC output of a Multiplus II to a load that can also act as a generation source (similar to regen braking) at certain times - will this generated power be able to feed back into the "AC output" and charge the battery? I assume this will be similar to an AC-coupled inverter on the output side of the Multiplus II?
Yes it will charge since the inverter is bidirectional.
The main thing is to control the charge source if it cannot be regulated by the inverter or GX to prevent over charge of batteries.
If there is no frequency shifting/control then switching off the AC2 output when batteries are closed to full might be an option. Not sure how that will affect the charge source you have in mind.
