Just be aware of the inverter full feedback load capability of the inverter. If I recall an 8 KVA can feedback a max of 12KVA. This is where the supply(input/mains) wiring calculations to the inverter is important.

The way I understand it works, if you install a 8000 watt unit (around 35 amps) then the unit can feedback around 12000 watts (50 amps)

If you install a 4 or 6 mm wire you are going to experience overheating on the cabling. You would need to install at least 10 mm wiring to the inverter input.

The output/UPS/essential or whatever you wan to call it, will only require a 6 mm wire.

Talking Sunsynk, you then have the aux terminal which can be assigned to be used as an output or generator connection.

I cant wait to get my demo so I can start tinkering.