Secondary Slave Inverter for non essential loads?

I have an oversized battery and panel system, 17280 watts of panels and 1100ah of lithium batteries with a 12kw Growatt inverter. I mostly use 3 or 4kw, often as much as 6kw during the day, but sometimes for short periods I use 10kw of power so I really don’t want to add any more load to this inverter. We get lots of clouds and rain here so I designed it to run on the solar even when there is light rain, so I have lots of wasted power during the day when the weather is nice. I have some old 5kw inverters I no longer use and they would not be capable of communication with the Growatt inverter. Has anyone ever tried connecting an inverter as a complete slave only connected to the battery? I was thinking of using one inverter set for low battery shutoff at 53 volts and turn on at 54 volts so that it would not work if the batteries were a bit low. I want to power 2 air conditioners that are not essential. The house has 4 totally independent electrical systems so and these 2 are on a separate system from the Growatt inverter. I know I can add a new Growatt inverter set up as a slave that communicates with the other but I don’t really want to buy a new inverter for this, I was just thinking of putting the extra power to use with an inverter we don’t use and on something we are not running right now. It seems to me that it should work since it would be only using battery power and not contributing anything and should shut off before draining too much power. Any thoughts on this insane idea? the dog

Very interesting idea. Since the second inverter cut-off is based on voltage and the loads are separate (non-essential) then I don’t see why this wouldn’t work.

Another way you could do this is to use a relay control - For example, the Victron BMV712 has a relay control that can be used to operate an AC contactor based on battery voltage or SOC.

Let us know how it goes.

Thanks! I was thinking of the relay idea as well but I didn’t see any around here that could work, so I’ll look into the Victron. I have a few more things to set up then I’ll try adding it as a total slave first and see how it goes and I’ll let you know. I was thinking of a relay for my grid tie system as well so maybe that will work there as well, here it’s not worth it to feed anything to the grid. I want to add load as the solar power increases and drop it off as it decreases. I’ve tried a few different things for that, but none seem to work. I always appreciate your input, it seems everything you tell me is right. the dog