Backup system advice

[ozman]

I'm in the process of completing a solar/generator backup system to run essential loads for my house. So far I have a 7000 watt inverter generator, a 10 circuit manual generator transfer switch/subpanel with a 240 volt split phase 4 lug plug mounted outside to plug the generator into. This works great to power my essentials like my gas furnace, fridge and freezers, kitchen appliances, lights, ceiling fans, some window unit a/c's and a bunch of outlets. I would also like to add solar and batteries to this system to run at night or when the generator is off, that can either be charged by solar panels (not mounted, just on the ground in my backyard) or by the generator on cloudy days (during a power outage). So far I have two growatt 24v 3000 watt all in ones, a 5kw signature solar 24v battery, and a 8kw diy 24volt battery on the way. I was intending to parallel the two growatts together to make split phase 240 that I can wire into the same generator transfer switch/subpanel I currently have for my generator. Obviously I would only use one system at a time (battery or generator), but haven't found any type of switch that I can switch between, just manually rewiring for now, but I know that would get old in a grid down scenerio. Does such a 240 split phase switch exist that I can choose between receiving power to my generator transfer switch/subpanel from the generator or from the growatts?

Secondly, would it make sense to parallel the two growatts or just run them independently since I have two different battery capacities? My generator transfer switch/panel is basically split into two sides, and everything on it is 120 (nothing tied into 240 on the two sides), so could I just wire one side onto one growatt and one side on the other? Would that make more sense since I have two different batteries? And could maybe conserve more power at night if I turn one side off? Thanks in advance. Great forum.

 

[NelsonAC]

The posting is a few weeks old now, not sure if you found your solution, however I have a similar setup, and I plan on using a Interlinked breaker box to transfer the Utility input of Growatt from Utility to Portable Gas Generator.

 

[Bvillebob]

My system is smaller than yours, I can run my house off a 4KW inverter, but I'm doing the same thing. My solution was to run power from the solar inverter to the transfer switch on the house, then run the generator output to the inverter's generator input, so that the house is purely powered by the solar but the solar can be easily recharged from the generator if needed.

Lithium cells are so efficient there's hardly any loss with an efficient inverter, and the genrator is much more efficient running at a constant load feeding the charger than with the fluctuating load from the household appliances. The charger output to the batteries can be fine tuned in software to get just the optimum load on the generator for best efficiency., Also, it means my generator is near my solar equipment, which is a couple of hundred feet behind the house in my pole barn, not sitting in my front yard near the breaker box from the. utility,