Growatt inverters and Gyll 100Ah LiFePO4 as a UPS

I currently have my 'home lab' environment running on two APC SMX3000 UPS units. These units each have ten 5Ah batteries wired in series, giving an output voltage from the batteries into the inverter of about 136v fully charged. My math could be off, but as each 12v 5Ah battery has about 60Wh, and with batteries, when wired in series, you get voltage increase but not capacity, so two 5Ah batteries in parallel would be 12v 10Ah, but in series, they would be 24v 5Ah, and as the batteries are in series, would that mean the pack would still only be 60Wh, or would it be 600Wh? Either way... I've been watching a lot of videos from Will Prowse, David Poz and others and got to thinking - what about using a pair of growatt inverters tied together and a 100Ah Gyll battery instead of the APC UPS? Ultimately, I'd LOVE to be able to add a bunch of solar and run it all off as much solar as possible, but I'm not sure of the feasibility of that right now. But as just a UPS, the Growatts and Gyll battery should provide a huge increase in runtime over the APC units, and realistically, be more serviceable than the APC units. Does this seem like something that would be feasible?

I have an APC SURT6000XLT and it came with 16x 12v batteries in it. In their manual they call it a 192v nominal voltage (12v x 16). Based on that, if yours has 10x 12v batteries in series, then that would be 120v nominal.

As far as Ah > Wh, if one single battery has xx many Ah, as you wire a bunch more in series, the Ah does not rise, but since voltage rises, it increases the Wh through raising the voltage potential.

If you wire the same 10x batteries in parallel, the Ah goes way up, but the voltage stays same as single battery, so the W/h stays the same (regardless of parallel or series configuration).

Use this calculator to help play with the concept:

EXAMPLE:








Also, I have seen all the David Poz videos on the Growatt pair with auto-transformer, and I like that setup. And the GYLL (which they now rebranded to EG4), says it supports BMS CANBUS communication with Growatt inverters, so that would be good, as it would provide full % SoC (State of Charge) information back to the inverters, which is awesome to me anyways.

I might buy a set like this later for my shop use at some point but for now my MPP pair of LV6548 will have to work for awhile yet...

Thanks for the Wh explanation. Makes more sense now. Yes, you're right, the batteries would be 12v nominal, so in my case, it would be 120v DC nominal, however, at 100% SoC, the pack is reported as 136.1v DC. I didn't realize that the Gyll/EG4 packs can communicate directly with the growatt inverters. That definitely sounds like a really good thing.