If I put in a server rack battery on a house, solar on the roof... use it for backup or all the time?

[Ampster]

Once that's all inspected, then put the battery back up and inverters in myself if they aren't exactly up to NEC.

That is exactly what I did with my DIY grid tie set up. After inspection I put in the hybrid inverter and the batteries. I did it all to code to the extent I could. The exception being that the battery pack was not compliant with NEC 2020.

 

[HarryN]

I have our garage refrigerator on a combo solar / grid battery backed system.

If power goes out, then I run an extension cord to the other fridge.

It also has a few USB ports for phone charging.

Looking at expanding it, but this solves a lot of grid power outage problems already and shaves off some grid power use as well.

 

[ruralsolar]

Where the power goes for me would depend mainly on net metering rules. For me where I'm at it's 1:1 per kwh with a once a year "true up" where I can get in theory 2 cents a kwh. Battery capacity and home usage monitoring would be large decider as I'd want to use up as much of my positive net metered kwh before the true up.