You should really look at grid tie. Arizona recently passed some rules that make the payback weak, but it is the preferred way to hook up.
You leave it hooked up all day. During the day, you don’t use any electricity. At night, you use electricity.
It can save you enough money to justify the cost of the system.
I have been involved in the design and such of 3MW UPS systems with 2N+2 reliability.
They were so large that we couldn’t use an ATS and the entire system was via automated switchgear controls.
