I'm in Texas and designed our own solar+battery setup in '21. I had an installer handle that bit and the interconnect though. I found the "secret" was the to leave room for expansion.

In Texas, residential grid-tied solar can be up to 20kWh so I chose cells that got me to 19.96kWh

Then I added an 29kWh battery stacks (18kWh total) but each stack could go to 18kWh (36kWh total). Then I also used a pair of Generac inverters which lets me get two more stacks for 72kWh total.

My goal was resiliency, not sufficiency, so I use it grid-tied so I charge during the day and use at night. When there are storms coming, I flip it to "priority backup" which will prioritize charging.. even using the grid to do it if there's not enough sun.

Anyway, it's been in production since January '22 and my annual* electric bill is ~$1100. Even better, when we have an outage (occasional as we live in a heavily wooded area) if our stack is full, we have ~5 days of battery backup for the fridge, a handful of appliances, and our Starlink.. therefore we have safe food storage, safe food prep, and non-terrestrial communications.

Of course, this cost ~$80k to get there in 2021 (aka before crazy inflation)