Not familiar with solar or batteries, but I had a 18kw Generac installed at my house 2 years ago. Whole house, auto transfer switch, 6-8 seconds after the power goes out it comes right back on. SUPER convenient. You wouldn’t know the power was out of you couldn’t hear it running (it isn’t too loud). I piped it myself to cut down on cost, and it was just shy of $9,000 with some extras (first year maintenance, cold start kit, WiFi monitoring). The cost was insane, but when the news was reading potential multi day power outages, the piece of mind it provided was priceless.