Well if it were set up as a UPS, there would be no problems using AGMs (i.e. no wear and tear from daily cycles) and no decrease in electric bill. i.e. the solar would only be there to charge the batteries during outages. But yeah, the $ spent efficacy drops off drastically in that use case, and the $ saved on batteries isn’t much (AGM vs LiFePO4). The technology is the easy part, it’s being efficient with money that’s hard. I mean the in laws bought a large 10kW Honda generator (read: spendy), and it just sits there collecting dust (and rust!). But they could in theory sell it and get most (80%?) of their $ back.