Why would you pass up on the free money of selling the power? You’re probably looking for a hybrid system if you just want to keep the lights on during a service outage. Or I guess you can just build an off grid system and wire it to a generator transfer switch if you want to power your house circuits but only during an outage.
Most half decent solar installers can help either way.
Oh so not really even your home circuits then. Just get something like a jackery, ecoflow, or bluetti. I’ve had a bluetti and ecoflow and recommend an ecoflow product. If you really really wanted to you could power an in wall circuit with one but it would be pretty jank.