Solar battery backup for a US home: which critical loads should it cover?

A critical-loads design can keep selected circuits powered with less storage than a whole-home system. Battery kWh affects runtime; inverter kW and surge capacity affect whether equipment starts and runs together.

A refrigerator, router and lights are a different load from central air or a well pump. A circuit list and equipment nameplates help an installer compare partial backup with whole-home backup.