How long can a home battery last in an outage?
It depends on what you run.
Runtime ≈ usable energy ÷ the power your devices draw. A few lights, the fridge and Wi‑Fi can last far longer than central AC. Solar panels alone generally shut off in an outage—backup needs a battery and a design for it.
Grid Pros advisory team · Updated October 14, 2026 · General education, not a quote, tax or legal advice.
Runtime estimator
Starting numbers are examples only, not typical systems. Change any of them.
From the battery’s spec sheet.
Add up the devices you choose.
Energy you don’t plan to use.
Allows for conversion losses.
Estimated runtime at a steady load
about 20 hours
An approximation, not a quote, guarantee or equipment recommendation. Real loads cycle on and off, motors draw a surge at start, and cold, heat and battery age change results. Recharging from solar is not counted.
Critical loads vs whole-home
Critical circuits
Back up a few chosen circuits—lights, fridge, outlets, internet. Smaller loads stretch stored energy.
AC or whole-home
Running AC or the whole house needs more capacity and a system designed for it. Ask how your proposal handles it.
Safety: only a licensed electrician should connect backup power. Follow local emergency officials—leave when told to, and never run a generator indoors.
Plan backup for your home.
Tell us what you need to keep running. We help you review options with qualified installation partners.
Plan my backup