Questions answered: Home batteries & backup

How long will a home battery power my house in an outage?

Q: How long will a home battery power my house in an outage?

One 13.5 kWh battery, such as a Tesla Powerwall 3, runs the average US home for about 11 hours, because the average home uses about 28 kWh a day (EIA, 2024). Cut back to essentials and it lasts days: a fridge, Wi-Fi, four LED bulbs for five hours and two phone charges come to about 2.7 kWh a day, so the same battery covers about 5 days of that.

Updated October 25, 2026. Every answer lists the sources we read it from. If we couldn't back an answer, we left the question out.

Home wiring is a job for a licensed electrician. New circuits, outlets, transfer switches and battery connections must meet the National Electrical Code and your local rules, and many need a permit and inspection.

To size your own: add up the daily kWh of what you want to keep running, multiply by the days of backup you want, and check the battery's continuous power rating covers everything that runs at once. The average US home's fridges use 839 kWh a year (EIA), about 2.3 kWh a day.

Hours of the average US home's use, or days of essentials, per battery
Battery	Usable energy	Average home	Essentials only
Tesla Powerwall 3	13.5 kWh	about 11 hours	about 5 days
FranklinWH aPower 2	15 kWh	about 13 hours	about 5.5 days
Enphase IQ Battery 10C	10 kWh	about 8 hours	about 3.5 days

Run your own numbers: Home battery sizer

Sources

All 7 questions on home batteries & backup · Every question we answer

Home battery sizerHow much battery your home needs.

Estimates only. Your actual costs depend on your utility's rate plan, how and when you charge or use power, and local prices. This is general information, not financial, tax or legal advice. See our disclaimer.

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