How to size a portable power station for a home outage
A useful backup plan starts with a short list of essentials, not the biggest battery on the shelf. Estimate the energy those essentials use over the hours you want to cover, then compare that number with a station’s usable watt-hours.
Reviewed October 23, 2026 · How we review guides
1. Choose the loads that matter
Write down the devices you would actually keep running: perhaps a refrigerator, modem, a few lights, and phone charging. A whole-house plan is a different project from keeping essentials on overnight.
Use the device label or manual when possible. A refrigerator cycles on and off, so its average draw over time is lower than its compressor’s running draw. Startup surge can also be several times higher than running watts; check both the power station’s continuous and surge ratings.
2. Estimate the energy you need
For each device, multiply watts by hours of use to get watt-hours (Wh). Add the devices together. For a cycling appliance, use its measured or documented average consumption rather than assuming it runs at full power all day.
A 60 W lamp used for 5 hours needs 300 Wh. A 20 W modem used for 10 hours needs 200 Wh. Together, those two example loads need 500 Wh before conversion losses.
3. Compare usable capacity, not just the headline number
Battery capacity is usually shown in watt-hours, but AC output conversion and the manufacturer’s reserve reduce the energy available to your appliances. For a first-pass estimate, multiply rated capacity by an editable usable-capacity factor and inverter-efficiency factor.
Then check the output limits. A battery can have enough total energy but still be unable to start a motor or run several high-wattage devices at once.
4. Plan how you will recharge it
A power station is a finite supply unless you can recharge it. Compare wall, vehicle, and solar charging specifications for your use case. Solar output changes with season, shade, panel angle, and weather; treat advertised peak watts as a best-condition rating, not an all-day average.
Keep a charging plan that fits your expected outage length, and follow the manufacturer’s instructions for temperature, indoor use, and storage.
Safety reference: CDC carbon monoxide information. For device-specific ratings, use the equipment maker’s manual.