Free calculator · Sourced data, as of 2026-10-25
How much backup power does your home really need?
Enter your ZIP and answer 3 quick questions. You'll get a ballpark battery size, the cheapest setup that covers it, installed and generator options, and your state's rebates, with a source for every number.
Email me my report
Get these exact results (your appliances, battery size, options, and rebates) in your inbox to come back to later.
Full calculator: pick every appliance
1. What do you need to keep running?
Wattage ranges: Champion Power Equipment wattage chart (as of 2026-10-25). Assumption Default "h/day" values are our estimates of how long each appliance actually draws power (e.g. a fridge compressor runs about 1/3 of the time = 8 h/day). Edit them to match your home. Not listed yet (no verified figures): EV Level 2 charging; Medical devices (oxygen concentrator etc.). For medical devices, use the watts on your device's label.
2. For how long?
3. Your state (for rebates)
Assumption We divide by 0.85 to cover inverter losses and capacity you can't fully use. Running watts use the midpoint of each sourced range; peak uses the top of the range plus the single biggest motor start-up surge. Real-world use varies with weather, appliance age, and settings.
Will my backup last X days?
Capacities: brand/retailer listings in our data (each links its source, as of Oct 2026). Solar uses our stated assumption of 4 peak sun hours at 75% output; winter storms and hurricanes often bring clouds, so real recharge can be much lower. A station can't accept more solar than its input limit.
Email me my report
Get these exact results (your appliances, battery size, options, and rebates) in your inbox to come back to later.
Outage Prep series
Plan for the outages you're most likely to see
Calm, sourced guides for storms, shutoffs, and long outages. Every number links to where it came from.
Winter storm: keep the heat on
Furnace blower watts, sump pumps, space heaters, and CO safety for a 3-day outage.
Read guide →Will my backup last X days?
Pick a scenario and see kWh needed, runtime, and what solar adds.
Read guide →Build your own home power plant
30-day and 90+ day setups: solar, batteries, generator fuel limits, real costs.
Read guide →72-hour power plan
A simple 3-day plan: what to keep running, how much battery, food and medicine timing.
Read guide →Hurricane: a week without power
About 74 kWh for a week of essentials, generator fuel per day, and storm safety.
Read guide →Wildfire power shutoffs (PSPS)
Notice timing, how long shutoffs last, ~8 kWh for 2 days, and CA rebates.
Read guide →CPAP and medical devices
Sourced CPAP watts, battery runtime math, and FDA's planning steps.
Read guide →Generator safety
The 20-foot rule, CO alarms, CO-shutoff models, and safe refueling.
Read guide →Power station vs generator cost
Upfront plus fuel for your outage, with noise and CO side by side.
Read guide →Portable power stations compared
Capacity, output, surge, and price for 11 models, with price dates.
Whole-home battery cost
Powerwall 3, FranklinWH, and EnergySage's installed price data.
What size do I need?
Running vs. starting watts, kWh, and worked examples.
Rebates by state
HOMES/HEAR status for every state plus utility programs.
Quick answers
How big a battery do I need to run a fridge during an outage?
A refrigerator draws about 150–400 running watts and 800–1,200 watts to start (Champion Power Equipment chart). If the compressor runs about a third of the time (our assumption), that is roughly 1–3 kWh per day. Use the calculator to add your other essentials.
Is there still a federal tax credit for home batteries?
No. Under the 2025 law known as the One Big Beautiful Bill, the Section 25D credit does not apply to installations completed after 12/31/2025, per the IRS FAQ.
How much does a whole-home battery cost installed?
EnergySage reports about $15,647 typical for roughly 13.5 kWh, or about $1,130–$1,159 per kWh, as of 2026-10-25.
Backup power, before the next outage
A short email when it matters: outage-season prep checklists before summer storms and winter freezes, state and utility rebates that open, change, or run out of money, and real price drops on the power stations in our data.