What size battery backup do you actually need?
Uses the appliances you set up in the House calculator. Choose how long you need backup for and get the battery capacity (kWh) and inverter rating (watts) that actually covers it. Silent, indoor-safe, no fuel.
Your appliances
7 of 11 House appliances count toward the numbers below.
Battery capacity is limited, so Luxury is excluded by default. 4 selected items also can't realistically run off a battery (pumps, big motors, heavy resistive loads) and are sized out regardless of tier.
How long without power?
Battery size you need
- Continuous
- 1,730 W
- Peak (surge)
- 3,230 W
That's the inverter/output rating a power station needs — anything smaller can't keep up with your load, regardless of battery size.
To run this load for 4 hours. Assumes your selected watts draw continuously the whole time — real cyclic loads like a fridge compressor draw less on average, so this is a conservative (safe-side) estimate, the same way the generator calculator treats running watts.
How this calculator works
Battery sizing is a different problem than generator sizing: instead of just covering continuous and peak watts, you also have to cover time— a battery only holds so many watt-hours before it's empty. We total your selected appliances' running watts, multiply by the backup duration you choose, and that's the battery capacity your power station needs.
This page intentionally stops at sizing — it doesn't point you at specific power stations yet, since we're still building out that catalog honestly rather than recommending products we haven't vetted. Once you have a target capacity, size the solar array to recharge it based on real sun hours where you live.
One thing battery backup won't solve: hard motor starts. Well pumps, central AC compressors, and similar loads need surge capacity most portable power stations don't have. For those, size a gas or dual-fuel generator instead.
Frequently asked questions
How big a battery do I need for backup power?
Two separate numbers matter. First, continuous and peak watts — the power station's inverter has to cover what your appliances draw, or it can't run them at all. Second, watt-hours (Wh) of capacity — multiply your continuous watts by how many hours you need backup for. A CPAP, router, and a few lights at ~190W for 12 hours needs roughly 2,280Wh (2.3 kWh).
What's the difference between watts and watt-hours?
Watts (W) measure how much power something draws right now — that's what the power station's inverter rating has to beat. Watt-hours (Wh) measure energy over time — that's what the battery's capacity has to beat. A 300W device running for 4 hours uses 1,200Wh, whether it drew that power in one burst or spread evenly.
Can a battery power station run a refrigerator?
Yes for output — a typical fridge draws around 700W running with a brief surge near 2,200W, which most 1,000Wh+ power stations handle fine. The limit is capacity: a 1,000Wh station running just a fridge lasts roughly 12–20 hours depending on duty cycle, so multi-day fridge backup needs either a bigger battery or a way to recharge it, which is a separate question — see the solar calculator.
Battery backup or a gas generator — which do I need?
They solve different problems. Battery power stations are silent, safe indoors, and need no fuel — ideal for electronics, medical devices, and short-to-medium outages. Gas and dual-fuel generators cost far less per watt, refuel in minutes instead of hours, and are the practical choice for high-surge loads like well pumps, central AC, or multi-day whole-house backup. Many households in outage-prone areas end up with both.