Battery backup calculator
Choose what you need to keep on and for how many days. The calculator balances your usage hour by hour against the battery, the sun and, if you want, a generator. It recommends the most affordable system that covers you, with today’s prices and stock.
- Hour-by-hour balance, worst case
- Today’s store prices and stock
- We help you review it before you buy
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How it works
Outages, hurricanes, medical equipment or away from home.
We start with the usual ones for that use; you adjust quantities and hours.
From 1 day to no limit, sunny, cloudy or hurricane.
The most affordable system that covers you, your battery hour by hour and the options with panels or a generator.
Battery, solar panels or a generator?
The calculator shows you all three options with their price. This is how they compare:
| Option | Best for | Keep in mind |
|---|---|---|
| Battery only | Outages of hours or one day. Quiet, no fuel and very little maintenance. | For several days without sun, the battery has to be very large. |
| Battery with solar panels | Multi-day outages with sun: the battery recharges every day. | Clouds lower production. Panels need space. |
| Battery with a small generator | Hurricanes and long outages: the generator recharges the battery so you don’t need a giant one. | It uses fuel, goes outdoors and makes noise while it runs. |
What the calculation assumes
We use simple assumptions and show them. If your case is different, email us and we review it with you.
- The worst momentThe outage can start at any hour, with the battery full. We test all 24 and show the worst one.
- The sunA clear day counts as 5 hours of full sun, and 75% of that energy reaches the battery. Where there is less sun, panels give less.
- The weatherHurricane: one day at 10% of the sun and another at 25%, then sun. Cloudy: one day at 25%. Sunny: every day at full sun.
- The panelsThey power the home first; what is left charges the battery. Rooftop panels count only when there is a documented connection to charge the battery in an outage. The Anker E10 takes up to 15.2 kW of inverters from any brand that meets IEEE 1547.
- The generator90% of the Smart Generator’s energy reaches the battery (planning assumption). It starts by itself when the battery drops under 20% and stops at 80%, the Anker app’s default. If you give it a schedule (no night or a maximum of hours), the plan assumes you start it before it is needed. Fuel comes from the hourly use Anker gave us for each mode: gasoline, propane or natural gas.
- The appliancesTypical usage published by manufacturers. Air conditioning hours are compressor hours. The E10 uses about 40 W of its own while backing up the home, and we add it. The electrician confirms motor starting current (LRA).
- Prices and installationPrices and stock published in the store today. Home systems need a licensed electrician and a permit, quoted separately.
Frequently asked questions
How big a battery do I need for my home?
It depends on what you want to keep on and for how long, not on the size of the house. Add up each appliance’s daily energy (watts times hours) and compare it with the battery’s usable energy for the days you want covered. The calculator does this hour by hour and adds the sun or a generator if you choose them.
How long will a portable power station last?
Divide its usable energy (Wh) by the average watts of what you plug in. A fridge cycles on and off, so on average it uses less than its label says. Pick a model under “Already have a model in mind?” to see the hours with your appliances.
Do solar panels work during a power outage?
Panels connected to a battery system keep charging it during an outage: the system disconnects from the grid and uses the sun. Most grid-tied rooftop panels without a battery shut down during an outage for safety. If you already have panels, the calculator explains how they can count and we review it with you.
Battery or generator for hurricanes?
For several days without sun, a battery alone gets very large. A small generator that recharges the battery covers those days with less battery, and panels lighten it on sunny days. The calculator shows the options side by side, with their price.
Can it run my central air conditioning?
Sometimes, with a home system. The calculator checks the power at once (W) and the voltage (240 V). The electrician confirms the motor’s starting current (LRA) on the unit’s plate.
Does the price include installation?
No. Home systems need a licensed electrician and a permit. After payment you can request installation from your order; we coordinate it and it is quoted separately.
Are the prices current?
Yes. The calculator uses the prices and stock the store publishes every hour.