Compare calculators
Both calculators run independently β change the inputs on either side to compare results.
Home Battery Sizing Calculator
Size a home battery storage system to cover a specific backup load for a chosen number of days without grid or solar input, accounting for depth of discharge, round-trip efficiency, and a safety reserve.
Battery capacity needed
29.63 kWh
20-40 kWh needs two stacked units. At ~29 kWh you are sizing for about 2 days of autonomy on a 10 kWh/day load; trimming autonomy by a day cuts capacity nearly in half.
This is the rated battery capacity needed to cover your backup load after depth-of-discharge, efficiency, and reserve losses; a single Tesla Powerwall is about 13.5 kWh usable.
Solar Battery Backup Calculator
Determines how many kilowatt-hours of battery capacity you need to keep essential appliances running during a grid outage. Use it when sizing a home battery bank paired with a solar array.
Key differences
| Home Battery Sizing Calculator | Solar Battery Backup Calculator | |
|---|---|---|
| Category | Solar Energy | Solar Energy |
| Inputs required | 5 | 4 |
| Result | Battery capacity needed (kWh) | Required Battery Capacity (kWh) |
| What it does | Size a home battery storage system to cover a specific backup load for a chosen number of days without grid or solar input, accounting for depth of discharge, round-trip efficiency, and a safety reserve. | Determines how many kilowatt-hours of battery capacity you need to keep essential appliances running during a grid outage. Use it when sizing a home battery bank paired with a solar array. |