Solar Battery Backup Calculator
List your appliances and the hours of backup you want to find the battery size you need.
Often lower for lead-acid, higher for lithium.
- Total connected load
- 285 W
- Energy per backup
- 1,140 Wh
- Required battery
- 1.6 kWh
- Capacity at 24 V
- 66 Ah
Assumptions and formulas
Energy (Wh) = watts x quantity x hours. Required battery energy = Wh / (efficiency x depth of discharge). Capacity (Ah) = required Wh / system voltage. Motor loads such as pumps and ACs draw extra at start-up; share them for a proper design.
Disclaimer: results are illustrative estimates based on the assumptions above, not a quotation or guarantee. Actual generation depends on your site, shading, season and equipment.
Key terms
- Depth of discharge: the share of battery capacity you can safely use
- Efficiency: energy lost in charging and discharging
- System voltage: 12, 24 or 48 V, set by the inverter and battery bank
Motor loads
Pumps, refrigerators and air conditioners draw extra current at start. Mention them so the inverter is sized correctly.
Frequently asked questions
Are these results a quotation?
No. They are illustrative estimates from the stated assumptions.