Solar Battery Bank Calculator
Size an off-grid battery bank from daily kWh, days of autonomy, voltage, depth of discharge, and inverter efficiency.
Processed locally in your browser — nothing is uploaded.
How long the bank must carry the load without sun.
Commonly 12, 24, or 48 V.
Results
- Required bank capacity
- 579 Ah
- Required energy
- 27.78 kWh
- Batteries needed
- 6
600 Ah installed at 100 Ah each.
Batteries in series raise voltage, in parallel raise Ah — the count here is total batteries at the system voltage. Cold temperatures and battery age reduce usable capacity.
About Solar Battery Bank Calculator
Multiply daily consumption by the days of autonomy you want to survive without sun, then inflate it for depth of discharge (about 50% usable for lead-acid, 80–90% for LiFePO4) and inverter losses. The result is the required bank capacity in Ah at your system voltage, plus how many batteries of a given size that takes.
Common uses
- Size batteries for an off-grid cabin that must ride out two cloudy days
- Compare how many lead-acid vs LiFePO4 batteries a load needs
- Check whether an existing bank actually covers your autonomy target
Example
Input
10 kWh/day · 2 days · 48 V · 80% DoD · 90% inverter
Output
≈ 579 Ah → 6 × 100 Ah batteries
Limitations
- Counts batteries at the system voltage — series strings to reach that voltage are up to your wiring plan. Cold weather reduces usable capacity.