Battery Bank Sizing Calculator
Size your off-grid battery bank.
Battery Bank Sizing Calculator
Size your off-grid battery bank
Formula
Ah = (Daily Wh × Days) / (Voltage × DOD)How to Use
- 1Calculate daily usage — Add up the watt-hours (Wh) of all appliances you use per day.
- 2Set autonomy days — Choose how many days of backup you need (typically 2-3 for solar).
- 3Select battery type — Choose between lithium (LiFePO4) or lead-acid batteries.
- 4Get bank size — See the total Ah capacity and number of batteries recommended.
Frequently Asked Questions
How do I calculate battery bank size?
Daily Wh ÷ system voltage × autonomy days ÷ depth of discharge = required Ah. Our calculator handles this automatically.
Lithium vs lead-acid for solar?
Lithium (LiFePO4) has 80-90% usable capacity, lasts 3000+ cycles, and is lighter. Lead-acid is cheaper upfront but only 50% usable and lasts 500-800 cycles.
What is depth of discharge (DoD)?
DoD is how much of the battery you use before recharging. Lead-acid should not exceed 50% DoD; lithium can safely go to 80-90%.
How many days of autonomy do I need?
2-3 days is standard for solar. More for locations with frequent cloudy periods. Less if you have a backup generator.