Battery Bank Size Calculator
Work out how big a battery bank you need for off-grid solar, backup power or an RV.
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Battery bank
- Nominal capacity
- Usable energy
- Example layout
- Note
- Work
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How to Size a Battery Bank
Battery Wh = daily Wh × days ÷ depth of discharge ÷ inverter efficiency Ah = Wh ÷ bank voltage
Depth of discharge is how much of the rated capacity you plan to use: about 80–90% for lithium iron phosphate and 50% for lead-acid, to protect battery life.
Worked Example
Tips
Batteries in series add voltage; in parallel they add amp-hours. Use identical batteries in a bank. Cold reduces capacity, especially for lead-acid.