Solar Battery Sizing Calculator
Battery bank size for days of autonomy.
Enter your values
ⓘ Live results
Results
- Battery bank size
- 23.61 kWh
- Amp hours at system voltage
- 492
- Usable energy
- 18.89 kWh
- Cost estimate at $400/kWh
- $9,444.44
Quick answer
Battery bank size must cover daily load across your autonomy days without exceeding depth of discharge.
Capacity = load × days ÷ (DoD × efficiency)
How to use the Solar Battery Sizing Calculator
- 1Enter your daily energy consumption.
- 2Choose days of autonomy without sun.
- 3Set depth of discharge for your battery chemistry.
Worked example
Using the values the calculator loads with:
Inputs
- Daily energy use8.5 kWh
- Days of autonomy2
- Depth of discharge80 %
- Round-trip efficiency90 %
- System voltage48 V
Results
- Battery bank size23.61 kWh
- Amp hours at system voltage492
- Usable energy18.89 kWh
- Cost estimate at $400/kWh$9,444.44
Frequently asked questions
What DoD for lithium?
80–90% is safe for LiFePO4; lead acid should stay near 50%.
How many autonomy days?
Two is typical; three for remote sites.
About this calculator
- Built and reviewed by James Whitfield · How we build and test calculators
- Report an error
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.