Battery Bank Sizing Calculator
Calculate the right battery bank size for your energy needs
Inputs
Total watt-hours consumed per day
Days to run without solar/charging
Daily energy needs
Depth of discharge
Common battery sizes
How to use this calculator
- 1Calculate your total daily energy consumption in watt-hours
- 2Decide how many days of autonomy you need (days without charging)
- 3Select your battery type (LiFePO4, AGM, or Lead Acid)
- 4Choose your system voltage (12V, 24V, or 48V)
How to size your battery bank
Proper battery sizing ensures you have enough power during cloudy days or high-use periods. The key factors are daily energy consumption and desired days of autonomy.
Days of autonomy is how long you want to run without any solar charging. For off-grid homes, 2-3 days is common. For RVs, 1-2 days may suffice.
System voltage affects wire sizing and efficiency. Higher voltage (24V or 48V) means lower current and smaller wires, which is important for larger systems.
Frequently asked questions
How do I calculate my daily energy needs?
Add up the wattage of each device multiplied by hours used. For example: LED lights (10W × 5 hrs) + laptop (50W × 4 hrs) + fridge (50W × 24 hrs) = 1,450Wh/day.
What are days of autonomy?
Days of autonomy is how long your system can run without any solar charging. For off-grid homes, 2-3 days is common to cover cloudy weather. RVs typically need 1-2 days.
Why does battery type matter for sizing?
Different batteries have different safe depth of discharge (DoD). LiFePO4 can use 80% of capacity, while lead acid should only use 50%. This means you need nearly twice the lead acid capacity for the same usable energy.
Result
209Ah
At system voltage