Battery Bank Size Calculator
Estimate battery capacity for an entered energy demand and autonomy period.
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What this tool does
Estimate battery capacity for an entered energy demand and autonomy period. Temperature, battery aging and surge limits are not included. Percentage inputs must represent usable fractional efficiencies.
How to use the Battery Bank Size Calculator
- Enter or select daily energy (kwh).
- Enter or select autonomy days.
- Enter or select bank voltage.
- Enter or select usable depth of discharge (%).
- Enter or select inverter efficiency (%).
- Read the calculated result; change any measurement to compare alternatives.
Formula
nominal kWh=daily×days/(DoD/100×efficiency/100); Ah=nominal kWh×1000/voltage
- daily
- Daily energy (kWh)
- days
- Autonomy days
- voltage
- Bank voltage
- dod
- Usable depth of discharge (%)
- efficiency
- Inverter efficiency (%)
Temperature, battery aging and surge limits are not included. Percentage inputs must represent usable fractional efficiencies.
Worked example
For battery bank size calculator, the following measurements illustrate the exact method: Daily energy (kWh): 10; Autonomy days: 2; Bank voltage: 48; Usable depth of discharge (%): 80; Inverter efficiency (%): 90.
Inputs
- Daily energy (kWh)10
- Autonomy days2
- Bank voltage48
- Usable depth of discharge (%)80
- Inverter efficiency (%)90
Result
- Required bank (Ah)578.7
- Nominal storage (kWh)27.78
Results explained
- Required bank (Ah)
- Required bank (Ah) from the formula above. Temperature, battery aging and surge limits are not included. Percentage inputs must represent usable fractional efficiencies.
- Nominal storage (kWh)
- Nominal storage (kWh) from the formula above. Temperature, battery aging and surge limits are not included. Percentage inputs must represent usable fractional efficiencies.
Frequently asked questions
nominal kWh=daily×days/(DoD/100×efficiency/100); Ah=nominal kWh×1000/voltage
Temperature, battery aging and surge limits are not included. Percentage inputs must represent usable fractional efficiencies.
No. Electrical and HVAC results are estimates. Installation must comply with local codes and be checked by a qualified licensed professional.
Nameplate values, conductor temperature, power factor, efficiency, weather and actual installation conditions may differ from your entered assumptions.
Confirm units, manufacturer data and the formula's assumptions, then verify sizing with the equipment instructions and applicable local standards.