All Calculators
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Battery Storage Sizer

Size your battery bank using autonomy, depth-of-discharge, and efficiency assumptions aligned with NREL REopt/SAM and IEC 61427-1 guidance.

Load & Autonomy

kWh/day

Average critical load to be backed up.

kW

Maximum instantaneous power draw.

days
kWh

Compare required vs installed capacity.

Battery Parameters

fraction
fraction
fraction

Accounts for lifecycle and climate.

×

Multiplier for startup/ motor loads.

hours

Target to recharge from PV/grid.

Calculate

📖 How to Use

Enter daily critical load, desired autonomy, and battery parameters (DoD, efficiency, derating). The calculator outputs the required DC nameplate capacity, power rating for charge/discharge, and state-of-charge window following IEC 61427-1 testing practices.

🧮 Formula Reference

Usable energy = Daily load × Days of autonomy
Nameplate capacity = Usable energy ÷ (DoD × RTE × TCF)
Duration = Usable energy ÷ Peak power
Charge power ≈ Nameplate ÷ Charge time

⚠️ Notes

  • Keep DoD within manufacturer warranty limits to maintain cycle life.
  • Adjust temperature derate for extremes (e.g., −20°C lithium may need 0.7 factor).
  • Include inverter AC/DC efficiency if sizing for AC loads.

🔗 References