Calculator

Battery capacity calculator

Estimate the battery storage you need based on daily load and backup time.

Adjust for depth of discharge and system voltage.

Formula

Battery Wh = Daily Wh × Days of autonomy ÷ Depth of discharge

Example: 2,000Wh × 1 day ÷ 0.8 = 2,500Wh

Tips

For solar systems, usable capacity matters more than nameplate. Match your battery bank to system voltage and inverter draw so cabling and protection stay realistic.

  • Li-ion often supports deeper discharge than lead-acid.
  • Factor in inverter efficiency for AC loads.
  • Size for critical loads first.
  • Cold temperatures reduce usable capacity.