Backup time calculator
How long will my backup last?
See how battery voltage, battery capacity and your load affect a rough backup time.
Rough estimateRuntime = nominal volts × Ah × usable fraction × efficiency ÷ watts. Simplified estimate; battery ageing, discharge rate, temperature, BMS cutoff and inverter self-consumption can reduce runtime. Inverter capacity and starting surges must be checked separately.
Official and manufacturer links
Links checked on 7 October 2026. These websites, and scheme rules, can change.