Calculator
Backup power sizing calculator
Pick the loads that genuinely have to stay alive, set the runtime you want, and get the inverter output and battery capacity to shop for.
Critical loads
POS terminal + tablet
Router + modem + switch
Card reader / cellular hotspot
Refrigeration (compressor cycling)
Lighting (LED, front of house)
Desktop workstation + monitor
Security cameras + NVR
Espresso machine (idle warm)
Columns: watts, then hours needed.
hrs
%
%
Shop for
6,100 Wh
usable capacity, with at least 1,050 W continuous output
Peak draw805 W
Recommended inverter1,050 W
Energy needed4,830 Wh
With reserve6,100 Wh
Sizing assumes usable capacity, so add reserve for battery efficiency losses and cold weather.
Compare battery stations →
Capacity, continuous output and recharge time.
Guide: sizing backup power →
Surge loads, efficiency losses and cold weather.
Resilience list
Get the outage readiness kit
Checklists, sizing worksheets and vendor comparisons for keeping revenue running during outages.