Planning calculator
Battery backup planner
Estimate a usable-energy target from your critical-load consumption and desired outage duration. This is a transparent starting point, not an electrical design or product quote.
Add the daily energy of refrigeration, internet, lights, pumps, medical devices and other essential loads.
Long outages may require solar or generator recharge rather than battery capacity alone.
This affects inverter size. Motors and compressors can have higher starting surges.
Reserve helps account for aging, uncertainty and minimum state of charge.
Your first-pass target
—usable kWh needed
—nominal kWh target
—suggested continuous inverter kW
Assumes 90% conversion efficiency plus the selected reserve. Final design must verify circuit loads, surge power, temperature, equipment limits, transfer method, code and permitting.
What to do next
Check your daily-load number
Use appliance labels, monitoring data or a circuit-level audit instead of guessing when possible.
List motor and HVAC surges
Well pumps, refrigerators, air conditioners and other motors can demand more power when starting.
Compare proposals on usable capacity and power
Nominal kWh alone does not describe what the system can deliver during an outage.