Battery & Backup Sizer

How many hours can a battery keep your chosen appliances running when the grid is down?

Battery

Start with the battery: nominal capacity, how much of it you can use (depth of discharge) and what the inverter loses on the way out. Then pick the appliances you want running when the grid is down.

Battery settings

Nominal capacity (kWh)

Depth of discharge (%)

Inverter efficiency (%)

Inverter output limit (kW)

Outage length you want to cover (hours)

Use the figures on your own datasheet. Defaults are typical examples, not a specific product.

Appliances

Add your own

Name

Watts

Hours per day

Your result

–energy per day

–average load

–peak if all run together

–estimated runtime

–suggested nominal capacity

Three battery sizes compared

Runtime assumes your daily appliance energy is spread evenly over 24 hours.
Scenario	Nominal	Deliverable	Runtime	Meets target?	Inverter covers peak?

Estimates only. Real runtime depends on the product, temperature, battery age and how loads cycle. Confirm figures with your installer.