Battery sizing tool
Solar Battery Size Calculator
Size storage from essential load and backup hours. kW is power; kWh is stored energy.
Result: About 3.8 kWh nominal storage (3.4 kWh usable) with a ~0.9 kW hybrid inverter for a 800 W essential load over 4.0 hours.
Usable energy
3.4 kWh
Nominal battery
3.78 kWh
Inverter power
≈ 0.9 kW
DoD used
0.9
kW vs kWh
Instantaneous power — how much electricity you can draw at once.
Stored energy — how long that power can last.
This tool sizes backup energy. It does not replace a full hybrid design that also considers solar recharge during the day.
Frequently asked questions
What is the difference between kW and kWh?
kW is power (how much you can draw at once). kWh is energy (how long that power lasts). A 5 kW inverter with a 10 kWh battery is not the same as a 10 kW system.
Related guides
Next step
Get a personalised estimate for your roof using satellite data, your usage and local tariff where available.