Home energy storage
How much battery
do you actually need?
Size a battery for outages, solar, or lower bills — start with what you need it to do.
Start here
Most people start with these
Home battery size calculator
Estimate usable and nominal battery capacity for essential-load backup.
Open calculator ↗Home battery backup runtime calculator
Estimate backup hours from usable battery capacity and essential appliance load.
Open calculator ↗Should I buy a home battery?
Assess whether backup needs, solar, outages, and electricity pricing support adding a battery.
Open calculator ↗All tools
8 battery storage calculators
Essential loads calculator
Estimate the energy needed to keep selected appliances running during an outage.
Battery storageInverter size calculator
Estimate normal load, peak load, and a practical inverter size from appliance demand.
Battery storageIPS / UPS backup battery calculator
Size the battery bank and inverter for load-shedding backup: Ah needed, batteries to buy, and inverter VA for your appliances and hours.
Battery storageGenerator size calculator
Size a standby or portable generator in kW and kVA from running load, motor starting surge, and a safety margin, with fuel use and running cost.
Battery storageBattery ROI and payback calculator
Estimate battery payback, degradation, export value, financing cost, replacement impact, and cumulative cash flow.
Battery storageBackup or solar storage?
A battery’s kWh capacity is how much energy it stores; its kW rating is how much power it can deliver at once. For outage backup, size the essential loads first. For solar storage, start with the battery size and runtime you need, then check the payback.
If you are comparing a battery with a generator or a UPS for load-shedding, read the home battery sizing guide or the IPS/UPS guide. Planning note: estimates are not engineering or installation guarantees — verify with a qualified professional.