Best home battery for whole-home backup (2026)

Whole-home backup is a power problem before it is a capacity problem. The question is not only how many kilowatt-hours a battery holds, but whether it can push enough kilowatts at once to run your house when the grid drops. Two datasheet numbers decide that, and most of the picking is done before price ever enters the conversation.

The five batteries below all publish enough power to be considered for a whole house, and each one fits a different home. Every figure comes from the manufacturer datasheet behind our model pages, quoted with the measurement basis the maker states. We have not hardware-tested any of these units.

How we picked

We ranked on the two specs that govern whole-home backup, then separated the models by the home each one fits:

• Continuous power (kW): the steady output the battery can hold. This is what carries your running loads, so it sets whether a unit can back up a whole house at all.
• Peak or surge power (kW): a brief, higher figure for the instant a motor starts. An air conditioner compressor or a well pump can pull far more on startup than it does while running, and a battery that clears your continuous load can still trip on that surge.
• Usable capacity (kWh) and stacking: how long the battery carries the load, and whether you can add units later for a larger home.
• Warranty: the term the maker publishes, as a proxy for how long they stand behind the unit.

Every number is pulled from the manufacturer's own datasheet, cited on each model page and verified July 2026. A missing figure is recorded as not published rather than estimated.

The two power numbers that decide it

Continuous power is the first cut. Whole-home backup generally starts around 7 to 10 kW of continuous output, enough to run heating or cooling on top of the everyday loads. The Tesla Powerwall 3 publishes 11.5 kW continuous, the Savant Power Storage 20 publishes 12.5 kW, and the Generac PWRcell publishes 10.5 kW. Lower-continuous units still back up a house, but a smaller slice of it at a time.

Surge is the second cut, and it is the one buyers miss. The Savant Power Storage 20 publishes a 30 kW peak, the highest we track, which is why it lands as the surge pick for homes with well pumps or large AC compressors. The FranklinWH aPower 2 publishes a 15 kW peak against 10 kW continuous. Where a maker does not publish a separate peak figure, we do not infer one, so read continuous power as the safe number and confirm your motor-start loads with the installer.

Match the pick to your home

• Solar-paired home: the Tesla Powerwall 3 builds the solar inverter into the battery, so a solar-plus-storage system is one integrated unit rather than two boxes, and it stacks up to 4 units for more power.
• Home with heavy motor loads: the Savant Power Storage 20 publishes the highest surge we track (30 kW peak) and stacks for large electrical services, so it is built for the well-pump-and-AC case.
• Larger home that wants to grow: the Generac PWRcell is modular at up to 18 kWh per cabinet, and two cabinets reach up to 36 kWh, so you can start smaller and add capacity later. The FranklinWH aPower 2 stacks even further, to 15 units.
• Microinverter (Enphase) system: the Enphase IQ Battery 10C puts microinverters on each battery, so one unit's fault does not take the rest of the storage down, which suits homes already on Enphase solar.

Two honest limits apply to all of it. First, a whole-home rating is not the same as running everything at once for days: capacity still empties, and only solar recharges it during a long outage. If you have not sized your actual backup loads yet, start with whole-home vs essential backup and the complete backup guide. Second, none of these figures is a substitute for confirming your own panel, service size, and motor-start loads against the datasheet before you buy. When you are ready to put numbers to it, run your own case in the calculator.