Updated for 2026 · specs from the manufacturers
Best whole-home battery backup
Four installed home batteries compared on the specs that are actually published: usable capacity, output, chemistry, and warranty. Installed cost is site-specific, so we point you to local quotes rather than guess a number.
Best overall
Tesla Powerwall 3
by Tesla
- 13.5 kWh
- 11,500 W
- LiFePO4 (LFP)
- 10-yr warranty
13.5 kWh usable with an 11.5 kW continuous output and a built-in solar inverter, so one box does storage and PV. Stacks to four units, with a 10-year warranty.
Best warranty
FranklinWH aPower
by FranklinWH
- 13.6 kWh
- 5,000 W
- LiFePO4 (LFP)
- 12-yr warranty
13.6 kWh LFP with a 12-year warranty, the longest here, and it scales to 15 units per aGate for very large homes or partial off-grid.
Best modular scaling
Generac PWRcell 2
by Generac
- 18 kWh
- 10,000 W
- Lithium NMC
- 10-yr warranty
Snap-in 3 kWh modules let you size from 9 kWh to 18 kWh in one cabinet and up to 36 kWh across two, from the largest US standby-generator maker's dealer network.
Best hybrid (portable + whole-home)
EcoFlow DELTA Pro Ultra
by EcoFlow
- 6.14 kWh
- 7,200 W
- LiFePO4 (LFP)
- 5-yr warranty
6.1 kWh and 7,200 W per unit with 5.6 kW of solar input, and it scales to 90 kWh, a middle path between a plug-in station and a hard-wired system.
Side-by-side
| System | Capacity | Output | Chemistry | Warranty |
|---|---|---|---|---|
| Tesla Powerwall 3 | 13.5 kWh | 11,500 W | LiFePO4 (LFP) | 10 yr |
| FranklinWH aPower | 13.6 kWh | 5,000 W | LiFePO4 (LFP) | 12 yr |
| Generac PWRcell 2 | 18 kWh | 10,000 W | Lithium NMC | 10 yr |
| EcoFlow DELTA Pro Ultra | 6.14 kWh | 7,200 W | LiFePO4 (LFP) | 5 yr |
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Installed price depends on your panel, electrical work, and local rates. Compare at least three quotes from licensed installers before you commit.
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