Solar battery backup
01 / battery backup
Solar battery backup that works when you need it.
A battery gives you backup power when the grid goes down, but it also helps on normal days. It stores daytime solar power you might otherwise send back to the grid, then uses it later when your home needs it more.
02 / spec sheet
The battery stack depends on your home.
| Battery | Capacity | Continuous power | Warranty | Why we pick it |
|---|---|---|---|---|
| Tesla Powerwall 3 | 13.5 kWh | 11.5 kW continuous | 10-yr unlimited cycles | Integrated hybrid inverter; lowest-cost-per-kWh in 2026 |
| Enphase IQ Battery 5P | 5 kWh per unit (stackable to 60+) | 3.84 kW per unit | 15-yr / 6,000 cycles | AC-coupled, modular, pairs with IQ8 microinverters |
| FranklinWH aPower2 | 15 kWh | 10 kW continuous | 15-yr / 70% capacity | Whole-home backup, integrated load controller |
All three are UL 9540A-tested for thermal runaway. Sizing varies by daily kWh usage, critical-load list, and how many days of backup you want.
03 / sizing
How we size the battery for your home.
Daily-use sizing.
In markets where exporting to the grid pays less, we size the battery to soak up your daytime solar and discharge through the evening. Most homes land in the one to two battery range.
Outage backup sizing.
If your priority is riding through long outages, we size for critical loads first: fridge, lights, internet, outlets, and the circuits you actually need. Larger homes may need two or three batteries and load-shedding controls.
Whole-home backup.
FranklinWH aPower2 + Smart Circuits or Tesla Powerwall 3 with the Tesla Gateway can back up the entire home (no critical-load panel) in many configurations. We model whether that's feasible for your service size during the design phase.