What is Tesla Powerwall installation?
The Tesla Powerwall is a lithium-ion home battery that stores power from your solar panels, or from the grid when rates are low, and gives it back in the evening or during an outage. Installing one means mounting the battery, adding a gateway or backup switch that disconnects the house from the grid when the power goes out, and rewiring some or all of your circuits so the battery can supply them.
The current model, the Powerwall 3, stores 13.5 kWh, can deliver up to 11.5 kW continuously and includes its own solar inverter. The older Powerwall 2, still on many homes, stores the same energy but delivers about 5 kW and needs a separate solar inverter. Beyond backup, the battery can be set to discharge during peak evening hours, which is where most of its financial value comes from under time-of-use rates or net billing.
Home batteries in the public records
Public installation records for 2023–2025 (Tracking the Sun, Lawrence Berkeley National Laboratory) show how home batteries are actually being installed:
- About 45% of new home solar systems included a battery in 2025, up from 10% in 2023 and under 1% in 2017. In California the share was 72%.
- Tesla supplied 50% of those batteries, followed by Enphase (19%), SolarEdge (14%) and LG (7%).
- The median battery stored 13.5 kWh, the capacity of one Powerwall.
- Solar systems with a battery had a median total price of $39,500, against $27,000 without one. Where the records price the battery on its own, mostly in California, the median was about $22,400, or roughly $1,200 per kWh of storage.
Whether that pays off depends on your utility’s rates and on how often you lose power. Our guide on whether solar batteries are worth it goes through the numbers.
How the installation works
- Load review: the installer looks at your panel and the circuits you want backed up, which decides whether you need one battery or more.
- Location: usually a garage or an exterior wall out of afternoon sun, with clearances set by fire and electrical codes.
- Mounting: the battery (about 290 pounds for a Powerwall 3) goes on the wall or floor, and the gateway or backup switch goes near the meter.
- Wiring: for partial backup, the chosen circuits move to a backup subpanel; for whole-home backup, the gateway switches the whole house.
- Solar connection: a Powerwall 3 connects directly to the panels; a Powerwall 2 connects to an existing solar inverter.
- Testing and setup: the installer simulates an outage and helps you set the backup reserve and operating mode in the app.
Cost factors
| Factor | Impact on cost |
|---|---|
| Number of batteries | Each Powerwall adds most of its price again, though labor per battery is lower when several go in at once. |
| Partial or whole-home backup | Partial backup needs a subpanel; whole-home backup needs enough battery power to cover the big loads. |
| Main panel | An old or undersized panel may need an upgrade first. |
| Existing solar | Adding a battery to an older system from another company can take extra wiring and equipment. |
Who it suits
- Homes with frequent or long outages, from storms, wildfire shutoffs or a weak rural grid.
- Time-of-use or net billing customers, where evening power costs much more than what the utility credits for midday exports.
- Households with medical equipment that must keep running, such as oxygen concentrators.
If outages are rare and your utility credits exports at close to the retail rate, a battery is harder to justify on savings alone.
Questions to ask your installer
- How many Powerwalls do I need to start my central air conditioner during an outage?
- Does the battery work with my existing solar inverter, and what extra equipment does that take?
- Do you recommend whole-home or partial backup for my loads and budget?
- Where should the battery go, given our summer and winter temperatures?
- Does the price include the gateway or backup switch and any panel work?
- What backup reserve do you recommend, and how will the battery operate day to day?
What to watch out for
The most common pitfall is misunderstanding the battery’s limits. Ask the installer which model you’re getting and what it can run at once: a Powerwall 2 delivers about 5 kW continuously, a Powerwall 3 up to 11.5 kW, and a large central air conditioner can use most of that by itself. Be wary of anyone who promises a single battery will run your whole house normally through a long outage. Ask whether the installer is certified by Tesla and how warranty claims are handled. Finally, think about the location: the battery is rated for outdoor use, but a spot out of direct afternoon sun keeps it cooler.