How Powerwall and Wall Connector owners can charge from spare solar
Tesla's Smart Charging times a Wall Connector to off-peak power or spare solar, if you have a Powerwall on firmware 26.34.
4300streetcar / Wikimedia Key points
- Smart Charging lets a Powerwall and Wall Connector charge the car from off-peak power or spare solar.
- It needs Powerwall 2 or 3 and a Wall Connector 3 or Universal, on firmware 26.34 or higher.
- It works on one Wall Connector per site and clashes with manual charge schedules.
With a Powerwall and Wall Connector, the Tesla app's Smart Charging can time car charging to use your tariff's cheapest power or spare solar, according to Tesla Support Australia.
Who can use it
Three things are needed:
- Powerwall 2 or Powerwall 3 with firmware version 26.34 or higher
- Wall Connector 3 or Universal Wall Connector with firmware version 26.34 or higher
- Tesla app version 4.57.5 or higher
The Powerwall and Wall Connector must be paired, registered to the same site and connected to the same Wi-Fi network. Your phone must also be paired to the Powerwall: in the Tesla app, switch to your energy site, tap Configure, then Phone Pairing.
Smart Charging works on only one Wall Connector per site. Other Wall Connectors can be set to charge whenever a car is plugged in or to follow a schedule.
It is not limited to Teslas. In Tesla's words, it "works with any electric vehicle that is compatible with Wall Connector 3 or Universal Wall Connector", as long as the home system meets the requirements.
Which Powerwall mode does what
There are two modes, and the Powerwall's own mode decides which one you can use:
- Low-Cost Charging needs the Powerwall in Savings mode. It uses your utility rate plan and solar forecasts to reach your charging target at the lowest cost, then keeps charging from the lowest-cost energy, including solar.
- Charge on Solar needs the Powerwall in Self-Powered mode. It charges mainly from excess solar, and uses the grid or the Powerwall only if the forecast shows too little to reach the target.
On Charge on Solar, the car charges only from excess solar once it reaches the target. A target of 0 kWh means solar only.
You set a target in kWh and a departure time, and the system delivers at least the target by then. It will not charge past the car's charge limit. To set it up, go to Settings, Vehicle Charging, Set Charging Configuration in the Tesla app.
What stops it working
- Smart Charging "is not compatible with manual Wall Connector schedules", and a charging schedule set in the car stops it working properly. Tesla "strongly recommend[s]" turning off all vehicle charge schedules.
- A car needs a minimum power before it starts charging, so a thin stream of excess solar may not be enough. The minimum depends on your grid type and charging equipment.
- During a Storm Watch event, excess solar may go to the Powerwall before the car.
- Tapping Start Charging in the app overrides the plan for that session.
What it could cost
Our estimate assumes a 40 km daily drive and AGL's Night Saver EV plan, which in NSW lists A$0.08/kWh between midnight and 6 am. Its solar feed-in tariff is A$0.03/kWh (excluding GST). The plan needs a digital meter, and its rates are variable.
The driving inputs come from our Volts & Bots 8-amp article: 14.5 kWh/100 km, CarsGuide's real-world Model Y L figure, and 0.85 wall-to-battery efficiency, our own assumption for low-current charging.
| Scenario | Energy from the wall for 40 km | Rate | Estimated cost a day |
|---|---|---|---|
| Low-Cost Charging, midnight to 6 am | 6.8 kWh | A$0.08/kWh | about A$0.55 |
| Charge on Solar, all from excess solar | 6.8 kWh | A$0.03/kWh feed-in not earned | about A$0.20 in lost export credit |
How we estimated this
Energy for 40 km = 40 x 0.145 = 5.8 kWh into the battery, and 5.8 / 0.85 = about 6.8 kWh from the wall.
Night: 6.82 x A$0.08 = about A$0.55. Solar: the cost is the feed-in credit you give up, 6.82 x A$0.03 = about A$0.20.
- AGL's page does not say whether the A$0.08 rate includes GST. The feed-in figure excludes it.
- Supply charges and any other tariff periods are left out, because they do not change with when you charge.
- On a cloudy day, Charge on Solar may top up from the grid or the Powerwall to reach your target, so the real cost sits somewhere between the two rows.
Rod Bland is the publisher and editor of Volts & Bots. He lives in Sydney and drives a Model Y L bought in Australia in 2026, with HW4 and FSD (Supervised). More about Rod Bland.