Tesla's Powerwall 3 and 3P reportedly send a "normal" or "boost" signal to SG Ready heat pumps so surplus solar or cheap grid power is stored as hot-water heat. It is live in Europe and needs firmware 26.26+ and Tesla app 4.59.1+.
Background: storing electricity as heat
A kWh is an amount of energy: a 1 kW device running for one hour uses 1 kWh. A heat pump moves heat instead of making it, so one unit of electricity can deliver about three units of heat. That ratio is the COP; at COP 3, about 3.5 kWh of electricity yields 10.5 kWh of heat.
Heat is cheap to store. Warming a 300-liter tank by 30 °C stores about 10.5 kWh (roughly 1.16 Wh per liter per °C), about one home battery's worth, using plain water. With time-of-use tariffs common in Europe, heating when power is cheap or solar is surplus lowers cost.
Summary in 3 lines
- Electrek reported on 2 Nov 2026 that Powerwall 3 and three-phase Powerwall 3P can signal a heat pump.
- Only two signals are used: normal or boost.
- It is reported as Europe-only; no US or Canada plans were announced.
What happened
Electrek says Tesla Energy described it on X: Powerwall boosts heating when there is surplus solar or cheap energy. Requirements as reported: Powerwall 3/3P with firmware 26.26+, Tesla app 4.59.1+, an SG Ready heat pump with an accessible SG-2 contact, and installation by a Tesla-certified installer.
Why it matters
Heat in a water tank is cheaper to store than electricity in a battery, leaving the battery free for backup and other uses.
How it works
| Mode | Boost is sent when |
|---|---|
| Self-Powered | solar is left over after household loads |
| Savings | solar is available or the 24-hour tariff forecast is cheapest |
SG Ready is a label the German Heat Pump Association (BWP) introduced in 2012; it uses two relay contacts, no cloud. Signals are recommendations, so the heat pump's thermostat can override them; each must last at least 10 minutes; during an outage it reverts to normal.
Timeline
- 2012: SG Ready introduced by BWP.
- 2023: sonnen added similar heat pump control (Electrek).
- 2025: Tesla announced its 1 millionth Powerwall; Germany sold 299,000 heating heat pumps, up 55% (BWP via Electrek).
- 2026: Powerwall 3P launched for DACH; Nov 2026 this feature reported live.
Explain it to a friend
- A heat pump gives about 3 units of heat per unit of electricity.
- Storing heat in water is cheap: 300 L × 30 °C ≈ 10.5 kWh.
- The Powerwall only sends a signal; the heat pump does the heating.
Next question
How much surplus can a tank really hold, given how fast it loses heat?
Read next
Sources
- Electrek, "Tesla Powerwall 3 now boosts heat pumps to store cheap solar as heat" (2 Nov 2026) → https://electrek.co/2026/11/02/tesla-powerwall-3-heat-pump-optimization-sg-ready/
- Tesla support page (cited by Electrek) → https://www.tesla.com/de_de/support/energy/powerwall/mobile-app/heat-pump-optimization
Verification status (2026-11-03): Based on press reporting; Tesla's own page was not read directly.
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