Tesla has launched Heat Pump Optimization in Europe, a feature that lets the Powerwall 3 and the three-phase Powerwall 3P tell a compatible heat pump when to run harder. The goal is to turn surplus solar, or grid power bought when it is cheap, into hot water that is used during expensive hours. For now, the feature is not available in the United States or Canada.
How it works
The battery tracks electricity prices and solar output through the day and sends the heat pump one of two signals: normal operation or boost. In boost, the pump heats water beyond the home's immediate needs, usually in the domestic hot water tank or a buffer tank. That stored heat carries the house through costly hours, when the pump can run less.
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The trigger depends on the Powerwall's mode. In Self-Powered mode, it boosts only if solar remains after the home's other loads are covered. In Savings mode, it can boost when solar is available or when grid power reaches its cheapest price, based on tariff forecasts for the next 24 hours.
The physical link
The system does not use the cloud or integrations with heat pump brands. It runs over a wire, based on SG-Ready, a German standard introduced in 2012 by the German Heat Pump Association (BWP) with 17 manufacturers. Through two relay contacts, the pump receives four possible operating states, and Tesla uses only the normal and boosted ones.
The requirements are specific: a Powerwall 3 or 3P on firmware 26.26 or later, an SG-Ready certified heat pump with an accessible SG-2 contact configured to accept external signals, wiring installed by a Tesla-certified installer, and the Tesla app at version 4.59.1 or later. The signals are only recommendations, so the pump's own thermostat can override them. Each signal must be held for at least ten minutes to comply with the standard, and during a power outage, the function reverts to normal so the Powerwall can prioritize backup loads. The app has no on/off switch: once wired, it is active.
Why a water tank works as a battery
A 300-litre tank heated an extra 30 degrees holds about 10.5 kWh of thermal energy, which at a COP of 3 requires only about 3.5 kWh of electricity. Many European heat pump homes already have such a tank, which can absorb a large share of midday solar without drawing on the battery cells. That leaves the Powerwall's 13.5 kWh for loads that cannot be stored as heat.
The market is ready. According to the BWP, Germany sold 299,000 heating heat pumps in 2025, up 55% year on year, and for the first time they made up nearly half of all new heating systems sold.
Tesla is late, however. sonnen introduced a software update in 2023 letting its sonnenBatterie run heat pumps off surplus solar, starting with NIBE units, and SG-Ready control has long been a standard feature of German solar energy managers.
The move fits Tesla Energy's Europe-first strategy, which in recent months has targeted Germany, Austria, and Switzerland. For the company, increasing the value of installed batteries through software is a way to extract more from its existing customer base.
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