Tesla Powerwall 3 Can Now Control Heat Pumps to Store Solar Heat

How it works

Behavior depends on the battery's mode. In Self-Powered mode, extra heating starts only once solar surplus remains after the home's other needs are met. In Savings mode, it runs when solar power is available or when grid prices hit their lowest point in a 24-hour forecast.

The feature relies on SG-Ready, a German standard for communication between energy management systems and heat pumps. It uses direct electrical contacts rather than a cloud link to manufacturers, and Tesla uses two of its modes: normal operation and boosted heating.

Requirements are strict. Owners need a Powerwall 3 or 3P running firmware 26.26 or later, an SG-Ready heat pump that supports the SG-2 contact and accepts external signals, a wired connection between the two, installation by a Tesla-certified technician, and Tesla app version 4.59.1 or later. Tesla says the signals are recommendations that the heat pump's thermostat settings can override, and each must last at least 10 minutes. During a power outage, the feature returns to normal operation so the battery can prioritize backup loads.

Why it matters

A hot water tank can work as a thermal battery. By the report's calculation, a 300-liter tank heated an extra 30°C stores about 10.5 kWh of heat. With a heat pump at a COP of 3, that takes only about 3.5 kWh of electricity, leaving the Powerwall's 13.5 kWh free for other uses.

The feature is available only in Europe, and Tesla has announced no plans for the United States or Canada. The timing fits a growing market: Germany sold 299,000 heating heat pumps in 2025, up 55% on the year, and they made up about half of new heating systems sold there for the first time. Tesla is not the first with this kind of integration, as sonnen released a software update for its batteries in 2023.