Sunsteer switches real heating equipment. Read this before you wire anything.
Sunsteer drives a relay connected to your heat pump's SG-Ready input. What that input does is defined by your heat pump manufacturer, not by Sunsteer: on most units the contact Sunsteer uses is a recommendation to raise setpoints and consume PV surplus, and the heat pump's own controller still protects the machine. Verify the SG-Ready semantics of your model with its documentation or your installer before connecting anything.
The SG-Ready input expects a potential-free contact. Wiring a relay into a heat pump is electrical work on a heating system — have it done (or at least checked) by a licensed electrician. A miswired contact can damage the heat pump, the relay, or worse.
Sunsteer is designed to fail towards "heat pump runs normally, surplus mode off":
- Stale or missing meter data → the controller switches the relay OFF (it never acts blind).
- A dead controller → the relay's hardware auto-off watchdog switches OFF on its own (the controller must actively re-arm it every cycle).
- Minimum runtimes and off-times limit compressor cycling.
- The web UI requires authentication and serves nothing without it.
These layers reduce risk; they do not eliminate it. Network outages, misconfiguration, hardware faults or bugs can still produce unwanted switching behaviour. Monitor your system, especially in the first weeks.
Sunsteer is published under the MIT license: the software is provided "as is", without warranty of any kind. You run it at your own risk and you are responsible for the safety and the consequences of its operation in your installation.
SMA, Sunny Home Manager, Shelly, Viessmann, ViCare and related names are trademarks of their respective owners. Sunsteer is a private open-source project and is not affiliated with, endorsed by, or supported by any of these companies.