Fronius + Vaillant

What Zerofy can do with Fronius and Vaillant

In practice

• Hot water is the simplest heat store: Autopilot can use the hot-water boost of your Vaillant heat pump to heat water in hours with surplus.
• Zerofy can also change the room temperature and flow temperature of your Vaillant heat pump, so space heating can shift into sunny hours.
• A heat pump draws roughly 1–3 kW while running, which a typical Fronius home system (3–10 kW) can cover on sunny days.
• Zerofy gets new Fronius data every 5 minutes. Heat pumps shouldn’t switch often, so set a minimum runtime in Autopilot.
• Zerofy also shows your Fronius battery, so you can see whether surplus goes into the battery or into the heat pump.
• The boost is a one-time cylinder charge up to the hot-water setpoint you set in the myVAILLANT app (Zerofy can’t change that setpoint for Vaillant), so set it a few degrees higher than you strictly need if you want the tank to soak up more midday solar.
• The Zerofy integration for Vaillant is in beta.

What Fronius and Vaillant offer on their own

Fronius: The Fronius Ohmpilot feeds surplus into a heating rod (0.3–3 kW single-phase, 0.9–9 kW three-phase) and has a control output for a heat pump with an SG Ready input. GEN24 inverters can also switch an SG Ready input through one of their four digital outputs plus a coupling relay, and Fronius lists direct integrations with heat pumps from IDM, Bosch and NIBE.

Vaillant: Vaillant has no PV energy manager of its own; instead the heat pump talks EEBUS over the VR 920/921/940f internet module to external energy managers, and Vaillant’s cloud API is opened to partner services. Both need a VRC 700(f) or VRC 720(f) controller and a hot-water or buffer tank to store surplus as heat. Vaillant lists Zerofy among the partners on its smart-interfaces page.

Zerofy connects the two: it reads Fronius production and controls your Vaillant heat pump to match, together with your other devices in one app, with dynamic tariffs and forecast-based Smart mode.

Setting up Fronius and Vaillant in Zerofy

1. Connect Fronius

Zerofy reads your system from Fronius Solar.web through a guest account that you create for Zerofy.

1. Make sure your Fronius inverter is online and shows up in Solar.web.
2. In Solar.web, go to Settings → Permissions and create a new guest account.
3. Add Fronius in Zerofy and log in with the guest account credentials.

Step-by-step guide for Fronius

2. Connect Vaillant

Zerofy connects through Vaillant’s cloud using your internet gateway’s serial number and shows a Space Heating and a Hot Water Tank device; you can adjust room and flow temperature, and Autopilot triggers the hot-water boost.

1. Make sure the system runs on a supported gateway (myVAILLANT connect, sensoNET, eRELAX) and is online.
2. Copy the gateway serial number from the back of the gateway or from the myVAILLANT app under Status > Gateway.
3. In Zerofy, add a Vaillant device and enter the serial number.
4. Enable Autopilot (Solar or Smart mode) for the Hot Water Tank.

Good to know: The Vaillant integration is in beta. Supported controllers are eRELAX, E7C, VRT-350, VRC-720, VRC-710 and VRT-380; Autopilot currently steers only the hot-water tank, space-heating control is coming.

Step-by-step guide for Vaillant

3. Turn on Autopilot

In Zerofy, open your Vaillant heat pump, turn on Autopilot and choose Solar – or Smart to also use dynamic tariffs and forecasts. Set the priority, activation threshold and minimum runtime.

Dynamic tariffs

Zerofy can also run your Vaillant heat pump on dynamic electricity prices (EPEX Spot or Nord Pool, e.g. Tibber or aWATTar) or on a fixed time-of-use tariff. Smart mode combines those prices with forecasts of your household consumption and your Fronius solar production.

Learn more about Smart Mode

About Fronius and Vaillant

Fronius – Austrian manufacturer of inverters, welding and battery-charging technology. Homeowners typically have a Primo GEN24 (single-phase, 3–6 kW) or Symo GEN24 (three-phase, 3–10 kW) hybrid inverter, older Primo/Symo SnapINverters, and the Fronius Reserva battery (6.3–15.8 kWh). Monitoring app: Fronius Solar.web.

Vaillant – Vaillant is a German heating manufacturer from Remscheid. Most homeowners have an aroTHERM air-to-water heat pump or an ecoTEC boiler, run by a sensoCOMFORT/multiMATIC controller (VRC 700/720) and connected to the internet with a myVAILLANT connect or sensoNET module. Products: aroTHERM plus, aroTHERM Split, flexoTHERM exclusive, flexoCOMPACT exclusive, recoCOMPACT exclusive, versoTHERM plus, ecoTEC boilers.

Manufacturer information last checked: October 2026.

All devices that work with Fronius