Hoymiles + Vaillant

What Zerofy can do with Hoymiles 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. A Hoymiles balcony system covers only a small part of that, a rooftop system (Hoymiles systems range up to 10 kW) much more on sunny days.
• Zerofy gets new Hoymiles data only every 15 minutes, so the heat pump reacts to clouds with some delay. A slightly higher activation threshold and a minimum runtime in Autopilot keep it steady.
• 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 Hoymiles and Vaillant offer on their own

Hoymiles: On the three-phase HiOne all-in-one storage system (G3), Hoymiles has a dry contact (DO1) for SG Ready heat pumps, but the manual (January 2026) lists heat pump control as “coming soon”. Hoymiles microinverters have no heating control.

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 Hoymiles 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 Hoymiles and Vaillant in Zerofy

1. Connect Hoymiles

Zerofy connects to the Hoymiles S-Miles Cloud with your S-Miles account and reads your PV production.

1. If your installer hasn’t set up your plant yet, register it in the S-Miles Installer app (use DIY mode if you install it yourself).
2. In Zerofy, add an inverter, choose Hoymiles and log in with your S-Miles credentials.
3. Use Autopilot (Solar Mode) to switch devices on solar surplus.

Good to know: Zerofy reads PV production only from Hoymiles, not grid meter or battery data, and stores the power history in 15-minute steps (5 minutes for most other brands).

Step-by-step guide for Hoymiles

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 Hoymiles solar production.

Learn more about Smart Mode

About Hoymiles and Vaillant

Hoymiles – Hoymiles (Hangzhou, China) is one of the largest microinverter makers. In Europe it is best known for balcony systems such as the HMS-800W-2T (switchable 600/800 W) with the MS-A2 balcony battery, and it also sells HYS/HYT hybrid inverters with home batteries. Monitoring app: S-Miles Cloud (S-Miles app).

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 Hoymiles