TSUN + Viessmann

What Zerofy can do with TSUN and Viessmann

In practice

• Hot water is the simplest heat store: Autopilot can use the hot-water boost of your Viessmann heat pump to heat water in hours with surplus.
• Zerofy can also change the room temperature of your Viessmann heat pump, so space heating can shift into sunny hours.
• A heat pump draws roughly 1–3 kW while running – more than many small TSUN systems (typically 0.8–3 kW) produce, so solar covers only part of its consumption.
• Zerofy gets new TSUN data every 5 minutes. Heat pumps shouldn’t switch often, so set a minimum runtime in Autopilot.
• Autopilot uses Viessmann’s one-time hot-water charge. Because Zerofy can also set the hot-water temperature for Viessmann, you can choose how much surplus the cylinder stores: a higher setpoint holds more energy, at the cost of a somewhat lower heat pump efficiency.
• The Zerofy integration for Viessmann is in beta.

What TSUN and Viessmann offer on their own

TSUN: TSUN has no heat pump or heating-rod control in its product range.

Viessmann: Viessmann’s Energy Management on One Base links Vitocal heat pumps, the Vitocharge VX3 battery, the Viessmann Charging Station and hot-water tanks, using an E380CA energy meter; ViCare then shows self-consumption and autarky. Third-party inverters are brought in through the Solar-Log Base Vi gateway, with compatibility per Solar-Log’s component database.

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

Setting up TSUN and Viessmann in Zerofy

1. Connect TSUN

Zerofy connects to the TSUN cloud with your TSUN Smart login and reads your inverter data.

1. Register your system in the TSUN Smart app.
2. In Zerofy, add an inverter, choose TSUN and log in with your TSUN Smart credentials.

Good to know: Only TSUN Smart accounts work (inverter IDs starting with Y); TSUN Home accounts are not supported. Battery and meter data are only partly available, depending on the system.

Step-by-step guide for TSUN

2. Connect Viessmann

Zerofy connects to the Viessmann cloud with your Viessmann (ViCare) account and shows a Space Heating and a Hot Water Tank device; you can adjust room and hot-water temperature, and Autopilot triggers the hot-water boost.

1. Check that the system runs on Viessmann One Base or has an Optolink interface with a Vitoconnect OPTO2 gateway, and that it is online.
2. In Zerofy, add a Viessmann device.
3. Log in with your Viessmann account credentials and follow the prompts.
4. Enable Autopilot (Solar or Smart mode) for the Hot Water Tank.

Good to know: The Viessmann integration is in beta. Flow/circuit temperature can’t be set from Zerofy, and Autopilot currently steers only the hot-water tank; space-heating control is coming.

Step-by-step guide for Viessmann

3. Turn on Autopilot

In Zerofy, open your Viessmann 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 Viessmann 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 TSUN solar production.

Learn more about Smart Mode

About TSUN and Viessmann

TSUN – TSUN (TSUNESS Co., Ltd., Suzhou, China, with a German office in Frankfurt) makes microinverters from 300 W single units to 3.3 kW 6-in-1 units. In Europe it is mainly found in 800 W balcony systems such as the TSOL-MS800, often combined with TSUN balcony storage (MSU2000, MSU4000Elite). Monitoring app: TSUN Smart.

Viessmann – Viessmann is a German heating manufacturer from Allendorf (Eder). Newer heat pumps such as the Vitocal 250-A and Vitodens boilers run on the Viessmann One Base platform with built-in Wi-Fi; older Vitotronic systems go online through a Vitoconnect gateway. Products: Vitocal 250-A, Vitocal 200-S, Vitodens 200-W/300-W boilers, Vitovalor fuel cells, older systems with Vitotronic controllers.

Manufacturer information last checked: October 2026.

All devices that work with TSUN