TSUN + CTA

What Zerofy can do with TSUN and CTA

In practice

• When there’s enough surplus, Zerofy switches the relay and the heat pump receives the SG Ready signal. How it reacts – for example by heating the hot-water tank to a higher temperature – is set in the heat pump’s own controller.
• 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.
• CTA’s own tip for SG Ready operation: if rooms get too warm or too cold, change the upper temperature limit by 1 °C at a time and leave it for one to two days before adjusting again; agree the values with your heating installer.

What TSUN and CTA offer on their own

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

CTA: For PV self-consumption, CTA connects its heat pumps to external energy management systems via a PV input, SG Ready or Modbus (Optiheat and Aeroheat). CTA publishes SG Ready instructions per model and a compatibility list for the Swiss Solar Manager gateway (Modbus TCP/RTU).

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

Setting up TSUN and CTA 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 CTA

The Zerofy docs have no CTA-specific guide; the documented way to control a CTA heat pump is Zerofy’s SG Ready integration, with a smart relay such as a Shelly wired to the heat pump’s SG Ready inputs.

1. Check in CTA’s SG Ready compatibility list that your model and controller (Optiplus, Optiplus 3, Aeroplus 2.0/2.1) are listed.
2. Have an electrician wire a smart relay (e.g. Shelly) to the heat pump’s SG Ready inputs.
3. Add the relay to Zerofy and configure it as SG Ready controller.

Good to know: CTA marks Optiheat Inverta units and several Aeroheat models as needing a software or controller update for SG Ready. For older or unlisted units, CTA says integration can mean extra cost, e.g. a controller replacement.

Step-by-step guide for CTA

3. Turn on Autopilot

In Zerofy, open your CTA 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 CTA 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 CTA

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.

CTA – CTA AG is a Swiss manufacturer of heat pumps and cooling machines, with production at its headquarters in Münsingen near Bern. Its home range covers Optiheat ground-source and water-source heat pumps and Aeroheat air-source heat pumps. Products: Optiheat (brine/water and water/water), Optiheat Inverta, Aeroheat (air/water, indoor and outdoor units), Aeroheat Inverta.

Manufacturer information last checked: October 2026.

All devices that work with TSUN