Fronius + CTC

What Zerofy can do with Fronius and CTC

In practice

• Hot water is the simplest heat store: Autopilot can use the hot-water boost of your CTC heat pump to heat water in hours with surplus.
• 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.
• If you use CTC’s own spot-price control in myUplink, its “Blocking” at high prices can lower the hot-water setpoint; check that the CTC price limits and Zerofy’s Smart mode don’t pull in opposite directions.

What Fronius and CTC 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.

CTC: CTC controllers have SmartGrid inputs (terminals K22–K25, a SmartControl wireless accessory or BMS): when an inverter or energy manager closes both contacts (“SmartGrid Overcapacity”), the controller raises the room/flow setpoint by 1–5 °C and the hot-water setpoint by up to 30 °C. Through myUplink, CTC can also download spot prices and switch between “Low price” and “Blocking” on its own.

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

Setting up Fronius and CTC 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 CTC

Zerofy reaches CTC heat pumps through the myUplink cloud, the same connector used for NIBE, with your myUplink login; Autopilot controls the hot-water boost.

1. Connect the heat pump to the internet and register it in the myUplink app.
2. Make sure your myUplink account has the subscription needed for remote control.
3. In Zerofy, connect myUplink and log in with your myUplink credentials.
4. Enable Autopilot (Solar or Smart mode) for the hot-water tank.

Good to know: Zerofy steers only the hot-water boost on CTC units, not room or flow temperature.

3. Turn on Autopilot

In Zerofy, open your CTC 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 CTC 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 CTC

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.

CTC – CTC is a Swedish heat pump maker from Ljungby. Its air-to-water, ground-source and exhaust-air heat pumps and EcoZenith indoor modules are controlled remotely through the myUplink app. Products: CTC EcoAir, CTC GS/GSi 600, CTC EcoZenith i255/i360/i555 Pro, CTC EcoPart i600M, CTC EcoVent i360F, CTC EcoLogic L/M.

Manufacturer information last checked: October 2026.

All devices that work with Fronius