Fronius + SG Ready

What Zerofy can do with Fronius and SG Ready

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, 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.
• Set in the heat pump controller how many degrees the hot-water and heating setpoints rise in the boost state (“recommended operation”); the default differs by manufacturer. Fronius and Enphase only switch between normal and recommended operation, so the heat pump keeps its own minimum run times.

What Fronius and SG Ready 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.

SG Ready: Several inverter energy managers drive SG Ready directly: Fronius (GEN24 or Datamanager 2.0 with Smart Meter and a 12 V relay), SMA Sunny Home Manager 2.0 (relay or I/O module), Huawei EMMA, SolarEdge Home Load Controller or Smart Energy Relay, Sungrow SH-RT hybrids (built-in DO relay) and the Enphase IQ Energy Router+. Most of them switch on a fixed surplus threshold.

Directly, without Zerofy: The Ohmpilot’s control output, or a GEN24 digital output with a coupling relay, switches the SG Ready input of a heat pump on surplus; a Fronius Smart Meter is needed.

Zerofy is the alternative if you want Fronius, SG Ready and your other devices in one app, with dynamic tariffs and forecast-based Smart mode.

Setting up Fronius and SG Ready 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 SG Ready

Zerofy switches the SG Ready inputs through a smart relay such as a Shelly that you connect to Zerofy; Autopilot then sends SG Ready signals based on solar surplus and low electricity prices.

1. Have an electrician wire a smart relay (e.g. Shelly) to the heat pump’s SG Ready inputs.
2. Add the relay to Zerofy.
3. Configure the relay as SG Ready controller in the app and turn on Autopilot.

Good to know: SG Ready gives Zerofy on/off-style states, not temperature readings or setpoints. To use all four states, the relay needs two channels, one per SG Ready input.

Step-by-step guide for SG Ready

3. Turn on Autopilot

In Zerofy, open your SG Ready 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 SG Ready 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 SG Ready

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.

SG Ready – SG Ready (Smart Grid Ready) is a label introduced in 2012 by the German Heat Pump Association (BWP) for heat pumps that an external controller can switch between four operating states via two contacts. It is a signalling convention, not a data protocol: the heat pump’s own controller decides how far to raise temperatures in the boost state. Products: Heat pumps with the SG Ready label (two potential-free control inputs), from many manufacturers.

Manufacturer information last checked: October 2026.

All devices that work with Fronius