Fronius + Shelly

What Zerofy can do with Fronius and Shelly

In practice

• Solar mode switches your Shelly plugs and relays on when there’s surplus, following your priority order and minimum runtime. Smart mode instead runs for a set number of minutes within the hours you allow.
• A Shelly plug can also measure a balcony solar system: set it as balcony solar meter in Zerofy.
• With a typical Fronius home system (3–10 kW), plug loads get surplus on most sunny days; use priorities to decide whether they or bigger devices such as an EV charger come first.
• Zerofy gets new Fronius data every 5 minutes and adjusts accordingly. A minimum runtime and an activation threshold in Autopilot keep passing clouds from interrupting switching.
• Zerofy also shows your Fronius battery, so you can see whether surplus goes into the battery or into your appliances.
• Zerofy only sees devices in your Shelly Cloud account: a Shelly that was set up only locally, with cloud access switched off, won’t appear until you add it to your account in the Shelly app.

What Fronius and Shelly offer on their own

Fronius: GEN24 inverters have four digital outputs for load management (Energy Management → Load Management in the inverter’s web interface), which switch loads such as heating rods or pool pumps through an external relay when surplus is available.

Shelly: In the Shelly Smart Control app, scenes can switch loads when a Shelly Pro 3EM measures export (negative power), e.g. a three-stage heating rod at 1,500, 3,000 and 4,500 W of surplus with a 2-minute validity condition. Shelly notes that load priorities or forecasts need an external control system; plain scenes only react to thresholds.

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

Setting up Fronius and Shelly 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 Shelly

Zerofy connects to your Shelly Cloud account; it switches plugs and relays on and off, records their power every 5 minutes and lets Autopilot run them on solar surplus or in Smart mode.

1. Set up new Shelly devices in the Shelly app first.
2. In Zerofy, open the Shelly section under HVAC and Appliances and enter your Shelly account credentials.
3. Select the devices you want to use in Zerofy.

Good to know: A Shelly Pro 3EM is added separately in the Meters section; the device list there only shows Shelly Pro EM meters.

Step-by-step guide for Shelly

3. Turn on Autopilot

In Zerofy, open your Shelly plugs and relays, 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 Shelly plugs and relays 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 Shelly

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.

Shelly – Shelly Group (formerly Allterco) is a Bulgarian company based in Sofia. It makes Wi-Fi smart plugs, relays for the switch box or DIN rail, and energy meters such as the Shelly Pro 3EM. Products: Shelly Plug S Gen3, Shelly Plus Plug S, Shelly 1PM / Plus 1PM / 1PM Gen3, Shelly Pro 2PM, Shelly Pro 3EM energy meter.

Manufacturer information last checked: October 2026.

All devices that work with Fronius