Adding a Shelly relay or smart plug to a plant

Shelly relays and smart plugs let a plant do more than measure — they can switch real loads (a heat-pump enable circuit, a water heater, an EV charger contactor). This doc covers connecting one to a plant so its state shows up live, and so automations can use it later.

Supported devices

Any Shelly device reachable through Shelly Cloud or your local network, including relay/plug models (Shelly 1, Plug S, Plus 1PM, PM Mini) and energy meters (3EM, Pro 3EM). Relay models report their switch state and, on metering models, live power draw.

Before you start

• The Shelly is set up in the Shelly app and online.
• For a cloud connection you’ll need your cloud server address and authorization key — in the Shelly app under Settings → Authorization cloud key.
• For a local connection, the device’s IP address on the plant’s network (give it a static lease in the router).

Connecting the device

1. Open the plant and go to the Devices tab, then click Add device.
2. Step 1 — connection type: pick Shelly Cloud or Shelly Local directly (Modbus TCP and Deye Cloud are the other two options on the same screen, for non-Shelly gear).
3. Step 2 — connection details:
   • Shelly Cloud: cloud server address, authorization key, and the device ID.
   • Shelly Local: the device’s IP address.
4. Step 3 — confirm & save: the device model is usually auto-detected from what it reports; if detection fails you’ll be asked to pick it from a list (or “Not labeled yet” if you’re unsure — we’ll get notified and add it). Optionally name the device, then Save & start polling.
5. Within a minute the device appears with its live state — switch position, and power/voltage on metering models.

Wiring advice for switched loads

A relay should switch a load’s control or enable circuit (thermostat input, contactor coil) — not the compressor or heater feed directly. That keeps the switched current far below the relay’s rating and lets the appliance manage its own start-up. If in doubt, drive a contactor.

If an inverter has its own smart-load output wired to the same appliance, disable it or set it permanently on — one controller per load, never two.

What if the device shows offline?

Check the Shelly app first: if it’s offline there too, it’s a Wi-Fi issue at the site. If it’s online in the app but offline here, re-check the authorization key (cloud) or the IP (local — DHCP may have moved it).

Where to go next

Once the relay is connected, see plant-automations-overview to make it respond to solar production and battery state automatically.