Shelly Pro 3EM MQTT scripts

A Shelly Pro 3EM does not provide a 1–2 second MQTT telemetry cadence natively, and Omnibattery's main sensor works best with a fast-updating grid sensor. The scripts on this page run on the device itself and publish telemetry every second over MQTT, with Home Assistant MQTT Discovery so the sensors appear automatically.

Which script do I need?

A Shelly Pro 3EM is configured with one of two metering profiles. Check yours in the Shelly web interface under Settings → Device profile before choosing a script — the two scripts are not interchangeable and only one should run on the device at a time.

Your Shelly profile	Use this script
Three single-phase meters (monophase / three independent EM1 channels)	Three single-phase meters profile
Triphase (one EM component across three phases)	Three-phase profile

Before you start

• MQTT enabled and connected on the Shelly device.
• Home Assistant connected to the same MQTT broker.
• MQTT Discovery enabled in Home Assistant (the default prefix is homeassistant).

Selecting the sensor in Omnibattery

Once the script is running, open Omnibattery's main sensor configuration and select the discovered total-power sensor (Total Active Power) as the grid consumption sensor. Watch the sensor's value while importing and exporting: Omnibattery's standard convention is a positive value for import and negative for export. If your installation reports the opposite, enable Inverted meter sign rather than editing the script.

Three single-phase meters profile

Scope

Use this script with a Shelly Pro 3EM configured in the three single-phase meters profile. It reads EM1.GetStatus for channels 0, 1 and 2 and exposes each channel as a separate clamp.

Install and verify

1. Open the Shelly web interface and go to Scripts.
2. Create a new script and paste the code below.
3. Save the script, then enable and run it.
4. In Home Assistant, confirm that Total Active Power and the three per-clamp sensors appear and update roughly once per second.
5. Select Total Active Power as described in Selecting the sensor in Omnibattery.

The script publishes state to shellypro3em/<device-id>/state and availability to shellypro3em/<device-id>/availability. Discovery messages are retained by the MQTT broker, while state is published once per second.

Script

// Shelly Pro 3EM in three single-phase meters profile
// MQTT telemetry + Home Assistant MQTT Discovery.
//
// Publishes every second:
// - Active power, voltage, current, and power factor per clamp
// - Total active power calculated from all three clamps
//
// Requirements:
// - MQTT enabled and connected on the Shelly device
// - Home Assistant connected to the same MQTT broker
// - MQTT Discovery enabled in Home Assistant (default prefix: homeassistant)

let DISCOVERY_PREFIX = "homeassistant";
let STATE_INTERVAL_MS = 1000;
let STATE_EXPIRE_AFTER_S = 5;

let dev = Shelly.getDeviceInfo();
let DEVICE_ID = dev.id || "shellypro3em";
let DEVICE_NAME = dev.name || "Shelly Pro 3EM";

let BASE_TOPIC = "shellypro3em/" + DEVICE_ID;
let STATE_TOPIC = BASE_TOPIC + "/state";
let AVAILABILITY_TOPIC = BASE_TOPIC + "/availability";

let lastAvailability = null;
let publishing = false;

function haConfigTopic(objectId) {
  return DISCOVERY_PREFIX + "/sensor/" + DEVICE_ID + "_" + objectId + "/config";
}

function setAvailability(online) {
  if (lastAvailability === online) return;

  lastAvailability = online;
  MQTT.publish(
    AVAILABILITY_TOPIC,
    online ? "online" : "offline",
    0,
    true
  );
}

function publishDiscoverySensor(
  objectId,
  name,
  unit,
  deviceClass,
  stateClass,
  valueTemplate
) {
  let payload = {
    name: name,
    unique_id: DEVICE_ID + "_" + objectId,
    object_id: DEVICE_ID + "_" + objectId,

    state_topic: STATE_TOPIC,
    value_template: valueTemplate,
    expire_after: STATE_EXPIRE_AFTER_S,

    availability_topic: AVAILABILITY_TOPIC,
    payload_available: "online",
    payload_not_available: "offline",

    unit_of_measurement: unit,
    device_class: deviceClass,
    state_class: stateClass,
    force_update: false,

    device: {
      identifiers: [DEVICE_ID],
      name: DEVICE_NAME,
      manufacturer: "Shelly",
      model: "Shelly Pro 3EM",
      sw_version: dev.fw_id || ""
    }
  };

  // Retained: Home Assistant can recreate the entities after a restart.
  MQTT.publish(haConfigTopic(objectId), JSON.stringify(payload), 0, true);
}

function publishDiscovery() {
  // Total active power
  publishDiscoverySensor(
    "total_active_power",
    "Total Active Power",
    "W",
    "power",
    "measurement",
    "{{ value_json.total_act_power | float(0) }}"
  );

  // Clamp 1
  publishDiscoverySensor(
    "clamp_1_active_power",
    "Clamp 1 Active Power",
    "W", "power", "measurement",
    "{{ value_json.clamp_1.act_power | float(0) }}"
  );
  publishDiscoverySensor(
    "clamp_1_voltage",
    "Clamp 1 Voltage",
    "V", "voltage", "measurement",
    "{{ value_json.clamp_1.voltage | float(0) }}"
  );
  publishDiscoverySensor(
    "clamp_1_current",
    "Clamp 1 Current",
    "A", "current", "measurement",
    "{{ value_json.clamp_1.current | float(0) }}"
  );
  publishDiscoverySensor(
    "clamp_1_power_factor",
    "Clamp 1 Power Factor",
    "", "power_factor", "measurement",
    "{{ value_json.clamp_1.pf | float(0) }}"
  );

  // Clamp 2
  publishDiscoverySensor(
    "clamp_2_active_power",
    "Clamp 2 Active Power",
    "W", "power", "measurement",
    "{{ value_json.clamp_2.act_power | float(0) }}"
  );
  publishDiscoverySensor(
    "clamp_2_voltage",
    "Clamp 2 Voltage",
    "V", "voltage", "measurement",
    "{{ value_json.clamp_2.voltage | float(0) }}"
  );
  publishDiscoverySensor(
    "clamp_2_current",
    "Clamp 2 Current",
    "A", "current", "measurement",
    "{{ value_json.clamp_2.current | float(0) }}"
  );
  publishDiscoverySensor(
    "clamp_2_power_factor",
    "Clamp 2 Power Factor",
    "", "power_factor", "measurement",
    "{{ value_json.clamp_2.pf | float(0) }}"
  );

  // Clamp 3
  publishDiscoverySensor(
    "clamp_3_active_power",
    "Clamp 3 Active Power",
    "W", "power", "measurement",
    "{{ value_json.clamp_3.act_power | float(0) }}"
  );
  publishDiscoverySensor(
    "clamp_3_voltage",
    "Clamp 3 Voltage",
    "V", "voltage", "measurement",
    "{{ value_json.clamp_3.voltage | float(0) }}"
  );
  publishDiscoverySensor(
    "clamp_3_current",
    "Clamp 3 Current",
    "A", "current", "measurement",
    "{{ value_json.clamp_3.current | float(0) }}"
  );
  publishDiscoverySensor(
    "clamp_3_power_factor",
    "Clamp 3 Power Factor",
    "", "power_factor", "measurement",
    "{{ value_json.clamp_3.pf | float(0) }}"
  );
}

function publishState() {
  // Prevent overlapping asynchronous requests.
  if (publishing) return;
  publishing = true;

  Shelly.call("EM1.GetStatus", { id: 0 }, function (c1, err1, msg1) {
    if (err1 !== 0) {
      print("EM1:0 error:", err1, msg1);
      setAvailability(false);
      publishing = false;
      return;
    }

    Shelly.call("EM1.GetStatus", { id: 1 }, function (c2, err2, msg2) {
      if (err2 !== 0) {
        print("EM1:1 error:", err2, msg2);
        setAvailability(false);
        publishing = false;
        return;
      }

      Shelly.call("EM1.GetStatus", { id: 2 }, function (c3, err3, msg3) {
        if (err3 !== 0) {
          print("EM1:2 error:", err3, msg3);
          setAvailability(false);
          publishing = false;
          return;
        }

        let p1 = c1.act_power || 0;
        let p2 = c2.act_power || 0;
        let p3 = c3.act_power || 0;

        let payload = {
          total_act_power: p1 + p2 + p3,

          clamp_1: {
            act_power: c1.act_power,
            aprt_power: c1.aprt_power,
            current: c1.current,
            voltage: c1.voltage,
            pf: c1.pf,
            freq: c1.freq
          },

          clamp_2: {
            act_power: c2.act_power,
            aprt_power: c2.aprt_power,
            current: c2.current,
            voltage: c2.voltage,
            pf: c2.pf,
            freq: c2.freq
          },

          clamp_3: {
            act_power: c3.act_power,
            aprt_power: c3.aprt_power,
            current: c3.current,
            voltage: c3.voltage,
            pf: c3.pf,
            freq: c3.freq
          }
        };

        setAvailability(true);
        MQTT.publish(STATE_TOPIC, JSON.stringify(payload), 0, false);
        publishing = false;
      });
    });
  });
}

// Publish discovery configuration once on each script start.
// Config messages are retained by the MQTT broker.
publishDiscovery();

// Publish immediately, then every second.
publishState();
Timer.set(STATE_INTERVAL_MS, true, publishState);

Three-phase profile

Scope

Use this script with a Shelly Pro 3EM configured with the triphase profile. It reads EM.GetStatus with id: 0 and publishes the three phases as phase_a, phase_b and phase_c. Run only one of the two profile scripts at a time.

Install and verify

1. Open the Shelly web interface and go to Scripts.
2. Create a new script, or replace the script for the other metering profile.
3. Paste the code below, save it, then enable and run it.
4. In Home Assistant, confirm that Total Active Power and the per-phase sensors appear and update roughly once per second.
5. Select Total Active Power as described in Selecting the sensor in Omnibattery.

This script uses the same state and availability topics as the single-phase-profile script, so do not run both scripts simultaneously for the same device.

Script

// Shelly Pro 3EM — triphase profile
// MQTT telemetry + Home Assistant MQTT Discovery.
//
// Requirements:
// - Shelly profile: "triphase"
// - MQTT enabled and connected
// - MQTT Discovery enabled in Home Assistant

let DISCOVERY_PREFIX = "homeassistant";
let STATE_INTERVAL_MS = 1000;
let STATE_EXPIRE_AFTER_S = 5;

let dev = Shelly.getDeviceInfo();
let DEVICE_ID = dev.id || "shellypro3em";
let DEVICE_NAME = dev.name || "Shelly Pro 3EM";

let BASE_TOPIC = "shellypro3em/" + DEVICE_ID;
let STATE_TOPIC = BASE_TOPIC + "/state";
let AVAILABILITY_TOPIC = BASE_TOPIC + "/availability";

let lastAvailability = null;
let publishing = false;

function haConfigTopic(objectId) {
  return DISCOVERY_PREFIX + "/sensor/" + DEVICE_ID + "_" + objectId + "/config";
}

function setAvailability(online) {
  if (lastAvailability === online) return;

  lastAvailability = online;
  MQTT.publish(
    AVAILABILITY_TOPIC,
    online ? "online" : "offline",
    0,
    true
  );
}

function publishDiscoverySensor(
  objectId,
  name,
  unit,
  deviceClass,
  stateClass,
  valueTemplate
) {
  let payload = {
    name: name,
    unique_id: DEVICE_ID + "_" + objectId,
    object_id: DEVICE_ID + "_" + objectId,

    state_topic: STATE_TOPIC,
    value_template: valueTemplate,
    expire_after: STATE_EXPIRE_AFTER_S,

    availability_topic: AVAILABILITY_TOPIC,
    payload_available: "online",
    payload_not_available: "offline",

    unit_of_measurement: unit,
    device_class: deviceClass,
    state_class: stateClass,

    device: {
      identifiers: [DEVICE_ID],
      name: DEVICE_NAME,
      manufacturer: "Shelly",
      model: "Shelly Pro 3EM",
      sw_version: dev.fw_id || ""
    }
  };

  MQTT.publish(haConfigTopic(objectId), JSON.stringify(payload), 0, true);
}

function publishPhaseDiscovery(phase, label) {
  publishDiscoverySensor(
    "phase_" + phase + "_active_power",
    "Phase " + label + " Active Power",
    "W", "power", "measurement",
    "{{ value_json.phase_" + phase + ".act_power | float(0) }}"
  );

  publishDiscoverySensor(
    "phase_" + phase + "_voltage",
    "Phase " + label + " Voltage",
    "V", "voltage", "measurement",
    "{{ value_json.phase_" + phase + ".voltage | float(0) }}"
  );

  publishDiscoverySensor(
    "phase_" + phase + "_current",
    "Phase " + label + " Current",
    "A", "current", "measurement",
    "{{ value_json.phase_" + phase + ".current | float(0) }}"
  );

  publishDiscoverySensor(
    "phase_" + phase + "_power_factor",
    "Phase " + label + " Power Factor",
    "", "power_factor", "measurement",
    "{{ value_json.phase_" + phase + ".pf | float(0) }}"
  );
}

function publishDiscovery() {
  publishDiscoverySensor(
    "total_active_power",
    "Total Active Power",
    "W", "power", "measurement",
    "{{ value_json.total_act_power | float(0) }}"
  );

  publishDiscoverySensor(
    "total_current",
    "Total Current",
    "A", "current", "measurement",
    "{{ value_json.total_current | float(0) }}"
  );

  publishPhaseDiscovery("a", "A");
  publishPhaseDiscovery("b", "B");
  publishPhaseDiscovery("c", "C");
}

function phasePayload(status, phase) {
  return {
    act_power: status[phase + "_act_power"],
    aprt_power: status[phase + "_aprt_power"],
    current: status[phase + "_current"],
    voltage: status[phase + "_voltage"],
    pf: status[phase + "_pf"],
    freq: status[phase + "_freq"]
  };
}

function publishState() {
  if (publishing) return;
  publishing = true;

  Shelly.call("EM.GetStatus", { id: 0 }, function (status, err, msg) {
    publishing = false;

    if (err !== 0) {
      print("EM:0 error:", err, msg);
      setAvailability(false);
      return;
    }

    let totalPower = status.total_act_power;
    if (totalPower === null || typeof totalPower === "undefined") {
      totalPower =
        (status.a_act_power || 0) +
        (status.b_act_power || 0) +
        (status.c_act_power || 0);
    }

    let payload = {
      total_act_power: totalPower,
      total_aprt_power: status.total_aprt_power,
      total_current: status.total_current,
      neutral_current: status.n_current,

      phase_a: phasePayload(status, "a"),
      phase_b: phasePayload(status, "b"),
      phase_c: phasePayload(status, "c")
    };

    setAvailability(true);
    MQTT.publish(STATE_TOPIC, JSON.stringify(payload), 0, false);
  });
}

publishDiscovery();
publishState();
Timer.set(STATE_INTERVAL_MS, true, publishState);

Uninstalling

Stop and disable the script in the Shelly web interface's Scripts page. The retained MQTT discovery and availability messages remain on the broker until they expire or are cleared; if you do not plan to reinstall, remove them from Home Assistant by publishing an empty, retained payload to each homeassistant/sensor/<device-id>_*/config topic, or delete the entities from Settings → Devices & services → MQTT.

If it does not work

Symptom	Likely cause	What to check
No sensors appear in Home Assistant	MQTT Discovery is disabled, or the broker is unreachable from the Shelly	The MQTT integration's discovery prefix matches homeassistant; the Shelly's MQTT connection status in its web interface
Sensors appear but never update	The script is not running, or the wrong profile's script is installed	The script is enabled and running (Shelly Scripts page, script log); the device profile matches the script
Sensors go unavailable after ~5 seconds	The script stopped publishing (device reboot, script error, MQTT disconnect)	The expire_after: 5 availability window; the script's log for EM1:* or EM:0 errors
Grid power reads the wrong sign	Import and export are reversed for this meter's wiring	The Inverted meter sign toggle on the main sensor — do not edit the script's sign convention