[OpenHAB] Energy Meter with PZEM004T and ESPHome on ESP32-C3

Requirements

• OpenHAB version: 4.3.3
• The MQTT binding is installed.
• PZEM004T v1 (export version) or local V3 — see Shopee .
• An ESP32 or ESP32-C3 SuperMini. For an ESP32-C3 SuperMini, a model with an antenna is recommended (see Shopee).

Additional hardware reference

If the current PZEM004T model is unsuitable or you want to compare another version, see another PZEM004T model on Shopee. Before wiring it, verify the exact version, pinout, and module voltage.

Build with ESPHome

• See the ESPHome project here.
• Install ESPHome on your PC using this guide.
• The following configuration publishes data to the MQTT broker every 2 seconds.

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esphome:
  name: pzem004t-mqtt
  friendly_name: PZEM004T to MQTT
  min_version: 2025.3.2
  name_add_mac_suffix: true
  platformio_options:
    board_build.f_flash: 40000000L
    board_build.flash_mode: dio
    board_build.flash_size: 4MB

esp32:
  board: esp32-c3-devkitm-1
  framework:
    type: esp-idf

uart:
  rx_pin: 8
  tx_pin: 9
  baud_rate: 9600

modbus:

mqtt:
  broker: "192.168.0.4"
  username: "user"
  password: "password"
  discovery: false
  discover_ip: false

wifi:
  ssid: "WIFI SSID"
  password: "********"

ota:
  - platform: esphome
    password: "******"

logger:
  level: INFO

sensor:
  - platform: pzemac
    current:
      name: "PZEM-004T Current"
    voltage:
      name: "PZEM-004T Voltage"
    energy:
      # Multiply Energy by 0.001 to convert Wh to kWh.
      name: "PZEM-004T Energy"
      filters:
        - multiply: 0.001
    power:
      name: "PZEM-004T Power"
    frequency:
      name: "PZEM-004T Frequency"
    power_factor:
      name: "PZEM-004T Power Factor"
    update_interval: 2s

  - platform: wifi_signal
    name: "WiFi Signal dB"
    id: wifi_signal_db
    update_interval: 300s

  - platform: copy
    source_id: wifi_signal_db
    name: "WiFi Signal Percent"
    filters:
      - lambda: return min(max(2 * (x + 100.0), 0.0), 100.0);
    unit_of_measurement: "Signal %"

• Lines 17-18 configure the RX/TX pins on the ESP32-C3.
• Lines 24-26 configure the MQTT broker.
• Lines 31-32 configure Wi-Fi.
• Line 36 configures the OTA update password.
• Line 58 sets the MQTT broker update interval.

Check the MQTT broker to confirm that it has received the measurements.

Configure the Things in OpenHAB

UID: mqtt:topic:17653025f5:3574a13d85
label: PZEM004T Power Monitor
thingTypeUID: mqtt:topic
configuration: {}
bridgeUID: mqtt:broker:17653025f5
location: House
channels:
  - id: PZEM004T_House_Voltage
    channelTypeUID: mqtt:number
    label: PZEM004T House Voltage
    description: ""
    configuration:
      stateTopic: pzem004t-mqtt-be5d84/sensor/pzem-004t_voltage/state
  - id: PZEM004T_House_Power
    channelTypeUID: mqtt:number
    label: PZEM004T House Power
    description: ""
    configuration:
      stateTopic: pzem004t-mqtt-be5d84/sensor/pzem-004t_power/state
  - id: PZEM004T_House_Current
    channelTypeUID: mqtt:number
    label: PZEM004T House Current
    description: ""
    configuration:
      stateTopic: pzem004t-mqtt-be5d84/sensor/pzem-004t_current/state
  - id: PZEM004T_House_Energy
    channelTypeUID: mqtt:number
    label: PZEM004T House Energy
    description: ""
    configuration:
      stateTopic: pzem004t-mqtt-be5d84/sensor/pzem-004t_energy/state
  - id: PZEM004T_House_Freq
    channelTypeUID: mqtt:number
    label: PZEM004T House Frequency
    description: ""
    configuration:
      stateTopic: pzem004t-mqtt-be5d84/sensor/pzem-004t_frequency/state
  - id: PZEM004T_House_PowerFactor
    channelTypeUID: mqtt:number
    label: PZEM004T House PowerFactor
    description: ""
    configuration:
      stateTopic: pzem004t-mqtt-be5d84/sensor/pzem-004t_power_factor/state
  - id: PZEM004T_House_Sensor_Status
    channelTypeUID: mqtt:string
    label: PZEM004T House Sensor Status
    description: ""
    configuration:
      stateTopic: pzem004t-mqtt/status
  - id: PZEM004T_House_Wifi_Sginal_Level_dB
    channelTypeUID: mqtt:number
    label: PZEM004T House Wifi Sginal Level dB
    description: ""
    configuration:
      stateTopic: pzem004t-mqtt-be5d84/sensor/wifi_signal_db/state
  - id: PZEM004T_House_Wifi_Sginal_Level_Percent
    channelTypeUID: mqtt:number
    label: PZEM004T House Wifi Sginal Level Percent
    description: ""
    configuration:
      stateTopic: pzem004t-mqtt-be5d84/sensor/wifi_signal_percent/state

• BONUS: DSL script to calculate energy consumption for the day, month, and a selected period.
  • The results are updated in Energy_Consumption_Day, Energy_Consumption_Month, and Energy_Consumption_Period.

    logInfo("EnergyConsumption", "Current Energy: " + PZEM004T_House_Energy.state.toString + " - " + now.toString)

    val startOfDay = now.with(LocalTime.MIDNIGHT)
    val startOfMonth = now.withDayOfMonth(1).with(LocalTime.MIDNIGHT)
    val startOfPeriod = now.withMonth(4).withDayOfMonth(1).with(LocalTime.MIDNIGHT) // Starts on April 1

    val dayAgoValue = PZEM004T_House_Energy.persistedState(startOfDay)
    val monthAgoValue = PZEM004T_House_Energy.persistedState(startOfMonth)
    val periodAgoValue = PZEM004T_House_Energy.persistedState(startOfPeriod)

    val currentEnergy = PZEM004T_House_Energy.state as QuantityType<Number>
    val dayEnergy = dayAgoValue.state as QuantityType<Number>
    val monthEnergy = monthAgoValue.state as QuantityType<Number>
    val periodEnergy = periodAgoValue.state as QuantityType<Number>

    val dailyConsumption = (currentEnergy.subtract(dayEnergy)).doubleValue
    val monthlyConsumption = (currentEnergy.subtract(monthEnergy)).doubleValue
    val periodConsumption = (currentEnergy.subtract(periodEnergy)).doubleValue

    // Update Items with calculated values
    Energy_Consumption_Day.postUpdate(dailyConsumption)
    Energy_Consumption_Month.postUpdate(monthlyConsumption)
    Energy_Consumption_Period.postUpdate(periodConsumption)