[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.

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: 4MBesp32:  board: esp32-c3-devkitm-1  framework:    type: esp-idfuart:  rx_pin: 8  tx_pin: 9  baud_rate: 9600modbus:mqtt:  broker: "192.168.0.4"  username: "user"  password: "password"  discovery: false  discover_ip: falsewifi:  ssid: "WIFI SSID"  password: "********"ota:  - platform: esphome    password: "******"logger:  level: INFOsensor:  - 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:17653025f5:3574a13d85label: PZEM004T Power MonitorthingTypeUID: mqtt:topicconfiguration: {}bridgeUID: mqtt:broker:17653025f5location: Housechannels:  - 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)