PZEM004T v3 Monitor with ESP8266, MQTT and Home Assistant

This project enables monitoring up to 4 PZEM-004T v3 modules using an ESP8266, publishing data to MQTT, and automatically integrating with Home Assistant using AutoDiscovery. It also includes a web debug interface, OTA support, and automatic network fault recovery.

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📦 Features

• 🔌 Reads data from 4 PZEM-004T v3 modules via SoftwareSerial (D5/D6)
• 📶 WiFi connection with automatic retry and reboot after 5 failed attempts
• 📡 MQTT connection with 512 byte buffer and reboot on failure
• 🏠 Full Home Assistant AutoDiscovery support via MQTT
• 🔄 Publishes data as retained, so HA reads values immediately after restart
• 🌐 Web interface with live readings and a remote ESP reboot button
• 🔧 Supports OTA updates over the network

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⚙️ Required Hardware

• 1x ESP8266 (NodeMCU or Wemos D1 Mini recommended)
• 4x PZEM-004T v3 modules
• 5V Power Supply
• TX line from PZEM to ESP RX must be adapted using a resistor divider

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📡 MQTT & Home Assistant

Each sensor (e.g. pzem1) publishes topics:

• homeassistant/pzem1/voltage
• homeassistant/pzem1/current
• homeassistant/pzem1/power
• homeassistant/pzem1/energy (in kWh, total_increasing)

Home Assistant discovers them using MQTT AutoDiscovery with:

• device_class, unit_of_measurement, state_class

The energy value can be used directly in the Energy Dashboard.

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🔐 Security

MQTT authentication is supported via username and password. WiFi and MQTT credentials are configurable at the top of the .ino file.

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🌐 Web Interface

Accessing the ESP's IP in a browser shows:

• Live readings of voltage, current, power, energy, frequency, power factor
• Button to remotely reboot the ESP

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🧠 Resilience

• If WiFi fails to connect after 5 tries → device reboots
• If MQTT fails after 5 attempts → device reboots
• If Serial fail → device reboots

📸 Screenshots

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✅ Author

Massimo Balestrieri
Feel free to fork or open pull requests! 🛠️