ESP32-C3 + Arduino Nano + PZEM-004T: Energy Monitoring with MQTT

This project uses an ESP32-C3 and an Arduino Nano to monitor energy consumption using multiple PZEM-004T sensors. Data is transmitted via UART from the Arduino Nano to the ESP32-C3, which then publishes the data via MQTT with support for Home Assistant Auto Discovery.

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📌 Features

✅ Real-time energy monitoring with up to 3 PZEM-004T sensors.
✅ Web interface to display voltage, current, power, energy, frequency, and power factor.
✅ WebSocket communication for fast data updates.
✅ OTA updates to update the ESP32-C3 firmware wirelessly.
✅ Automatic PZEM detection (if a PZEM is not connected, it won't cause errors). ✅ MQTT data publishing for integration with Home Assistant or other systems. ✅ Support for Home Assistant Auto Discovery.

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📌 Web Interface Preview

Here is a preview of the web interface displaying real-time energy data:

The web interface allows users to:

• View real-time energy data.
• Toggle relays ON/OFF.
• Perform OTA firmware updates.

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📌 Hardware Used

1️⃣ Microcontrollers

• ESP32-C3 Super Mini (handles MQTT communication and Auto Discovery for Home Assistant)
• Arduino Nano (handles PZEM-004T communication)

2️⃣ Energy Monitoring Sensors

• PZEM-004T v3.0 (up to 3 units)

3️⃣ Other Components

• Logic Level Shifter (5V ↔ 3.3V) (for safe UART communication)
• Jumper wires
• 5V Power Supply for the Arduino Nano

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📌 Wiring Diagram

🔹 Connections between Arduino Nano and ESP32-C3

Arduino Nano	ESP32-C3	Function
TX (Pin 8)	RX (GPIO6)	UART Communication
RX (Pin 9)	TX (GPIO7)	UART Communication
GND	GND	Common Ground

🔹 Connections between Arduino Nano and PZEM-004T

Arduino Nano	PZEM-004T	Function
6 (SoftwareSerial TX)	RX (PZEM)	Serial Communication
7 (SoftwareSerial RX)	TX (PZEM)	Serial Communication
GND	GND	Common Ground

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📌 Software Setup

1️⃣ Required Libraries

Make sure to install the following libraries in the Arduino IDE:

• ESP32
• WiFi.h (for Wi-Fi connectivity)
• PubSubClient.h (for MQTT)
• SoftwareSerial.h (for serial communication with PZEM-004T)
• PZEM004Tv30.h (for PZEM-004T management)
• ArduinoOTA.h (for over-the-air updates)

2️⃣ Flashing the Firmware

• Flash the Arduino Nano first (handles PZEM-004T sensors).
• Flash the ESP32-C3 next (handles MQTT communication and Auto Discovery).
• Set the baud rate to 115200 for correct UART communication.

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📌 How It Works

1️⃣ Arduino Nano reads data from PZEM-004T sensors and sends it via UART. 2️⃣ ESP32-C3 receives the data and publishes it to MQTT. 3️⃣ Home Assistant automatically detects the sensors using Auto Discovery. 4️⃣ Users can monitor energy consumption in real time. 5️⃣ If a PZEM-004T is missing, it will be ignored automatically. 6️⃣ Utility to change PZEM-004T addresses allows easy configuration of multiple sensors.

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📌 Home Assistant Integration

Thanks to Auto Discovery, PZEM-004T sensors are automatically detected by Home Assistant. Data is published to MQTT under the following topics:

• pzem32/energy/pzem1
• pzem32/energy/pzem2
• pzem32/energy/pzem3
• pzem32/energy/ct_current
• pzem32/analog/A0

Auto Discovery uses the prefix:

pzem32/autodiscovery/

to simplify the configuration in Home Assistant.

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📌 PZEM-004T Address Change Utility

To change the PZEM-004T device address, an integrated utility allows users to set unique addresses for multiple sensors. This ensures correct data acquisition without conflicts.

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📌 License

This project is open-source. Feel free to modify and improve it!