Hardware Architecture of My IoT-Based Single-Socket kWh Energy Monitoring System

Monitoring electrical energy consumption at the socket level provides valuable insight into real-time power usage, cost estimation, and load behavior. In this project, I designed a single-socket IoT-based kWh monitoring system capable of measuring voltage, current, power, and accumulated energy, while transmitting data over WiFi for remote monitoring.

This first version focuses on a compact single-output architecture using ESP32 and a PZEM-based energy measurement module.

System Overview

The hardware consists of the following main blocks:

• ESP32 microcontroller (main controller with WiFi)
• PZEM-004T energy measurement module
• AC-DC power supply (220VAC to 5VDC)
• High-power relay for load control
• LCD 16x2 display for local monitoring
• Terminal block for AC input/output

The internal board layout and power separation can be seen in the device assembly documentation:

Energy Measurement Module

For accurate measurement of voltage, current, power, and accumulated energy (kWh), I used the PZEM-004T module. This module simplifies high-voltage measurement because it provides built-in isolation between the AC line and the low-voltage microcontroller side.

Key specifications include:

• Voltage measurement up to 260VAC
• Current measurement up to 100A (using CT)
• Frequency range 45–65Hz

Using a dedicated metering module reduces ADC complexity and improves reliability compared to raw analog sensing.

Power Supply and Isolation

The system operates from a 220VAC input. A compact AC-DC converter module steps down the voltage to 5VDC, which powers the ESP32, relay driver, and LCD.

Important hardware considerations:

• Clear separation between high-voltage AC section and low-voltage logic section
• Proper terminal block insulation
• Short wiring between PSU and ESP32
• Adequate spacing to reduce electrical noise

Even in prototype form (matrix board), I ensured physical separation between AC terminals and control circuitry to minimize risk and interference.

Load Control Section

A high-power relay is used to control the socket output. The relay allows:

• Remote ON/OFF switching
• Automatic cut-off based on energy limit
• Integration with IoT platforms for smart control

The relay driver circuit includes proper transistor switching and flyback protection to ensure ESP32 safety.

Local Monitoring Interface

A 16x2 LCD is used to display:

• Voltage (V)
• Current (A)
• Power (W)
• Energy (kWh)

This ensures the device remains functional even without internet connectivity.

Design Lessons

Designing an AC-powered IoT device requires careful attention to isolation, grounding, and layout discipline. Even small wiring mistakes can introduce noise into measurement readings.

Although this version was built as a prototype, migrating to a properly manufactured PCB would significantly improve safety, signal integrity, and long-term reliability.

This single-socket design became the foundation for more advanced multi-socket and cloud-integrated versions developed later.

#Embedded# #ESP32# #PZEM# #Energy Monitor#