The Energy Meter for Home Assistant is an ESP32-S3-based single-phase energy monitoring and control module designed to work with Home Assistant via ESPHome. It measures real-time power and energy consumption and also has a remote on/off control.
The device is built around the BL0942 calibration-free energy metering IC, which supports voltage, current, power, and energy measurements with less than 1% error. It operates directly from AC 100–240V, includes an onboard 15A relay for switching loads, and provides electrical isolation for safety. Connectivity is done through USB and Wi-Fi using ESPHome for easy firmware flashing, API encryption, and automatic discovery in Home Assistant. These features make it suitable for smart homes, DIY energy monitoring, smart sockets, home energy dashboards, and automation projects.
Energy Meter for Home Assistant specifications:
- Core module – Espressif Systems ESP32-S3-WROOM-1
- SoC – ESP32-S3
- CPU – Dual-core Tensilica LX7 up to 240 MHz with vector extension for AI/ML workloads
- Memory – 512KB SRAM
- Storage – TBD
- Wireless – WiFi 4 802.11b/g/n and Bluetooth 5.0 LE
- PCB antenna
- SoC – ESP32-S3
- Energy Measurement IC – BL0942 calibration-free IC
- Active energy measurement error – less than 1%
- Dynamic range – 4000:1
- Voltage, current, power, and energy measurements
- Relay – Onboard a single 15A Relay for load control
- USB – USB Type-C port for programming and power (Native USB no UART converter)
- Misc
- Boot and Reset button
- Power LED
- Â Power
- Input terminals – Neutral (N), Live (L)
- Input voltage – 100-240V AC, 50/60Hz
- Output terminals – Neutral and Live through relay
- Output voltage – 100-240V AC, 50/60Hz
- Maximum load – 15A, 3600W
- 3.3V Hi-Link module powers the ESP32
- Dimensions – TBD
- Operating Temperature – –40°C to +85°C
The board is designed to work out of the box with Home Assistant using ESPHome. Makerfabs provides a guide with instructions for setting it up using Docker on a Raspberry Pi, along with a ready-made YAML configuration file. Since the BL0942 metering chip is already supported by ESPHome, you don’t need to write complex code or calibrate it manually. You simply flash the firmware once via the USB-C port, and it will show up in Home Assistant with controls for the relay (GPIO16) and live data for voltage, current, and power. It also supports wireless Over-the-Air (OTA) updates after the initial setup. More information, including configuration files, hardware design references, and the datasheet for the BL0942 IC, is available on the Makerfabs GitHub repository.
Previously, we have covered the ESP32-C3-based 2-channel Wi-Fi AC relay, which features the same built-in BL0942 power meter chip, and the T2-U development board, which supports the BL0942 chip (as an external chip) for energy meter projects. Other Home Assistant-compatible products with power meter function include the Seeed Studio XIAO-2CH-EM with two CT clamps, SONOFF POW Ring with one CT Clamp, and Voidbox’s PwrTool 500 battery and power monitor, among others.
The ESP32-S3-based Home Assistant-compatible energy meter is available on the Makerfabs online store for $21.80. The package includes the assembled module with the enclosure, but you will need a USB-C cable for the initial configuration.
Debashis Das is a technical content writer and embedded engineer with over five years of experience in the industry. With expertise in Embedded C, PCB Design, and SEO optimization, he effectively blends difficult technical topics with clear communication
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