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ESPHome SML Smart Energy Meter Reader with display — image 1

ESPHome SML Smart Energy Meter Reader with display

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Read your electricity meter through its infrared port — **no direct mains wiring required!** This build combines an aff

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Model information

Category
Electronics
License
Creative Commons — Attribution — Noncommercial

ESPHome SML Smart Meter Reader

Read your electricity meter through its infrared port — no direct mains wiring required!

This build combines an affordable ESP32-C3 with OLED display and a BPW40 photodiode right on your meter. All values are streamed to Home Assistant in real time.

Visit on GitHub


What does it do?

  • Reads SML data from your meter via infrared (IR) — no tapping into live wires

  • Shows on the tiny OLED display:

    • Current power (W)

    • Grid import total (kWh)

    • Grid export total (kWh)

  • Pushes all values over Wi-Fi to Home Assistant

  • Blue status LED blinks whenever data arrives

  • Built-in web dashboard (port 80)

  • OTA updates over Wi-Fi


Bill of materials (all together about 5$)

Part

Notes

ESP32-C3 OLED board (ABRobot 0.42")

Includes a 72×40 SSD1306 display

BPW40 photodiode

Receives the meter's IR signal

1 kΩ resistor

Pull-down for the photodiode signal

3D-printed case + magnet holder

STL files included in this project

Neodymium magnet (5 mm ⌀ × 3 mm)

Keeps the case on the meter cover

USB-C cable + power supply

Powers the ESP32


3D printable files

Two STL files are part of this release:

File

Description

MINI_SML_case.stl

Main enclosure for ESP32 and photodiode

MINI_SML_lid.stl

Matching lid for the enclosure

Print recommendations

  • Material: PLA or PETG

  • Layer height: 0.2 mm

  • Infill: 20% is sufficient

  • Supports: Not required

  • Important: The photodiode chamber must be light-tight

  • Tip: Depending on your printer, the diode leg holes may be tight. A 3 mm drill bit cleans them up nicely.

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