Referring to the post I published a couple of weeks ago, I’ve decided to share my way of measuring energy consumption. I’ve got a pretty standard setup consisting of a 3-phase energy meter outside the flat. It’s not very handy when it comes to integrating it with Home Assistant, so I bought a cheap 3-phase energy meter instead and installed it internally. It has a single pulse output with 800 pulses per kWh, and it costs less than $40 (1-phase version is available too). The pulse output is quite an important feature - having it exposed is much more convenient than interfacing with a blinking LED.

The cheapest way of counting pulses I’ve found is adding a simple Sonoff Mini R2 for less than $10, and using its “switch terminals” for pulse detection. It works flawlessly and it’s easy to set up in ESPHome:

sensor:
  - platform: pulse_counter
    id: home_power
    pin: GPIO4
    unit_of_measurement: "kW"
    name: "Home Power"
        filters:
      - multiply: 0.075 # 60/800
    total:
      accuracy_decimals: 5
      unit_of_measurement: "kWh"
      name: 'Home Total Energy'
      filters:
        - multiply: 0.00125 # 1/800

This setup costs less than $50 in total and it’s actually quite reliable - it’s composed of off-the-shelf components only, no need for soldering.