Using an ESP8266 ESP-01 module and an Arduino Pro Mini 3.3V I wirelessly update all outputs from my thermostat to here for data analysis and because it's cool. This requires a voltage divided rectifier since thermostats run at least 24 VAC RMS.
Readings from a PowerBlade power meter through an ESP32 BLE Gateway
Computed hourly power usage (in Watts) from an energy reader. Average is computed over X hours.
Electricity / Energy meters @ DTU Diplom Energy 400VAC meter ID: 44480 M0.20