We are using the popular WeMos D1 Mini ESP8266 development board to build a low cost energy meter with off the shelf devices like the Peacefair Pzem-004T and EmonPi.
This is what the Peacefair Pzem-004T looks like with an easy to use split core transformer and costs around $10 including LED display.
The image below is the PCB for the WeMos and the connections from the Pzem.
The project is all packaged up into a smartphone app for Android and iOS. In addition to energy monitoring you can hook up cheap IP cameras for video surveillance and use geo-location control of your home appliances.
Effectively it’s a cheap alternative to Hive from British Gas and Nest from Google. Why pay several hundred dollars when you can now build your own with Espressif’s popular ESP8266 for around $30.
The project and smartphone app is known as ESPproMon which is an abbreviation of ESP8266 Professional Monitor.
We hope you will check out our project and look forward to receiving your feedback in due course.
Paul (aka Costas the coder)