Controlling the electrical consumption in your home is one of the most important thing you can do, both because of environmental concerns & to reduce the electricity bill at the end of the month. There are countless of electrical power meters out there, but in this guide, I’ll show you how to build your own, and to use the ESP8266 feather board to measure how much power a single device is using. Note that this guide is about measuring power for DC (Direct Current) devices only.

Here, we are going to do something different: we are going to measure the power used by a device, and then display it right on top of the ESP8266 board, user the featherwing OLED add-on board. This way, you’ll be able to build your own power meter based on the ESP8266, that is completely independent from any external components. As an additional function, we'll also send the data on Adafruit IO so it can be monitored online. Let’s start!