A Non-Invasive ESP32 Energy Monitor

Whether for environmental reasons, to save a few bucks, or very likely some combination, nearly all of us want to reduce our home energy usage. On the other hand, few of us have a very good idea of how much we’re using beyond a monthly demand letter from our local utility company. While you could step outside and take a look at your power meter every day — or perhaps even more often if you’re feeling really ambitious— Xavier Decuyper, AKA Savjee of the Simply Explained YouTube channel, has a better alternative in the form of a CT/ESP32 auto-monitoring device.

His build, the concept for which he “Simply Explains” in the video below, uses a CT (current transformer) that clips onto a main power line to read current usage, and requires no direct electrical modifications. It works by using the magnetic field generated in a power line to generate another smaller current in the sensor, and the device he’s implemented further manipulates the reading into a proportional voltage signal.

This voltage signal is fed into an ESP32 module that controls the device, and pushes it to the AWS cloud over WiFi. From here, Savjee created a custom app to visualize his usage, which can show nearly instantaneous readings and graphs things nicely over time. In the future, he hopes to expand this project to multiple CT sensors, but for now this looks like a great place to start on a path to enhanced energy monitoring. More info is found in the project’s write-up.