PROJECT: Create your own Real Time Whole House Energy Meter

ESP32 is a series of low-cost, low-power system on a chip microcontrollers with integrated Wi-Fi and dual-mode Bluetooth. A reddit user tavenger5 used the ESP32 along with couple of other boards to create a low cost (< 30$) real time energy monitor for his home.

Here's the summary of the hardware used, in his own words:

• The Current Transformers can be these as long as they fit around your mains cables in your breaker box: https://www.amazon.com/gp/product/B075541WVT (And you'd have to cut off the connectors since the board has screw terminals)
  
• The AC Transformer for measuring voltage, and powering the board and ESP32: https://www.amazon.com/gp/product/B00B886CWS
  
• This ESP32 (or ESP8266) will work: https://www.amazon.com/dp/B0718T232Z Yeah, it's like a Ras Pi, but smaller. Can be programmed with the Arduino IDE.
  
• Jumper wires with Dupont connectors to connect the two boards.
  
• Software from my GitHub to load on the ESP32 to link everything together: https://github.com/jdeglavina/EmonESP and https://github.com/jdeglavina/ATM90E32_Arduino
  
• EmonCMS has their own servers that you can send data to. It looks like they just started charging a small fee per feed for this though: https://emoncms.org/ You can host the software locally if you know how to setup a web server (or rent one from a host for cheap)
  

Honestly, the hardest part is calibrating the transformers with the board. You need something to measure against, like a hair dryer and a kill-a-watt. Then there's some math and changing some values in the main program. After some time I will probably have some baseline calibrations for various CTs.

Mike-Barn

posted on 02 Oct 18