OpenEnergyMonitor Community

Energy monitor equipment

Hello friends. I would like to build an electronic equipment that monitors the electrical current consumption in my house.
I would like you to measure and send the data via wifi with an esp8266 and that you can see the graphics on the computer or in the phone.
I think this is the right place for this project but I really can’t find an organized information that shows from the hardware to the software the pc.
For this I have a NodeMCU and an arduino uno, but I would like everything to be as simple as possible.
If someone could guide me where to start.
Thanks a lot.

Welcome, Jose, to the OEM forum.

All the information you need is here. I understand how difficult it is for you to find it.

  1. Start in ‘Learn’ and look at “Electricity Monitoring”. The first section tells you the basic theory. You should certainly read the first part, and possibly the next two.
  2. The next three sections “C.T.Sensors”, “Voltage Sensing” & “Current & Voltage” tell you how to wire up your Arduino to measure current, or voltage, or both. If you want only current, or a reasonable estimate of the power, then you only need “C.T.Sensors”. If you want to measure the power more accurately, you must measure the voltage as well. (This is because the voltage changes minute-to-minute.)
  3. When you have that working, connect your ESP8266 to the serial port of your Arduino, and that will send the data via WiFi. You must look at one of our sketches for the emonTx to see the format you need for the data, and you’ll need to look at the “Resources” and the section “emonESP” for how to connect the two. That section also tells you where to get the software for the ESP8266.
  4. Next you need a computer running emonCMS (or you can buy an account at to receive the data and present it as web pages. The easiest is a Raspberry Pi, and download the pre-built emonSD SD-card Image (also in “Resources”). Connect the RPi to your router and, when you’ve put the correct address of the RPi into the ESP8266, you should receive your data. I do not recommend using a p.c. - you must build the complete emonCMS system from the beginning, and because every computer is slightly different, you are likely to have problems that we cannot solve for you.

You will have very many more questions, of course. Do not be afraid to ask.

Hi Robert .
Thank you very much for your clarifications, they have been very useful.
I have found the information I was looking for thanks to your help.
Thanks a lot.