Have fun and win via JLCPCB E-exhibition: https://jlcpcb.com/E-exhibition
$2 for 4-Layer PCBs: https://jlcpcb.com
Previous video: https://youtu.be/RoSIzgvEGtA
Home Assistant video: https://youtu.be/IvI1RqYPO24
Power video: https://youtu.be/cxXmWZDwNEs
Facebook: https://www.facebook.com/greatscottlab
Twitter: https://twitter.com/GreatScottLab
Support me for more videos: https://www.patreon.com/GreatScott?ty=h
More project information (pictures, schematics,….) on Patreon: https://www.patreon.com/posts/esp32-power-43701117

Parts list: (affiliate links)
ESP32: https://s.click.aliexpress.com/e/_AfKZrJ
Current Transformer: https://s.click.aliexpress.com/e/_A661E9
Voltage Transformer: https://s.click.aliexpress.com/e/_Adyvfr
Resistor Kit: https://s.click.aliexpress.com/e/_dTPpXjt
Capacitor Kit: https://s.click.aliexpress.com/e/_d7dOwRz

Websites which were shown in the video:

In this project I will show you how to build an ESP32 AC power meter that can be used with your home assistant setup. That means I will firstly explain how to actually measure and calculate real and apparent power along with the power factor and then I will show you how to use the ESP32 in combination with some complementary components in order to create the power meter. Let’s get started!

Thanks to JLCPCB for sponsoring this video.
Visit https://jlcpcb.com to get professional PCBs for low prices.

2011 Lookalike by Bartlebeats

, https://i.ytimg.com/vi/PSzkaSy5lHY/hqdefault.jpg



  1. I was wondering what is the phase relationship between input/output for the mains voltage sensing transformer. There may be a few degrees lag here.

  2. I understand the safety aspect of using an isolation transformer in this project for sensing the voltage. But, for low loss, such transformer must be large and expensive. Since you know which mains wires are hot and return (connected to earth) can you simply use very large valued resistors, to form an ac voltage divider, capacitively couple the signal to a VDD/2 bias string?

  3. I laugh when you I see the video is sponsored by JLC PCB and you build your circuit on a perf board.

  4. isnt the area underneath the instantaneous power waveform the total energy consumed? Not average power. The sum of the area divided by time is the average power. Two different but related concepts.

  5. Hi,
    Thanks for your project, I did exactly your steps but I get a couple of erros with compiling in Home Assistant. Does the files have been or need to be updated since you made the video?

  6. You should add a money had to pay by you for electricity , it will be shown in your home assistant

  7. Thank you. I will cehck on the emon code. but do you know if i can connect multiple current transformers and use a few more pins on the esp32. will the controller be able to handle 4-5 CT coils ?

  8. Thank you for the great tutorial,
    Just a quick question, I have never used my oscilloscope to measure 220v AC, what is the safest way to do it without damaging my oscilloscope? Thanks again

  9. Hi Scott, I am a great fan of yours. I see tons of equipment like in a lab. What do you do as a job?

    All the best for your efforts. You are a great teacher ???

  10. The number of likes of this comment is the number of people that want a collab of GreatScott with ElectroBOOM

  11. The low team ganguly shiver because pancreas regrettably subtract out a capricious mark. jaded, wiggly locket

  12. waiting for a video on "main electricity safety essentials". What care should be taken when handling AC 230 V

  13. Hey, I saw your face for the first time 🙂 After watching soooo many videos where I have only heard your voice. 🙂 Nice to see you 🙂

  14. Hi, May be a stupid question: I have got solar panels and I would like to measure the power going home from grid but eventually the one going out when solar production is greater than consumption. For that I need to identify the direction of current. Do you think this is feasable ? Thanks for advise.

  15. Hi!
    Which scope probes did you use to measure the mains voltage and the current? Or asked differently: which would you recommend? 🙂
    Thanks, Hansi

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