One year with CitizenWatt

We started to work on CitizenWatt a year ago. Maybe it’s time for a quick summary about this exiting project in collaboration with Capteurs Citoyens and HackEns.

This project is about creating an open hardware electricity consumption monitor, that gives a user-friendly feedback to the whole family. It enables them to monitor and to reduce their consumption by understanding what consumes energy and what is not.


We designed a simple sensor that can run on battery, as not anyone have a power plug near the electric counter. Based on OpenEnergy Monitor design, we simplified it so it cost less that 30€ to make. Also, we changed the RF technology with NRF24L01+, a 2.4GHz low cost and easy to find transmitter.
We used rechargeable AA batteries as the power supply for the ease of use by a non-technical people, but our design is compatible with single cell LiPo battery, with its JST connector.

The sensor sends the measures to a Raspberry Pi that keeps the data inside the house. It can be displayed on a web device (phone, computer, smartTV, etc…). It never goes to a cloud. It stays in the house, as we value privacy.

On the software side, it’s all Python 3, HML5 and Javascript, running on the Raspberry Pi.

CitizenWatt soudathon1

We organized a few meeting where families, parents and children, made their sensors, soldering components for the first time. It was great events, with experts and beginners.




All our designs and software sources are available here :


CitizenWatt is now installed in a few flats in Paris, giving us our first real life feedbacks. Now, we need to fix the flaws and improve the WebUI, according to them.

More info here : and on

Finally, I would like to thank the CRI and the city of Paris for their support along this year.