Inspired by this Mastodon account, I programmed an ESP8266 microcontroller to act as a traffic light, indicating the current electricity mix. Check it out on Codeberg! It uses an API from the Fraunhofer Institute and the parts cost around 5€. In my shared flat we use it as an indicator on when to run demanding devices, like the washing machine.
Oh, sorry, didn’t understand it like that 😁… thought that was the price of the license for the library 😁.
Of course, the parts come at a price, no surprise there 😂.