https://wiki.freifunk.net/Freifunk-MPP-Tracker https://github.com/elektra42/freifunk-open-mppt
The Workshop can be given in english and german to 5 people, so please register early. The kit costs 45€, including housing, with the most difficult SMD parts already preassembled and the controller preprogrammed. You need to bring good eyes or glasses, since some parts are small.
Please add your name/nick here, so we can prepare solder stations and material: