Thanks for your hint!
Haven’t that in mind. The hardware should be not too old. I’m not sure if theee boxes are still available (in Germany) right now. 
Running a 10 watt machine 365 days per year costs about 25 € for energy. At the end of the day it’s also an economic kind of question. The virtual server option is still in mind… but the storage and security questions needs to be adressed 