Build a Solar-Powered Raspberry Pi
An enterprising Hacker News user has built a
Raspberry Pi can do a lot of neat things and the server this user built is just one of many. The neat part, though, is that this device is being run entirely on a solar panel. As some commenters on the hacker News thread are pointing out, the solar panel pictured is probably overkill for some users' needs.
Check out the source link below for instructions on how to build the server, but be sure to check out the Hacker News thread for a lot of valuable input on alternatives to save even more money and power.