This might be the most popular of the entire bunch. After all, who wouldn't want to make a solar powered radio that fits in an Altoids tin and can cost as little as $3 to create? Any hands? That's what I thought. This $3 emergency solar radio by Joshua Zimmerman is a perfect project to start off with because it's fun and can teach you some of the basics for the more involved projects in this round-up.
Keep clicking through for how to make a spa heater for your roof, how to build a robot that moves your houseplants into sunny spots, how to hack your e-reader to run on solar power, and so much more!