Solar panels tend to do best when they are pointed at the sun. Unfortunately, the sun moves. While there have been many, fancy, high-tech solar-tracking systems invented, it's also true to say that the sun tends to follow a fairly predictable path from one day to the next—so maybe simple, low tech solutions could work too?

That's the thinking behind the "SunSaluter", a simple solar panel rotator that's powered only by the magic of gravity and dripping water. AS Rachel reported back in 2011, the SunSaluter was invented by former Princeton student Eden Full when she was just 19, the SunSaluter is now promoted by a non-profit 501(c)3 which goes by the same name, and which helps local entrepreneurs in developing countries establish for-profit businesses based on Full's design.

Check it out here in operation at a home in Sirohi, India, where it provides Saavan and his family of 15 with a source of clean, reliable electricity at a fraction of the cost of a conventional motorized rotator device.