There was another great story about a girl in her final year of high school that built a mounting for solar panels that followed the sun. The difference being there were no mechanical parts, just two bi-metallic strips, meaning they cost about 10p and give something like a 40% increase in efficiency.
Though these numbers are a bit misleading - solar panels are currently only about 30-40% efficient, and those are the really high grade ones, so a 20-40% increase in that is still only getting you to around 50%!