Look up youtube user: NurdrageHe has a video on how to make a solar cell out of several chemicals and materials that can be done by your average joe. http://www.youtube.com/watch?v=WHTbw5jy6qU&feature=plcpIt uses titanium dioxide, acetic acid, dishwashing detergent, indium tin oxide glass, alcohol, carbon (from a burning candle), pure iodine, potassium iodide, ethylene glycol, and raspberries.The solar cell itself isn't meant to power much. It can only supply a few microamps, making it pretty much useless. When you hook it up to a multimeter though, it CLEARLY reacts to light. However, if you're looking to build a solar cell to actually power something, forget about it. Like iknowvations said below, silicon itself is cheap, but the technology and machinery used to process it is not. I live close to the University of Michigan, and they had a small scale semiconductor fabrication lab installed in one of their buildings. I had the privilege to tour the facility, and everyone who came got to make and process their own little piece of silicon to take home. Someone there asked how much the plant cost, and the director said it cost them about $4 billion to buy and install! Bear in mind this is SMALL SCALE, and the stuff they do there is nowhere NEAR on par with what large semiconductor plants can do. I remember asking the very same question you just asked when I was younger, and when I heard the answer, I was disappointed to say the least. But believe me when I say, it's just not practical.