Solar project that looks easy enough

First Solar Panel Project. Four solar cells bought from Ebay. Right now they're hooked up in series with copper wiring. Took a shoebox and put the solar panels inside. The panels have tape to keep them in place. Positive and negative wires, hooked up to two LED lights. 2.5 volts, enough to power two LED lights. Neat little project. I might try something similar myself just for kicks.