I was looking online on how to build small solar bots. I came across this website mysolarbot.com. It has lot of interesting ideas on how to convert small bugs and cars into solar bots. The solar engine thats used in the bots is based a 1381 voltage trigger engine that releases power to the motors when the trigger voltage is reached. I decided to buy a hexbug and a brainchild solar engine to build my own. Unfortunately the solar engine came with a voltage trigger that activates at 4.5V, which was too high for the bug to walk forward so it kept reversing. I thought the whiskers sensor had gone bad. But after discussing it with a rep at mysolarbot.com, he explained that I needed a lower voltage trigger, around 2V-3V. I bought the triggers and able to replace it fairly easily and get it working.
My next goal is to work on BEAM robots.