The self-adjusting solar cell
The self-adjusting solar cell is a device that follows the sun automatically. By that it is able to gain a high amount of energy throughout the day. With this construction I have won the first prize in the "Stawag Solarfreaks" competiton 2008.
Idea
A very important aspect while thinking of a device for the contest was the fact that the device had to have an actual usage. Sure one could build a model car or the like but all these moving models have one problem in common: if they move out of a direct light source, they'll stop working. In contrast to that, my device follows the sun and by that gains energy throughout the day. Additionally, if the device is not adjusting its position, it consumes nearly any current. This allows you to use the produced energy for something else, e.g. a fan on hot summer days ;-).
Construction
Basically the device can be split up into two parts. On the one hand there is the baseplate. It contains the whole circuitry that is necessary to steer the solar cells. On the other hand there is the movable platform which contains the solar cells as well as the light sensors. These 'sensors' are simple light dependent resitors, i.e. a resistor that varies its resistance depending on the amount of light that shines on it. The values of those resitors are then compared by the microcontroller (a PIC16F628A) that decides in which way to turn the platform.
Media
I have attatched some additional media to the project, for example the source code of the micro-controller software and the schematics to build the device. Furthermore there are scans of two newspapers that reported about my success (in German) and a video of the working construction.