Here i show a simple system i built to track the Sun passing the sky. Some people call it Sun tracking, but i dont like it because it suggest that the Sun is moving. Yeah the sun is indeed moving, but it is not what is tracked.
Electrical parts used:
1 x Photoresitor, 1 x Transistor, 1 x Solarpanel, 1 x Operational amplifier, 2x Potentiometers, 1 x Motor with gear
If the Photoresistor is under direkt Sunlight the Motor is switched on. This rotates the complete device. This will move the shadow over the Photoresistor. This switches of the Motor.