Solar panels are most effective when facing sun directly. So if you want to get most energy, you need to track sun trajectory in order to keep panels always facing towards the sun. Actually this is fairly easy task. In this solution vigneshraja shares setup built of couple light dependent resistors (LDR) and single motor to track sun.
Tracker is built on MSP430G2231 microcontroller that sit in Launchpad. Interesting thing is that two LDRs are in stationary position that determine sun position by comparing their values. Motor is driven through H-Bridge motor controller. Such solution is great for near equator locations, but in other areas sun wont travel directly above, so probably more suitable tracker should have two motors controlling both angles to point sun directly.