You can imlement solar tracker in two ways,
1. By using LDR(light dependent resistor).
In this method LDR senses the light in track of sun moving and by using the motor you can move the solar panel.
2. By using RTC
In the method U you can use real time clock and set the timings to move the position of solar panel. eg at 6am panel at east, 12pm panel facing upward and in evening to the west.