This is a solar sensor used to find sun (in only 2 dimention). It use to photoresistors to measure the brightness diferential. The photoresistances are insert in their emplacement by piercing two holes il the platick cavity (with a hot pin, it the simplier), for the to pins. It as to be placed on a rotating device. For example, I use it to rotate a solar dryer in front of the sun all day automaticly. The photoresistors has to be conected to analog inputs of an arduino board (check how to connect it on internet). In the program, the arduino have to activate the rotation in the direction were the brightness is higher, so were the analog entree value is higher.