I remember something similar back in ~2000 - made out of a directv satellite dish. It was dead simple. Mirror the parabolic surface of a satellite dish, put a

I remember something similar back in ~2000 - made out of a directv satellite dish. It was dead simple. Mirror the parabolic surface of a satellite dish, put a hole in the dish, and use an optical sensor to track the beam of light that shone through that hole on the rooftop. Use a couple of motors and an IC to move the dish according to the suns' position.