If I put a hole in a piece of opaque material then sunlight shining through will make a dot on a surface below. If I put a ring of sensors around that then when the sun moves the dot would strike a sensor. My accuracy goes up with the distance between the material with the hole and the surface below and the number of sensors in the ring.
For me, something like that might be used to tilt reflective panels to put more light on the collector. After all, they use solar panels in space where the light is far brighter than down on the ground -- especially at the latitudes most of us live.