Abstract: A sun tracker for use on a sun following device such as a concentrating solar collector. The sun tracker includes two spaced apart photosensitive elements which are separated by an opaque splitter plate so that when the splitter plate points directly at the sun the photosensitive devices are uniformly excited. The west facing surface of the splitter plate is reflective so that movement into alignment with the sun can be achieved even after long periods during which the sun is obscured by clouds. The outer edge of the splitter plate is arcuately formed so that excitation of the photocells is substantially independent of the angular orientation of the sun tracker.