the present invention relates to a dual zone solar sensor incorporating a calibratable diffuser overlying a vertically oriented circuit board having at least one photodetector affixed to either side of the circuit board in a vertical plane . each detector preferably has a mutually exclusive hemispherical view . by mounting the photodetectors in the vertical plane , the dual zone solar sensor device is capable of providing information about the intensity of a source of incident solar radiation and the relative position of that source of radiation . while the angular responses of the photodetectors in their vertical orientation are very close to those desired by skilled artisans for a dual zone sensor , the addition of a diffuser that is slidable , and therefore calibratable , provides a method by which the angular response of each photodetector may be permanently calibrated to achieve a precise desired angular response . the present inventive combination of features eliminates the need for complex and bulky electronic signal processing circuitry and decreases the number of parts necessary to achieve functions previously achieved only by larger sensors having a far greater number of component parts .