From a study of the effect of light exposure on photoconductivity and solar cell performance of hydrogenated amorphous silicon alloys for different exposure time and intensity, we show that the light‐induced changes do not obey reciprocity. Degradation is larger at high intensity light exposure for a shorter time than at low intensity exposure for a longer time even though the product of the exposure time and light intensity is kept a constant. A model that can explain the failure of reciprocity is discussed.