An accelerated irradiance and temperature cycle test (AITCT) has been developed as a method to evaluate the long‐term performance stability of amorphous silicon (a‐Si) photovoltaic (PV) devices. The AITCT simulates the daily light–dark cycle in 6 min (0.1 h). It also simulates the annual temperature cycle while controlling the temperature at 45 °C above the average monthly outdoor ambient temperature. This allows the influence of the day–night cycle and seasonal variation to be included in the acceleration factor for single‐junction a‐Si PV devices. The initial degradation and seasonal variation of performance of a‐Si PV devices simulated by the AITCT agreed well with experimental results of 4‐year outdoor exposure. Subsequent tests with the AITCT equivalent of 30‐year outdoor exposure revealed that rapid degradation in the efficiency of a‐Si PV devices would not occur by repeating the cyclic changes corresponding to seasonal variations following the initial degradation. The AITCT is able to accelerate further recovery in addition to light‐induced degradation. Furthermore, the AITCT is applicable to other PV devices with light‐intensity dependencies related to light‐induced degradation as well as thermal recovery dependencies, such as multi‐junction PV devices consisting of a‐Si layers and other materials. This point will be discussed. Copyright © 2012 John Wiley & Sons, Ltd.