Long-term reliability of amorphous silicon solar cells

The long-term reliability of amorphous silicon solar cells of 1988 products over more than ten years is estimated by a simulation method using the Weibull function with the experimental data of 1988 products exposed outdoors for five years and those of 1983 products exposed outdoors for ten years. The mathematical model is developed based on the accelerated tests and recovery tests in a laboratory for a short period of time. The simulation method is discussed. The decrease of the conversion efficiency of 1988 products after ten years of exposure is estimated to be 25% and 35% at best and worst, respectively. The newest products having initial conversion efficiency of over 13% in a small cell are expected to maintain an efficiency of about 10% at best over a decade.