Outdoor stability performance of single and tandem amorphous silicon modules

Stability performance test results are presented for tests conducted at SERI on single and tandem amorphous silicon solar cell modules and submodules made by various manufacturers. Two sets of commercially available first-generation single-junction amorphous silicon solar cell modules manufactured by two different manufacturers, one single-junction submodule fabricated under a SERI subcontract, and one tandem amorphous silicon research submodule fabricated by another SERI subcontractor are described. Based on the test data, the efficiency degradation for the two best first-generation single-junction amorphous silicon modules for the test period of three to four years is on the order of 20%.