Performance Characterization of Cadmium Telluride Modules Validated by Utility-Scale and Test Systems

Performance of First Solar CdTe modules deployed at both test and utility-scales are reviewed with characterization of the critical inputs to lifetime energy generation models. Systems reviewed in detail are a 15-month-old facility containing more than 30 MWdc, a 10-year-old 1.2 kWdc NREL test array, 19-year-old 600 Wdc NREL test array. A statistical analysis of an aggregate population of 600 MWdc of systems with up to 10 years of operation is undertaken. Data from the utility-scale installation are used to validate First Solar's energy prediction guidance and internal prediction software, Isis, which predicts energy to within +/- 0.2% of measured. Plane-of-array irradiance and module temperature accuracy are also reviewed. The field test arrays at NREL exhibit long-term degradation rates ranging from -0.3%/yr to -0.5%/yr for First Solar CdTe modules.