Large area Apollo(R) module performance and reliability

This paper describes the work performed at BP Solar, Fairfield, California highlighting advances in the Apollo(R) CdTe technology. The paper describes the eight basic process steps involved in making the module. The state of the art CdTe reactor is also detailed with its sophisticated design and control features. Various techniques were utilized to characterize the semiconductor materials. Using AFM and X-ray diffraction, the morphology and crystallographic properties of the films were investigated. This work showed the grain structure was small, even after post deposition air anneals. Optical characterization determined quantum efficiency of the device and helped optimize window layer thickness for record performances. NREL confirmed module efficiency of 10.8% is reported for a 0.55m² module and a maximum power of 91.5 W for a 0.94m² monolithic module. Indoor stress testing and outdoor performance test beds are also described. The data presented shows good indoor stability at various stress conditions