Research Leading to High Throughput Processing of Thin-Film CdTe PV Module: Phase I Annual Report, October 2003 (Revised)

Work under this subcontract contributes to the overall manufacturing operation. During Phase I, average module efficiency on the line was improved from 7.1% to 7.9%, due primarily to increased photocurrent resulting from a decrease in CdS thickness. At the same time, production volume for commercial sale increased from 1.5 to 2.5 MW/yr. First Solar is committed to commercializing CdTe-basedthin-film photovoltaics. This commercialization effort includes a major addition of floor space and equipment, as well as process improvements to achieve higher efficiency and greater durability. This report presents the results of Phase I of the subcontract entitled 'Research Leading to High Throughput Processing of Thin-Film CdTe PV Modules.' The subcontract supports several important aspectsneeded to begin high-volume manufacturing, including further development of the semiconductor deposition reactor, advancement of accelerated life testing methods and understanding, and improvements to the environmental, health, and safety programs. Progress in the development of the semiconductor deposition reactor was made in several areas. First, a new style of vapor transport depositiondistributor with simpler operational behavior and the potential for improved cross-web uniformity was demonstrated. Second, an improved CdS feed system that will improve down-web uniformity was developed. Third, the core of a numerical model of fluid and heat flow within the distributor was developed, including flow in a 3-component gas system at high temperature and low pressure and particlesublimation.