Book excerpt: The main objective of this project is to develop high-efficiency CdTe solar cells based on processing conditions favorable for manufacturing processes. This report presents the results on work performed during the first phase of this project. One of the major issues addressed is the use of soda-lime glass substrates in place of the borosilicate glass often used for laboratory devices; another task is the preparation of Cu(In,Ga) Se2 solar cells by selenizing suitable precursor films. Emphasis is placed on processing and how different reaction schemes affect device performance. It was found that different reaction schemes not only change the bulk properties of Cu(In,Ga)Se2, but also its surface properties, which critically affect device performance. Although the objective is to optimize processing to meet the manufacturing constraints, work has not been limited within these requirements.