With the recent extension of the U.S. federal investment tax credit (ITC), more photovoltaic (PV) power plants are expected to be installed in ever increasing capacities in various climatic regions of the United States over the next few years. While the major industry-leading technology has been mono- and poly- crystalline silicon (c-Si), great strides in the commercial development of other PV technologies (such as cadmium telluride [CdTe] and heterojunction with intrinsic thin layer [HIT]) have been made, and a number of power plants are now being powered by these other technologies. In this study, performance and reliability data of strings and modules were collected from the fielded power plants consisting of different module technologies (mono-Si, poly-Si, HIT, amorphous Si [a-Si], CdTe and copper indium gallium diselenide [CIGS]). The collected data were analyzed to determine the degradation rates in different climatological regions of the United States. This paper evaluates the degradation rates of approximately 59,000 PV modules from 26 operational PV power plants in various climatological regions of the U.S. (Arizona-Hot-dry; California-Temperate; ColoradoTemperate; New York-Cold-dry; Texas-Hot-humid).