a study was performed to obtain data regarding the performance of materials in operational solar energy systems, to identify and assess available standards for evaluating materials, to provide recommendations for the development of test method standards for materials, and to provide guidelines to aid the selection of materials for use in solar energy systems. during the study, field inspections of approximately twenty-five operational solar energy systems were performed, and a questionnaire was sent to 459 manufacturers and installation contractors to obtain materials performance data. this report contains the findings of the study. a primary conclusion is that the process of selecting materials for specific applications within solar energy systems is hindered by the lack of an adequate data base of materials performance under the conditions experienced in solar systems and subsystems recommendations are made that would help in establishing an improved data base