This UNE standard provides definitions of performance parameters, their minimum requirements and the testing methods for reflectors (reflector panels, mirrors and/or mirror panels) to be used in concentrating solar systems for solar thermal electric (STE) plants (also concentrating solar power, CSP) and other types of concentrating solar technologies. This standard includes the testing methods for reflectors and the supporting elements and shall be applicable to silvered glass reflectors and also to any other reflector material such as polymeric and metallic mirrors, including films, composite and laminated products.