Advanced Cyclic Accelerated Aging Testing of Solar Reflector Materials

Realistic lifetime prediction and testing procedures for solar mirrors have been demanded by investors, plant developers and material manufacturers during the last years. It has been proven that most of the commonly used accelerated aging tests, which were adopted from other industries, cannot be correlated to outdoor exposure. This work studies different accelerated aging test sequences and analyzes the produced degradation. The results made it possible to discover the most demanding environmental conditions for the three tested mirror types. The degradation of the mirrors was strongly affected by the share of the Copper Accelerated Salt Spray (CASS, ISO9227) testing time in the cycle. The CASS test was combined with several other aging tests and it was concluded that especially the combination with the UV/humidity test according to ISO16474-3 was harmful for the protective coatings of the tested silvered-glass mirrors. The conclusions from the testing campaign presented in this paper are helpful to design suited comparative accelerated aging testing procedures.