Optical durability of reflector materials for solar energy applications

In line with The Paris Agreement, the world is now changing towards more sustainable options for all sorts of energy development. The solar energy sector is growing rapidly as a result of this. One area that holds great potential in changing many of the worlds heating processes, is concentrating solar power (CSP). The basic principle of CSP is to reflect incoming sunlight and concen- trate it to heat a fluid. To do so, it is crucial to find a reflector material that shows both good optical performance initially as well as over time to produce heat in the most efficient way possible and compete with the fossil fueled options. In this investigation, four different, commercially available reflecting materi- als, for concentrating solar power, have been tested under accelerated aging conditions to simulate the wear of outside conditions for many years. Impacts from humidity, temperature fluctuations, UV radiation and acid rain have been included in the study. From the results, it will be argued that a silver based polymer film is the best option, out of the four tested, in terms of the combination of durability and high reflectance properties. However, conclusions about how to properly mea- sure the reflectance of a solar reflector is also presented and advices on how to get reliable results in a similar investigation in the future is presented.