Soiling Comparison of Mirror Film and Glass Concentrating Solar Power Reflectors in Southwest Louisiana

Soiling effects influence the output of solar thermal plants, significantly causing unwanted transmittance, reflectance, and absorbance losses. Research is needed to identify what type of reflective surfaces are best suited for semitropical climates, such as the southeastern United States. This paper initially presents a review of several concentrating solar power (CSP) reflector testbeds used to analyze the soiling effects of various reflective materials. A soiling testbed is developed for this study that comprised six sets of reflective surfaces mounted at a fixed tilt of 30 degrees: three sets of thin-film surfaces and three sets of glass types. Two generations of 3M solar mirror film (SMF), 3M SMF 1100 and 3M SMF 2020, were used along with Konica Minolta SMF, silvered Corning Willow Glass, a dichroic cold mirror, and a standard mirror. Results show that the 3M SMF 2020 and Konica Minolta SMF performed the best during regular cleaning intervals, whereas the silvered Corning Willow Glass gave the best performance if only cleaned naturally. The other glass types showed the least average loss due to soiling throughout this study but gave the lowest performance for specular reflection.