Soiling and abrasion testing of surfaces for solar energy systems adapted to extreme climatic conditions

Extreme climatic locations, such as arid or maritime regions, are very demanding for solar energy systems. In this paper we share experiences about the soiling of surfaces, exposed for one and two years at outdoor weathering tests sites with different climatic conditions, and their effect on the surface properties. We describe an inhouse developed soiling test, to qualify glazing with realistic dust for reproducible and homogeneous test results. The second part of this paper describes characterization measurements by spectral transmittance, especially after applying the dusting method. Next to soiling, a roughening of glazing surfaces in arid areas is most likely to occur, especially due to sand storms. To simulate this abrasive stress an additional test of the stability of the functional coatings is developed and applied. The abrasion test is conducted with an in-house developed sand trickling test stand according to DIN 52 348. Results of the outdoor and indoor tested material show the strong influence of dust types and material properties on soiling and durability of the surfaces.