Microstructural analysis of the cementation process during soiling on glass surfaces in arid and semi-arid climates

To investigate the soiling behavior of solar energy systems like photovoltaics or concentrated solar power, glass samples were exposed to outdoor conditions in Doha, Qatar for one month. Soil formation on the glass was characterized at microstructural level using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Further, elemental analysis of the crust was done with energy‐dispersive X‐ray spectroscopy (EDX). Small fibrous structures were found on the glass surface and dust particles, providing evidence of a cementation process leading to a strong adhesion of airborne dust particles. In contrast to the common perception, that cementation occurs via the precipitation of salt (sodium chloride) these needle structures were found to be mainly composed of oxides of Si, Mg and Al. This indicates that cementation processes in desert regions are enhanced by the growth of fibrous clay minerals. Cross section of cemented dust particle, connected via small needles to the glass surface. Accumulation of dust and dirt on PV modules and solar reflectors leads to significant power losses due to shading or scattering of sunlight. Especially in arid and semi‐arid regions, this becomes more and more a severe performance issue for solar energy systems. In this Letter, the authors present a microstructural study of the soiling process on glass surfaces in desert regions, identifying fibrous structures as a main reason for particle cementation.