EUROPEAN CONGRESS AND EXHIBITION ON ADVANCED MATERIALS AND PROCESSES - EUROMAT 2021

Soiling, dust accumulation on the protective glass of photovoltaics (PV) systems, leads to a loss of light transmittance to the solar cells, which considerably reduces the efficiency of the PV process. Active mitigation of soiling, i.e., cleaning of PV modules, is a key process for modules performance; however, it is not always an easy and economical action. In this work, a passive soiling mitigation method is presented. It consists in a surface modification of solar glasses, specifically by changing the roughness.
Several glasses were chemical etched in different acid and alkaline conditions. Roughness of these glasses was determined by atomic force microscopy (AFM) and light transmittance analysis was also carried out using a spectrophotometer. In order to simulate the outdoor conditions, glasses were soiled in a reproducible, fast, and reliable system designed for this purpose. The deposited dust, percentage of surface covered, and agglomerates size were measured.
The results showed the change in roughness when acid or alkaline reagents are used, as well as the diminution of roughness when etching time increases. Respect to the soiling of etched samples, higher rugosity when compared with untreated solar glass showed less dust deposition. This is mainly due to the contact points between glasses and dust particles, which decrease the adhesion forces. However, from the point of view of the loss of transmittance, the parameters that strongly affects the behavior of the glasses in soiling would seem skewness and kurtosis. These shape factors influence the generation of dust agglomerates in the surface of the glasses controlling the covered area.
The best samples, etched in alkaline media, showed a 6.3 % less of transmittance loss when compared with un-treated solar glasses and a 64.7 % less of soiling.