Susceptibility of CPV Optical Materials to Abrasion.

In this work, the susceptibility to abrasion of several CPV optical materials, namely glass, glass with anti-reflective treatment, PMMA, and polycarbonate has been investigated. This abrasion simulates the potential effect of a cleaning procedure of photovoltaic modules in the field. To this aim 200 linear passes with a Nylon brush have been performed on the optical samples, and their response to abrasion has been compared. Besides, the presence of soiling has been included in the abrasion test, simulating real conditions encountered by the cleaning procedures in the field. In this respect, two types of soiling, i. e. Aramco Test Dust and silica, deposited on the optical surfaces with two different adhesion degrees have been investigated. The samples were characterized by means of the direct spectral transmittance and roughness, and compared to the initial values, before the abrasion test. Optical microscopy images have also been included in the characterization. Taking into account the spectral response of typical multijunction solar cells, the power losses due to the abrasion procedures have been calculated. [ABSTRACT FROM AUTHOR]