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Modelling photovoltaic soiling losses through optical characterization

Published

Author(s)

Greg P. Smestad, Thomas A. Germer, Hameed Alrashidi, Eduardo F. Fern?ndez, Sumon Dey, Paidisetty S. Kumar, Honey Brahma, Aritra Ghosh, Nazmi Sellami, Ibrahim A. Hassan, Amal Kasry, Bala Pesala, S. Senthilarasu, Florencia Almonacid, K. S. Reddy, Tapas K. Mallick, Leonardo Micheli

Abstract

The accumulation of soiling on photovoltaic (PV) modules affects PV systems worldwide. Soiling consists of mineral dust, soot particles, aerosols, pollen, fungi and/or other contaminants that deposit on the surface of PV modules. Soiling absorbs, scatters, and reflects a fraction of the incoming sunlight, reducing the intensity that reaches the active part of the solar cell. Here, we report on the comparison of naturally accumulated soiling on coupons of PV glass soiled at seven locations worldwide. The spectral hemispherical transmittance of the glass coupons has been measured with a spectrophotometer. It was found that natural soiling disproportionately impacts the blue and ultraviolet (UV) portions of the spectrum compared to the visible and infrared (IR). Also, the general shape of the transmittance spectra was similar for the coupons soiled at the different sites and could adequately be described by a modified form of the Ångström turbidity equation. In addition, the distribution of particles sizes was found to follow the IEST-STD-CC 1246E cleanliness standard. The fractional coverage of the glass surface by particles could be determined directly or indirectly and, as expected, has a linear correlation with the transmittance. It thus becomes feasible to estimate the optical consequences of the soiling of PV modules from the particle size distribution and the cleanliness value.
Citation
Nature - Scientific Reports
Volume
10

Keywords

photovoltaics, soiling, solar cells
Created January 8, 2020, Updated July 10, 2020