Correlating Photovoltaic Soiling Losses to Waveband and Single-Value Transmittance Measurements

TL;DR

This study demonstrates that measuring spectral transmittance of soiled PV glass can effectively estimate soiling losses, with specific wavelengths providing the most accurate predictions for different PV technologies.

Contribution

It introduces a method to quantify PV soiling losses using spectral transmittance measurements, highlighting the importance of specific wavelengths for accurate estimation.

Findings

Spectral transmittance correlates with soiling losses across PV technologies.

Single wavelength measurements between 500-600 nm are most effective for estimation.

Spectral analysis can improve field detection and impact assessment of soiling.

Abstract

This paper presents the results of an investigation on the spectral losses of photovoltaic (PV) soiling. The transmittance of a glass coupon exposed to natural soiling outdoors in Ja\'en, southern Spain, has been measured weekly and used to estimate the soiling losses that various types of photovoltaic materials would experience if installed in the same location. The results suggest that measuring the hemispherical transmittance of the soiling accumulated on a PV glass coupon can give enough information to quantify the impact of soiling on energy production. Each PV technology is found to have a preferred spectral region, or a specific single wavelength, for which the transmittance through a PV glass coupon could be used for the best estimation of soiling losses. Overall, considering the average spectral transmittance between the extreme wavelengths of the material-specific absorption band, or the transmittance of soiling at a single wavelength between 500 and 600 nm yields the best estimations for different PV technologies. The results of this work can lead to innovative approaches to detect soiling in the field and to estimate the impact of spectral changes induced by soiling on PV energy production.