Predicting the spectral effects of soils on high concentrating photovoltaic systems

Abstract

Soiling losses on high concentrating photovoltaic (HCPV) systems may be influenced by the spectral properties of accumulated soil. We have predicted the response of an isotype cell to changes in spectral content and reduction in transmission due to soiling using measured UV/vis transmittance through soil films. Artificial soil test blends deposited on glass coupons were used to supply the transmission data, which was then used to calculate the effect on model spectra. The wavelength transparency of the test soil was varied by incorporating red and yellow mineral pigments into graded sand. The more spectrally responsive (yellow) soils were predicted to alter the current balance between the top and middle subcells throughout a range of air masses corresponding to daily and seasonal variation.

Correlating photovoltaic soiling losses to waveband and single-value transmittance measurements

“…So far, most of the research addressing the spectral impact of soiling has been conducted by analyzing artificial soiling [2,19,20]. These studies have been crucial to understanding the effects of soiling on the performance of PV systems.…”

Spectral nature of soiling and its impact on multi-junction based concentrator systems

“…Despite of this, the intention of this work is to contribute to the understanding of the wavelength dependence of the attenuation of soiling and its impact on the spectral performance of MJ-based CPV systems. In this sense, soiling is here considered as a stand-alone optical element, as previously considered by other authors [16]. The investigation of the scattering that may be produced between soiling and the concentrator optics would imply to gather detailed information regarding the size and distribution of soiling across the surface of the CPV system under consideration.…”

“…Bearing the above in mind, it can be expected that soiling modifies the spectral performance of MJ-based CPV systems and introduces additional non-negligible losses in the system. However, to the present, the only study concerning this issue has been conducted in [16]. The authors investigated the impact of soiling by considering artificial soiling and a set of simulated spectra.…”

A Handbook on Artificial Soils for Indoor Photovoltaic Soiling Tests

“…Secondary scattering is not detected in this configuration, making it a useful analogue to changes in direct normal irradiance (DNI). This technique was used to predict the response of triple junction HCPV devices to various soils [20]. It is useful to fully subtract the effect of the substrate by conducting a baseline scan with a clean coupon in both the reference and test positions.…”