Effect of Dust Shading on Photovoltaic Modules

This paper investigates the effect of dust on photovoltaic (PV) modules with respect to dust concentration and spectral transmittance. Dust samples were collected from Kuwait in the form of raw dust and accumulated dust on sample glasses at different tilt angles. The spectral transmittance was measured at the Centre for Renewable Energy Systems Technology (CREST) laboratory with a spectrophotometer. Total transmittance variation was identified for samples at different tilted positions, where the worst case was presented at a tilt angle of 30o with a non uniformity of 4.4% in comparison to 0.2% for the 90o tilt between the top, middle and bottom. Finally the data was translated to an effective spectral response for different technologies using spectral response data measured by the European Solar Test Installation (ESTI). The measured data showed a decrease in transmittance at wavelengths <570 nm. This affects wide band-gap thin-film technologies more than crystalline silicon technologies and especially amorphous silicon which showed a 33% reduction in photocurrent when a dust concentration of 8.5 mg/cm2 was applied. In comparison, the crystalline silicon and CIGS technologies showed 28.6% and 28.5% reductions at the same dust density.JRC.F.8-Renewable Energy (Ispra