Dust-induced shading on photovoltaic modules

Abstract

The effect of dust on photovoltaic modules is investigated with respect to concentration and spectral transmittance. Samples were collected in the form of raw dust as well as accumulated dust on exposed sheets of glass at different tilt angles. Spectral transmittance of the samples was determined. Transmittance variation between top, middle and bottom was identified for samples collected at different inclinations, where the worst case was seen at a tilt angle of 30 o with a nonuniformity of 4.4% in comparison with 0.2% for the 90 tilt. The measured data showed a decrease in transmittance at wavelengths <570 nm. Integrating this with measured spectral responses of different technologies demonstrates that wide band-gap thin-film technologies are affected more than, for example crystalline silicon technologies. The worst case is amorphous silicon, where a 33% reduction in photocurrent is predicted for a dust concentration of 4.25 mg/cm 2 . Similarly, crystalline silicon and CIGS technologies are predicted to be less affected, with 28.6% and 28.5% reductions in photocurrent, respectively. The same procedure was repeated with varying Air Mass (AM), tilt angle and dust concentration values to produce a soiling ratio table for different technologies under different AM, tilt angle and dust concentration values. Copyright

The contribution of dust to performance degradation of PV modules in a temperate climate zone

“…It can be postulated that the soiling at ROTA has an equal impact on the performance between the technology types. On the contrary, Qasem et al (2012) in Kuwait found that the transmittance is affected more by dust at lower wavelengths. Therefore, wider band gap PV technologies such as a-Si and CdTe are more affected by dust deposition than c-Si and CIGS.…”

“…The artificial dust collected from ROTA was then deposited onto the surface of the storage container. The deposition of dust was performed by free fall technical using a cylindrical tube to minimize the influence of wind flow as performed by Qasem et al (2012). The accumulated dust on the container was coated with carbon; a recommended material as it doesn't interfere with the characteristic X-ray peaks from the elements in the sample and prevents static charging of the dust before the SEM and EDS experiments were applied.…”

“…In addition to location, dust accumulation is affected by the PV's tilt angle (Mani and Pillai, 2010;Qasem et al, 2012;Sarver et al, 2013). Elminir et al (2006) in their experiments in Egypt reported that the difference of transmittance reduction for tilt angle of 0 o (dust accumulation maximum) and 90 o (dust accumulation minimum) is 21.3%.…”

“…Deposited dust on a PV module's cover glass diminishes the illumination by absorbing and scattering sun light received by the solar cells (Elminir et al, 2006;Qasem et al, 2012;Appels et al, 2013). The accumulation of dust on a PV module's surface is different from location to location and depends on the environmental conditions of ambient temperature and humidity, rainfall and wind velocity (Sarver et al, 2013).…”

“…The result revealed a more severe power reduction for mc-Si modules (77.75%) than pc-Si modules (18.02%). Moreover, a spectral analysis performed by Qasem et al (2012) to investigate the effect of dust on PV technologies concluded that dust has a more significant effect on the performance of those PV modules that have a wider spectral response e.g. a-Si.…”