Effects of Environmental Factors on Dust Particle Adhesion on Glass Substrates

Qatar is a dessert country full of solar resource to be further exploited. Despite the fact that Qatar has abundant petroleum resources, the first major solar power plant is expected to operate by 2016. Several projects related to solar power plants are also ongoing as well, which indicates that electricity generated by solar power will become more important and gradually have higher percentage among total electricity production. However, one of the major issues of PV power system is the dust soiling on photovoltaics (PV) panels due to the dusty weather conditions in Qatar. The dust soiling on PV panels has been confirmed to cause a significant performance loss due to the dust deposited on the surface of PV panels resulting in blocking the transmission of light. The performance loss can be from 5% up to 35%. Maintaining the surface with minimum dust soiling will be crucial to keep PV panels performing at higher efficiency. This research aims to investigate the effects of environmental factors on dust particle adhesion of common materials used at Doha as glass windows and solar panels, among others. The main scientific question is to how the dust particles are attached to the surfaces of different morphology. From Rumpf and Rabinovich theory, the surface roughness of substrate has a significant impact on adhesion force of particles on surface. Other theories such as Johnson-Kendall-Roberts (JKR) and Derjaguin-Muller-Toporov (DMT) theories all assume that surface of particle and substrate are atomically smooth, which does not take surface roughness into consideration. However, there are surface roughness in nanoscale existed on both surfaces of particles and substrates. The surface asperity is assumed to be hemisphere on the substrate for model development. When particles are attached to substrate, the contact area actually reduces due to the existence of surface asperity of substrate and roughness of dust particles. Since the contact area is reduced, the adhesion force of particles reduces. This research is to investigate the effects of environmental factors on adhesion of dust particles on glass substrates. The factors include Doha's climate such as temperature, humidity, wind gust, and among others that may contribute to the change in surface morphology of glass substrate. Surface roughness and morphology of glass substrates is evaluated by atomic force microscope. Morphological evaluation of dust particles is carried out using microscopic techniques such as optical microscope, scanning electron microscope. The particle analysis of optical images is conducted by using image-processing software ImageJ, which can provide the detailed information of shape, diameter, and size distribution of dust particles. The comparative study of adhesion of particles in terms of particle area density is conducted. The purpose of the study is to evaluate the soiling tendency or dust adhesion of glass substrates with various surface conditions. The result of dust adhesion of glass substrate is shown in terms of particle area density. The Results indicate that optimization of surface roughness could lead to better control of dust adhesion. The research is expected to give more fundamental study on dust to mitigate the dust soiling on PV panels.