5. 3 Operation, Performance and Maintenance of PV Systems
Summary / Abstract:
Solar modules installed in the Pre Aral region of Uzbekistan are subjected to high frequency and intensity of dust emissions from three Deserts such as the Aralkum, Karakum and Kyzylkum. The aim of this work is study of physical and chemical properties of dust for the geographical location and its influence on solar modules. Glass plates used in solar modules were exposed to the ambient atmosphere in the city Nukus, Republic of Karakalpakstan and in the village Dosumbiy, Gurlan district, Khorezm region located in ~170 km distance from Nukus. The glass sheet in Nukus city is placed in private territory on 1 m distance from the Earth surface in a ~600 m2 surrounded with walls. The glass in Khorezm was placed on roof of a building located at the border of the village, ~2.5 m from the Earth surface. The dust particles were collected from the glass sheets every week carefully by glass cleaning wiper and stored in glass bottles. The particles collected within several week have been used for compositional analysis. The mass has been correlated to speed of wind, temperature of the environment, humidity, and atmospheric pressure. Particle size distribution has been measured with maximum ~600 nm and ~10 µm by zetasizer and master size instruments. Various particle shape, size, and morphologies have been established by scanning electron microscope with the largest particle size ~10 µm and smaller size of around 600 nm. The smallest particles dispersed with DI water are of size ~20 nm. By study of pH we found that the size distribution of particles changes with time, because of, probably, chemical reactions between some substances involved into the dust with DI water and that influences on acidity of the dispersion. Dust composition has been studied systematically by X-ray fluorescence spectroscopy, energy dispersive X-ray diffraction, inductively coupled plasma optical emission spectroscopy. Quartz, hematite, lime, corundum, magnesia and several other trace minerals have been identified in the dust particles. Main characteristic absorption bands corresponding to Si–O, Si-O-Si bonding in quartz, Fe-O bonds in hematite Fe2O3 have been identified by infrared and Raman spectroscopy. According to x-ray diffraction analysis, the peaks corresponding to quartz, hematite, and corundum are sharp and are more crystalline with some level of disorder. Dust particles felt on glass within two days reduces optical transmittance of glass of the solar modules to ~10%. 0.30 g dust has been collected from top of a solar module installed near to Urgench State University that reduced short circuit current 5.46 A and open curcuit voltage 22.53 V to 4.9 A and 21.9 V, respectively.