EXPERIMENT AND MODELING OF COPPER INDIUM GALLIUM DISELENIDE (CIGS) SOLAR CELL: EFFECT OF AXIAL LOADING AND ROLLING
thesisposted on 15.05.2020 by Arturo Garcia
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In this paper various applications of axial tensile load, bending load, and rolling loading has been applied to a Copper Indium Gallium Diselenide (CIGS) Solar Cell to lean how it would affect the solar cell parameters of: Open circuit voltage (Voc), Short circuit current, (Isc), Maximum power (Pmax), and Efficiency (EFF), and Fill Factor (FF). These Relationships were found for with three different experiments. The first experiment the applies axial tensile stress is to a CIGS solar cell ranging from 0 to 200 psi with various strain rates: 0.0001, 0.001, 0.01, and 0.1 in/sec as well as various relaxation time: 1min, 5min, and 10 min while the performance of solar cell is measured. The results of this gave several trends couple pertaining the Voc . The first is that open circuit voltage increases slightly with increasing stress. The second is the rate of increase (the slope) increases with longer relaxation times. The second set of trend pertains to the Isc. The first is that short circuit current generally is larger with larger stress. The second is there seems to be a general increase in the Isc up to a given threshold of stress. After that threshold the Isc seems to decrease. The threshold stress varies depending on strain rate and relaxation time. The second set of experiments consisted of holding a CIGS solar cell in a fixed curved position while it was in operational use. The radii of the curved cells were: 0.41, 0.20, 0.16, 0.13, 0.11, 0.094, and 0.082 m. The radii were performed for both concave and convex cell curvature. The trends for this show a slight decrease in all cell parameters with decreasing radii, the exception being Voc which is not effecting, the convex curvature causing a slightly faster decrease than the concave. This set of experiments were also processed to find the trends of the single diode model parameters of series resistance (Rs), shunt resistance (Rsh), dark current (I0), and saturation current (IL), which agreed with the experimental results. The second experiment consisted of rolling a CIGS solar cell in tensile (cells towards dowel.) and compression (cells away from dowel) around a dowel to create internal damage. The diameter of the dowels decreased. The dowel diameters were: 2. 1.75, 1.25, 1, 0.75, 0.5, and 0.25 inches. This experiment showed similar trends as the bending one but also had a critical diameter of 1.75 in where beyond that damage much greater. Finally a parametric study was done in COMSOL Multiphysics® to examine how changes in the CIGS material properties of electron mobility (EM), electron life time, (EL), hole mobility 15 (HM), and Hole life time (HL) effect the cell parameters. The trends are of an exponential manner that converges to a given value as the material properties increase. When EL, EM, HL are very small, on the order of 10-4 times smaller than their accepted values, a transient like responses occurs.