Current Issue : October - December Volume : 2018 Issue Number : 4 Articles : 5 Articles
We report the study of the temperature dependance of the performance\nelectronic parameters of an N-P solar cell by considering as model, the columnar\ncylindrical orientation associated to the dynamic junction velocity\n(SF) concept. We presented the photocurrent-photovoltage (I-V) and Power-\nphotovoltage (P-V) characteristic curves. The short-circuit photocurrent\n(Isc), the open circuit photo voltage (Uoc), the fill factor (FF) and the efficiency\n(�·) are linearly dependent on the temperature. The temperature coefficients\n(T-coefficient) relative to the short-circuit, open-circuit photovoltage and efficiency\nare calculated and the comparison with data from the literature\nshowed the accuracy of the considered model....
In this paper, we investigate interdigitated back contact solar cells with the front floating\nemitter structure systematically by using simulated and experimental methods. By comparing the\nfront floating emitter structure with the front surface field structure, it is found that the efficiency of\nsolar cells with the front surface field structure quickly reduces with the increasing of back surface\nfield width; while solar cells with the front floating emitter structure can have a wider front surface\nfield width range with minimum impact on the cell efficiency. More importantly, solar cells with\nthe front floating emitter structure have a larger fabrication process tolerance, especially for the\nback surface field width, emitter width, and the bulk resistivity, which means that the fabrication\nprocess flow can be simplified and the production cost can be reduced. Based on the above results,\nlarge area (156.75 mm Ã?â?? 156.75 mm) interdigitated back contact solar cells with the front floating\nemitter structure are fabricated by using the simplified process with only one masking step. SiOx:B\nis used as the passivation layer, which can lead to a higher open circuit voltage and lower surface\nsaturation current density. Finally, an efficiency of 20.39% is achieved for the large area solar cells....
Some of the technical problems that appear are obtaining solar cell parameters from I-V curve measurement data. One simple\nmethod is using linear graphical fit at zero current or voltage conditions. Although the accuracy of the obtained values is\nacceptable, other problems may arise regarding the number of parameters which could be obtained. We report a comparison\nbetween manual or graphical fit and fit using Shockley�s equation. The single I-V curve under the lighting was inferred to obtain\nthe intrinsic parameters of the solar cells� performance. The fittings were performed using the nonlinear equation of Shockley by\ndetermining some initial values of fittings such as Rs, Rsh, n, I0, Iph, and T. In the case of the Shockley equation fit, the iteration\nwas performed several times to obtain the least possible inferred parameters. We have successfully obtained a better result of\nnonlinear Shockley fitting compared to the manual linear fit....
The capacitance is one of the key dynamic parameters of solar cells, which can provide\nessential information regarding the quality and health state of the cell. However, the measurement\nof this parameter is not a trivial task, as it typically requires high accuracy instruments using, e.g.,\nelectrical impedance spectroscopy (IS). This paper introduces a simple and effective method to\ndetermine the electric capacitance of the solar cells. An RLC (Resistor Inductance Capacitor) circuit is\nformed by using an inductor as a load for the solar cell. The capacitance of the solar cell is found\nby measuring the frequency of the damped oscillation that occurs at the moment of connecting the\ninductor to the solar cell. The study is performed through simulation based on National Instruments\n(NI) Multisim application as SPICE simulation software and through experimental capacitance\nmeasurements of a monocrystalline silicon commercial solar cell and a photovoltaic panel using\nthe proposed method. The results were validated using impedance spectroscopy. The differences\nbetween the capacitance values obtained by the two methods are of 1% for the solar cells and of\n9.6% for the PV panel. The irradiance level effect upon the solar cell capacitance was studied obtaining\nan increase in the capacitance in function of the irradiance. By connecting different inductors to\nthe solar cell, the frequency effect upon the solar cell capacitance was studied noticing a very small\ndecrease in the capacitance with the frequency. Additionally, the temperature effect over the solar cell\ncapacitance was studied achieving an increase in capacitance with temperature....
Concentrating solar power (CSP) technologies are foreseen to be a crucial actor in the future\nrenewable energy mix. Soil accumulation on the optical surfaces of CSP plants involves significant\nexpenses of the operation and maintenance activities because a high cleanliness level is required\nto achieve proper plant revenues. Normally, only the front side of the solar reflectors is cleaned\nto reflect the maximum possible amount of direct solar radiation towards the receiver. However,\nsoil deposited on the backside of the reflector could provoke degradation and might need to be\nconsidered in the cleaning strategy. As this possible degradation has never been studied, this work\nis dedicated to assess if the backside of reflectors should be regularly cleaned. The influence of\nthe sand in the possible paint degradation depends on its chemical composition and the weather\nconditions. Therefore, several climatic conditions of artificially soiled reflector samples with different\ntypes of sand were simulated in accelerated aging tests. Concerning the results obtained, the ambient\nconditions simulated by the damp heat and thermal cycling tests were the only ones that produced a\nsignificant degradation of the backside paints. Also, the sand from Ouarzazate was responsible for\nhigher deterioration....
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