Determination of Diode Parameters of Silicon Solar Cell from Variation of Slopes of the I-V Curves at Open and Short Circuit Conditions with Intensity of Illumination (original) (raw)
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Semiconductor Science and Technology, 2010
An analytical method of determination of all the four diode parameters of the single exponential model of a silicon solar cell, namely shunt resistance R sh , series resistance R s , diode ideality factor n and reverse saturation current I 0 from the variation of slopes of the I-V curve of the cell near short circuit and open circuit conditions with intensity of illumination in a small range of intensity, is presented for the first time. In a suitable range of intensity the variation of dI/dV at short circuit enables determination of R sh , whereas the variation of dI/dV at open circuit enables determination of R s , n and I 0 . The diode parameters of a silicon solar cell were determined with this method using I-V characteristics of the cell in 40-125 mW cm −2 intensity range of a simulated AM1.5 solar radiation. Theoretical I-V curves generated using so determined values of the diode parameters matched well with the experimental I-V curves of the cell obtained under various intensities of illumination in the above range.
Extraction of Diode Parameters of Silicon Solar Cells under High Illumination Conditions
An analytical method has been developed to extract all four diode parameters, namely the shunt resistance, series resistance, diode ideality factor, and reverse saturation current density, using a single J-V curve, based on one exponential model of silicon solar cells under high illumination conditions. The slope of the J-V curve (dV/dJ) at a short circuit condition is used to determine the value of the shunt resistance. The slope of the J-V curve at an open circuit condition together with the short circuit current density, open circuit voltage, current density, and voltage at maximum power point have been used to determine the values of the series resistance, diode ideality factor, and reverse saturation current density. The determined values of the diode parameters have been used to compute the theoretical values of the open circuit voltage, curve factor, and efficiency of the solar cell. The theoretical J-V curves matched well with the corresponding experimental curves. This method is applied to determine the diode parameters of concentrator silicon solar cells at different illumination conditions in a temperature range of 298-323 K. The computed values of the open circuit voltage, curve factor, and efficiency obtained using diode parameters determined with this method showed good agreement (<2% discrepancy) with the experimental values.
An attempt has been made for the determination of diode parameters viz. shunt resistance R sh , series resistance R s , diode ideality factor n and reverse saturation current density J 0 of three solar modules: a-Si 47-37, a-Si 51-13 and CdTe 14407. In this regard, two approaches namely and (B) reported by Khan et al. (2010) have been used to determine all the four diode parameters R sh , R s , n and J 0 . The data of slopes of J-V curve at open circuit conditions (m oc ) and open circuit voltage (V oc ) at different illumination intensities obtained by Del Cueto (1998) for two a-Si and one CdTe solar modules have been used to determine the above diode parameters. The determined values of diode parameters have been used to generate the theoretical J-V curves. The theoretical fill factor (FF) and V oc have been calculated from the theoretical J-V curves and are plotted along with the experimental FF and V oc values. The theoretical values of FF and V oc obtained by the approach (B) of method of Khan et al. (2010) are in good agreement with the experimental values.
Effect of illumination intensity on cell parameters of a silicon solar cell
Solar Energy Materials and Solar Cells, 2010
The effect of illumination intensity P in on the cell parameters of a silicon solar cell has been investigated based on one diode model. The variation of slopes of the I-V curves of a cell at short circuit and open circuit conditions with intensity of illumination in small span of intensity has been applied to determine the cell parameters, viz. shunt resistance R sh , series resistance R s , diode ideality factor n and reverse saturation current I 0 of the cell. The dependence of cell parameters on intensity has been investigated for a fairly wide illumination intensity range 15-180 mW/cm 2 of AM1.5 solar radiations by dividing this intensity range into a desirable number of small intensity ranges for measurements of the slopes of the I-V curves at short circuit and open circuit conditions. Initially R sh increases slightly with P in and then becomes constant at higher P in values. However, R s , n and I 0 all decrease continuously with P in , but the rate of decrease of each of these becomes smaller at higher P in values. Theoretical values of open circuit voltage V oc , curve factor CF and efficiency Z calculated using the cell parameters determined by the present method match well with the corresponding experimental values.
Effect of Intensity on Solar Cell Parameters of a Silicon Solar Cell
The effect of illumination intensity P in on the cell parameters of a silicon solar cell has been investigated based on one diode model. The variation of slopes of the I-V curves of a cell at short circuit and open circuit conditions with intensity of illumination in small span of intensity has been applied to determine the cell parameters, viz. shunt resistance R sh , series resistance R s , diode ideality factor n and reverse saturation current I 0 of the cell. The dependence of cell parameters on intensity has been investigated for a fairly wide illumination intensity range 15-180 mW/cm 2 of AM1.5 solar radiations by dividing this intensity range into a desirable number of small intensity ranges for measurements of the slopes of the I-V curves at short circuit and open circuit conditions. Initially R sh increases slightly with P in and then becomes constant at higher P in values. However, R s , n and I 0 all decrease continuously with P in , but the rate of decrease of each of these becomes smaller at higher P in values. Theoretical values of open circuit voltage V oc , curve factor CF and efficiency Z calculated using the cell parameters determined by the present method match well with the corresponding experimental values.
Current Applied Physics, 2013
The diode ideality factor (m) and the series resistance (R s) of a Si solar cell represent two critical performance-indicator parameters of the device. Since both m and R s are functions of voltage (V) and temperature (T), simultaneous electrical measurements of these parameters under variable conditions of V and T can often be difficult with traditional direct current (D.C.) techniques. Using the electro-analytical method of linear sweep voltammetry (LSV) and a commonly available Si solar cell, we explore these specific confines of such D.C. measurements. The results are compared with those obtained from a parallel set of alternating current (A.C.) measurements using impedance spectroscopy (IS). LSV provides the main D.C. parameters (open circuit voltage, short circuit current, fill factor, and efficiency) of the cell, but is limited in terms of independently measuring m and R s beyond strong forward biased conditions. The IS approach is free of the latter experimental constraints, and at the same time can provide several other important electrical parameters of the solar cell. Specifically, IS detects the presence of a low-high (pep þ) junction at the back surface of the cell, and serves as an efficient probe of certain electrical characteristics of this junction.
2010
Current-voltage characteristics of multi-crystalline silicon solar cells measured under several low illumination levels are analyzed. The fitting analysis is conducted using a modified two-diode equivalent circuit accounting for an additional ohmic series resistance in the vicinity of grain boundaries and allowing for variable diode ideality factors. Apart from the shunt resistance-a key factor at very low illumination levels-the model indicates two other current transport mechanisms at low illumination levels, both related to recombination, but each of them can be allocated to a different region in the cell: (1) recombination in the crystalline region and (2) recombination at grain boundaries. The role played by each mechanism is studied depending on illumination level.
Dependency of PV cell parameters on T has been investigated. The PV cell parameters analytically determined using single J-V curve. The analytically predicted values of R sh , R s and n decreased with increases of T. J 0 is increased by 3583% and 5988% under 10 and 15 suns, respectively. Relations between PV cell parameters and T have also been developed. g r a p h i c a l a b s t r a c t The temperature (T) dependence of the performance and cell parameters of photovoltaic (PV) Si solar cells was studied in the 298–353 K temperature range and under high illumination conditions (10 and 15 suns). The PV cell parameters were analytically predicted using the short circuit current density (J sc), and open circuit voltage (V oc), inverse of the slopes at short circuit and open circuit conditions along with the current density and voltage values at the maximum power point. When T was varied from 298 K to 353 K, the obtained variations of the performance parameters under illumination intensities of 10 and 15 suns were, respectively: J sc increased by 5.38% and 2.86%; V oc , on the other hand, decreased approximately by 16.87% and 17.75%; the obtained fill factor losses were 5.84% and 5.34%, and the overall losses in efficiency were approximately 17.52% and 19.91%. The inverse of the slopes in the short and open circuit conditions did also decrease with increasing T. Both current and voltage at the maximum power point decreased with the rise in T, whereas J ph appeared to increase linearly with temperature (5.84% and 3.51% at 10 and 15 suns, respectively). The value of R sh decreased linearly with T under both illumination intensities (20.42% at 10 suns and 23.73% at 15 suns), while R s showed an exponential decrease with increasing T (15.38% at 10 suns and 17.73% at 15 suns). The diode ideality factor decreased with T (13.36% at 10 suns and 12.41% at 15 suns); in contrast, J 0 increased with the rise in temperature. The losses resulting from the series resistance and surface charge recombination were reduced with the increase in temperature, whereas the losses caused by the shunt resistance and the reverse saturation current increased. The reverse saturation current density was increased by 3583% and 5988% under the 10 and 15 suns illumination levels, respectively.
Effect of Illumination Intensity on Solar Cells Parameters
Energy Procedia, 2013
This work presents the influence of the irradiance intensity level on different parameters (ideality factor, saturation current, series resistance, shunt resistance…) of polycrystalline silicon solar cells. I-V characteristics of these cells were plotted with measurements done at room temperature, and were modeled using the single diode model. We find that the short circuit current, the photocurrent and the ideality factor increase linearly with the irradiation level intensity while the open circuit voltage and efficiency increase logarithmically. The fill factor increases slightly for low intensities, and then it decreases with higher intensities of irradiation. The saturation current increases exponentially. The series resistance remains invariant and the shunt resistance decreases linearly.
Solar Cells, 1990
A method for the determination of the standard deviations of the solar cell characteristic curve fitting parameters is presented for the first time. In this method, a Taylor series expansion of the parameters, around their best values, is made resulting in linear functions which permit the determination of the standard deviations with the least-squares method. The parameters, with the respective standard deviations, were determined from the experimental I-V characteristic curves obtained under illuminated and dark conditions. For the studied experimental I-V curves, the diode saturation currents, the diode factor and the shunt resistance showed smaller standard deviations in the dark condition, and the series resistance appeared to be more precise in the illuminated I-V characteristic.