"Practical 3Characteristics of PV Cells with and without Parallel ResistanceAim:The aim of this practical is to evaluate I-V characteristic of a simple PV cell and investigatethe effects of parallel resistance on I-V characteristic using standard MATLAB/SIMULINKblock diagramObjective:? Representation of mathematical model of a PV cell in Matlab/Simulink? Evaluation of I-V characteristic of the cell with and without parallel resistanceIntroduction:The characteristic of an ideal PV cell (at 250C) can be described by a set of equations givenin the following. The ideal/simplified circuit model of the cell is shown in Fig. 1. The I-Vcharacteristic of the cell can be established by varying the output voltage V of the cellPV through an external input signal and measuring the corresponding output current i . NotePV that i = 0 under open circuit condition.PVIn practice, more complex model or equivalent circuit of a PV cell is used. For example,consider the impact of shading on a string of cells connected in series. If any cell in thestring is in the dark (or shaded), it produces no current. In the ideal/simplified circuit asshown in Fig. 1, the current of the current source (of the shaded cell) would become zeroand the diode is reversely biased. Thus, the circuit would not allow to flow any current(except a tiny amount of reverse saturation current). In other words, the ideal/simplifiedequivalent circuit would not allow to deliver any power to a load if only one of the cells isshaded. While it is true that characteristics of PV modules are very sensitive to shading, thesituation is not quite as bad as that. Therefore, a more accurate/complex model of PV cell isrequired in order to be able to deal with realities such as shading problems.Fig. 2 illustrates a PV equivalent circuit that includes a parallel leakage resistance R . Thep ideal current source ISC in this case delivers current to the diode, the parallel resistance RP,and the load:The term in the parentheses is the same current as in the simplified model. Therefore, atany given voltage, the parallel leakage resistance causes load current for the ideal model tobe decreased by V/RP as is shown in Fig. 3. Exercise 1: The given below figure illustrates the corresponding Simulink model block diagram of a PV cell,this model is used to perform analysis for PV cells on Simulink matlab, also oscilloscopes areattached with it to show the behavior of the PV cell with light as a variant.The below given plot show the behavior of a PV cell. The current remains constant with theincreasing voltages and when the voltage exceeds a limit, the current starts to decrease. Itis the graph for an ideal PV cell, in which the Maximum power transfer point lies at theknee point of the curve. Ideal PV Rp = ? 5 4.5 4 3.5 3 2.5 2 1.5 1 0.5 0 0 0.1 0.2 0.3 0.4 0.5 0.6 Voltage (V) Figure: current vs. voltage for ideal PVThe below graph is for the power delivered by a PV module, as stated above that themaximum power transfer is at the peak point, and after that power starts decreasing due tosemiconductor properties. Ideal PV Rp = ? 2 1.8 1.6 1.4 1.2 1 0.8 0.6 0.4 0.2 0 0 0.1 0.2 0.3 0.4 0.5 0.6 Voltage (V) Figure: power vs. voltage for ideal PCurrent (A) Power (W)Exercise 2:The below given figure illustrates the corresponding Simulink model block diagram. In order tostudy the impact of the parallel resistance of the PV cell, you will be developing both simplifiedPV cell and the PV cell with R in the same MATLAB/SIMULINK model, and comparing thep results by plotting the graphs. This model is drawn to compare the real PV cell with an ideal PVcell.The given below plot shows the comparison of an ideal PV cell with a real PV cell. The redline shows the graph of a real PV cell with R not equal to infinity and the blue line showsp the plot of an ideal PV cell with R =infinity. The current remains constant with thep increasing voltages and when the voltage exceeds a limit, the current starts to decrease. Itis the graph for an ideal PV cell, in which the Maximum power transfer point lies at theknee point of the curve.54.5 4 3.5 3 2.5 2 Rp =/= ? 1.5 Rp = ? 1 0.5 0 0 0.1 0.2 0.3 0.4 0.5 0.6 Voltage (V) Figure: current vs. voltage for ideal PV (R =) and R = 1p p The given below plot shows the comparison of an ideal PV cell with a real PV cell. The redline shows the graph of a real PV cell with R not equal to infinity and the blue line showsp the plot of an ideal PV cell with R =infinity. As stated above that the maximum powerp transfer is at the peak point, and after that power starts decreasing due to semiconductorproperties. 21.8 Rp =/= ? Rp = ? 1.6 1.4 1.2 1 0.8 0.6 0.4 0.2 00 0.1 0.2 0.3 0.4 0.5 0.6 Voltage (V) Power (W) Current (A)1)When the insolation is 4 Sun, then the current is 4A. However when insolation becomes2 suns, the current goes to 2A. There is no effect on the voltage. As power is the product ofcurrent and voltage, so the maximum power becomes half as well with 2 suns instead of 4suns.The current increases as the intensity of light increases, it is due the fact that morenumber of electrons and holes cross the PN junction, and vice versa. Ideal PV Rp = ? 5 Ideal PV Rp = ? 2 4.5 1.8 4 1.6 3.5 1.4 3 1.2 2.5 1 2 0.8 1.5 0.6 1 0.4 0.5 0.2 0 0 0 0.1 0.2 0.3 0.4 0.5 0.6 0 0.1 0.2 0.3 0.4 0.5 0.6 Voltage (V) Voltage (V) Figure: 4 sunsIdeal PV Rp = ? Ideal PV Rp = ? 5 2 4.5 1.8 4 1.6 3.5 1.4 3 1.2 2.5 1 2 0.8 1.5 0.6 1 0.4 0.5 0.2 0 0 0 0.1 0.2 0.3 0.4 0.5 0.6 0 0.1 0.2 0.3 0.4 0.5 0.6 Voltage (V) Voltage (V) Figure: 2 suns2) The parallel resistance will cause the output current to drop as the voltage increases. ThePV cell can only supply fixed amount of current and some of it is diverted across theparallel resistance rather than the load.As we know that if the resistances will increase inparallel, the current will start decreasing, however the voltages will remain same. The totalcurrent will remain the same, as per the rating of the PV cell.Current (A) Current (A) Power (W) Power (W)"