Effects of Parameter Variations of PV Module based on MATLAB-Simulink Modeling

Recent applications in remote areas need low-cost source of power. Standalone PV system could assure this power. This paper includes the effect of variation of parameters of PV panel model in MATLAB/Simulink. This build model is based on mathematical equations of the equivalent circuits which consists of a current source, series resistance, and parallel resistance along with a diode. The model is built for the predetermination of nature of the SolarPV module for different radiation, temperature and other physical parameters. Moreover, PV-array system has been studied in the given research work. For the validation of Simulink results, a real time set also has been studied. Keyword: MATLAB /simulink, solar radiation; series and shunt resistance; saturation current; panel temperature; maximum power point


INTRODUCTION
Photovoltaic cell has been widely used because of ability to convert solar energy coming from sunlight into electrical energy [1]. In the constructional theory of photovoltaic cell, it consists of semiconductor materials of p and n type, connected with each other. The basic principle of PV cell is shown in figure 1. It shows, when photons of sunlight strikes on cells, electrons free from the outer layer of the atom. Then electrons starts flowing from negative to positive terminal. The opposite direction of flow of electrons shows the flow of current from positive terminal to negative terminal in the electric circuit.
The "photovoltaic effect" is the fundamental physical and chemical process by which, voltage or electric current is obtained in a solar cell when it is exposed on sun light [2]. As shown in the figure 1, it is a phenomenon through which a collection of lightgenerated carriers causes flow of electrons and holes towards N-type and P-type of the junction respectively. This acts as a source of current. Because of the high cost of PV modules, optimal exploitation of the available abundant solar energy is imperative needs a precise, consistent and comprehensive simulation of the designed system before installation. PV panel modeling is a very important factor that affects the output of the PV panel.
The simplest way of representing the solar cell is the single diode model. It is shown with a current source parallel with a diode [2]. A single PV cell generates 0.5-0.8V and therefore, connected in series in a number of 36 to 72 to make PV module. Short circuit current (Ishc), open circuit voltage (Voc) and diode ideality factor are the required parameter fo circuit. Diode ideality factor can be obtained from the principle that describes how nearly it follows ideal diode equation. The basic model is improved for accuracy by introducing the series resistance (Rs). It does not prove to be efficient under t variations [4] [5]. To overcome this drawback, an additional shunt resistance (Rsh) is included. This paper carried out a model of PV panel of 72 cells connected in series in MATLAB/Simulink. The Proposed model is used to forecast the PV panel characteristics by varying different physical parameters such as solar radiation and ambient temperature. Moreover, same model is used to predict the behavior of the solar panel by varying circuit parameters such as series resistor, shunt resistor, diode saturation current, etc [6] [7] [8].
The single diode model and double diode model has been extensively used in the many literatures but single diode model is more effective due to its comprehensive approach towards the modeling II. Equivalent Single Diode Circuit of photovoltaic Cell Figure 2 shows the equivalent circuit of photovoltaic cell. The main components of the circuit have a current source, a diode, a shunt resistance as well as a parallel resistance. The equivalent circuit is based on the equation given below sh D ph where, Iph represents the photocurrent, denotes the reverse saturation current of the diode, q stands for the electron charge, V is the voltage across the diode, K International Journal of Trend in Scientific Research and Development, Volume 1(4), ISSN: This acts as a source of current. Because of the high cost of PV modules, optimal exploitation of the available abundant solar energy is imperative [3]. This needs a precise, consistent and comprehensive simulation of the designed system before installation. PV panel modeling is a very important factor that The simplest way of representing the solar cell is the diode model. It is shown with a current source . A single PV cell generates 0.8V and therefore, connected in series in a number of 36 to 72 to make PV module. Short circuit current (Ishc), open circuit voltage (Voc) and diode ideality factor are the required parameter for the circuit. Diode ideality factor can be obtained from the principle that describes how nearly it follows ideal diode equation. The basic model is improved for accuracy by introducing the series resistance (Rs). It does not prove to be efficient under temperature . To overcome this drawback, an additional shunt resistance (Rsh) is included. This paper carried out a model of PV panel of 72 cells connected in series in MATLAB/Simulink. The Proposed model is used to forecast the PV panel s by varying different physical parameters such as solar radiation and ambient temperature. Moreover, same model is used to predict the behavior of the solar panel by varying circuit parameters such as series resistor, shunt resistor, diode The single diode model and double diode model has been extensively used in the many literatures but single diode model is more effective due to its comprehensive approach towards the modeling [9]. Figure 2 shows the equivalent circuit of photovoltaic cell. The main components of the circuit have a current source, a diode, a shunt resistance as well as a equivalent circuit is based on

Equivalent Single Diode Circuit of photovoltaic
where, Iph represents the photocurrent, denotes the reverse saturation current of the diode, q stands for the electron charge, V is the voltage across the diode, K stands for the Boltzmann's constant, T denotes the junction temperature, N represents the i of the diode, Rs and Rsh are the series and shunt resistors of the cell respectively   stands for the Boltzmann's constant, T denotes the junction temperature, N represents the ideality factor of the diode, Rs and Rsh are the series and shunt resistors of the cell respectively [10].  V curves and P-V curves for a given PV cell.
The MATLAB/Simulink model shown in the figure 3 is developed from the equation 1. Figure 4 shows the graph I-V and P-V for some particular values of temperature and irradiation.

Impact of Change in Solar Radiation
Influence of spectral distribution of solar irradiance widely effects the output performance of a solar panel [11]. The equivalent circuit shown in figure 2 have a current source showing Iph which depends on temperature and irradiation as shown in equation 3.
where, B is solar irradiation in (W/m 0.0017 A/°C stands for the cell short circuit current. where, B is solar irradiation in (W/m 2 ) and Ki = stands for the cell short circuit current.

VI. Effects of Varying reverse saturation current(Isc)
In the short circuited solar panel, voltage across the panel becomes zero. The current through the solar panel in this condition is referred as short circuit current and usually denoted by as Isc as shown in figure. 15.

VII. VIII. PV Array
The identical 6 PV panels connected in series with different MPPT topologies and figure 22 shows that different output current Vs voltage and power Vs Voltage grap

VIII. IX. Experimental Results and Validation
In the real time experiment, a PV Module (model number: JP36F150) as shown in the figure 19 has been tested under the solar radiation with multimeter and thermometer to measure the temperature the Table 1.
The JP36F150 model is developed in the MATLAB/Simulink with the same specifications. The identical 6 PV panels connected in series with different MPPT topologies [12][13] [14]. Figure 21 and figure 22 shows that different output current Vs voltage and power Vs Voltage graph.
V curves for the PV panel V curves for the PV array model The PV modules connected in series can have faults consist of open circuits, short circuits, mismatch between PV modules, and partial shading. Mismatch faults are generally caused by encapsulant degradation, antireflection coating deterioration, [15].

Experimental Results and Validation
In