OPTIMIZATION OF PV MODULE WITH SINGLE-DIODE MODEL FOR TOKAT REGION

In this study single diode model of photovoltaic cell is is simulated with using all cell parameters for Tokat Region in TURKEY. Retscreen software and matlab were used to determine model parameters. Simulation studies were carried out with different irradiations and temperatures in Tokat Region. The output power, voltage and current characteristics of PV model are analyzied especially with taking the effect of temperature and irradiance. Komaes 140W PV module is referenced to analyze the presented model. Also Euclidean distance, Manhattan distance and Minskowski distance methods are used to determine distance from maximum panel power. Introduction Over the last decades, renewable energy sources has been most popular and credible for humankind. Because fossil fuels cause pollution and limited sources [1]. So, solar energy, wind energy, biomass etc. become most popular in alternative energy sources. In that context, solar energy is inexhaustible, renewable and nonpolluting. Therefore it can be used in different energy applications [2]. But solar energy has less energy contribution than other energy sources. Because it has low efficiency and high cost [3]. Our country has a position of having second highest potential of solar energy in Europe. However, Turkey is falling behind of many of European countries in terms using its potential. Nevertheless, due to the new regulations put in place in last years, benefiting from solar energy has begun to be chosen in Turkey as well, for producing electricity. That is why, today, Energy Ministry of Turkey encourages setting up Solar Power Plants and it is permitted to produce electricity up to 500kW without licence. Solar cell is the main part of PV systems and these systems directly produce the electiric from sun. Cells are suitable to be connected to power electronic systems and loads [4]. Efficiency is very important for photovoltaic systems. Thereby maximum power point tracking control is prefered in many PV systems. PV system parameters also have an important role and the circuit based model is needed for modelling for the PV cell [5]. Generally non-linear I-V curve is used for modeling of PV module. Many researchers used single-diode model to characterize the PV module as the current source in parallel to a diode [6-8]. The single diode model use a series resistance for good performance.These models are known to as Rs-models [9-10]. Also many researchers have used this model that includes a shunt resistance (Rsh) for right approach [11-13]. On the other hand the second model is two-diode model of a solar cell. Difference between Rs model and two-diode model is a second diode. But especially Rs model is commanly prefered . Because this model is very simple and to determine parameters of cell is easy [14-17]. In literature; Celik et.al., have used analytical models that are used fourand five-parameter for current of photovoltaic module [9]. For PV panel behavior Neural network revised under realistic weather conditions [19]. Ghani et.al., have studied numerical solition about series and shunt resistances [20]. PV cell's dynamic resistance is calculated using I-V characteristics in Ref [21]. Zagrouba et.al., calculated the electrical parameters using genetic algorithms [22]. Ishibashi et.al., offered a new approach using a single I-V curve to derive cell parameters [23]. [Emeksiz* et al., 4(6): June, 2017] ISSN: 234-5197 Impact Factor: 2.715 INTERNATIONAL JOURNAL OF RESEARCH SCIENCE & MANAGEMENT http: // www.ijrsm. com © International Journal of Research Science & Management [79] In this study; single diode model is preferenced to determine unknown parameters of solar cell and focused on distances from the maximum panel power according to meteorological data of Tokat. Numerical analysis showed a 40% loss of maximum panel power. Mathematical Model of A Solar Cell One-Diode model is shown in Fig.1 where represents series and parallel resistance, espectively. IL light current (A), ID ideal diode current (A), Ish shunt resistance current, I cell’s current. Figure 1 Electrical Device of Solar Cell with One-Diode Generally to calculate relation between the cell`s current and voltage is used following equation: I = IL − I0 (e (V+ Rs I) aVT − 1) − V+IRs Rsh (1) Where; IL : Photocurrent (A) I0 : Diode Saturation Current (A) Rs : Series Resistance (Ω) Rsh : Shunt Resistance (Ω) a : Diode Ideality Factor VT : Thermal Voltage equivalent (V) Cell Parameters And Equations To Determine Cell Parameters Photocurrent (IL) The photocurrent can simply be calculated using Equation 2. This equation is a function of temperature and irradiance values. [24], IL = Iscref Tcref GTc − α(Tc − Tcref) (2) GTc : Irradiance (W/m ) GTcref : Reference irradiance (1000 W/m ) Iscref : Reference condition’s short circuit current (A) α : Curve Fitting Parameter Tc : Condition Temperature Tcref : Reference Temperature (25 C) [Emeksiz* et al., 4(6): June, 2017] ISSN: 234-5197 Impact Factor: 2.715 INTERNATIONAL JOURNAL OF RESEARCH SCIENCE & MANAGEMENT http: // www.ijrsm. com © International Journal of Research Science & Management [80] α = Tcref+273 Tc+273 αref (3) αref : The value of α the reference condition (1000W/m 2 and 25 C) [25], αref = 2Vmpref− Vocref Iscref Iscref−Impref +ln(1− Impref Iscref ) (4) Vmpref : The Reference Condition’s Maximum Power Point Voltage (V) Vocref : The Reference Condition’s Open Circuit Voltage (V) Impref : Maximum Power Point Current At The Reference Condition (A) Diode Saturation Current ( I0) According to variations in cell temperature to calculate the diode saturation current ( I0) is used the following equation [26]; I0 = (Rsh+ Rs)Isc−Voc Rshe ( Voc a VT ) (5)