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1 Modelling of Photovoltaic using MATLAB/SIMULINK Varuni Agarwal M.Tech (Student), Dit University Electrical and Electronics Department Dr.Gagan Singh Hod,Dit University Electrical and Electronics Department ABSTRACT- Due to the increasing demand of energy there is a need of power generation using renewable energy. Solar energy is essential source of renewable energy available in abundance. In this paper modelling of PV(photovoltaic)array is developed which can be used by researchers who need a simple, accurate and versatile model of PV system for further studies. The model is implemented using MATLAB/simulink software.the proposed model is to find the characteristics at different atmospheric conditions (i.e. solar irradiance and temperature). Keywords-array,PV module, MATLAB/simulink. INTRODUCTION Due to the limitations of global resources of fossil, instability in oil prices, there is a increasing demand of renewable energy resources. Solar energy is one of the most essential resource because of its availability in abundance and sustainability of solar radiant energy [1].The Photovoltaic system works on the principle of photoelectric effect which was introduced by French scientist Edmund Becquerel in Further in 1905,albert Einstein explained the nature of light and the photoelectric effect. PV panel- A set of connected PV cell forms a PV panel. Panels are composed of series cells to obtain output current and output current is achieved by connecting a PV cells in parallel.[3] PV array- A panel or set of panels are connected in series or parallel to form large PV system.[3] WORKING OF A PV CELL A Photovoltaic cell is a semiconductor diode whose p-n junctions are exposed to sunlight. Silicon PV cells are composed of a thin layer of bulk Si or a thin Si film connected to electrical terminals. The basic principle behind the operation of PV cell is photoelectric effect. In this effect when sunlight hits the surface of the p-n junction electrons gets ejected from the conduction band as a result of absorption of sunlight of a certain wavelength by the matter. The electrons from valence band jump to the conduction band when absorbed energy is greater than the band gap energy of the semiconductor [1]. The electronhole pairs created in the illuminated region of the semiconductor.the electrons created in the conduction band are free to move. These free electrons are enforced to move in a particular direction by the action of electric field present in the PV cells. MAIN TERMS PV cell-a PV device is an element that converts sunlight into electricity. The elementary PV device is called PV cell.[3] ISSN: Page 465

2 LIGHT The practical PV device has a series resistance whose influence is stronger when the device operates in voltage source region and for current source region parallel METAL GRID N P METAL BASE resistance is used. resistance is sum of several resistance. It depends on the contact resistance of metal base with p semiconductor layer,resistance of p-n junction bodies,the contact resistance of the n layer with top layer of the n layer with top grid and the resistance of grid[2]. resistance exists due to the leakage current of the FIG 1 PHYSICAL STRUCTURE OF A PV CELL p-n junction. Generally is high and is low. The I-V characteristics of a practical PV device is given as fig 3. These electrons flowing comprises current and can be drawn for external use by connecting metal grid on top and bottom of the semiconductor. The rate of generation of electric current depends on the flux of the incident and the capacity of absorption of the semiconductor. The capacity of absorption depends on the semiconductor band gap, on the reflectance of the cell surface, on intrinsic concentration of carrier of the semiconductor, on the electron mobility, on the recombination rate, on the temperature and other factors. This current and voltage produces required power. MODELLING AND DESIGN OF A PV CELL Fig 2 shows the equivalent circuit of the practical PV device including the series and parallel resistance.[1] Fig 3 characteristics I-V curve of a practical PV deevice The above curve represents the I-V characteristics of a practical PV device which shows three remarkable points:open circuit (,0).short circuit (0, ),MPP (, ) According to circuit in fig 2 kirchhoff s law is applied to present the photovoltaic current [1]..[1].[2] Fig2 equivalent circuit of PV cell Where is the light generated current by incident light, is the reverse saturation current, k is Boltzmann s constant(1.38* J/K),T is the temperature of the p-n junction,a is the ideality factor. The photocurrent depends on the solar irradiation and cell temperature is given as ISSN: Page 466

3 [3] The I-V and P-V output characteristics of PV model is shown in fig 4 and fig 5.depend on the solar irradiation and Where is the temperature coefficient of cells short temperature and cells operating voltage. circuit current, is the cells nominal temperature, is the light generated current at nominal temperature(25 & 1000w/m2)...[4] where is the thermal voltage of the connected cell at nominal temperature[4]. is the voltage coefficient. In this study, a general PV model is implemented using MATLAB/SIMULINK. In this model inputs are the solar irradiation and temperature and outputs are photovoltaic voltage and current. Fig 4 power v/s voltage SIMULATIONS RESULTS AND DISCUSSIONS The major inputs in the PV model are solar irradiation and temperature and experimental data is taken from kc200gt at nominal operating conditions[2]. The I-v characteristics is shown in fig 5 by which we can find the three remarkable points. parameters of the PV model at nominal operating conditions PARAMETER VALUE G amp 8.21amp W T 298K 32.9V 26.3V Fig 5 current v/s voltage Simulation results of PV array for varying load conditions Fig6 to fig9 shows the output characteristics of PV model at different load conditions ISSN: Page 467

4 From the above characteristics it was found that with an increase in solar radiation there is an increase in both the maximum power output and the short circuit current.on the other hand, we observe that with an increase in cell temperature,the maximum power output decreases while the short circuit current increases. CONCLUSION Fig 6 current v/s voltage at G=800 In this paper mathematical model of PV array is analysed using MATLAB/SIMULINK. The power of PV array is dependent on solar radiation. The objective of the model is to study the I-V and P-V characteristics of PV array for different solar radiation and temperature. And remarkable points are also shown and discussed. The proposed model is to find the maximum power point to track the maximum power available. REFERENCES Fig 7 current v/s voltage at T=50 [1] Marcelo gradella villalva, Jonas Rafael Gazoli, and Ernesto Ruppert Filho, comprehensive appraoach to modelling and simulation of photovoltaic arrays,vol.2,no.5,may [2]E.M.Natsheh,Member,IEEE,AAlbarbar,Member,IEEE,a nd J. Yazdani,Member,IEEE, Modelling and control for smart grid integration of solar/wind energy conversion system. [3] IEEE standars definitions of terms for solar cells,1969. Fig 8 power v/s voltage at G=800 Fig 9 power v/s voltage at T=50 [4]S.Chowdhary,G.ATaylor,S.P.Chowdhary,A.K.Saha,and Y.H.Song, modelling, simulation and performance analysis of a PV array in an embedded environment, in Pro.42 nd Int. Uni. Power Eng.Conf(UPEC),2007,pp [5]Rajesh.K, Kailash Krishna Prasad.B"Hardware Realization of Single Axis Solar Tracking System by Using a Cost Effective Microcontroller", International Journal of Engineering Trends and Technology (IJETT), V23(7), May ISSN: ISSN: Page 468

5 [6]Biren Gevaria and Khushbu Shah, Simulation and Prototyping of Microcontroller Based Maximum Power Point Tracking of PV Array, International Journal of Engineering Trends and Technology (IJETT) Volume 21 Number 7 March [7]Kailash Krishna Prasad.B"Analysis and Design of Distributed MPPT System Suitable for Non-Uniform Solar Irradiation", International Journal of Engineering Trends and Technology (IJETT), V22(9), April ISSN: ISSN: Page 469