M. Bouzguenda*1, T. Salmi#2, A. Gastli*3 and A. Masmoudi#4

*Department of Electrical and Computer Engineering, College of Engineering,

Sultan Qaboos University, P.O. Box 33, P.C. 123, Al-Khoudh, Sultanate of Oman. #Research Unit on Renewable Energies and Electric Vehicles,

National Engineering School of Sfax, P.O.B: W, 3038 Sfax, Tunisia. 1buzganda@squ.edu.om 2tarak_sel@yahoo.fr

3gastli@squ.edu.om 4a.masmoudi@enis.rnu.tn

ABSTRACT This paper focuses on the modeling of solar photovoltaic (PV) cell and the performance of typical solar PV panels in selected areas in the Sultanate of Oman. An accurate solar PV cell electrical model is based on the junction diode equations. The model consists of a photo-current current source, a single diode junction and a series resistance, and takes into account temperature and solar irradiation dependence. The model is developed using MATLAB/Simulink and is used to investigate the variation of the maximum power point for different temperatures and solar irradiation levels. Finally, the model is experimentally validated for a typical 30 Watt solar module connected to a variable load.

Index Terms solar irradiation, performance, irradiance, experimental validation, I-V curve, maximum power point, Oman.

1. INTRODUCTION

Worldwide power generation is facing three equally

important issues-increasing oil prices, worsening environmental issues and depleting conventional fossil fuel energy resources. In light of these issues, renewable energy sources, in particular, solar PV and wind are getting more attention around the world and the Middle East.

According to the World Energy Council, the Gulf

Cooperation Council (GCC) needs additional power of 100 GW over the current decade. It is estimated that about $25 billion are needed to develop this additional capacity in GCC [1].

The GCC countries are wealthy in solar irradiation. As

shown in Table 1, the average solar irradiation for solar PV applications ranges between 5.1 and 7.0 kWh/m2/day. For solar rough concentrators, direct solar irradiation ranges between 5.6 and 6.5 kWh/m2/day [1]. In fact, GCC countries are reported to have very good solar energy potential throughout the year [2].

Table 2 lists the GCCs annual and per capita electricity

consumption for 2009 [3]. First, while Saudi Arabia leads the GCC in terms of energy consumption, Kuwait has the highest per capita energy consumption. Second, three countries have the highest per capita energy consumption around the world. The fourth column of Table 2 displays the estimated land required for each country to meet 20% of its

energy consumption using solar PV systems. These values are based on a solar energy conversion efficiency of 10%.

Moreover, GCC countries are reported to contribute

about 45-50 % of Arab countries CO2 emissions [4] and their energy consumption is driven largely by home use. In 2008, almost 47% of the GCCs energy consumption was residential and represented about twice the worldwide average of 25% [5]. Therefore, distributed and residential solar PV systems represent a good alternative to meet residential energy demand and reduce transmission and distribution losses. Several solar PV projects are planned in the GCC area. Recently, Dubai has released plans to build a 48 km2 solar PV facility in phases, over the next 20 years. The planned facility consists of solar PV and concentrated solar thermal and would provide 1000 MW of green power. This facility would make Dubai as one of the worlds greenest metropolitan areas and it is estimated to cost $3.25 billion [6].

The paper is organized as follows. Section 2 deals with

the solar cell modeling using MATLAB/Simulink, followed by the solar cell model simulation. Section 3 covers the modeling of a typical 60-W solar panel performance as a function of ambient temperature and solar irradiation. In Section 4, the experimental validation of the proposed model is carried out for a 30W GE high efficiency solar module. Concluding remarks and future work are presented at the end of the paper.

Evaluating Solar Photovoltaic System Performance using MATLAB

2012 First International Conference on Renewable Energies and Vehicular Technology

978-1-4673-1170-0/12/$31.00 2012 IEEE 55

Table 1. Annual average solar PV resources in the GCC

Country Global Solar Irradiation

(kWh/m2/day)

Direct Solar Irradiation

(kWh/m2/day) Bahrain 6.4 6.5 Kuwait 6.2 6.5 Oman 5.1 6.2 Qatar 5.5 5.6 Saudi Arabia 7.0 6.5 UAE 6.5 6.0

Table 2. Annual energy consumption and land for solar PV

installations in the GCC countries.

Country

Annual electric energy consumption

(GWh)

Per capita electric energy consumption

(kWh)

Land (km2)

Bahrain 10,763 9,214 9.215 Kuwait 42,802 17,610 37.828 Oman 12,198 5,724 13.106 Qatar 18,074 14,421 18.006 Saudi Arabia 174,845 6,856 136.865 UAE 79,544 11,464 67.055

2. SOLAR PV CELL MODELING

A typical PV cell consists of a silicon P-N junction that when exposed to light releases electrons around a closed electrical circuit. The equivalent circuit of the PV cell is shown in Fig. 1 [7].

IL is the photo current generated in the PV cell and depends on the solar irradiation (G).

I is the PV cell output current. Id is the bypass diode current and depends on junction

voltage and the cell reverse saturation current (Io). V is the PV cell output voltage. Rsh is the shunt resistance and it has a large value. Rs is the series resistance and it has a small value.

Figure 1. Solar PV cell equivalent circuit.

The following relationships among the above quantities define the solar cell model:

)1(

11

1

1)(

+

=nkT

qV

SCoT

Toc

eTII (1)

)11(/3

1

11

)( TTnkqV

noTo

g

eTTII

= (2)

nomnomSCL G

GTITI )()( ,11 = (3)

))(1()( 11 TTKTII oLL += (4) ( )shR

sIRVeIII nKTIRVq

oL

S +=

+

)1()

)((

(5)

Where n is the diode quality factor. Ko is the short circuit current temperature coefficient T1 is the reference temperature. T is climate temperature. Vg is band gap energy. k is the Boltzmanns constant. q is the electron charge. VocT1 is the open circuit voltage per cell. ISC is the short circuit current per cell. G is the ambient irradiation. G=1 for 1000 W/m2. Based on equations (1) through (5), a model was

developed and tested using MATLAB/Simulink. The results, shown in Figures 2, 3, 4 and 5, are discussed in the following sections.

2.1 Effects of Solar Irradiation

The influence of the solar irradiation on the solar cell voltage, current and maximum power point is shown in Fig 2. As it can be seen from this figure, more power is delivered from the solar cell as the irradiation level increases. This is due to increase in both the voltage and the current when solar cell is exposed to more irradiation.

a

b

Figure 2. Effects of the solar irradiation on the cell current (a) and power (b).

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2.2 Effects of Temperature

The impacts of the ambient temperature on the current and maximum power output are shown in Fig 3. The increase in the short circuit current and decrease in the open voltage due to temperature rise resulted in overall reduced power output.

2.3 Effects of Series Resistance

The effect of the series resistance RS on the cell power output is shown in Fig. 4. Reducing the series resistance lead to an increase in the power output and a deviation of the maximum power point as well.

2.4 Effects of Diode Reverse Saturation Current

As seen in Fig 5, reducing the diode saturation current increased the open circuit voltage and the maximum power point delivered by the solar cell.

a

b

Figure 3. Effects of the ambient temperature on the cell current (a) and power output (b).

a

b Figure 4. Effects of the series resistance on the cell current (a) and power output (b).

a

b

Figure 5. Effects of the diode reverse saturation current on the cell current (a) and power (b) for G=1000W/m2, Rs=8m, Rsh=10k and T=75oC.

3. PV MODULE MATLAB MODEL

A typical PV module consists of several solar cells connected in parallel and series so as to provide operational voltage and current levels. Based on the solar PV cell model developed in Section 2, a model was built and validated for the Solarex MSX60 module using MATLAB/Simulink for different solar irradiation levels and ambient temperatures. The main characteristics of the Solarex MSX60 module are listed in Table 3. The effects of solar irradiation and ambient temperature are displayed in Figures 6 and 7.

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Table 3. The key specifications for the Solarex MSX60 PV panel [7].

Cell technology polycrystalline Number of cells in series 36 Temperature T 25oC Open circuit voltage VOC 21.00 V Short circuit current ISC 3.74 A Voltage at maximum power VM 17.10 V Current at maximum power IM 3.50 A Maximum power PM 59.90 W

a

b

Figure 6. Effects of solar irradiation on the Solarex MSX60 current (a) and power output (b).

a

b

Figure 7. Effects of the temperature on the Solarex MSX60 current (a) and power output (b).

4. EXPERIMENTAL VALIDATION OF THE PROPOSED MATLAB/SIMULINK MODEL

It is expected that the performance of a given solar PV system depends mainly on the solar irradiation and the temperature. Other parameters such as wind speed, humidity and dust accumulation are important as well and are not undertaken in the study. To experimentally validate the developed Simulink model, a 30-Watt GE high efficiency monocrystalline PV solar module was tested and the results are compared with the simulation results. In the experimental setup, a variable DC load was connected to the solar module. Temperature, solar irradiation, voltage and current are monitored throughout the experiment. The results for the I-V and P-V curves are displayed in Figures 8 and 9, respectively. The discrete data points indicate the experimental values and show excellent agreement with the model shown in solid line.

Accordingly, the developed model can be used as PV generator in SimPower tool for system conversion platform. In addition, the developed model would assist in predicting the performance of PV cells and extracting the internal physical parameters of the solar cell.

Figure 8. The I-V curve for the GE 30 Watt module. The discrete data points indicate the experimental values

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Figure 9. The P-V curve for the GE 30 W Module. The discrete data points indicate the experimental values

5. CONCLUSION

In this paper, the models for solar photovoltaic cell and module have been developed and analyzed for different weather conditions and devices main parameters. The models were validated by constructing the characteristic curves under different scenarios. Finally, the results were compared with the solar cell and module main characteristics given by the manufacturers.

The aim of future work would be to develop a complete

model to simulate the electrical behavior of a PV array and subsequently an entire standalone or grid connected solar PV system.

6. REFERENCES

[1] W. E. Alnaser and N. W. Alnaser, Solar and wind energy potential in GCC countries and some related projects, J. Renewable Sustainable Energy 1, 022301 (2009); doi: 10.1063/1.3076058.

[2] D. Reiche, Energy Policies of Gulf Cooperation Council (GCC) countries-possibilities and limitations of ecological modernization in rentier states, Journal of Energy Policy (May 2010), pp 2395-2403.

[3] World Development Indicators (CD-ROM), IBRD, World Bank, Washington, DC 2010.

[4] M. R. Qader, Electricity Consumption and GHG Emissions in GCC Countries, Energies 2009, 2, 1201-1213; doi:10.3390/en20401201

[5] Deloitte: Middle East Energy and Resources Managing Scarcity for the Future - Energy on Demand-The Future of GCC Energy Efficiency, Nov. 3rd, 2011.

[6] http://www.pv-magazine.com/news/details beitrag/ uae--1-gw-solar-project-launched_100005433/, accessed January 12, 2012.

[7] G. Walker, Evaluating MPPT converter topologies using a Matlab PV model, Journal of Electrical & Electronics Engineering, Australia, Vol.21, No. 1. (2001), pp. 49-56.

[8] J.A. Ramos Hernanz, J.J. Campayo Martn, I. Zamora Belver, J. Larraaga Lesaka, E. Zulueta Guerrero, and E. Puelles Prez, Modelling of Photovoltaic Module, International Conference on Renewable Energies and Power Quality (ICREPQ10), Granada, Spain, March 23-25, 2010.

7. BIOGRAPHIES Mounir Bouzguenda received his B.S. degree in Electrical Engineering the Pennsylvania State University, USA, in 1985. He also received his M.S. and Ph.D. degrees in Electrical Engineering from Virginia Polytechnic Institute and State University, USA in 1988 and 1992, respectively. Dr. Mounir taught in Virginia, Maryland, Tunisia and

Sultanate of Oman. He also worked as a consultant with Standard Technologies Institute, Maryland and Temple Group, Washington DC and Computer Engineering Services, Sfax-Tunisia. Dr. Mounir joined Sultan Qaboos University-Oman as an Associate Professor in 2009. Currently, he is teaching in the Electrical and Computer Engineering. His research interests include smart grid, renewable energy systems, power systems and power electronics. He has authored and co-authored many technical papers in these areas.

Tarak Salmi was born in Kairouan in Tunisia, on September 2, 1975. He graduated from Nasrallah Secondary School, Kairouan, and studied at the University Sfax. His special fields of interest include Power Electronics and Photovoltaic Systems. Tarak received the B.S. degree from Tunis University of Sciences in 2000 and the MS degree from Monastir

University of Sciences in 2007. Currently, he is pursuing his Ph.D. at the National Engineering School of Sfax (ENIS) in Tunisia.

Adel Gastli received the B.Sc. degree in Electrical Engineering from National School of Engineers of Tunis, Tunisia in 1985. He worked two year in the standardization and certification of electric products in Tunisia. He received the M.Sc. and Ph.D. degrees from Nagoya Institute of Technology, Japan in 1990 and 1993 respectively. He joined the R&D Department at Inazawa

Works (elevators and escalators) of Mitsubishi Electric Corporation in Japan from April 1993 to Aug. 1995. He joined Sultan Qaboos University in Aug. 1995. He is currently a Professor of Electrical Engineering at Sultan Qaboos University, Muscat, Oman. He has established, in 2003, the Renewable and Sustainable Energy Research Group (RASERG) at Sultan Qaboos University and served as RASERG coordinator since then. He has authored and co-authored more than 80 papers. His current research interests include electrical machines, power electronics, drives, as well as renewable energy.

Ahmed Masmoudi received the BS degree from Sfax Engineering School (SES), University of Sfax, Tunisia, in 1984, the PhD from Pierre and Marie Curie University, Paris, France, in 1994, and the Research Management Ability degree from SES, in 2001, all in Electrical Engineering. In 1988, he joined the Tunisian University where he held different positions involved in both education and research activities. He is

currently a Professor of Electric Power Engineering at SES. Ahmed Masmoudi is the Manager of the Research Unit on Renewable Energies and Electric Vehicles. He is the Editor in Chief of the Transactions on Systems, Signals and Devices (TSSD), issues on Power Electrical Systems, published by Shaker-Verlag, Germany. He is the Program Committee Chairman of the International Conference and Exhibition on Ecological Vehicles and Renewable Energies (EVER), held every year in Monaco, since 2006. He is a senior member IEEE. Ahmed Masmoudi is the author and co-author of more than 70 journal papers among which three are published in the IEEE Transactions on Magnetics. He is the co-inventor of a US patent. His main interests are focused towards the design of new topologies of electrical machines and the implementation of advanced, efficient and robust control strategies in electrical machine drives and generators, applied in automotive as well as in renewable energy systems.

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