suresh than a kod imf ke 2009

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MODELING AND SIMULATION OF GRID CONNECTED PHOTOVOLTAIC

SYSTEM USING MATLAB / SIMULINK

SURESH A/L THANAKODI

A project report submitted in fulfilment of therequirements for the award of the degree of

Master of Engineering (Electrical-Power)

Faculty of Electrical Engineering

Universiti Teknologi Malaysia

NOVEMBER 2009


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Dedicated with deep gratitude feeling to Paramahamsa Nithyananda

The embodiment of all the existential and non-existential energy

That ever guiding the path towards enlightenment in blissful


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ACKNOWLEDGEMENT

In the name of God, the world begins and so this master project, hence to HIM

the Most Blissful I would like to extend my gratitude. With HIS help, guidance and

permission this master project came to existence. Thank you againNithyananda

(Eternal Bliss). I also would like to use this space to extend my gratitude to those that

had rendered help, guidance, moral support and prayers in championing this project.

I would like to dedicate my appreciation to my supervisor Assoc.Prof

Md.Shah Majid to accept me as a student and also not forgetting Puan Hjh Hasimah

Abd Rahman whom had been there always to guide me and provide me with plenty ofinputs in order to achieve better results in this project. Thank you again to both of

them from bottom of the heart.

My sincere thank you to my parents, family members and also to those very

close to my heart. Without their guidance and support, I would not have made this far

in my life. Every moment with them will be cherished and also motivates me to go

further into a new dimension in this life. Thank you again to all my family members

including nithyananda family members.

Last but not least, I would like to express my gratitude to all my lecturers, to

all my friends including faculty staff and Meteorological department especially

Pn.Zureen Norhaizatul Che Hassan to made this project possible.

Thank you again


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ABSTRACT

Photovoltaic System is a huge topic that can be researched and studied on

such as the arrangement of PV array is one of the issues that can be studied. Besides

that, the control techniques can as well be delved into. Another important area that

makes concern to the PV world would be the maximum power point tracker (MPPT)

for PV to maximize the sun energy, and so many more can be said in these advanced

millennia. Yet in this research work, the scope has to be scaled down in appreciation

to the given time. This research project would mainly concern on the different PV

technologies (amorphous silicon, polycrystalline) and their effect to the system interms of energy output. Besides that, this project work would be designed nearly to

the BIPV-PTM projects that have been implemented in Malaysia in order to verify

the energy output results from the modeling and simulation activities. The project

works will emphasis on Malaysias temperature and solar radiation. On the other

hand, having so much respect to the given time, the grid connected PV system

modeling may not have protection system to be included in the design and only the

best inverter model would be chosen for the simulation purpose. Overall findings

indicate that the modeling using MATLAB / SIMULINK can be further used for

investigation and make improvement in order to identify which best technologies to

be implemented. The polycrystalline PV System yields higher energy output

compared to the amorphous silicon technology is another finding thru this project.


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ABSTRAK

Sistem Fotovoltaik merupakan satu tajuk besar yang boleh dikaji dan

dipelajari dari pelbagai aspek seperti jenis susunan panel, cara pengawalan dan

sebagainya. Disamping itu, penemuan dalam sistem penjejakan titik operasi maksima

(MPPT) turut menyumbang kepada perkembangan sistem fotovoltaik ini. Namun

begitu, projek ini hanya membincangkan perbezaan teknologi fotovoltaik(amorphous

silicon, polycrystalline) dan impaknya terhadap penghasilan tenaga elektrik. Projek

ini juga dimodelkan serupa dengan projek yang telah dibangunkan oleh Pusat Tenaga

Malaysia (PTM) secara praktikal melalui projek Sistem Bangunan BerintegrasikanSistem Fotovoltaik.(BIPV). Tujuan pemodelan sebegini adalah untuk menentusahkan

tenaga elektrik yang dijana melalui pemodelan sistem. Projek ini memberi penekanan

kepada suhu dan radiasi solar Malaysia. Sistem perlindungan tidak diberi penekanan

dalam projek ini dan penyongsang terbaik dipilih dalam aktiviti pemodelan ini.

Secara amnya, melalui projek ini, didapati pemodelan menggunakan perisian

MATLAB / SIMULINK, amat relevan dan boleh diguna pakai serta ditambah baik

untuk mengenalpasti teknologi fotovoltaik yang sesuai diimplemen di Malaysia.

Melalui projek ini juga, didapati teknologipolycrystalline menjana tenaga elektrik

yang tinggi berbanding dengan teknologiamorphous silicon.


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TABLE OF CONTENT

CHAPTER TITLE PAGE

STUDENT DECLARATION ii

DEDICATION iii

ACKNOWLEDGEMENT iv

ABSTRACT v

ABSTRAK vi

TABLE OF CONTENT vii

LIST OF TABLES ix

LIST OF FIGURES xi

LIST OF SYMBOLS xvii

1 INTRODUCTION 1

1.1 Project Background 1

1.2 Research Objective 4

1.3 Research Scope 5

1.4 Methodology 6

1.6 Thesis Outline 10

2 LITERATURE REVIEW 11

2.1 Malaysias Next Potential Energy 12

2.2 Different technology of Photovoltaics 14

2.3 Electrical Equivalent of Solar Cells 19

2.4 Grid Connected PV System 24


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2.5 Solar Cell and its Characteristics 26

2.6 Converters and Inverters 34

2.7 Related Works 39

3. MODELING USING MATLAB / SIMULINK 44

3.1 Introduction 44

3.2 Building the Mathematical Modeling and Circuit 46

4. SIMULATION RESULTS AND DISCUSSION 56

4.1 Introduction 56

4.2 Simulation of Single Junction and Verification 58

4.3 Case Study 1 63

4.4 Case Study 2 66

5. CONCLUSION AND DISCUSSION 70

5.1 Introduction 70

5.2 Summary 70

5.3 Suggestion 71

REFERENCES 73


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LIST OF TABLES

TABLE NO. TITLE PAGE

2.1 Summarize the different technology in

Thin Film technology 14

2.2 PV module characteristic for standard technologies 32

2.3 The Switches State for a full bridge single phase inverters 39

4.1 Details of Case Study 1 63

4.2 Energy Output with = 0.45 64



4.5 Details of Case Study 2 67



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4.8 Table 4.8: Energy Output with = 0.55 69


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LIST OF FIGURES

FIGURE NO. TITLE PAGE

1.0 Methodology Flow Chart 7

1.1 Flow Chart for Literature Review 8

1.2 Flow Chart on Simulation 9

2.0 Map of Solar Irradiation for Malaysia 12

2.1 Resources Energy Trend 13

2.2(a) Single junction amorphous 14

2.2(b) Cells deposited onto a glass sheet are laterally

connected in series 14

2.3 Multiple-junction stacked or tandem solar cells where

two or more current-matched cells are stacked on top of

one another 15

2.4(a) Mixed-phase microcrystalline/amorphous material 16


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2.18 CharacteristicI-Vcurve of the photovoltaic cell 27

2.19(a) Characteristic shown on the influence of ambient

irradiation 28

2.19(b) Characteristic shown on the influence of cell temperature 28

2.20(a) TheI-Vcurve responses with two identical cells

connected in series 29

2.20(b) TheI-Vcurve responses with two identical cells

connected in parallel 29

2.21 Electrical characteristics of Sharp NE-80EJEA solar cell 31

2.22 Electrical characteristics of Sharp NE-80EJEA solar cell 31

2.23 The Schematic of a Buck Converter 35

2.24 Connection of Inverter 37

2.25 Fullbridge Voltage Source Inverter 38

2.26 Equivalent circuit models of PV cell 40

3.1 First stage in modeling the solar cell 45

3.2 Second stage in modeling the solar cell 45


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3.3 Third stage in modeling the solar cell 46

3.4 Parameter for resistor block 47

3.5 Mathematical Modeling Implementation for Io 48

3.6 Mathematical Modeling Implementation for Ipv 48

3.7 Mathematical Modeling Implementation for

model current Im 49

3.8 Mathematical model for cell temperature (Tc) 50

3.9 The cell temperature block after subsystem process 50

3.10 An Example of the menu after Mask Process 51

3.11 PV array modeling 51

3.12 Circuitry Design for PV 52

3.13 Mask of PV Array 52

3.14 The PV Menu after Mask Process 53

3.15 The energy block and after masking process 54

3.16 The Menu of the energy block 54


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3.17 The Whole PV System with Load 55

4.1 Setting the Simulation Parameter 57

4.2 Configuring the simulation parameter 57

4.3 The I-V curve from BP Solar MSX-60 datasheet 58

4.4 Simulation Output when the Tc = 0 C and Sx = 1kW/m2 59

4.5 Simulation Output when the Tc = 25 C

and Sx = 1kW/m2 59

4.6 Simulation Output when the Tc = 50 Cand Sx = 1kW/m

2 60


and Sx = 1kW/m2 61


and Sx = 0.4kW/m2 61


and Sx = 0.6kW/m2

61




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LIST OF SYMBOLS

PV - Photovoltaic

TNB - Tenaga Nasional Berhad

PTM - Pusat Tenaga Malaysia

BIPV - Building Integrated Photovoltaic System

kWp - kilowatt peak

kWh - kilowatt hour

d.c - direct current

a.c - alternating currentr - PV module efficiency at reference temperature (Tr= 25

oC)

p - Temperature coefficient for module efficiency (% /oC)

Tc - Surrounding Temperature

Tr - Reference Temperature (25oC)

Tr - Reference Temperature (25oC)


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CHAPTER I

INTRODUCTION

1.1 Project Background

Photovoltaic System (PV) is getting popular by day as the crude oil price

increases and unstable in the global market. Furthermore with green peace movement,

and the consciousness of mankind has heightened up regarding green energy,

photovoltaic maybe one of the solution for better as well cleaner energy as it is

naturally harness from the Sun energy. Although the technology is mainly well

known in the space mission, yet its still an alien for domestic usages. This is due to

the high initial cost, generation efficiency and reliability [1]. On the other hand, to

answer the cry for alternative energy has made the PV system again popular among

the researchers. Having said so, the rural areas where the grid connection is extremely

expensive, PV Systems have been implied to give hope to these areas, while for the

urban life, the PV Water Heater is common and can be found on the roof of the

houses.

Currently, more than 3500MW of photovoltaic system have been installed all

over the world [2]. Referring to the results from Earth Policy Institute (EPI), the


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world production of solar PV cells increased 32% in 2003, compared to the most

recent 5-year average of 27% a year. Production increased to 742 MW, with

cumulative global production at 3145 MW at the end of year 2003, enough to meet

the electricity niche of one million homes. Referring to the EPI, this extraordinary

growth is driven to some degree by improvements in materials and technology, but

primarily by market introduction programs and government incentives [2].This fact

can clearly conclude that this solar energy (photovoltaic) is a very promising as next

generation energy source.

On the other hand, in Malaysia there are plenty of sectors join hands inpromoting the photovoltaic including the government as well with the private sectors.

Some of the projects are pilot project by TNB (Tenaga Nasional Berhad) whereby 6

pilot plants was installed during 1998 2001 in various places in Malaysia such as in

Uniten, Port Dickson and Subang Jaya [3]. Pusat Tenaga Malaysia (PTM) is another

building integrated with photovoltaics, using polycrystalline (47.28kWh) and

amorphous (6.08kWh) [3]. This is inevitable evidence that shows solar energy is one

of the practical renewable energy sources for Malaysia.

In this context, lots of research needs to be done in order to achieve a reliable

and efficient energy. Looking at the grid connected system, whereby the system

mainly consists of photovoltaic (PV) modules, inverter, battery, and switching point

for the utility [4]. Different types of photovoltaic cell will yield different energy

output, meanwhile the controlling technique of inverter is very crucial in

championing the PV system. Inverter design should consider the size and capacity of

the plant, on the other hand choosing the right controlling technique is needed as well

in order to achieve an efficient renewable energy system.

There are many types of inverter used in converting the direct current (d.c)

produced by the PV to alternating current (a.c). The conversion is a must in order to

suit the AC grid system that have been implemented and practiced for so long. Some

of the types that can be used are multilevel inverters such as flyback capacitor, neutral


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point clamped multilevel inverter, diode clamped inverter and many more. Each

topology has its own plus point and drawbacks depending on the usage of it.

Applying certain controlling techniques to the inverters such as Pulse Width

Modulation (PWM), Space Vector Pulse Width Modulation (SVPWM), Step

Modulation etc, the efficiency of the conversion can be obtain up to an optimum

level. Hence this is another part for research in the PV Grid-Connected system.

On the other hand, there are many types of technology used in producing the

photovoltaic cell, such as using the Silicon Photovoltaic (crystalline silicon,

nanocrystalline), Thin Film solar cells (amorphous silicon, cadmium telluride,gallium arsenide, copper indium gallium deselenide) and Concentrating Photovoltaic

(multijunction cells) [5]. As said above, the different types and topologies of

photovoltaic gives different energy output, such as the amorphous silicon typically

efficiency is 6%-8%, while multicrystalline is 11% - 14%, and mono-crystalline is

12% - 17%, etc [6]. Hence in this work, the major part of research will be a study on

the impact of the different topologies of PV cells on the energy output generated.

Besides that, its a common knowledge that, the PV system has different

seasonal pattern behavior depending on the temperature as well as the solar

irradiation. Due to the different temperature co-efficient of voltage and current the PV

system has different output. Yet, to simplify the work of manufacturer mostly, the PV

modules are rated at STC (standard test conditions) of solar irradiation as 1000 Wm-2,

while the spectrum is fixed and related to a sun-spectrum at air mass of 1.5 (AM =

1.5). The STC temperature operating for the PV cell is at 25oC which does not relate

to the practical world especially to Malaysia. Hence this project aims to have some

practical simulation work to suit to Malaysian tropical weather and climate.

In promoting, grid connected photovoltaic system by building integrated

photovoltaic system (BIPV) the Malaysian government has been very supportive via

Malaysian Industrial Development Authority (MIDA) in terms of tax holiday,

industry park and many more incentives. Besides that competitive electricity tariff


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(USD 4-6 cents / kWh) is another plus point in the blooming of PV system industry.

Political and economic stability in Malaysia act as a catalyst for this new industry [7].

As a conclusion, its worthwhile to research on this photovoltaic system as it

is the next generation energy source, while its green and promotes to cleaner world.

On top of that, this research work is in line with the government aspiration on

becoming a greener nation with a renewable energy source. This in return will mark

Malaysia another step higher in the eyes of the world. Impact of different topologies

and technology of PV will be the main concern on this research work. Although the

single cell and multijunction solar types have different energy output in various

technology, yet the research in terms of comparison have to be conduct in finding theadvantages and disadvantages of the system as well the behavior of the system to the

Malaysian climate. These are the issues pertaining to this research work.

1.2 Research Objective

Following are the objectives that hopefully to be achieved at the end of this

project implementation. Those objectives are:-

To study solar cell circuit model

To model and simulate a single junction solar cell

To determine energy output of different PV technologies.


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1.3 Research Scopes

In accomplishing this research, the work has been divided into few parts. As

for the beginning part, the literature review on the photovoltaic theory, topology and

its operation as well grid-connected PV system will be glanced thru to have a better

understanding on the system as a whole. On the second stage after the understanding

of theory, modeling and building up the equivalent electrical circuit shall commence

at once. As to mark the end of the work, the simulation result using the single

junction cell will be used to determine the energy output (kWh) using the inputparameters temperature and solar radiation obtained from Malaysian Meteorological

Data (MMD).

As mention above the general scope and flow of this research work, the single

cell PV shall be modeled first and simulated. Then it will be verified using the I-V

curve of a manufacturers data sheet. After all the verification process done, the

modeling part for Malaysian context shall be done and analyzed.

In this work, PV cells from amorphous silicon and polycrystalline silicon

types will be used. The first one represents the thin film technology and the later part

the silicon technology. These technologies will the major research on this project. The

simulation later part will be done to Malaysian solar irradiation and temperature

value.

As for the accomplishment of this project, the project will be extended up to

the verification thru actual monitored Malaysian Building Integrated Photovoltaic

(MBIPV) system.


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1.4 Methodology

The approach that has been applied in championing this project can be divided

into two major segments. The first segment is the literature review and the second

part is on the circuitry modeling and simulation. In the beginning, the literature

review will help to understand the photovoltaic cell by understanding their types, and

identifying all the PV system components. Then literature part will continue as the

studies will be extended to different technology of single cell for amorphous and

polycrystalline cells.

Later on the literature review continues up to grid components as well studies

on the inverter models for the grid conducted concurrently. On the other hand, the

meteorological data is also gathered in order to make this research work to be

contextualized for Malaysian environment. Site visiting to MBIPV is also part of the

literature review as well to gather data for the literature review on the simulation

software also done in order to be able to use the software effectively.

On the second part, the single junction cell will be simulated and verified thru

manufacturer data sheet using I-V curve. After all verification successfully done, the

modeling and simulation part for inverter shall take place. After all the major

components of grid connected PV successfully done, the component shall be

interconnected and simulated to the Malaysian context. After completion of the

system simulation, using few bench marks the results will be analyzed. Following are

the summarized flow chart on this project.


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Figure 1.0: Methodology Flow Chart


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Figure 1.1: Flow Chart for Literature Review


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Figure 1.2: Flow Chart on Simulation


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1.5 Thesis Outline

This theses will is a compilation of many chapters that will elaborate in stages

the research work that have been carried out. As in general this theses mainly consist

of five main chapters; introduction, literature review, circuitry buildings and

simulation using MATLAB / SIMULINK software, simulation results analysis and

conclusion.

In chapter I, this thesis will discuss the research project in collectively. Thischapter explained the crucial aspect of the research work such as background studies,

objectives, research scopes, and methodology as well the thesis outline will also be

discussed finally.

Chapter II completely dedicated to literature review about the grid connected

PV system. This chapter will be solely theoretical in detail discussing on the types

photovoltaic cell, inverters, and the whole system about it. In this academic scribbling

some of the controlling techniques for inverters will be discussed as well. In this

section the related works also will be discussed.

Chapter III will be explaining on how the circuit modeling being development

using the MATLAB / SIMULINK. The single cell for both amorphous and

polycrystalline will be developed first. All the components used in building the

models shall be included as well to add value in the academia world.

Chapter IV will be discussion in depth on the obtain simulation results. The

result will be analyzed in terms of energy output and also verification using the online

monitored data gathered from Malaysian Building Integrated Photovoltaic (MBPIV).

Conclusion and suggestion in improvising this research work shall be detailed

out in Chapter V.


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CHAPTER II

LITERATURE REVIEW

Thru this chapter, hopefully it will give some idea to the reader regarding the

different technologies of photovoltaic cells and different modeling techniques as well.

Besides that, basic concepts regarding photovoltaic will be reviewed as well as the

power electronics converters. On the other hand, the inverters and grid connected PV

system also shall be discussed. In addition, related works regarding to this research

project work also will be conferred in depth. Its an honor to be the medium of

knowledge manifestation from the universe.


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2.1 Malaysias Next Potential Energy

Before cruising any point beyond this, it would be very crucial; to know that

solar can be identified as a next potential energy for Malaysia. Malaysias

geographical factor as it lies in the tropical region between 1N and 7N, and 100E

and 119E makes it possible to have approximately 6 hours of sunshine per day [11].

The temperature is hot and humid throughout the year with heavy rainfall. with the

range of rainfall is 2032-2540mm, temperature 21-32C, relative humidity 80-90%,

solar radiation 12-20 MJ/m2 and wind speed 2-22 m/s is very suitable and feasible

condition to capture solar energy for the electricity usage [11].

Figure 2.0: Map of Solar Irradiation for Malaysia [7]

According to a research done by National University Malaysia, the Ultra-

violet radiation pattern in Malaysia has been divided to five types as stated below

Sunshine everyday

Cloud or Rain everyday

Cloud pattern is not stable everyday

Rain in the evening

UV radiation is more than UV constant


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As such the same study also stated that ultra-violet pattern in Malaysia for

sunshine 15.7%, rain 13.7%, cloudy 51%, rain in the evening 16.5% and ultra-violet

radiation more than ultra-violet constant are 2.8%. Having said so, the potential of PV

system application at Malaysia is very high. Currently, there many Building

Integrated Photovoltaic Systems (BIPV) projects are being carried out thru Malaysia.

Some of the projects are:-

Pusat Tenaga Malaysia (PTM ZEO)

SMK (P) Sri Aman Petaling Jaya

Monash University

Figure 2.1: Resources Energy Trend [12]

From Figure 2.1, it can clearly deduce that the natural sources are depleting in

years to come and this eventually results on the cost of energy production. It can also

clearly see the trend moves towards renewable energy especially on photovoltaic

system. Hence, as a conclusion, the photovoltaic system can be the next best energy

source for Malaysia.


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2.2 Different technology of Photovoltaics

There are many types of technology in thin film photovoltaic technology. For

an example in this thin film technology there is Silicon based and Chalcogenide-

based cells. Table 2.1 shows the summary of the types that shall be discussed in this

topic.

Table 2.1 Summarize the different technology in Thin Film technology

Thin Film Technologies

Silicon based Chalcogenide-based cells

Single junction amorphous silicon Cadmium Sulphite (CdS)

Multiple junction amorphous silicon Cadmium Telluride (CdTe)

Crystalline Silicon on Glass Copper Indium deselenide (CIS)

In the thin film technology it can be divided into two major parts which is

silicon based and chalcogenide based. As for beginning look at silicon based which

consists of single junction amorphous silicon, multiple junction amorphous silicon

and crystalline silicon on glass. Below in Figure 2.2 (a) is the single junction

amorphous silicon and Figure 2.2 (b) is the individual cells deposited onto a glass

sheet are laterally connected in series by the approach shown [8].

Figure 2.2 (a): Single junction amorphous, Figure 2.2 (b): Cells deposited onto a glass

sheet are laterally connected in series


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In the early 1980s the calculators and digital watches have been using the

amorphous silicon solar. At that time, many efforts were carried out but currently

Kaneka and Mitsubishi are the companies that successfully supplies single junction

amorphous silicon [8]. This is due to its characteristics that in the low temperature the

amorphous silicon allows 10% hydrogen to be incorporated. Quality of the material is

improved in the presence of the hydrogen atom [8]. The amorphous silicon is not very

conductive hence the transparent conductive tin oxide layer between the silicon and

the glass being used and connected in series as depicted in Figure 2.2(b)[8].

The next is the multiple junction amorphous silicon devices, where it isdesigned in thinner layers to accommodate the decreased material quality under light

exposure such as in single junction amorphous. Its made possible by stacking two or

more cells on top of one and another as in Figure 2.3. In effort to boost its

performance the upper cells bandgap is made larger compared to the lower cells [8].

Figure 2.3: Multiple-junction stacked or tandem solar cells where two or more

current-matched cells are stacked on top of one another

As discussed above, by increasing the bandgap of the uppercell theres a

change in performance and the earliest effort made in reducing the bandgap by

alloying it with germanium. This result in the performance was around the 67%

range, compared to the best of the single junction amorphous silicon (a-Si). Currently


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theres another way of doing it whereby an a-Si as top cell combined with a bottom

cell which consists a mixture of amorphous and microcrystalline as in Figure 2.4.

This technology can improve the performance by 8-10%. This cell is still in small

scale and hasnt been commercialized yet. [8]

Figure 2.4 (a): Mixed-phase microcrystalline/amorphous material;

Figure 2.4(b): Single-phase polycrystalline film

Another type of solar cell is crystalline silicon on glass as depicted in Figure

2.5 whereby this technology uses high temperature to transform the amorphous

silicon material to polycrystalline. This technology has some similarity with the

polycrystalline wafer. The advantage of this technology is that the material is more

conductive and theres no need for a transparent conducting oxide that results in cost

reduction. The instability possessed by a-Si is also solved using this material [8]. The

glass texture is also another plus point in this technology as it allows the silicon layer

to be very thin.


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Figure 2.5: Crystalline silicon on glass (CSG) unit cell structure.

A fault tolerant metallization approach and the use of higher grade

borosilicate float glass compared to the soda-lime glass have improved the

ruggedness in the CSG technology compared to the module.

Earlier the discussions were on the silicon based, now lets have a preview on

the Chalcogenide-based cells. The Chalcogenide-based cells kick off with the

cadmium sulphite technology in the early 1980s. Yet this technology was beat down

by the biggest contender at the time; amorphous silicon. Besides that, the instability

issue with cadmium sulphite was another major issue. When the amorphous silicon

was going thru dark ages as it had problem with commercialization, this technology

had a good time and became famous.

BP solar and Matsushita were manufacturing Cadmium Telluride solar cell

and then later move on to other technology due to environmental issues. The toxicity

of cadmium was one of the reasons. A layer of cadmium sulphide is deposited from

solution onto a glass sheet coated with a transparent conducting layer of tin oxide.

This is followed by the deposition of the main cadmium telluride cell by as variety of

techniques including close-spaced sublimation, vapour transport, chemical spraying,

or electroplating.[8]. The cadmium telluride structure has been depicted in Figure 2.6.


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Figure 2.6: Device schematic for a cadmium telluride cell

Copper Indium diselenide known as CIS technology has demonstrated 19.5%

efficiency in experiments yet its hard to commercialize. CIS technology generally

involves deposition onto a glass substrate and then interconnected as in Figure 2.7

[8]. An additional glass top-cover is then laminated to the cell/substrate combination.

Research are being conducted in order to replace the thin layer of CdS as many

environmental controversy issues submerged as noted earlier. Yet the CIS technology

is one of available resources as reserves of indium would only produce enough solarcells to provide a capacity equal to all present wind generators [8].

Figure 2.7: Basic CIS (copper indium diselenide) cell structure


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2.3 Electrical Equivalent of Solar Cells

Earlier in sub topic 2.2 the discussion were about types of solar cells in terms

of materials, but in this sub topic the discussion will be on the solar cell equivalent

electrical circuits and their mathematical equations in depth. Before going deep in the

topic, lets have some basic on how the solar cell works. As discussed earlier since

the solar cell are made of specially treated silicon whereby positive (on the backside)

while the negative part (facing the sun), when the sun light (radiation) hits the solar

cell, the electrons gets excited and loose creating the electron-hole pairs [9].

This phenomena when extended by attaching the electrical wires on positive

and negative part creating a close loop while then results in current flows which

known as electric photocurrent (IPH). This is clearly shown in Figure 2.8 courtesy of

PV Industry Hand Book by PTM.

Figure 2.8: Summary on how solar cells work (courtesy from Pusat Tenaga Malaysia)

As for the kick start, the understanding on the operation and electrical

equivalent circuit of single solar cell will be discussed. Referring to Figure 2.9,

without the sun light (dark), the solar cell shall function as a normal diode. If any

external supply connects to it, the solar cell will function and produce the diode

current (ID). In the dark, the solar cell will not produce any electric current or voltage.

This solar cell model consists of a current source (Iph), series resistance (Rs) which


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representing the resistance inside the each cell as well in the connection between the

cells, and a diode [9]. The difference between Iph and ID will give the net current

output from the solar cell.

Figure 2.9: Model for single solar cell

The mathematical equation can be represented as in equation 2.1. The

equation is actually using Kirchhoff Current Law (KCL) and also diode Shockley

equation. The m is the representation of idealizing factor, kBoltzmans gas constant,

Tc will be absolute temperature of the cell, e will be electric charge, andVwill be the

voltage implied across the cell. Io is saturation current in dark surroundings and

depends on the temperature [9].

(2.1)

The solar cell has certain parameters, such as short circuit current, open circuit

voltage, maximum power point, maximum efficiency, and fill factor. Short circuit

current is the best current produced when the solar cell under short circuited situation

which means the voltage as zero. In other word Isc = Iph. Then another parameter of

solar cell is open circuit voltage. This open circuit voltage can be obtained during

night time (dark) whereby the current produced is zero and related to voltage drop

across the diode.

Ipv


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It can also represented by mathematical equation such as in equation 2.2 whereby

is known as thermal voltage and Tc is the absolute cell temperature.

(2.2)

Maximum power point is another parameter that being used in the solar cell

operation whereby it states the maximum power dissipated at the load. Referring to

Figure 2.9 courtesy from Model for Stand Alone PV system by Anca D Hansen, the

maximum operating point is depicted in the said figure.

Figure 2.10: A typical current-voltage (I-V) curve for a solar cell.

Maximum efficiency is another parameter for solar cell need to be considered

as well. Maximum efficiency in the solar cell context means the ratio betweenincident light power and maximum power. The equation 2.3 depicts clearly and as Ga

is the ambient irradiation as well theA is the cell area.

(2.3)


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Fill factor (FF) is another parameter used in the solar cell analysis. Fill factor

can be defined as how close theI-Vcurve can get close to be a square wave. Another

definition of fill factor is the ratio of maximum power that can be delivered to the

load compared to Isc and Voc. In equation 2.4, the formula is shown clearly.

(2.4)

The PV system normally uses solar panels, which is in arrays. There are many

types of PV system, starting from a cell up to arrays. This is shown in Figure 2.11.

Figure 2.11: The PV from cell to module


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In ensuring protection for solar cells and electrical connectors from the raging

environment the cells were grouped together into modules As depicted in Figure

2.12, the manufacturer normally supplies the module with Npm(number of parallel

module) and in the each branch with Nsm (number of cells in series).

Figure 2.12: PV module consists of parallel and series cells

As shown in Figure 2.13, the PV modules in Figure 2.12 now are connected in

arrays. Figure 2.13 clearly shows that an array with Mp (module in parallel) parallel

branches each with Ms (module in series).

Figure 2.13: Solar cells array consist of Mp parallel branches each with Ms Modules in

series


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The arrangement of the module is also plays a big role in terms of efficiency.

In the Figure 2.14, show different types of module connection. The A configuration

have demonstrated efficiency up to 97.2% while configuration B efficiency at 96.8%

and C at 96.2% [10].

Figure 2.14: Series-parallel configuration for PV generator

2.4 Grid Connected PV System

In this subtopic the detail explanation on how the solar cell being bring into

the big picture of energy generation will be discussed in depth. A grid connected PV

system also known as utility interactive PV system, whereby it feed solar electricity

directly to a utility power grid. For a general knowledge about we are discussing,

kindly refer to Figure 2.15.

Figure 2.15: Grid-connected PV System


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This grid connected PV System, consists of a PV Generated, an array of PV

modules converting solar energy to DC electricity and an inverter also known as a

power conditioning unit that converts direct current generated by PV to alternating

current for the grid usage. Surge protector and load are also the grid-connected PV

components.

When the sun shines, the DC power generated by the PV modules is converted

to AC electricity by the inverter. This AC electrical power can either be supply the

systems AC load and the excess energy output transmit to the utility grid. Figure2.16 will give basically the detail component about the grid connected PV system.

Referring to Figure 2.16, a first protection level is formed by fuses and

blocking diodes between the PV array output and the main DC conductor. Surge

protection elements have to be included at the inverter input and output as well. The

grid-connected PV system can be classified by its sizing whereby from 1-10kWh is

considered as small scale and normally for the domestic usages. While medium size is

defined from 10kWh to 100kWh and these kind of system is known as building

integrated PV (BIPV). The system with output of 500kWh MWh is considered as

large size and normally operated by electric companies [11].

Figure 2.16: A detailed Grid-Connected PV System


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2.5 Solar Cell and its Characteristics

This subtopic will be discussing in depth about the solar cell and its

characteristics. The I-V curve, crucial parameters from manufacturers datasheet,

effect on the I-V curve when theres change on solar radiation and temperature as

well the mathematical equation used for modeling in this project shall be discussed in

this subtopic which will help to have deeper understanding in verifying the solar

modeling later part of the project.

Figure 2.17: CharacteristicI-Vcurve of a practical photovoltaic device [13]

Figure 2.17, depicting the solar cell I-V curve of a practical photovoltaic

device where it is clearly notice that when voltage is short circuit, the short circuit

current (Isc) happens and also practically given in the manufacturers data sheet. On

the other hand when the circuit is open, theres no current flow and the point is

known as the open voltage (Voc) also given by the manufacturers datasheet. Anotherparameter also available to us thru the data sheet is the maximum current and voltage

point. These three main points will be used later part in verifying our modeling.

For a solar cell, the non-linear relationship means the maximum power point

has to be determined by calculating the product of the voltage and output current. In

order to extract maximum power from the solar cell, the solar cell must always be


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operated at or very close to where the product of the voltage and output current is the

highest. This point is referred to as the maximum power point (MPP), and it is located

around the bend or knee of the I-V characteristic [13].

Figure 2.18: CharacteristicI-Vcurve of the photovoltaic cell [13]

From Figure 2.18 it can be concluded that photovoltaic is a non-linear device

and using Figure 2.19 a great height of understanding can be achieved as the Ipv is the

light generated current and the Id is the diode current andI is the net cell current

composing both Ipv and Id.

Referring to Figure 2.17, it can also be understood that from the operating

characteristic of a solar cell consists of two regions: the current source region, and the

voltage source region.[10]. Whereby in the current source region, the internal

impedance of the solar cell is high and this region is located on the left side of the

current-voltage curve (0, Isc.).

While the voltage source region, where the internal impedance is low, is

located on the right side of the current-voltage curve (Voc, 0). As can be observed

from the characteristic curve, in the current source region, the output current remains

almost constant as the terminal voltage changes and in the voltage source region, the

terminal voltage varies only minimally over a wide range of output current [10].


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According to the maximum power transfer theory, the power delivered to the

load is maximum when the source internal impedance matches the load impedance

[14]. For the system to operate at or close to the maximum power point (MPP) of the

solar panel, the impedance seen from the input of the maximum power point tracker

needs to match the internal impedance of the solar panel. Although controlling these

points can produce a better voltage yield yet, the temperature and solar radiation is

just unpredictable. Thats another reason why many research are being also conduct

to have smart solar system.

Figure 2.19(a): Characteristic shown on the influence of ambient irradiation [15]

Figure 2.19(b): Characteristic shown on the influence of cell temperature [15]

When the solar radiation changes the current produced is also change

accordingly for an example when the solar radiation increase increases, clearly from

Figure 2.19(a) clearly depicts that the short circuit current will increase and vice

versa. Figure 2.19(b) shows the response from solar cell when theres a change on the

temperature. When the cell temperature decreases the open circuit voltage shifts to a

lower voltage and thus the changes in solar radiation and temperature shifts the

maximum power point operation, which can influence the overall performance. Thru

this Figure 2.19(a) and (b), it can be concluded that solar radiation and cell

temperature are two most important parameters that should be considered while

modeling the photovoltaic.


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Normally in the practical world, solar cell can be connected in many different

manner as discussed earlier it can be connected in series or parallel. Figure 2.20

shows the responses on theI-Vcurves when the two identical cells are connected in

series and in parallel. Referring to Figure 2.20, for a series connection, the voltage

would be increased and the analysis would be adding the voltages for each current,

while for parallel connection, current of each individual cell can be add up at each

voltage in order to arrive at the same response as depicted in Figure 2.20.

Figure 2.20 (a): TheI-Vcurve responses with two identical cells connected in series

Figure 2.20 (b): TheI-Vcurve responses with two identical cells connected in parallel

As the discussion on the solar cell characteristics and also on how the

surroundings factor effect on the solar cell have come to an end. It would be very

helpful in modeling and verification if the right understanding about standard testing

condition well known as STC in reading the manufactures data sheet is understood.

STC conditions known as the reference vertical irradiance Eo with a typical value of

1000W/m2, the cells reference temperature for performance rating, To with a typical

value of 25 C and a tolerance of 2C; and a specified light spectral distribution with

an air mass, AM =1.5. The air mass (AM) figures provide a relative measure of the

path the sun must travel through the atmosphere.[16]


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Furthermore in supplying the performance parameters at the Standard Test

Conditions manufacturers also provide performance data under the Nominal

Operating Cell Temperature (NOCT) [16]. This is known as the temperature reached

by the open circuited cells in a module under the following conditions:

Irradiance on cell surface is 800W/m2 [16]

The ambient temperature is 20 C (293 K) [16]

Wind speed is 1m/s with the mounting is open back side [16]

According to Evans, 1981 formula the cell temperature Tc (o

C) is related to themean monthly ambient temperature, Ta (

oC) and this formula will be used in this

project to as a parameter input, and given in the expression below

(2.5)

where (NOCT) is the Nominal Operating Cell Temperature and is the monthly

clearness index (range between 0.2 for a very overcast climate and 0.8 for a very

sunny climate) [16]

As for familiarization, Figure 2.21 is taken from Sharp NE-80EJEA solar cell

which depicting its electrical characteristics and the important parameter that need to

be used during the modeling time for an example number of cells and the connection

type This literature will come in handy to understand the modeling process in Chapter

3 later on. Besides that Figure 2.22 also were included in order to familiar the reader

with the I-Vcurve, and these is the type of graph from manufacturer which will be

helpful during verification process after the modeling. TheI-V curve clearly also

shows to us on how the solar radiation will play its role in the current generated from

the solar cells.


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Figure 2.21: Electrical characteristics of Sharp NE-80EJEA solar cell

Figure 2.22: Electrical characteristics of Sharp NE-80EJEA solar cell


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The efficiency, of the solar module is another crucial criterion that needs to

consider before selecting the module. This efficiency mostly influence by the

temperature. The equation of the efficiency and energy of the solar module are shown

as following and Table 2.2 shows to us the PV module characteristics for standard

technologies [17]

p = rx [1 p (Tc Tr)/100] (2.6)

whereby given

r= PV module efficiency at reference temperature (Tr= 25o

C)p = Temperature coefficient for module efficiency (% /

oC)

Tc = Surrounding Temperature

Tr= Reference Temperature (25oC)

Table 2.2: PV module characteristic for standard technologies

PV module type r (5) NOCT (oC) p(% /

oC)

Mono-Si 13.0 45 0.40

Poly-Si 11.0 45 0.4

a-Si 5.0 50 0.11

CdTe 7.0 46 0.24

CIS 7.5 47 0.46

In order to determine the effectiveness of PV system the efficiency of the PV

module plays a big role. Theres plenty of factor that can affect the efficiency of the

PV system such as natural climatic conditions of the place where the system is to be

used, optimal matching of the system with the load, appropriate spatial placement of

the modules (placing the modules at an optimal inclination angle to the horizontal

plane) and availability of a concentrator (reflector) and or solar tracking mechanism

in the system [17].


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This project will emphasize more on the energy delivered by the PV array, Ep,

and energy that available to the load Ea. As both these parameter are given by the

formula as in equation 2.7 and equation 2.8. In addition to that, as the energy pass

thru the inverter there will some losses depending on the inverters efficiency which

is given by the equation 2.9 and after the energy travel thru the grid, there will be

some energy absorption in the grid that need to be considered which is given in the

equation 2.10 [15].

(2.7)

whereby given:

p = array average efficiency

A = area of the array

= solar radiation

Ep = energy delivered by the PV array

(2.8)

whereby given:

p = miscellaneous PV array losses

c = other power conditioning losses

Ep = energy delivered by the PV array

EA = energy available to the load

(2.9)

whereby given:

EA = energy available to the load

inv = inverter efficiency


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(2.10)

whereby given:

Edlvd = energy delivered to load

abs = PV energy absorption rate

Egrid = energy available to the load

2.6 Converters and Inverters

The rise of power electronics in the industry have always been a factor for the

growth in the PV system. As for that, this literature review will be incomplete without

the power electronic discussion. As gratitude and to pay some tribute for the works

done in the power electronic world some basic power electronics shall be covered

here. The role of power electronic converters is to provide power to the user in a

suitable form at high efficiency. Power electronic converters are needed in PV

systems to convert direct current (DC) voltage to the required values and to convert

from DC to alternating current (AC) and vice versa [18]. In addition they control the

charging and discharging of batteries in systems where batteries are storage elements

especially for the standalone PV system

One of the simplest power electronics circuits is the buck converter and

basically consists of an inductor, a power electronic switch (usually a MOSFET or an

IGBT) and a diode. It may have a capacitor to smooth the output. Its function is to

step down DC voltage as depicted in Figure 2.23.


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Figure 2.23: The Schematic of a Buck Converter [18]

If the switch is turned on and off repeatedly at very high frequencies (10kHz !

100MHz) and assuming that in the steady state the output will be periodical then[18]:

vo(t + T) = vo (2.11)

io(t + T) = io (2.12)

The current in the load is given by IR= Vo/R. The average DC component ofthe capacitor current must be equal to zero otherwise the capacitor voltage will be

increasing and there will be no periodic steady state. If the switch is turned on and off

repeatedly at very high frequencies such as 10kHz to 100MHz and assuming that in

the steady state the output will be periodical then:

(2.13)

Likewise the DC component of voltage across the inductor has to be zero:

(2.14)


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The duty ratio D is defined as the fraction of the switch period during which the

switch is on given by:

(2.15)

The average voltage across the inductor will be given by:

(2.16)

After solving we will get

(2.17)

It can be seen that the output voltage is always less than or equal to the input

voltage (0 D 1). The converter may operate in the continuous conduction mode

CCM or the discontinuous conduction mode DCM. In the CCM the inductor current

is always greater than zero while in the DCM the inductor current is zero during

certain portions of the switching period. In some applications both modes may be

mixed. The filter inductor that determines the boundary is given by [18]:


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(2.18)

Typically D = 0:5, R = 10, and f = 100 kHz, the boundary is Lb = 25H [18].

Thus for any inductance larger than this value the buck converter will operate in the

continuous conduction mode. In order to limit the ripple across the dc output voltage

Vo to a value below a specific value Vr, the filter capacitance C must be greater than

in the equation 2.19. The key design for buck mainly lies in the equation 2.18 and

equation 2.19.

(2.19)

Next we will view on the inverter, inverter is basically quite famous and a hot

topic in the world of power electronics. In PV world, inverter plays a key point role as

its efficiency is also taken into accountability for the success of PV system. Due to

the PV output is in DC form, the inverter will convert the DC to AC current. The

inverter is characterized by the power dependant efficiency. Inverter plays the

important role by keeping the voltage on AC side constant as well to perform power

conversion from the input to output at efficient rate. The formula is given by equation

2.20 [9].

Figure 2.24: Connection of Inverter


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(2.20)

There many inverters topologies, from three level up to multilevel inverters

are there for usage and there are also several topologies exist for both single phase

and multi-phase inverters. For an example is a full bridge single phase inverter shown

in Figure 2.25. It consists of four switches that are turned is such a way that within a

branch the upper and lower switches are never on at the same time to avoid short-

circuiting the DC source.

Figure 2.25: Fullbridge Voltage Source Inverter

The inverter consist of four defined states and one undefined state as shown in

Table 2.3. There are plenty of modulating techniques can be used to control the

switching of the inverter switches but one common rule for all of them must avoid the

undefined state and the short circuit conditions. There are two general types of

inverters namely, square wave inverters (line frequency switching) and pulse width

modulation PWM inverters (high frequency switching) depending on the switching

techniques used. The norm practice to avoid the short circuit condition is by a very

small time interval must be inserted between the turning off one switch and turning


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on the other. This short time interval time is referred to as the blanking time and

largely depends on the type of semiconductor switch employed.

Table 2.3 The Switches State for a full bridge single phase inverters

State Switch States Van Vbn Vo

1 S1+ and S2- are on and S1- and S2+ are off Vdc / 2 -Vdc / 2 Vdc

2 S1+ and S2+ are on and S1- and S2- are off -Vdc / 2 Vdc / 2 -Vdc

3 S1+ and S2+ are on and S1- and S2- are off Vdc / 2 Vdc / 2 0

4 S1- and S2- are on and S1+ and S are off -Vdc / 2 -Vdc / 2 0

5 S1-, S1+, S2- and S2+ are all off -Vdc / 2 Vdc / 2 - Vdc

2.7 Related Works

In this section some of the essence that have been contributed by many

researches that had the common interest on photovoltaic system will be glance thru

and our greatest gratitude to all of them for their contribution which came in handy in

making things easier for understanding and take this project to another level.

Huan-Liang Tsai thru the Development of Generalized Photovoltaic Model

Using Matlab/Simulink paper has suggested many types of models for solar cell

modeling. Each model will yield different types of mathematical equation due to

different number of components in the circuit. Figure 2.26 shows four types of

different PV cell models.


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Figure 2.26: Equivalent circuit models of PV cell

The writer have summarize there are four types of models and each have their

own mathematical equation for current generated. In his work modeling work, the

appropriate model was used for the modeling purposes. Many researcher prefer to use

the appropriate model and general model for their modeling because basically the

simplified models doesnt reflect the real case scenario while the double shunt diode

in double exponential model doesnt have much influence.

Having said so, I.H Altas in hisA photovoltaic Array Simulation Model for

Matlab/Simulink GUI environmentwork used the appropriate model while Francisco

M.Gonzalez inModel of Photovoltaic Module in MATLAB models his work using the

general model .Even though the PV efficiency is insensitive to the presence of shunt

resistor in general model still M.G.Villalva in his workModelling and Circuit-based

Simulation of Photovoltaic Arrays have used this modeling to accomplish his

verification with manufacturers data sheet. This project work was inspired by

M.G.Villalvas work, hence the general model have been used throughout this thesis.

Below are the mathematical equation suggested by Huan-Liang Tsai[19] and Omid

Shekoofa [20]


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(2.21)

whereby equation 2.21 given for the general model:

IPH is a light-generated current or photocurrent

IS is the cell saturation of dark current,

q = 1.6 1019C is an electron charge,

k(= 1.38 1023J/K) is a Boltzmanns constant,

TC is the cells working temperature,

A is an ideal factor depending on PV technology,RSH is a shunt resistance,

RS is a series resistance.

(2.22)

whereby equation 2.22 given for the double exponential model:

Jcell current density

Vcell voltage

Jph induced photocurrent density

Jd1 dark current density due to the carriers diffusion

Jd2 dark current density due to the carriers recombination

Eg band gap energy

Rs series resistance

Rp shunt resistance


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(2.23)

whereby equation 2.23 given for the appropriate model:






A is an ideal factor depending on PV technology,RS is a series resistance

(2.24)

whereby equation 2.24 given for the ideal model:






A is an ideal factor depending on PV technology,

In this related work section, we also found that there are three types of

modeling input parameter, first is just temperature or solar radiation as an input

parameter only, which is a less complicated circuitry. While the second one is, having

both parameter which better represents the PV system although the system is

complicated. The third one is the best representation of all whereby it takes into

consideration the solar radiation on horizontal surface, beam irradiance, diffuse

irradiance the zenith angle of the sun, the inclination of the PV array, wind speed,

longitude and latitude as an input parameter which is a real challenging work. In this


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project work, we choose to use both solar radiation and temperature as an input

parameter as suggested as used by many researchers such as Anca D.Hansen, Huan-

Liang Tsai and M.G.Villalva.

Another finding, we manage to grasp while doing this related work research

that, some of the researchers prefer to use completely mathematical modeling such as

Omid Shekoofa [20], while others use completely a circuitry approach like

Adedamole Omole [10]. In this thesis, we choose to model it using both mathematical

modeling combining circuitry like suggested by the I.H Altas [21].

Many of the researchers have done the PV modeling using plenty of different

softwares like PSPICE, PVSIM, MATLAB, and MATLAB/SIMULINK. There

various method proposed by these researchers like purely programming using Matlab

Script whereby the experimented curve fitting process done first before modeling

them. In other cases, SIMULINK models being used to model but the graphical user

interface not been applied, hence its not so user friendly. As to add in contribution to

the PV world, we have landed with using the Matlab Script as well Matlab/Simulink

together with graphical user interface to make it user friendly


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CHAPTER III

MODELING USING MATLAB/SIMULINK

3.1 Introduction

The MATLAB/SIMULINK software will be used for the modeling and

simulation purposes. This software prepares all the electrical and mathematical blocks

that needed in the project underPower System Blockset, Signal Routing and Math

Operations (Simulink).This software is easy to use as it is more on graphical user

interface pertaining to building or modeling any circuits or mathematical equations.

Through this chapter, hopefully the reader will be able to grasp some idea on

the usage of MATLAB/SIMULINK software. In addition, the method and steps in

modeling the solar cell up to PV array are shown clearly. The modeling was done by

stages. The first stage was modeling the mathematical equation for the Shockley

diode current and the light generated photovoltaic current and later part will be


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extended for the array model. On the second stage will be modeling for the cell

temperature and also the energy delivered model for the third stage.

Figure 3.1: First stage in modeling the solar cell

Figure 3.2: Second stage in modeling the solar cell

Stage 1

Modeling the solar cell

Modeling mathematical

equation for Io

Modeling mathematical

equation for Ipv

Stage 2

Modeling the solar cell & cell temperature

Modeling mathematicalequation for Im (model

current

Modeling the cell

temperature equation Tc


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Figure 3.4: Parameter for resistor block

In order to have just resistor element, just pull down the menu in parameters

block under branch type for only R element. In a older version of MATLAB /

SIMULINK this menu will be different, just type in the resistor value while the

inductor value set to 0 (which means short-circuit) and for capacitor set the value to

infinity (inf).

Figure 3.5 shows the mathematical modeling for the reverse current saturation

(Io/IRS) at the reference temperature which given by the equation 3.1 as below.

(3.1)


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Figure 3.5: Mathematical Modeling Implementation for Io

Figure 3.6 shows the mathematical modeling for the light generated current of

the photovoltaic cell which depends linearly on the influence of temperature and solar

radiation as given by the equation 3.2 below.

(3.2)

Figure 3.6: Mathematical Modeling Implementation for Ipv


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Figure 3.7 shows the mathematical modeling for the model current Im

referring to the appropriate model circuit as in Figure 2.26 for which given by the

equation 3.3 below.

(3.3)

Figure 3.7: Mathematical Modeling Implementation for model current Im

Figure 3.8 shows the mathematical modeling implementation for the cell

temperature (Tc) as given by the equation 2.5 earlier. In order to have a neat block

diagram, this mathematical model then been made to subsystem. This can be achieved

by selecting the block with Ctrl+A button on the keyboard and right-click on mouseto choose in order to create subsystem. Hence, to have user friendly model, repeat the

same process and choose mask subsystem. Figure 3.9 and Figure 3.10 results from

create subsystem and masking process.

In Figure 3.9, MET temp1 is the temperature input gathered from

meteorological department while Cell Temp input1 in the block is for the cell

temperature Tc.


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Figure 3.8: Mathematical model for cell temperature (Tc)

Figure 3.9: The cell temperature block after subsystem process


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Figure 3.10: An Example of the menu after Mask Process

Figure 3.11 depicts the PV array modeling, and Figure 3.12 shows the

circuitry modeling part. Figure 3.13 depicts PV array after the mask process and itsuser friendly menu in Figure 3.14. In Figure 3.15, the energy delivered block shown

and the user friendly menu shown in Figure 3.16. The whole system is shown in

Figure 3.17

Figure 3.11: PV array modeling


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Figure 3.12: Circuitry Design for PV

Figure 3.13: Mask of PV Array


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Figure 3.14: The PV Menu after Mask Process


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Figure 3.17: The Whole PV System with Load

The diode in the system is to prevent the back current to flow. While the

isolation transformer used to smooth and isolate the load directly from universal

bridge which act as an inverter. Pulse block is a PWM (pulse width modulation)

generator to drive the inverter in the circuit.


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CHAPTER IV

SIMULATION RESULTS AND DISCUSSION

4.1 Introduction

The mathematical block and circuit modeling simulated using SIMULINK,

one of the MATLAB components. Before simulating the circuit, the simulink

POWERGUI block will be set to discrete mode and the sampling time, Ts = 5.144e-

006. The next step will be configuring the simulation parameters. This can be done by

following the steps shown in Figure 4.1 and Figure 4.2

In this chapter, the simulation of single junction different technology PV will

be viewed and verified thru the manufacturers datasheet. The next stage will be

simulation of the grid connected PV system and analysis thru energy output and also

verification thru actual case study with different PV technology. Case study 1

conducted with the polycrystalline technology while Case study 2 conducted using

the amorphous silicon technology. Energy output yield from implementing the Case

study 1 and Case study 2 using MATLAB / SIMULINK were analyzed and later will


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be verified using the actual monitored data from the photovoltaic monitoring center in

UiTM (University of Technology MARA)

Figure 4.1: Setting the Simulation Parameter

Figure 4.2: Configuring the simulation parameter


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4.2 Simulation of Single Junction and Verification

In this subtopic, the MSX-60 simulation results will be discussed by varying

the hourly input of solar radiation and ambient temperature. This simulation and

model verification work done based on manufacturers data sheet.

Figure 4.3, shows the I-V curves from the MSX-60 datasheet, while Figure

4.4 to Figure 4.7 shows the results from the simulation when cell temperature act as a

variable while the solar radiation was set to 1kW/m2

. On the other hand, Figure 4.8 toFigure 4.11 shows results from the simulation when cell temperature was constant at

25C while the solar radiation acts as a variable. The simulation results show clear

accuracy it changes accordingly to the temperature and solar irradiance factors. This

also verifies the theoretical that had been discussed in page 31.

Figure 4.3: The I-V curve from BP Solar MSX-60 datasheet


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Figure 4.4: Simulation Output when the Tc = 0 C and Sx = 1kW/m2



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Figure 4.8: Simulation Output when the Tc = 25 C and Sx = 0.4kW/m2



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The simulation results validate the manufacturers data sheet and also confirm

the theory that has been discussed earlier. Whereby when the solar temperature (Tc) is

made constant at Tc = 25 C and solar radiaton (Sx) was made variable the current

generated by the solar cell also changes accordingly. When the solar radiation

increases, clearly from Figure 4.8 to Figure 4.11 show that the short circuit current

will increase and vice versa.

On the other hand, when the solar radiation (Sx) was set as a constant value,

while the cell temperature Tc set as a variable, the open circuit voltage shifts to a

lower voltage as in Figure 4.4 to 4.7, and resulting in the changes of the maximumpower point operation, which can influence the overall performance. Thru this two

parameters, can conclude that the model still valid and verified.

4.3 Case Study 1

The case study 1 was performed using Pusat Tenaga Malaysia (PTM ZEO 1)

and for the data verification, the data was available from PVMC monitoring centre.

Table 4.1 show details information for the types of PV technology and inverter used.

Table 4.1: Details of Case Study 1

Site PTM ZEO 1

Location Bandar Baru Bangi, Selangor

Type of System Grid Connected

Nominal Power 45.36 kWh

PV module Mitsubishi PVMF120EC3 (polycrystalline)

Inverter Fronius IG500


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Table 4.2 to Table 4.4 shows the energy yield for the year 2008 for Case study

1 and Case study 2 where it consists of simulated results and the actual monitored

data. Each case study was analyzed with different known as the monthly

clearness index which ranges from 0.2 up to 0.8. For Malaysia climate the value

ranges 0.45 up to 0.55. Figure 4.12 to Figure 4.14 shows the simulated results and

actual monitored data.

Table 4.2: Energy Output with = 0.45

Figure 4.12: Energy Output with = 0.45

0

1000

2000

3000

4000

5000

6000

Jan Feb Mac April May June July Aug Sept Oct Nov Dec

kWh

ENERGY OUTPUT(kWh) in 2008

ENERGY OUTPUT(kWh)-SIMULATION ENERGY OUTPUT(kWh)-UITM

Month Jan Feb Mac April May June July Aug Sept Oct Nov Dec

SIMULATION

(kWh)4717 4849 4759 4460 4510 4514 4551 4830 4405 5222 4409 4257

ACTUAL

MONITORED

DATA

(kWh)

4786 4064 4434 4637 2932 4210 3935 3915 4758 4811 4423 4221


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0

2000

4000

6000


kWh




SIMULATION

(kWh)4690 4821 4731 4435 4483 4487 4525 4802 4379 5191 4383 4233

ACTUAL

MONITORED

DATA

(kWh)

4786 4065 4434 4638 2933 4211 3936 3916 4759 4811 4423 4222


SIMULATION

(kWh)4662 4792 4703 4408 4457 4461 4498 4774 4353 5160 4357 4208

ACTUAL

MONITORED

DATA

(kWh)

4786 4065 4434 4638 2933 4211 3936 3916 4759 4811 4423 4222


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In conclusion, the used of equals to 0.55 in the model indicate the most

suitable and nearest to the actual monitored output. The simulated results differs

7.23% - 8.52% due to some practical constraint such as the beam radiance, diffuseradiance, the zenith angle of the sun, the incidence angle of beam irradiance on the

array have not been taken into modeling consideration.

4.4 Case Study 2

The case study 2 was performed using Pusat Tenaga Malaysia (PTM ZEO 1) and for

the data verification, the data was available from PVMC monitoring centre. Table 4.5

show details information for the types of PV technology and inverter used.

0

1000

2000

3000

4000

5000

6000


kWh




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Table 4.5: Details of Case Study 2

Site PTM ZEO B

Location Bandar Baru Bangi, Selangor

Type of System Grid Connected

Nominal Power 6.08 kWh

PV module Kaneka GPA 064 (amorphous silicon)

Inverter Fronius IG60

Table 4.6 to Table 4.8 shows the energy yield for the year 2008 in this case

study location whereby it consists of simulated results as well as actual monitored

data. Each case study will be analyzed with different as per discussed earlier for

Malaysia climate the value ranges 0.45 up to 0.55. Figure 4.15 to Figure 4.17 shows

the simulated results and actual monitored data.



SIMULATION

(kWh)678 698 683 641 649 648 653 694 633 750 633 611

ACTUAL

MONITORED

DATA

(kWh)

719 741 779 762 751 701 691 713 719 757 680 627


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0

500

1000


kWh



0

200

400600

800

1000


kWh




SIMULATION

(kWh)677 697 682 640 648 647 652 693 632 749 632 611

ACTUAL

MONITOREDDATA

(kWh)

719 741 779 762 751 701 691 713 719 757 680 627


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In conclusion, case study 2 the with the value of 0.45 more suited in

representing the actual monitored output. The simulated results differ from 7.71% to

8.01% due to some practical constraint as discussed earlier. In this case, a different

value of best represent due to the geographical factor.

Overall findings indicate that this MATLAB modeling can be further used for

investigation and make improvement in order to identify which best technologies to

be implemented. Another conclusion that can be drawn, the polycrystalline PV

System yields higher energy output compared to the amorphous silicon technology.

0

200

400

600

800

1000


kWh



Month Jan Feb Mac April May June July Aug Sept Oct Nov DecSIMULATION

(kWh)676 696 681 639 647 646 651 692 631 748 631 611

ACTUAL

MONITORED

DATA

(kWh)

719 741 779 762 751 701 691 713 719 757 680 627


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CHAPTER V

CONCLUSION AND DISCUSSION

5.1 Introduction

In this chapter, all the findings will be summarized and analyze on how far the

research objectives were met. Finally, some suggestions on the research work will be

conclude. Its a mountain hope that thru these suggestions, many other interested

researchers can improve this work as well add in more contribution towards the PV

world. Hopefully this work can be some basic guidance for those who are seeking.

5.2 Summary

The main objective of this project is to analyze the impact of different

technology on the PV system. Besides that, it also intends to study the single cell


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circuit model and simulate the single junction. Hence in modeling the single solar cell

two important parameters need to be model such as temperature and solar radiation.

As collectively, this project has successfully met its objectives. In terms of

modeling the circuit, four important solar cell models have been viewed, and the

appropriate model chosen to be model as it can be a basic and user-friendly for all the

single junction different technology PV system. Thru the model verification and

validation process, the strength of this thesis and also weakness have been identified.

By the case study done, polycrystalline technology yield is proven higher thanamorphous silicon technology. Hence in selecting the best PV technology actually it

depends on the usage and also niche e area on where the PV system would be applied.

Finally thru verification using the actual monitored system, the grid connected model

can be use for energy output estimation and its a user friendly system.

5.3 Suggestion

Theres always room for improvement, hence all the suggestion given here to

help the other interested researchers to continue this journey in future. The first

suggestion is that in the modeling part, instead of just modeling two parameters which

is solar radiation and cell temperature, perhaps beam radiance, diffuse radiance, the

zenith angle of the sun, the incidence angle of beam irradiance on the array and the

ratio of beam radiation on the PV array to that on the horizontal should taken into

account while modeling to have better accuracy simulation results which will help in

estimating energy output while designing the PV system.

Another research suggestion is on the analysis part where the efficiency of the

PV system also can be studied. On the other hand, the smart PV panel is another


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interesting part to work on as the maximum power point changes according to cell

temperature and solar radiation. The maximum power point tracking system can be

studied using the artificial intelligence to have better yield of energy output. As grid

connected project concerns the power electronics, the inverters also can be studied

too in achieving a better and quality energy output.

Finally, all the studies go in vain if the market is not convinced to use PV

system. Having said so, the economic impact studies should be conducted. This study

can be in terms of payback period, initial cost and total cost as well as how to

implement the grid connected PV system in Malaysia can also a great and helpful;research work.


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REFERENCES

[1] A Photovoltaic Array Simulation Model for Matlab-Simulink GUI

Environment, by Yun Tiam Tan, Student Member, IEEE, Daniel S. Kirschen,

Senior Member, IEEE, andNicholas Jenkins, Senior Member, IEEE

[2] PVSIM : A Simulation Program for Photovoltaic Cells, Modules, and Arrays

by David L. King, James K. Dudley, and William E. Boyson Sandia National

Laboratories

[3] A Model of PV Generation Suitable for Stability Analysis by Yun Tiam Tan,

Student Member, IEEE, Daniel S. Kirschen, Senior Member, IEEE, and

Nicholas Jenkins, Senior Member, IEEE

[4] Circuit Simulation Of Photovoltaic Systems For Optimum Interface Between

PV Generator And Grid by Federico ScapinoIEEE member

[5] Micro-grid powered by photovoltaic and micro turbine by Ph. Degobert, S.

Kreuawan and X. Guillaud, Laboratoire dElectrotechnique et dElectronique

de Puissance de Lille, France

[6] A Study of Dynamic Behavior of Load Voltage PV-grid Connected under

Islanding Phenomena via PSPICE Program by Krissanapong Kirtikara, King

Mongkuts University of Technology Thonburi, Bangkok, Thailand

[7] http://www.mbipv.net.my (Pusat Tenaga Malaysia)


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[8] http://www.met.gov.my (Jabatan Meterologi)

[9] http://www.ieeexplorer.com

[10] Optimal Power Tracking theses by Adedamole Omole College of

Engineering The Florida State University, 2006

[11] Faisal Mohammed Seif Al-Shamiry, Desa Ahmad, Abdul Rashid Mohamed

Sharif, "Design and Development of a Photovoltaic Power System for

Tropical Greenhouse Cooling" , Biological and Agricultural EngineeringDepartment, University Putra Malaysia (UPM

[12] R.Faranada, S.Leva and V.MaugeriMPPT techniques for PV System;

energetic & cost comparison, Member IEEE

[13] M.G.Villalva, J.R. Gazoli, E. Ruppert F.Modelling and Circuit Based

Simulation of Photovoltaic Arrays University of Campinas-Brazil.

[14] Antunes, F.L.M., Santos, J.L., Maximum Power Point Tracker for PV

Systems, World Climate & Energy Event, December 2003

[15] Anca D.Hansen, Poul Sorensen, Cars H.Hansen, and Henrik Bindner, Model

for a Stand Alone PV System Sandia Laboratory

[16] Gwinyai Dzimanu Modelling of Photovoltaic System The Ohio StateUniversity 2008

[17] M A Saqib A Photovoltaic System with Load Control,University of

Engineering and Technology, Lahore Pakistan

[18] M. H. Rashid,Power Electronics Handbook. Academic Press, 2001.


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[19] Huan-Liang Tsai Development of Generalized Photovoltaic Model using

Matlab/Simulink, 2008

[20] Omid Shekoofa

suresh than a kod imf ke 2009

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