2016

Sabrina Chowdhury

Email : sabrina.chowdhury29@gmail.com

4/30/2016

Design & Estimation of Rooftop Grid-tied Solar Photovoltaic System

Acknowledgement

Every honor on earth is due to the Great Almighty, descended from Him and must be ascribed to Him. He has given us the capability to do this work with good health. This thesis is a result of research of one year and this is by far the most significant accomplishment in our life. It would have been impossible without support and appreciation of those who mattered the most.

At the outset, we hereby extend our heartfelt thanks to our mentor, Dr. Muhammad Riazul Hamid, Associate Professor, Department of Electrical & Electronic Engineering, Ahsanullah University of Science &Technology, who have been guiding us since the inception of thesis work. He made many valuable suggestions which we continually availed of, and also caused the removal of many obscurities. Without his constant guidance, this work would not have been possible. His valuable suggestion and kind support had made it possible to complete this thesis.

We are also thankful to all the teachers and officials of the department for their contribution.

Last but not the least we are thankful to our family and friends for their support over the whole time of our work. Without them it would never have been possible for us to make this far.

ABSTRACT

The depletion of fossil fuel resources on a worldwide basis has necessitated an urgent search for alternative energy sources to meet up the present day demands. Solar energy is clean, inexhaustible and environment-friendly potential resource among renewable energy options. But neither a standalone solar photovoltaic system nor a wind energy system can provide a continuous supply of energy due to seasonal and periodic variations. Therefore, in order to satisfy the load demand, grid connected energy systems are now being implemented that combine solar and conventional conversion units. The objective of this work is to identify and design the potentials of grid quality solar photovoltaic power system at the rooftop of AHSANIA MISSION CANCER HOSPITAL, Dhaka, Bangladesh and finally develop a system based on the potential estimations made for a chosen area of 20600 ft². Equipment specifications are provided based on the availability of the components in Bangladesh. In the last, cost estimation of grid connected power plant to show whether it is economically viable or not.

TABLE OF CONTENTS

Contents Page

Approval ………………………………………………………………… 1 Declaration …………………………………………………………….….…2 Acknowledgement …………………………………………………….….…3 Abstract .………………………………………………………………….....4 Table of contents …………………………………………………………....5 CHAPTER 1: INTRODUCTION

1.1 Energy Classification ………………………………………………….....14

1.1.1 Primary and Secondary Energy…………………………………..….14

1.1.2 Commercial Energy and Non Commercial Energy……………….....15

1.1.3 Renewable and Non- Renewable Energy……………………………15

1.2 Renewable Energy and Trends in Solar Photovoltaic Energy Production.16

1.2.1 Energy Scenario……………………………………………………...16

1.2.2 World Energy Scenario………………………………………………16

1.2.3 Energy Scenario in Bangladesh…………………………………...…18

1.2.4 Status of solar PV in Bangladesh…………………………………….20

1.3 Solar PV Applications In Bangladesh…………………………………....23

1.3.1 Energy and Pollution…………………………………………….......24

1.3.2 Why we prefer Sun……………………………………………………24

1.4 Ways for Converting Solar Energy into Electrical Energy………………...25

1.4.1 Solar Thermal………………………………………………………....26

1.4.2 Solar PV……………………………………………………………….26

1.4.3 Comparison between Solar PV and Thermal………………………….27

1.5 Importance of Solar energy ………………………………………………..28

1.6 Advantages of Solar Energy………………………………………………..29

1.7 Disadvantages of Solar energy……………………………………………..31

CHAPTER 2: LITERATURE REVIEW OF SOLAR PHOTOVOLTAIC TECHNOLOGY

2.1 Brief History of Solar Photovoltaic Technology………………………...33

2.2 Basic Theory of PV Cell…………………………………………..……..33

2.3 Series and Parallel connection of PV Cells……………………………....36

2.4 Types of PV Cells………………………………………………………..36

2.5 PV Modules………………………………………………………….......39

2.6 Describing V-I Characteristics of PV Module………………………..…39

2.6.1 Standard V-I Characteristics Curve………………………………...40

2.6.2 Impact of Solar Radiation V-I Curve……………………………....41

2.6.3 Impact of Temperature on V-I characteristic curve of Photovoltaic Module…………………………………………………………………………..42

2.6.4 Impact of shading effect on V-I characteristic curve of Photovoltaic Module…………………………………………………………………………..43

2.7 Photovoltaic Array…………………………………………………………..44

2.8 Solar Photovoltaic System…………………………………………………..45

2.8.1 PV System……………………………………………………………...46

2.8.2 Stand Alone System……………………………………………………46

2.8.3 Grid Linked System……………………………………………………48

2.8.4 We Prefer Grid Connected PV System………………………………..50

CHAPTER 3: GRID-TIED PV SYSTEM

3.1 Grid Connected PV System All Over The World………………………….51

3.2 Basic Components of Grid Connected System…………………………….52

3.3 Working Principle of Grid Connected System…………………………….52

3.4 Conditions for Grid Interfacing……………………………………………53

CHAPTER 4: PROJECT LOCATION ANALYSIS 4.1 Project Location…………………………………………………………...54

4.2 Description of Study Area…………………………………………………55

4.3 Rooftop Illustration Of The Project……………………………………….57

CHAPTER 5: DESIGN PROCEDURES

5.1 Rooftop and Installation Requirements………………………………….…58

5.1.1 Technical Details………………………………………………………..59 5.1.2 Scope and Purpose……………………………………………………....59 5.1.3 Grid Connected Solar PV System…………………………………..…...60 5.1.4 System Components……………………………………………………..60 5.1.5 Supplier Details……………………………………………………….....61

5.2 Design Parameter……………………………………………………….......63 5.2.1 Solar PV system Capacity Sizing……………………………………...63 5.2.2 Solar Grid Inverter Capacity…………………………………………..63 5.3 Specification of Solar PV Modules………………………………………....63 5.4 Data Sheet Of TRINA Solar TSM PC-14 Utility Module………………….65 5.5 Description Of Designing Elements……………………………………….66 5.5.1 Data Sheet Of Sunny Tripower 20000 TL Inverter…………………....67 5.6 Connection to The Building Electrical System………………………….....74 5.7 Earthing…………………………………………………………………….74 5.8 Surge Protection……………………………………………………………75 5.9 Typical Wiring Diagrams For Grid Connected Solar System……………..76 5.10 Power Factor Requirements……………………………………………....76 5.11 Grid Protection Requirements………………………………………….…76 5.12 Power Quality issues Related to Solar PV System…………………….…77 5.12.1 Harmonic Distortion…………………………………………...……...77

5.12.2 Power Factor…………………………………………………..…..…..77

5.12.3 Local Voltage Rise……………………………………………..….….78

5.12.4 Other Network Issues Related to Solar PV Systems…………...……81

5.12.5 PV Systems and Stability………………………………………...…...82

CHAPTER 6: DESIGN AND CALCULATIONS

6.1 System design……………………………………………………………..82

6.2 Design Overview by Sunny Design Software…………………………….83

6.3 Design Layout By AUTOCAD…………………………………………...87

6.4 Calculations……………………………………………………………....88

6.5 Financial Overview in Brief……………………………………………...104

CHAPTER 7: CONCLUSION

7.1 Conclusion………………………………………………………………..109

REFERENCE……………………………………………………………….110

LIST OF FIGURES

Fig 1.1 Renewable energy sources and Non renewable energy sources

Fig 1.2 Ways of Converting solar energy into electrical energy

Fig 1.3 Solar thermal plant

Fig 1.4 Solar photovoltaic plant

Fig 2.1 Photovoltaic cell

Fig 2.2 Basic theory of photovoltaic cell 1

Fig 2.3 Basic theory of photovoltaic cell 2

Fig 2.4 Basic theory of photovoltaic cell 3

Fig 2.5 Series Connection of cells

Fig 2.6 Parallel Connection of cells

Fig2.7 Types of Solar Cells

Fig2.8 Monocrystalline Solar Cells

Fig2.9 PV cells are combine to create PV modules which are linked to create PV Arrays

Fig2.10 Schematic of solar PV system

Fig2.11 PV system directed connected to load

Fig2.12 Basic Stand-alone PV System

Fig2.13 Hybrid Stand-alone solar farm

Fig2.14 Grid Tied Solar System

Fig 3.1 Block Diagram Grid Connected System

Fig4.1 Ahsania Mission Cancer Hospital , Mirpur Road, Dhaka, Bangladesh

Fig 4.2 Ahsania Mission Cancer Hospital, Mirpur Road, Dhaka, Bangladesh

Fig 4.3 Rooftop of Ahsania Mission Cancer Hospital, Mirpur Road, Dhaka, Bangladesh

Fig 5.1 TSM PC-14 Trina Solar Utility Module

Fig 5.2.1 NYYF (Flexible) Cable

Fig 5.2.2 NYY Cable

Fig 5.3 Wiring Diagram for Grid Connected Solar System

Fig 5.4 How PV system can impact on distribution substation power factor

Fig 5.5 Simple Illustration of Voltage rise due to PV generation

Fig 5.6 Graph showing PV generation that maybe connected for a given grid impedence before disconnect voltage of 253 V is reached

Fig 5.7 How High penetration of solar PV system may reduce fault currents

Fig 6.1 Block Diagram representation of group A

Fig 6.2 Block Diagram representation of group A

Fig 6.3 System Design Illustration

LIST OF TABLES

Table 1.1Installed capacity and maximum generation

Table 1.2 Current situation and future Projection of electricity demand generation and load shedding

Table 1.3 Different household provided with different solar system

Table 5.1 System components

Table 5.2 Specifications of solar PV modules

Table 5.3 Solar Grid inverter specifications

Table 6.1 Overview of simulation by Sunny Design Software

Table 6.2 Overview of simulation by Sunny Design Software

Table 6.3 Financial Overview in short

LIST OF GRAPHS

GRAPH 2.1 The standard VI Characteristics curve of PV

GRAPH 2.2 Change PV module voltage and current in solar radiation

GRAPH 2.3 A typical current voltage curve for a Module at 25 degree Celsius

GRAPH 2.4 A typical Current-voltage curve for an unshaded module and for a module with one shaded cell.

CHAPTER 1: INTRODUCTION

Energy plays a pivotal role in our daily activities. The degree of development and civilization of a country is measured by the amount of utilization of energy by human beings. Energy demand is increasing day by day due to increase in population, urbanization and industrialization. The world’s fossil fuel supply viz. coal, petroleum and natural gas will thus be depleted in a few hundred years. The rate of energy consumption increasing, supply is depleting resulting in inflation and energy shortage. This is called energy crisis. Hence alternative or renewable sources of energy have to be developed to meet future energy requirement.

1.1 ENERGY CLASSIFICATION

Energy can be classified into several types:

1.1.1 Primary and Secondary Energy

Primary energy sources are those that are either found or stored in nature. Common primary energy sources are coal, oil, natural gas, and biomass (such as wood). Other primary energy sources available include nuclear energy from radioactive substances, thermal energy stored in earth’s interior, and potential energy due to earth’s gravity. The major primary and secondary energy sources are Coal, hydro power, natural gas, petroleum etc.

Primary energy sources are mostly converted in industrial utilities into secondary energy sources; for example coal, oil or gas converted into steam and electricity. Primary energy can also be used directly. Some energy sources have non-energy uses, for example coal or natural gas can be used as a feedstock in fertilizer plants.

1.1.2 Commercial Energy and Non Commercial Energy:

The energy sources that are available in the market for a definite price are known as commercial energy. By far the most important forms of commercial energy are electricity, coal and refined petroleum products. Commercial energy forms the basis of industrial, agricultural, transport and commercial development in the modern world. In the industrialized countries, commercialized fuels are predominant source not only for economic production, but also for many household tasks of general population.

The energy sources that are not available in the commercial market for a price are classified as non-commercial energy. Non-commercial energy sources include fuels such as firewood, cattle dung and agricultural wastes, which are traditionally gathered, and not bought at a price used especially in rural households. These are also called traditional fuels. Non-commercial energy is often ignored in energy accounting.

1.1.3 Renewable and Non- Renewable Energy

All forms of energy are stored in different ways, in the energy sources that we use every day. These sources are divided into two groups -- renewable (an energy source that we can use over and over again) and nonrenewable (an energy source that we are using up and cannot recreate in a short period of time). [2]

Figure 1.1: Renewable Energy Sources and Non-Renewable Energy Sources

Renewable and nonrenewable energy sources can be used to produce secondary energy sources including electricity and hydrogen. Renewable energy sources include solar energy, which comes from the sun and can be turned into electricity and heat. Wind, geothermal energy from inside the earth, biomass from plants, and hydropower and ocean energy from water are also renewable energy sources. However, we get most of our energy from non-renewable energy sources, which include the fossil fuels --oil, natural gas, and coal.[2] They're called fossil fuels because they were formed over millions and millions of years by the action of heat from the Earth's core and pressure from rock and soil on the remains (or "fossils") of dead plants and animals. Another nonrenewable energy source is the element

uranium, whose atoms we split (through a process called nuclear fission) to create heat and ultimately electricity. We use all these energy sources to generate the electricity we need for our homes, businesses, schools, and factories. Electricity "energizes" our computers, lights, refrigerators, washing machines, and air conditioners, to name only a few uses. [1]We use energy to run our cars and trucks. Both the gasoline used in our cars, and the diesel fuel used in our trucks are made from oil. The propane that fuels our outdoor grills and makes hot air balloons soar is made from oil and natural gas.

1.2 Renewable Energy and Trends in Solar Photovoltaic Energy Production

1.2.1 Energy Scenario

The present energy scenario is discussed under categorical division of World, Bangladesh.

1.2.2 World Energy Scenario

Global economic recession drove energy consumption lower in 2009 – the first decline since 1982. World primary energy consumption – including oil, natural gas, coal, nuclear and hydro power – fell by 1.1% in 2009. Hydroelectric power generation increased by 1.5%. Around the globe, concern is mounting over conventional carbon based energy production. The issues at hand are numerous and include increasing atmospheric carbon dioxide concentrations from greenhouse gas emissions, environmental safety of energy production techniques, volatile energy prices, and depleting carbon based fuel reserves to name a few (Nguyen and Pearce 2010; Choi et al. 2011).[5] As a result, countries are facing an increasing challenge to diversify energy sources and bringing renewable generation to the forefront of policy discussion.

Graph 1.1: Power generation capacity in world by source, 2009

In the United States, a rise in renewable energy generation has been supported by the availability of federal tax credits and programs in individual states (U.S. Energy Information Administration 2013a).[3]Many states are implementing renewable portfolio standards, or renewable energy standards, that outline goals to increase electricity generation from renewable resources (U.S. Energy Information Administration 2013a).

These policies seek to remove barriers to install renewable generation and can include grant programs, loan programs, and state renewable electricity tax credits. The Database of State Incentives for Renewables & Efficiency (DSIRE) provides an outline of state renewable portfolio standards available throughout the nation (North Carolina State University 2013).[8]

In 2012, about 12 percent of U.S. electricity was generated from renewable sources (U.S. Energy Information Administration 2013b). The United States Energy Information Administration states that the five renewable sources most often utilized include biomass, water, geothermal, wind and solar (U.S. Energy Information &!!

Administration 2013b).[9] Of these, hydropower (water) contributed 7 percent of renewable electricity generation (U.S. Energy Information Administration 2013c). The other common renewable sources make up the remaining 5 percent including wind (3.46 percent), biomass (1.42 percent), geothermal (0.41 percent), and solar (0.11 percent) (U.S. Energy Information Administration 2013c). The study presented in this manuscript focuses on renewable generation from solar energy. Solar energy is received from the sun’s light rays hitting the earth and is commonly referred to as solar radiation (U.S. Energy Information Administration 2013d).[10]

Solar radiation can be harnessed and converted to electricity by photovoltaic (PV) technologies. Photovoltaic cells produce electricity by absorbing photons and releasing electrons that can be captured in the form of an electric current (Knier 2011).[18] Cells can be used individually to power small electronics or grouped together into modules and arrays to generate larger amounts of power (U.S. Energy Information Administration 2013d). PV array systems are becoming an increasingly popular means for powering residential and commercial locations in the form of distributed generation (Loudat 2013).

In addition to existing renewable portfolio standards and tax credits, many state, city and local governments to break down barriers for distributed PV installation have implemented GIS-based modeling and decision support tools (Voivontas, Assimacopolous and Mourelatos 1998). Online solar potential maps are one type of decision support tool that is becoming increasingly popular throughout cities in the United States. Currently cities such as Boston, Denver, New York, Portland, San Diego, and San Francisco host online solar potential mapping sites available to the public.[21] These allow users to evaluate the geographical, technological and financial factors that affect system performance and then predict the costs and benefits associated with installing solar PV panels for both residential and commercial buildings.

1.2.3 Energy Scenario in Bangladesh

Bangladesh's energy infrastructure is quite small, insufficient and poorly managed. The per capita energy consumption in Bangladesh is one of the lowest (321 kWh) in the world. Noncommercial energy sources, such as wood fuel, animal waste, and crop residues, are estimated to account for over half of the country's energy consumption. Bangladesh has small reserves of oil and coal, but very large natural gas resources. Commercial energy consumption is mostly natural gas (around 66%), followed by oil, hydropower and coal.[15]

Electricity is the major source of power for most of the country's economic activities. Bangladesh's installed electric generation capacity was 10289 MW in January, 2014; only three-fourth of which is considered to be ‘available’. Only 62% of the population has access to electricity with a per capita availability of 321 kWh per annum. Problems in the Bangladesh's electric power sector include corruption in administration, high system losses, delays in completion of new plants, low plant efficiencies, erratic power supply, electricity theft, blackouts, and shortages of funds for power plant maintenance. Overall, the country's generation plants have been unable to meet system demand over the past decade.[27]

On November 2, 2014, electricity was restored after a day-long nationwide blackout. A transmission line from India had failed, which "led to a cascade of failures throughout the national power grid," and criticism of "old grid infrastructure and poor management." However, in a recent root-cause analysis report the investing team has clarified that fault was actually due to Lack in electricity management & poor Transmission & Distribution health infrastructure that caused the blackout.[14]

Table 1.1: Installed Capacity and Maximum Generation

Table 1.2: Current Situation and Future Projection of Electricity Demand, Generation and Load Shedding

1.2.4 Status of Solar Photovoltaic in Bangladesh

The World Bank has offered to loan the Bangladeshi government $78.4 million in order to finance 480,000 solar home systems. This huge solar home systems project aims to install about 7,000 photovoltaic systems in Bangladesh every month. If it achieves this rate, it will be the largest of its kind in the world.

There are already 3 million home solar systems in the country, and they were installed because the World Bank provided the support. “Together, the government of Bangladesh and the World Bank is scaling up a program that delivered development results for millions of rural Bangladeshis .This is a proven model that works. Investing in electricity in rural areas empowers both men and women, leading to increased income and growth opportunities, and reducing poverty,” said acting head of World Bank Bangladesh, Christine E. Kimes.[22]

Nearly 60% of the Bangladeshi people do not have access to grid-connected electricity. The government has set a goal of 100% citizen access by 2021. Millions of people’s lives have been impacted in Bangladesh because of the addition of more solar PV power. The interest in renewable energy has been revived over last few year, especially after global awareness regarding the ill effects of fossil fuel burning.

Energy is the source of growth and the mover for economic and social development of a nation and its people. No matter how we cry about development or poverty alleviation- it is not going to come until lights are provided to our people for seeing, reading and working. Natural resources or energy sources such as: fossil fuels, oil, natural gas etc. are completely used or economically depleted. Because we are rapidly exhausting, our non-renewable resources, degrading the potentially renewable resources and even threatening the perpetual resources. It demands immediate attention especially in the third world countries, where only scarce resources are available for an enormous size of population. The civilization is dependent on electric power. There is a relationship between GDP growth rate and electricity growth rate in a country.

The electricity sector in Bangladesh is handled by three state agencies under the Ministry of Energy and Mineral resources (MEMR). These are

· Bangladesh Power Development board (BPDB)

· Dhaka Electric Supply authority (DESA)

· Rural Electrification Board (REB)

Bangladesh is a largely rural agrarian country of about 120 million people situated on the Bay of Bengal in south Central Asia. Fossil energy resources in Bangladesh consist primarily of natural gas. Domestic oil supply in considered negligible. Several small deposits of coal exist on the north eastern region of the country, but these consist of peat, with low caloric value and very deep bituminous coal that will be quite expensive to extract. Only 15% of the total population has got access to the electricity. In 1990 only 2.2% of total households (mostly in urban areas) has piped natural gas connections for cooking and only 3.9% of total households used kerosene for cooking. These are by no means a pleasant scenario.[5]

Per capita consumption of commercial energy and electricity in Bangladesh is one of the lowest among the developing countries. In 1990, more than 73% of total final energy consumption was met by different type of biomass fuels (e.g. agricultural residues, wood fuels, animal dung etc.).

Solar Energy is inexhaustible and pollution free. It is available everywhere; but the greatest amount is available between two broad bands encircling the earth between 15” and 35” latitude north and south. [7]

Fortunately, Bangladesh is situated between 20′′43′ north and 26′′38′ north latitude and as such Bangladesh is in a very favorable position in respect of the utilization of solar energy. Annual amount of radiation varies from 1840 to 1575 kwh/m2 which is 50-100% higher than in Europe. Taking an average solar radiation of 1900 kwh per square meter, total annual solar radiation in Bangladesh is equivalent to 1010 X 1018 J. present total yearly consumption of energy is about 700 X 1018 J. this shows even if 0.07% of the incident radiation can be utilized, total requirement of energy in the country can be met. At present energy utilization in Bangladesh is about 0.15 watt/sq. meter land area, whereas the availability is above 208 watt/sq. meter. This shows the enormity of the potentiality of this source in this country (Eusuf, 1997).

A good number of organizations and departments are doing research, development, demonstration, diffusion and commercialization of solar energy technology. Diffusion aspects of the solar energy technologies are using mostly in Bangladesh specially solar Photovoltaic (PV) systems, solar cooker, solar oven, solar water heater and solar dryer.

The rural and remote sector of Bangladesh economy, where 85% of the population live, is characterized by an abundance of open and disguised unemployment, high Man-land ratio, alarmingly large numbers of landless farmers, extremely inadequate economic and social facilities, low standard of living and a general environment of poverty and deprivation. Larger energy supplies and greater efficiency of energy use are thus necessary to meet the basic needs of a growing population. It will therefore, be necessary to tap all sources of renewable energy and to use these in an efficient converted form for benefit of the people. Primarily this will be done in remote inaccessible un-electrified area in a stand-alone system where grid expansion is expensive. This energy conversion will reduce pressure on the national power demand. This will not only save excessive grid expansion cost but will also keep environment friendly.

Recently a number of experimental and pilot projects are being undertaking by different organizations in different sectors of alternative energy technologies in Bangladesh. Rural electrification Board (REB), Atomic Energy Commission (AEC), Local Government Engineering Department (LGED), and Grameen Shakti (GS) have installed (are in the process of installation of) a number of solar PV systems in different parts of the country

1.3 Solar PV applications in Bangladesh

REB has undertaken a pilot project for supply of solar electricity in some islands of one main river (Meghna) in Narshingdi district. Five types of PV systems are delivered to 1370 consumers. Under this project, PV systems have been installed at one rural health clinic for running fans, lights and refrigerators. Same systems are being set up in another clinic. The first solar module was installed on 3rd August 1996 and since then till 10-05-97 a total households have been provided with different types of systems as shown in Table-1.3

Table 1.3: Different household provided with different solar systems

More than 500 potential consumers have been trained on the operation and maintenance of the entire PV system. This was conducted by BCAS and CMES experts. [30]

AEC initiated solar PV program (SPV) in 1985. The systems installed over the period 1985-1994 are 9790 watt peak. Most of the systems are not functional at present because of the lack of fund for spare parts, maintenance and back-up service.

LGED has so far installed SPV systems in 5 cyclone shelters, one at Cox’s Bazar, four at Patuakhali. According to LGED all the systems have been working satisfactory since their installation.[25]

During the year 1996-1997, GS has installed 67 units of solar home systems (SHS) at different districts of Bangladesh. This includes Fluorescent Tube lights, T.V.

point, Fluorescent lamps etc. GS is planning to install a total of 400 under next phase of the solar PV development project.

1.3.1 Energy and Pollution

The usage of conventional energy resources in industry leads to environmental damages by polluting the atmosphere. Few of examples of air pollution are Sulphur dioxide (SO2), Nitrous oxide (NOX) and Carbon oxides (CO, CO2) emissions from boilers and furnaces, chloro-fluro carbons (CFC) emissions from refrigerants use, etc. In chemical and fertilizers industries, toxic gases are released. Cement plants and power plants spew out particulate matter and volatile organic compounds (VOCs). But most of the renewable energy is pollution free. So it will be better to go for renewable energies. [28]

1.3.2 Why We Prefer Sun Non-conventional Energy Source Than Another Non-conventional Energy Sources

Various types of non-conventional energy sources are such as geothermal ocean tides, wind and sun. All non-conventional energy sources have geographical limitations. but Solar energy has less geographical limitation as compared to other non-conventional energy sources because solar energy is available over the entire globe, and only the size of the collector field needs to be increased to provide the same amount of heat or electricity. It is the primary task of the solar energy system designer to determine the amount, quality and timing of the solar energy available at the site selected for installing a solar energy conversion system so among all these solar energy seems to hold out the greatest promise for the mankind. It is free, inexhaustible, nonpolluting and devoid of political control. Solar water heaters, space heaters and cookers are already on the market and seem to be economically viable. Solar photo voltaic cells, solar refrigerators and solar thermal power plants will be 'technically and economically viable in a short time. It is optimistically estimated that 50% of the world power requirements in the middle of 21st century will come only from solar energy. Enough strides have been made during last two decades to develop the direct energy conversion systems to increase the plant efficiency 60% to 70% by avoiding the conversion of thermal energy into mechanical energy. Still this technology is on the threshold of the success and it is hoped that this will also play a vital role in power generation in coming future. In one minute, the sun provides enough energy to supply the world’s energy needs for one year. In one day, it provides more energy than the world’s population could

consume in 27years. The energy is free and the supply is unlimited. All we need to do is find a way to use it. The largest solar electric generating plant in the world produces a maximum of 354 megawatts (MW) of electricity and is located at Kramer Junction, California. Since Bangladesh has abundant sources of RE especially sunlight, it can cater to all the energy needs of the country.[4]

1.4 Ways For Converting Solar Energy Into Electrical Energy

There are two ways by which we can convert solar energy into electrical energy. These are as shown in figure 1.2.

Figure 1.2: Ways of converting solar energy into electrical energy

1.4.1 Solar thermal

The solar collectors concentrate sunlight to heat a heat transfer fluid to a high temperature. The hot heat transfer fluid is then used to generate steam that drives the power conversion subsystem, producing electricity. Thermal energy storage provides heat for operation during periods without adequate sunshine.

Figure 1.3: Solar thermal Plant

1.4.2 Solar Photovoltaic

Another way to generate electricity from solar energy is to use photovoltaic cells; magic slivers of silicon that converts the solar energy falling on them directly into electricity. Large scale applications of photovoltaic for power generation, either on the rooftops of houses or in large fields connected to the utility grid are promising as well to provide clean, safe and strategically sound alternatives to current methods of electricity generation.

Figure 1.4: Solar Photovoltaic Plant

1.4.3 Comparison Between Solar Photovoltaic and Solar Thermal Power Plant

Any people associate solar energy directly with photovoltaic and not with solar thermal power generation. In contrast to photovoltaic plants, solar thermal power plants are not based on the photo effect, but generate electricity from the heat produced by sunlight. A fossil burner can drive the water-steam cycle during periods of bad weather or at night. In contrast to photovoltaic systems, solar thermal power plants can guarantee capacity. Due to their modularity, photovoltaic operation covers a wide range from less than one Watt to several megawatts and solar thermal power plants are small units in the kilowatt range. On the other hand, Global solar irradiance consists of direct and diffuse irradiance. When skies are overcast, only diffuse irradiance is available. While solar thermal power plants can only use direct irradiance for power generation, photovoltaic systems can convert the diffuse irradiance as well. That means, they can produce some electricity even with cloud-covered skies. From economical point of view market introduction of photovoltaic systems is much more aggressive than that of solar thermal power plants, cost reduction can be expected to be faster for photovoltaic systems. But even if there is

a 50% cost reduction in photovoltaic systems and no cost reduction at all in solar thermal power plants. Thus we conclude that solar PV power plant is better than solar thermal power plant. In the next chapter we study about solar photovoltaic technology. [7]

1.5 Importance of Solar energy

Solar energy is an important part of life and has been since the beginning of time. Increasingly, man is learning how to harness this important resource and use it to replace traditional energy sources.[8]

Solar Energy Is Important in Nature: Solar energy is an important part of almost every life process, if not, all life processes. Plants and animals, alike, use solar energy to produce important nutrients in their cells. Plants use the energy to produce the green chlorophyll that they need to survive, while humans use the sun rays to produce vitamin D in their bodies. However, when man learned to actually convert solar energy into usable energy, it became even more important.

Solar Energy Is Important as Clean Energy: Since solar energy is completely natural, it is considered a clean energy source. It does not disrupt the environment or create a threat to Eco-systems the way oil and some other energy sources might. It does not cause greenhouse gases, air or water pollution. The small amount of impact it does have on the environment is usually from the chemicals and solvents that are used during the manufacture of the photovoltaic cells that are needed to convert the sun's energy into electricity. This is a small problem compared to the huge impact that one oil spill can have on the environment.

Versatility of solar energy: Solar energy cells can be used to produce the power for a calculator or a watch. They can also be used to produce enough power to run an entire city. With that kind of versatility, it is a great energy source. Some of the ways solar energy is being used today are:

*Cars

*Cooking

*Coffee Roasters

*Electricity for homes and businesses

*Thermal heating for homes and businesses

*Watches

*Water heaters

*Water treatment plants

There are many other things that are or can be powered by solar energy.

As finally we can say that for use of solar energy:

1. Source of Conventional Energy is Limited.

2. Production of power from conventional Energy causes CO2 Emission.

3. Easy to install and use.

4. Noise free

5. Less maintenance.

6. Source is unlimited.

7. There are no moving parts, so its life is long.

1.6 Advantages of Solar Energy

1. Renewable Energy Source

Solar energy is a truly renewable energy source. It can be harnessed in all areas of the world and is available every day. We cannot run out of solar energy, unlike some of the other sources of energy. Solar energy will be accessible as long as we have the sun, therefore sunlight will be available to us for at least 5 billion years, when according to scientists the sun is going to die.

2. Reduces Electricity Bills

Since you will be meeting some of your energy needs with the electricity your solar system has generated, your energy bills will drop. How much you save on your bill will be dependent on the size of the solar system and your electricity or heat usage. Moreover, not only will you be saving on the electricity bill, but if you generate more electricity than you use, the surplus will be exported back to the grid and you will receive bonus payments for that amount (considering that your solar panel system is connected to the grid). Savings can further grow if you sell excess

electricity at high rates during the day and then buy electricity from the grid during the evening when the rates are lower.

3. Diverse Applications

Solar energy can be used for diverse purposes. You can generate electricity (photovoltaics) or heat (solar thermal). Solar energy can be used to produce electricity in areas without access to the energy grid, to distill water in regions with limited clean water supplies and to power satellites in space. Solar energy can also be integrated in the materials used for buildings

4. Low Maintenance Costs

Solar energy systems generally don’t require a lot of maintenance. You only need to keep them relatively clean, so cleaning them a couple of times per year will do the job. Most reliable solar panel manufacturers give 20-25 years warranty. Also, as there are no moving parts, there is no wear and tear. The inverter is usually the only part that needs to changed after 5-10 years because it is continuously working to convert solar energy into electricity (solar PV) and heat (solar thermal). So, after covering the initial cost of the solar system, you can expect very little spending on maintenance and repair work.[10]

5. Technology Development

Technology in the solar power industry is constantly advancing and improvements will intensify in the future. Innovations in quantum physics and nanotechnology can potentially increase the effectiveness of solar panels and double, or even triple, the electrical input of the solar power systems.

6.solar power helps to slow/stop global warming

Global warming threatens the survival of human society, as well as the survival of countless species. Luckily, decades (or even centuries) of research have led to efficient solar panel systems that create electricity without producing global warming pollution. Solar power is now very clearly one of the most important solutions to the global warming crisis.

7. Solar power provides energy reliability

The rising and setting of the sun is extremely consistent. All across the world, we know exactly when it will rise and set every day of the year. While clouds may be a bit less predictable, we do also have fairly good seasonal and daily projections

for the amount of sunlight that will be received in different locations. All in all, this makes solar power an extremely reliable source of energy.

1.7 Disadvantages of Solar energy

1. Cost

The initial cost for purchasing a solar system is fairly high. Although the UK government has introduced some schemes for encouraging the adoption of renewable energy sources, for example the Feed-in Tariff, you still have to cover the upfront costs. This includes paying for solar panels, inverter, batteries, wiring and for the installation. Nevertheless, solar technologies are constantly developing, so it is safe to assume that prices will go down in the future.

2. Weather Dependent

Although solar energy can still be collected during cloudy and rainy days, the efficiency of the solar system drops. Solar panels are dependent on sunlight to effectively gather solar energy. Therefore, a few cloudy, rainy days can have a noticeable effect on the energy system. You should also take into account that solar energy cannot be collected during the night.

3. Solar Energy Storage Is Expensive

Solar energy has to be used right away, or it can be stored in large batteries. These batteries, used in off-the-grid solar systems, can be charged during the day so that the energy is used at night. This is good solution for using solar energy all day long but it is also quite expensive. In most cases it is smarter to just use solar energy during the day and take energy from the grid during the night (you can only do this if your system is connected to the grid). Luckily our energy demand is usually higher during the day so we can meet most of it with solar energy.[9]

4. Uses a Lot of Space

The more electricity you want to produce, the more solar panels you will need, because you want to collect as much sunlight as possible. Solar panels require a lot of space and some roofs are not big enough to fit the number of solar panels that you would like to have. An alternative is to install some of the panels in your yard but they need to have access to sunlight. Anyways, if you don’t have the space for all

the panels that you wanted, you can just get a fewer and they will still be satisfying some of your energy needs.

5. Associated with Pollution

Although pollution related to solar energy systems is far less compared to other sources of energy, solar energy can be associated with pollution. Transportation and installation of solar systems have been associated with the emission of greenhouse gases. There are also some toxic materials and hazardous products used during the manufacturing process of solar photovoltaics, which can indirectly affect the environment. Nevertheless, solar energy pollutes far less than the other alternative energy sources.

CHAPTER 2: LITERATURE REVIEW AND INTRODUCTION OF SOLAR PHOTOVOLTAIC TECHNOLOGY

Photovoltaic’s offer consumers the ability to generate electricity in a clean, quiet and reliable way. Photovoltaic systems are comprised of photovoltaic cells, devices that convert light energy directly into electricity. Because the source of light is usually the sun, they are often called solar cells. The word photovoltaic comes from “photo” meaning light and “voltaic” which refers to producing electricity. Therefore, the photovoltaic process is “producing electricity directly from sunlight. Photovoltaic are often referred to as PV.

2.1 BRIEF HISTORY

In 1839 Edmond Becquerel accidentally discovered photovoltaic effect when he was working on solid-state physics. In 1878 Adam and Day presented a paper on photovoltaic effect. In 1883 Fxitz fabricated the first thin film solar cell. In 1941 Ohl fabricated silicon PV cell but that was very inefficient. In 1954 Bell labs Chopin, Fuller, Pearson fabricated PV cell with efficiency of 6%. In 1958 PV cell was used as a backup power source in satellite Vanguard-1. This extended the life of satellite for about 6 years [24].

2 .2 Photovoltaic Cell

A device that produces an electric reaction to light, producing electricity. PV cells do not use the sun’s heat to produce electricity. They produce electricity directly when sunlight interacts with semiconductor materials in the PV cells.

Figure 2.1: Photovoltaic cell

“A typical PV cell made of crystalline silicon is 12 centimeters in diameter and 0.25 millimeters thick. In full sunlight, it generates 4 amperes of direct current at 0.5 volts or 2 watts of electrical power [25].

2.2 Basic theory of photovoltaic cell:

Photovoltaic cells are made of silicon or other semi conductive materials that are also used in LSIs and transistors for electronic equipment. Photovoltaic cells use two types of semiconductors, one is P-type and other is N-type to generate electricity [27].

When sunlight strikes a semiconductor, it generate pairs of electrons (-) and protons (+).

Figure 2.2: Basic theory of photovoltaic cell 1

When an electron (-) and a proton (+) reach the joint surface between the two types of semiconductors, the former is attracted to N-type and the latter to the P-type semiconductor. Since the joint surface supports only one way traffic, they are not able to rejoin once they are drawn apart and separated.

Figure 2.3: Basic theory of photovoltaic cell 2

Since the N-type semiconductor now contains an electron (-), and P-type semiconductor contains a proton (+), an electromotive (voltage) force is generated. Connect both electrodes with conductors and the electrons runs from N- type to P-type semiconductors, and the proton from P-type to N-type semiconductors to make an electrical current.

Figure 2.4: Basic theory of photovoltaic cell 3

2.3 Series and parallel connection of PV cells

Solar cells can be thought of as solar batteries. If solar cells are connected in series, then the current stays the same and the voltage increases [27].

Figure 2.5: Series connection of cells

If solar cells are connected in parallel, the voltage stays the same, but the current increases.

Figure 2.6: Parallel connection of cells

As we know those Solar cells are combined to form a „module‟ to obtain the voltage and current (and therefore power) desired.

2.4 Types of Solar Cells

There are number of different types of solar panel, from an ever increasing range of manufacturers. Each claims that they are best for one reason or another, with different sales people all giving different information. We are not tied to any particular manufacturer and do not hold stocks of solar panels, so that we are flexible enough to be able to recommend whichever solar panel we think is best for your project and can just order and fit the type of panel you prefer.

This means that we are able to give completely independent advice about our views on different panels and, hopefully, help you distinguish the sales blarney from the real facts

Fig 2.7: Types of Solar Cells

(i) Polycrystalline vs Monocrystalline vs Hybrid

Monocrystalline Panels

The solar cells in monocrystalline panels are slices cut from pure drawn crystalline silicon bars. The entire cell is aligned in one direction, which means that when the sun is shining brightly on them at the correct angle, they are extremely efficient. So, these panels work best in bright sunshine with the sun shining directly on them. They have a uniform blacker color because they are absorbing most of the light.

Pure cells are octagonal, so there is unused space in the corners when lots of cells are made into a solar module. Mono panels are slightly smaller than poly panels for the same power, but this is only really noticeable on industrial scale installations where you may be able to fit a higher overall power with monocrystalline.

Fig 2.8: Monocrystalline Solar Cells

Polycrsytalline Panels (also known as multicrystalline)

Polycrystalline panels are made up from the silicon offcuts, molded to form blocks and create a cell made up of several bits of pure crystal. Because the individual crystals are not necessarily all perfectly aligned together and there are losses at the joints between them, they are not quite as efficient. However, this mis-alignment can help in some circumstances, because the cells work better from light at all angles, in low light, etc. For this reason, I would argue that polycrystalline is slightly better suited to the UK’s duller conditions, but the difference is marginal.

The appearance is also different – you can see the random crystal arrangement and the panels look a little bluer as they reflect some of the light.[20]

Since they are cut into rectangular blocks, there is very little wasted space on the panel and you do not see the little diamonds that are typical of mono or hybrid panels. Some people prefer this more uniform appearance, others like the diamonds. The choice is yours because the overall size and cost is very similar to monocrystalline

Hybrid Panels – Panasonic (Sanyo) HIT:

The main manufacturer of hybrid panels is Panasonic (formerly Sanyo). Their HIT module which has a thin layer of amorphous solar film behind the monocrystalline cells. The extra amorphous layer extracts even more energy from the available sunlight, particularly in low light conditions. These are the most efficient panels available, so they take up the least space on your roof.

Unless you have a very small roof and want to extract the maximum amount of energy from it, we would not recommend using the hybrid panels at the moment. Hybrid panels are a lot more expensive than mono or poly-crystalline panels, so that the increase in energy produced does not justify the extra cost of buying them. Never choose hybrid panels if there is space on your roof to fit the same amount of power with crystalline panels, otherwise you will just be paying a lot more to generate the same amount of electricity.

2.5 PHOTOVOLAIC MODULES

PV cells are the basic building blocks of PV modules. For almost all applications, the one-half volt produced by a single cell is inadequate. Therefore, cells are connected together in series to increase the voltage. Several of these series strings of cells may be connected together in parallel to increase the current as well. These interconnected cells and their electrical connections are then sandwiched between a top layer of glass or clear plastic and a lower level of plastic or plastic and metal. An outer frame is attached to increase mechanical strength, and to provide a way to mount the unit. This package is called a "module" or "panel". Typically, a module is the basic building block of photovoltaic systems. PV modules consist of PV cells connected in series (to increase the voltage) and in parallel (to increase the current), so that the output of a PV system can match the requirements of the load to be powered. The PV cells in a module can be wired to any desired voltage and current. The amount of current produced is directly proportional to the cell’s size, conversion efficiency, and the intensity of light. Groups of 36 series connected PV cells are packaged together into standard modules that provide a nominal 12 volt (or 18 volts

@ peak power). PV modules were originally configured in this manner to charge 12-volt batteries.

2.6 Describing Photovoltaic Module Characteristics

To insure compatibility with storage batteries or loads, it is necessary to know the electrical characteristics of photovoltaic modules. As a reminder, "I" is the abbreviation for current, expressed in amps. "V" is used for voltage in volts, and "R" is used for resistance in ohms.

2.6.1 The standard V-I characteristic curve of Photovoltaic Module

A photovoltaic module will produce its maximum current when there is essentially no resistance in the circuit. This would be a short circuit between its positive and negative terminals. This maximum current is called the short circuit current, abbreviated I(sc). When the module is shorted, the voltage in the circuit is zero.

Conversely, the maximum voltage is produced when there is a break in the circuit. This is called the open circuit voltage, abbreviated V(oc). Under this condition the resistance is infinitely high and there is no current, since the circuit is incomplete [28]. These two extremes in load resistance, and the whole range of conditions in between them, are depicted on a graph called a I-V (current-voltage) curve. Current, expressed in amps, is on the vertical Y-axis. Voltage, in volts, is on the horizontal X-axis as in Figure.

Graph 2.1: The standard V-I characteristic curve of Photovoltaic Module

As you can see in above Figure, the short circuit current occurs on a point on the curve where the voltage is zero. The open circuit voltage occurs where the current is zero. The power available from a photovoltaic module at any point along the curve is expressed in watts. Watts are calculated by multiplying the voltage times the current (watts = volts × amps, or W = VA).

At the short circuit current point, the power output is zero, since the voltage is zero. At the open circuit voltage point, the power output is also zero, but this time it is because the current is zero. [35]

There is a point on the "knee" of the curve where the maximum power output is located. This point on our example curve is where the voltage is 17 volts, and the current is 2.5 amps. Therefore the maximum power in watts is 17 volts times 2.5 amps, equaling 42.5 watts.

The power, expressed in watts, at the maximum power point is described as peak, maximum, or ideal, among other terms. Maximum power is generally abbreviated as "I (mp)." Various manufacturers call it maximum output power, output, peak power, rated power, or other terms. The current-voltage (I-V) curve is based on the module being under standard conditions of sunlight and module temperature. It assumes there is no shading on the module.

2.6.2 Impact of solar radiation on V-I characteristic curve of Photovoltaic Module

Standard sunlight conditions on a clear day are assumed to be 1000 watts of solar energy per square meter (1000 W/m2). This is sometimes called "one sun," or a "peak sun." Less than one sun will reduce the current output of the module by a proportional amount. For example, if only one-half sun (500 W/m2) is available, the amount of output current is roughly cut in half.

Graph 2.2: Change in Photovoltaic module voltage and current on change in solar radiation

For maximum output, the face of the photovoltaic modules should be pointed as straight toward the sun as possible.

2.6.3 Impact of temperature on V-I characteristic curve of Photovoltaic Module

Module temperature affects the output voltage inversely. Higher module temperatures will reduce the voltage by 0.04 to 0.1 volts for every one Celsius degree rise in temperature (0.04V/0C to 0.1V/0C). In Fahrenheit degrees, the voltage loss is from 0.022 to 0.056 volts per degree of temperature rise.

Graph 2.3: A Typical Current-Voltage Curve for a Module at 25°C (77°F) and 85°C (185°F)

This is why modules should not be installed flush against a surface. Air should be allowed to circulate behind the back of each module so it's temperature does not rise and reducing its output. An air space of 4-6 inches is usually required to provide proper ventilation.

2.6.4 Impact of shading effect on V-I characteristic curve of Photovoltaic Module

Because photovoltaic cells are electrical semiconductors, partial shading of the module will cause the shaded cells to heat up. They are now acting as inefficient conductors instead of electrical generators. Partial shading may ruin shaded cells. Partial module shading has a serious effect on module power output. For a typical module, completely shading only one cell can reduce the module output by as much as 80%. One or more damaged cells in a module can have the same effect as shading.

Graph 2.4: A Typical Current-Voltage Curve for an Unshaded Module and for a Module with One Shaded Cell

This is why modules should be completely unshaded during operation. A shadow across a module can almost stop electricity production. Thin film modules are not as affected by this problem, but they should still be unshaded.[25]

2.7 PHOTOVOLAIC ARRAY

Desired power, voltage, and current can be obtained by connecting individual PV modules in series and parallel combinations in much the same way as batteries. When modules are fixed together in a single mount they are called a panel and when two or more panels are used together, they are called an array. Single panels are also called arrays. When circuits are wired in series (positive to negative), the voltage of each panel is added together but the amperage remains the same. When circuits are wired in parallel (positive to positive, negative to negative), the voltage of each panel remains the same and the amperage of each panel is added. This wiring principle is

used to build photovoltaic (PV) modules. Photovoltaic modules can then be wired together to create PV arrays.

Figure 2.9: PV cells are combined to create PV modules, which are linked to create PV arrays

2.8 SOLAR PHOTOVOLTAIC SYSTEM

A photovoltaic system consists of photovoltaic module, energy storage, converter, charge controller and Balance-Of-System (BOS) components. The solar cells are the heart of a PV system. A typical PV cell produces less than 2 watts at approximately 0.5 volt DC. So, for high power applications, photovoltaic cells must be connected in series parallel configurations to produce enough power. A single solar cell or a suitable interconnected matrix of solar cells when hermitically sealed with a transparent front cover and durable back cover constitutes a solar PV module. The cells are configured into modules and modules are connected as array. Modules may have peak output powers ranging from a few watts to more than 300 watts. Typical array output power may be of hundred watts to kilowatt range, although megawatt arrays exist.

Fig 2.10: Schematic of Solar PV system

2.8.1 PV System Category

PV systems fall into two basic categories: stand-alone and grid linked. The grid is the low AC voltage electricity supply network, also known as the ‘utility’ or the ‘mains’. Each of these categories is described below:

2.8.2 Stand-alone systems

A stand-alone PV system is any system incorporating PV modules and not having a connection to the grid. The simplest stand-alone system consists of a module supplying a load directly. Such a system is shown in Fig. 2.11, which can be used to power a pump or to charge a battery.

Fig. 2.11: PV system directly connected to load

Beyond a certain size of system a charge regulator is necessary to protect the battery from over-charging with subsequent reduction in life. This forms the basic DC PV system and is illustrated in Fig.3.4. As loads are added the charge regulator would also serve the function of protecting the battery from over discharging.

Fig 2.12: Basic stand–alone PV system

Further energy generator can be added to contribute charge to the battery resulting in a ‘hybrid’ system, as shown in Fig. These generators can include diesel generators, wind turbines or fuel cells. [31]

The diesel generator is usually limited by automatic control to run for short periods at or near its most efficient operating point to supply large loads, such as washing machines, and also to charge the battery. Other generators each have their own method of regulation with the battery PV charge regulator protecting the battery from over-charge by the PV system and over-discharge by the load.

Fig 2.13: Hybrid Stand Alone Solar Farm

2.8.3 Grid linked systems

Grid linked systems are sub-divided into those in which the grid acts only as an auxiliary supply (grid back-up) and those in which the grid acts as a form of storage or two-way supply (grid-connected). In these systems surplus energy flows into the grid and energy deficit is met from the grid. Alternatively, the grid connected PV system energy supply to the grid can be considered totally separately from building energy demand which is met from the grid. In grid back-up systems the grid could be unavailable at meeting the demand so a standalone AC system consisting of PV array, batteries and stand-alone inverter is used, with changeover to inverter output when the grid supply goes. Fig.2.12 illustrates the basic grid back-up PV system. In grid connected systems the grid is assumed to be available most of the time and a grid connected inverter converts the DC output of the PV array to 230V or 400V 50Hz AC for direct connection to the grid supply without the need for a battery. Fig.2.12 illustrates a typical grid connected PV system. The disadvantage of the system is the need for the presence of the grid for the inverter to function; if the grid fails then no energy is generated even at times of high irradiance.

Fig 2.14 : Grid Tied Solar System

Four configurations of metering are possible for grid-connected systems:

(i) C-B, A-D, E-F Parallel metering, no demand offset

(ii) C-B, A-D, E-F, C-F parallel metering with demand offset

(iii)C-E, E-F Reversible or no metering with demand offset

(iv) C-B, C-E, E-A Series metering with demand offset.

2.8.4 WE PREFER GRID CONNECTED PV SYSTEM

Because as day by day the demand of electricity is increased and that much demand cannot be meeting up by the conventional power plants. And also these plants create pollution. So if we go for the renewable energy it will be better but throughout the

year the generation of all renewable energy power plants. Grid tied PV system is more reliable than other PV system. No use of battery reduces its capital cost so we go for the grid connected topology. If generated solar energy is integrated to the conventional grid, it can supply the demand from morning to afternoon (total 6 hours mainly in sunny days) that is the particular time range when the SPV system can fed to grid. As no battery backup is there, that means the utility will continue supply to the rest of the time period. Grid-connected systems have demonstrated an advantage in natural disasters by providing emergency power capabilities when utility power was interrupted. Although PV power is generally more expensive than utility-provided power, the use of grid connected systems is increasing

Fig 2.15 : Grid Tied PV System

CHAPTER 03 : GRID TIED PV SYSTEM

3.1 GRID CONNECTED PV POWER GENERATION ALL OVER THE WORLD

The first large sized (1MW) grid interactive PV power plant was installed in Lugo in California, USA. The second and largest (6.5 MW) plant was installed in Carissa Plains, California, USA. Also some other large sized plant are operating in various countries and many other proposed in Italy, Switzerland, Germany, Australia, Spain and Japan. Several small capacity systems in the range of 25 KW – 200 KW are being experimentally tried out in Africa, Asia and Latin America. In India, 33 SPV, grid connected plants with total installed capacity of 2.54 MW have been installed so far, and another 550 KW aggregate installed capacity plants are undergoing installation process.

3.2 BASIC COMPONENTS OF GRID CONNECTED PV SYSTEM

The basic Grid Connected PV system design has the following components:

Figure 3.1: Block diagram Grid Connected System

PV ARRAY: A number of PV panels connected in series and/or in parallel

giving a DC output out of the incident irradiance. Orientation and tilt of these

panels are important design parameters, as well as shading from surrounding

obstructions.

INVERTER: A power converter that 'inverts' the DC power from the panels

into AC power. The characteristics of the output signal should match the

voltage, frequency and power quality limits in the supply network.

TRANSFORMER: A transformer can boost up the ac output voltage from

inverter when needed. Otherwise transformer less design is also acceptable.

LOAD: Stands for the network connected appliances that are fed from the

inverter, or, alternatively, from the grid.

METERS: They account for the energy being drawn from or fed into the local

supply network.

DC Isolator: The DC isolator provides a safe means of disconnecting the solar array from the inverter, for example for periodic maintenance. Some inverters have integrated DC isolators.

AC Isolator: A main isolator is included to provide a means of disconnecting the solar PV system from the building electricity supply. This may be important if there is an emergency, but (more usually) is needed when electricians have to do work on the building supply.

The Grid: The mains electricity network which supplies power to you may now

also supply excess solar PV production to other consumers.

Use of Electricity: At times you will be using solar PV electricity, at other

times you will be drawing from the mains supply as normal. You will not notice

any difference.

Protective Devices: Some protective devices is also installed, like under voltage

relay, circuit breakers etc for resisting power flow from utility to SPV system.

Other Devices : Other devices like dc-dc boost converter, ac filter can also be

used for better performance.

3.3 WORKING PRINCIPLE OF GRID CONNECTED PHOTOVOLTAIC SYSTEM

Electricity is produced by the PV array most efficiently during sunny periods. At night or during cloudy periods, independent power systems use storage batteries to supply electricity needs. With grid interactive systems, the grid acts as the battery, supplying electricity when the PV array cannot. During the day, the power produced by the PV array supplies loads. An inverter converts direct current (DC) produced by the PV array to alternating current (AC) and transformer stepped up the voltage level as need for export to the grid. Grid interactive PV systems can vary substantially in size. However all consist of solar arrays, inverters, electrical metering and components necessary for wiring and mounting.

3.4 CONDITIONS FOR GRID INTER FACING

There are some conditions to be satisfied for interfacing or synchronizing the SPV system with grid or utility. If proper synchronizing is not done then SPV potential cannot be fed to the grid. The conditions for proper interfacing between two systems are discussed below: Phase sequence matching: Phase sequence of SPV system with conventional grid should be matched otherwise synchronization is not possible. For a three phase system three phases should be 120 deg phase apart from each other for both the system. [15]

Frequency matching: Frequency of the SPV system should be same as grid.

Generally grid is of 50 Hz frequency capacity, now if SPV systems frequency

is slightly higher than grid frequency (0.1 to 0.5) synchronization is possible

but SPV system frequency should not be less than grid frequency.

Voltage matching: One of the vital point is voltage matching. Voltage level

of both the system should same, otherwise synchronization is not possible.

CHAPTER 4: PROJECT LOCATION ANALYSIS

4.1: Project Location

Fig 4.1 : Ahsania Mission Cancer Hospital, Mirpur Road, Dhaka, Bangladesh

Fig 4.2: Ahsania Mission Cancer Hospital, Mirpur Road, Dhaka, Bangladesh

4.2 Description of Study Area

Illustration of Ahsania Mission Cancer Hospital :

Building on the ideas of the founder Sufi Saint Hazrat Khan Bahadur Ahsan

ullah (Rahmatullah Alaihee), Dhaka Ahsania Mission embarked on establis

hing a modern cancer hospital where world-class treatment will be available

Ahsania Mission Cancer and General Hospital is one of major projects to fi

ght cancer in Bangladesh Dhaka Ahsania Mission as part of the total project

took the initiative in 2001 to open a Cancer detection & Treatment Center a

t Mirpur, Dhaka. In course of its progress it is now a 42 bed Cancer Hospita

l with required operation facilities, Chemotherapy, X-Ray and Imaging facil

ities.

A team of experienced and dedicated cancer specialists and general physici

ans are working there to provide health service at a reasonably low cost. He

free services are offered to poor and ultra - poor patients.

In the year 2008 the hospital continues to provide health care services, speci

ally to cancer patients, with some additional facilities. Ultimately the drea

m materialized into reality and a plan was made to construct a 500 bed Canc

er Hospital at a staggering cost of 2.56 billion taka (US$ 36.97 million).

The thirteen story hospital designed by a US based architectural firm "Desig

n Alliance f Bultimore", got started its construction with foundation laid on

10th July 2004 on a 3 acre land at the bank of the river Turag in Uttara Mod

el Town in the Capital.

The location is about 5 Km from Zia International Airport and the construct

ion in full gear started on 16th July 2005.

This 450,000 square feet 13 storied hospital is expected to open in late 2009

with about 200 inpatient beds, Outpatient department with about 40 Examin

ation/consultation Rooms, Medical Imaging, Pathology, Surgical Suite, Rad

iotherapy Department, non-interventional Cardiac and Neuro Diagnostics, D

ay Care and the requisite support services. By 2010 all 500 beds are expecte

d to be operational. the poor patients.

4.3 Rooftop Illustration of the project:

Fig 4.3 :Rooftop of Ahsania Mission Cancer Hospital, Mirpur Road, Dhaka, Bangladesh

Based upon a review of existing data and research reports, the site visit, and

on-site discussions with the rooftop a number of initial conclusions and

recommendations can be made as part of the site visit analysis. The total open

field area is around 20600 ft square.

First, it is recommended that the solar system be sited on the southern portion

of the rooftop. Second, based on discussions with area management, and it

would be interesting to develop the site with a multi crystalline silicon solar

panels, it was possible to develop an approximate footprint of the proposed

150 kW solar system.

The solar panel modules are large, utility scale panels with dimensions of

1956×992×40 mm , and would be mounted with a fixed tilt of 37 degrees if

designed to maximize for annual energy production.

CHAPTER 5: DESIGN PROCEDURES

5.1 Rooftop and Installation Requirements :

The shadow-free area required for installation of a rooftop solar PV system is about 110 ft square. This number includes provision for clearances between solar PV array rows. The solar panels will be installed on the roof of the building with a south facing tilt angle that is usually in Bangladesh is 30 degrees depending on the latitude of the location. The considered area lies in 23.8035 lattitude. Sufficient area shall be available for servicing the system. The minimum clearance required for cleaning and servicing of the panels is 5 ft from the parapet wall and in between rows of panels. In between the rows of solar panels sufficient gap needs to be provided to avoid the shading of a row by an adjacent row. The solar grid inverter shall be placed outdoor in a safe and easily accessible place.

In grid-connected solar photo-voltaic (PV) systems, solar energy is fed into the building loads that are connected to the grid through a service connection with surplus energy being fed into the grid and shortfall being drawn from the grid. Production of surplus energy may happen when solar energy produced exceeds the energy consumption of the building. This surplus is fed into the grid. During the night, or when during the day energy demand in the building exceeds solar energy generation, energy is drawn from the grid. Grid-connected solar PV systems have no battery storage and will not work during grid outage. For buildings with grid-connected solar PV systems, the service connection meter needs to be of the bidirectional type, whereby import kWh and export kWh are separately recorded.

A grid-connected solar PV system generally consists of the solar panels, solar panels mounting structure, one or more solar grid inverters, protection devices, meters, interconnection cables and switches.

5.1.1 TECHNICAL DETAILS

PV array capacity: 150 kWp

Cell Technology: Multi crystalline of about 15.2% efficiency

Module characteristics: Modules of output 295 Wp at standard test conditions

(STC) of 1000 W/m2insolation, Air Mass 1.5, and temperature of 25℃

Array inclined at 15 degree, facing south

A power conditioning unit will convert the DC power generated by the PV

array to 3-phase AC and feed it into the grid in synchronization with the grid

power

The IGBT based inverter in the PCU will be of very high efficiency – about

90% for output ranging from 20% to 90% of rated capacity and about 95% at

full load

The current harmonic distortion will be less that 5%

Array support structure of galvanized mild steel sections on concrete pads.

5.1.2 Scope and Purpose :

These Guidelines for grid-connected small scale (rooftop) solar PV systems have been prepared for the benefit of departments of the organization, Ahsania Mission ,that plans to install these systems for it’s cancer hospital building, Ahsania Mission Cancer Hospital. This paper is a guideline document on the analysis and system design only and the Government Departments and Organizations may make suitable modifications to these documents to meet their specific (process) requirements.

5.1.3 Grid-connected solar PV Systems

There are basically two solar PV systems: stand-alone and grid-connected. Stand-alone solar PV systems work with batteries. The solar energy is stored in the battery and used to feed building loads after conversion from DC to AC power with a stand-alone inverter. These systems are generally used in remote areas without grid supply or with unreliable grid supply. The disadvantage of these systems is that the batteries require replacement once in every 3 – 5 years.

Grid-connected solar PV systems feed solar energy directly into the building loads without battery storage. Surplus energy, if any, is exported to the grid and shortfall, if any, is imported from the grid.

5.1.4 System Components

These guidelines apply to grid-connected small scale (rooftop) solar PV systems.

A grid-connected solar PV system consists of the following main components: −

-Solar PV (photo-voltaic) array

-Solar PV array support structure

- Solar grid inverter

-Protection devices

-Cables

Equipment Supplier Country Of

Origin

Photovoltaic Module Trina Solar China

Grid Inverter SMA Solar Technology

AG

Germany

Sunny Web box & Protection

Devices

SMA Solar Technology

AG

Germany

Cable BRB Cables Ltd. Bangladesh

Table 5.1 : System components

5.1.5 Supplier Details

SMA Solar Technology AG. SMA is world’s largest producer in this

segment and has a product range with the matching inverter type for any

module type and any power class. This applies for grid tied applications as

well as island and backup operation. The Sunny Mini Central produced by

SMA already has an efficiency of over 98%, which allows for increased

electricity production. SMA‟s business model is driven by technological

progress. Due to its flexible and scalable production, SMA is in a position

to quickly respond to customer demands and promptly implement

product innovations. This allows the Company to easily keep pace with

the dynamic market trends of the photovoltaic industry.

Trina Solar Limited is a Chinese company located in the province

of Jiangsu, with numerous branches in the USA, Europe and Asia, which is

listed on the PPVX solar share index and on the NYSE. The company

develops and produces ingots, wafers, solar cells and solar modules. In the

past few years Trina Solar was listed repeatedly on the Fortune list of the top

100 of the world’s fastest growing companies (in 2011 no 11) .Trina Solar

has developed a vertically integrated supply chain, from the production of

ingots, wafers and cells to the assembly of high quality modules. The

company has shipped solar modules with a total output of 11 GW until the

end of 2014.Trina Solar specializes in the manufacture of crystalline silicon

photovoltaic modules and system integration. Trina Solar is not only a

pioneer of China's PV industry, but has become an influential shaper of the

global solar industry and a leader in solar modules, solutions and services

BRB Cable Industries Ltd is a private Limited Company was established with a view to manufacture Wires & Cables in 1978. The factory started commercial production in the year 1980 and it has become a leading manufacturer of XLPE & PVC Insulated LT & HT Cables, FRLS Cables, House and Appliances Wiring Cables, Dry & Jelly filled Telecommunication Cables, Instrumentation Cables, Aluminium Overhead Conductors, Dual

Coated Super Enamelled Copper Wire (Winding Wire), Marine Type Cables, practically all cables required from the substation down to the lighting point. All the products are approved by BSTI (Bangladesh Standards and Testing Institution) and certified by the world-renowned internationally reputed individual Testing laboratory CPRI (Central Power Research Institute), India.[38]

For its product quality, the company has earned fame in the country and its product has been approved and being used by BPDB, REB, DESA, DESCO, BMDA, PWD, BTMC, BSFIC, T&T, MES, BADC, Bangladesh Port Authority, Bangladesh Railway, Autonomous bodies, Private sector, Industrial and Apartment projects and individuals. To meet up increasing demand in the market, the company has set-up Unit-2 for producing Wires & Cables, AAAC, AAC & ACSR Conductor, XLPE & PVC Insulated LT & HT Cables, FRLS Cables, House and Appliances Wiring Cables, Dry & Jelly filled Telecommunication Cables, Instrumentation Cables, Aluminium Overhead Conductors and set-up Unit-3 for producing special type of Dual Coated Super Enamelled Copper Wire (Winding Wire).

The Company was earlier certified as an ISO-9002 certified Company for its quality management system. Keeping its commitment to ensure gradual improvement of its quality products through Research and Development, prompt customer service, the company later undertook ISO-9001:2008 certificate. This Study incorporated 3,000 Wires & Cables manufacturers of 200 countries.

5.2 Design Parameters

5.2.1 Solar PV System Capacity Sizing

The size of a solar PV system depends on the 90% energy consumption of the building and the shade-free rooftop (or other) area available. A guideline for calculating the solar PV system size is described below :

Assumptions − The roof (or elevated structure) area available is 20600 ft square

( Open Field) .

With these assumptions, the recommended capacity of the solar modules array of a proposed grid-connected solar PV system can be calculated with the following steps:

Step 1: Calculate the maximum system capacity on the basis of the shade free rooftop area. Formula:

Capacity = shade-free rooftop area (in square meters) divided by 12.

5.2.2 Solar Grid Inverter Capacity :

The recommended solar grid inverter capacity in kW shall be in a range of 95% -110% of the solar PV array capacity. In the above example, the solar array capacity was calculated to be 1 kW. The solar grid inverter required for this array would be in a range of 0.95 kW -1.1 kW.

5.3 Specification of Solar PV Modules:

The selected utility module of solar panel is TSM 295 -PC 14.

Fig 5.1 : TSM PC-14 Trina Solar Utility Module

Type Multi Crystalline Silicon (6 inches)

Origin China

Efficiency 15.2%

Degradation

warranty

10 year workmanship & 25 year linear performance

warranty

Module Frame Anodized Aluminium Alloy

Cell orientation 72 Cells ( 6 × 12 )

Module

Dimensions

77 × 39.05 × 1.57 inches

Weight 27.6 Kg

Termination Box IP 67 rated

Cables Photovoltaic Technology Cable 4.0 mm square

Connector Original MC4

Table 5.2:Specification of Solar PV Modules

5.4 Data Sheet of Trina Solar TSM PC-14 Utility Module

The data sheet is attached here:

5.5 Description Of Design Elements

(i) Solar Grid Inverter:

The solar grid inverter converts the DC power of the solar PV modules to grid-compatible AC power. The selected inverter model is Sunny Tripower 20000 TL. The detailed specifications of the solar grid inverter are given below:

Input (DC)

Max DC Power 20440 W

Max input voltage 1000 V

MPP voltage range 32 V-800 V

Min input voltage 150 V/180 V

Max input current input A/input B 33 A/33 A

Number of independent MPP inputs 2/ A:3,B:3

Output(AC)

Rated power(@230 V, 50 Hz) 20 kW

Max AC apparent power 20 kVA

AC nominal Voltage 3/N/ PE; 230V/400V

AC grid frequency 50 Hz

AC voltage range 180V-280V

Max output current/ Rated output current 29 A/36.2 A

Power factor at rated power / Adjustable

displacement power factor

1/0 overexcited to 0

underexcited

THD ≤ 3%

Feed in phases 3/3

Max efficiency 98.4 % / 98.0%

Topology/ cooling concept Transformerless /opticool

Degree of protection IP65

Table 5.3: Solar grid inverter specifications

5.5.1 Data Sheet of Sunny Tripower 20000 TL Inverter

Technical Data Sunny

Tripower

Sunny

Tripower

20000TL 25000TL

Input (DC) Input (DC)

Max. DC power (@ cos φ = 1) 20440 W 25550 W

Max. input voltage 1000 V 1000 V

MPP voltage range / rated input voltage 320 V to 800 V

/ 600 V

390 V to 800 V

/ 600 V

Min. input voltage / start input voltage 150 V / 188 V 150 V / 188 V

Max. input current input A / input B 33 A / 33 A 33 A / 33 A

Number of independent MPP inputs / strings

per MPP input

2 / A:3; B:3 2 / A:3; B:3

Output (AC)

Rated power (@ 230 V, 50 Hz) 20000 W 25000 W

Max. AC apparent power 20000 VA 25000 VA

AC nominal voltage 3 / N / PE; 220 /

380 V

3 / N / PE; 230 /

400 V

3 / N / PE; 240 /

415 V

3 / N / PE; 220 /

380 V

3 / N / PE; 230 /

400 V

3 / N / PE; 240 /

415 V

Nominal AC voltage range 160 V to 280 V 160 V to 280 V

AC grid frequency / range 50 Hz, 60 Hz / -

6 Hz to +5 Hz

50 Hz, 60 Hz /

6 Hz to +5 Hz

Rated power frequency / rated grid voltage 50 Hz / 230 V 50 Hz / 230 V

Max. output current 29 A 36.2 A

Power factor at rated power 1 1

Adjustable displacement power factor 0 overexcited to

0 underexcited

0 overexcited to

0 underexcited

Feed-in phases / connection phases 3 / 3 3 / 3

Efficiency

Max. efficiency / European Efficiency 98.4 % / 98.0 % 98.3 % / 98.1 %

Protective devices

DC-side disconnection device ● ●

Ground fault monitoring / grid monitoring ● / ● ● / ●

DC surge arrester (type II) can be integrated ○ ○

DC reverse polarity protection / AC short-

circuit current capability / galvanically

isolated

● / ● / — ● / ● / —

All-pole sensitive residual-current monitoring

unit

● ●

Protection class (according to IEC 62103) /

overvoltage category (according to IEC 60664-

1)

I / III I / III

General data

Dimensions (W / H / D) 665 / 690 / 265

mm (26.2 /

27.2 / 10.4

inch)

665 / 690 / 265

mm (26.2 /

27.2 / 10.4

inch)

Weight 61 kg (134.48 lb) 61 kg (134.48 lb)

Operating temperature range -25 °C to +60 °C

(-13 °F to +140

°F)

-25 °C to +60 °C

(-13 °F to +140

°F)

Noise emission (typical) 51 dB(A) 51 dB(A)

Self-consumption (at night) 1 W 1 W

Topology / cooling concept Transformerless /

Opticool

Transformerless /

Opticool

Degree of protection (as per IEC 60529) IP65 IP65

Climatic category (according to IEC 60721-3-

4)

4K4H 4K4H

Maximum permissible value for relative

humidity (non-condensing)

100 % 100 %

Features

DC connection / AC connection SUNCLIX /

spring-cage

terminal

SUNCLIX /

spring-cage

terminal

Display – –

Interface: RS485, Speedwire/Webconnect

Multifunction relay / Power Control Module

○ / ● ○ / ●

○ / ○ ○ / ○

Guarantee: 5 / 10 / 15 / 20 / 25 years ● / ○ / ○ / ○ / ○ ● / ○ / ○ / ○ / ○

Planned certificates and permits (more

available on request)

AS 4777, BDEW 2008, C10/11, CE,

CEI 0-16, CEI 0-21, EN 50438

G59/3, IEC61727, IEC 62109

NEN EN 50438, NRS 097-2

PPC, RD 1699, RD 661/2007,

SI4777, UTE C15-712-1, VDE 0126

1-1, VDE-AR-N 4105, VFR 2014

Type designation STP 20000TL-

30

STP 25000TL

30

www.SMA-Solar.com SMA Solar Technology

(ii) Solar Array Fuse:

The cables from the array strings to the solar grid inverters shall be provided with DC fuse protection. Fuses shall have a voltage rating and current rating as required. The fuse shall have DIN rail mountable fuse holders and shall be housed in thermoplastic IP 65 enclosures with transparent covers.

(iii) DC Combiner Box :

A DC Combiner Box shall be used to combine the DC cables of the solar module arrays with DC fuse protection for the outgoing DC cable(s) to the DC Distribution Box.

(iv) DC Distribution Box

A DC distribution box shall be mounted close to the solar grid inverter. The DC distribution box shall be of the thermo-plastic IP65 DIN-rail mounting type and shall comprise the following components and cable terminations: − Incoming positive and negative DC cables from the DC Combiner Box;

− DC circuit breaker, 2 pole (the cables from the DC Combiner Box will be connected to this circuit breaker on the incoming side);

− DC surge protection device (SPD)

− Outgoing positive and negative DC cables to the solar grid inverter. As an alternative to the DC circuit breaker a DC isolator may be used inside the DC Distribution Box or in a separate external thermoplastic IP 65 enclosure adjacent to the DC Distribution Box. If a DC isolator is used instead of a DC circuit breaker, a DC fuse shall be installed inside the DC Distribution Box to protect the DC cable that runs from the DC Distribution Box to the Solar Grid Inverter.[31]

(v) AC Distribution Box :

An AC distribution box shall be mounted close to the solar grid inverter. The AC distribution box shall be of the thermo-plastic IP65 DIN rail mounting type and shall comprise the following components and cable terminations:

− Incoming 3-core / 5-core (three-phase) cable from the solar grid inverter

− AC circuit breaker, 2-pole / 4-pole

− AC surge protection device (SPD)

− Outgoing cable to the building electrical distribution board.

(vi) Cables :

All cables shall be supplied conforming to IEC 60227/ IS 694 & IEC 60502/

IS 1554. Voltage rating: 1,100V AC, 1,500V DC

For the DC cabling, XLPE or XLPO insulated and sheathed, UV stabilized

single core flexible copper cables shall be used. Multi-core cables shall not

be used.

For the AC cabling, PVC or XLPE insulated and PVC sheathed single or

multi-core flexible copper cables shall be used. Outdoor AC cables shall have

a UV-stabilized outer sheath.

The total voltage drop on the cable segments from the solar PV modules to

the solar grid inverter shall not exceed 2.0%.

The total voltage drop on the cable segments from the solar grid inverter to

the building distribution board shall not exceed 2.0%

The DC cables from the SPV module array shall run through a UV stabilized

PVC conduit pipe of adequate diameter with a minimum wall thickness of

1.5mm.

Cables and wires used for the interconnection of solar PV modules shall be

provided with solar PV connectors (MC4) and couplers.

All cables and conduit pipes shall be clamped to the rooftop, walls and

ceilings with thermo-plastic clamps at intervals not exceeding 50 cm. The

minimum DC cable size shall be 4.0 mm2 copper. The minimum AC cable

size shall be 10 mm2 copper. In three phase systems, the size of the neutral

wire size shall be equal to the size of the phase wires. The following color

coding shall be used for cable wires:

− DC positive: red (the outer PVC sheath can be black with a red line

marking) − DC negative: black

− AC single phase: Phase: red; neutral: black

− AC three phase: Phases: red, yellow, blue; neutral: black

− Earth wires: green

Cables and conduits that have to pass through walls or ceilings shall be taken

through a PVC pipe sleeve.

Cable conductors shall be terminated with tinned copper end-ferrules to

prevent fraying and breaking of individual wire strands. The termination of

the DC and AC cables at the Solar Grid Inverter shall be done as per

instructions of the manufacturer, which in most cases will include the use of

special connectors.

Fig 5.2.1 : 1× 6 �� NYYF (Flexible) Cable

Fig 5.2.2 : 1× 4 �� NYY Cable

(vii) Junction Boxes

Junction boxes and solar panel terminal boxes shall be of the thermos-plastic

type with IP 65 protection for outdoor use and IP 54 protection for indoor

use.

Cable terminations shall be taken through thermo-plastic cable glands. Cable

ferrules shall be fitted at the cable termination points for identification.

(viii) Metering

An energy meter shall be installed in between the solar grid inverter and the

building distribution board to measure gross solar AC energy production (the

“Solar Generation Meter”). The Solar Generation Meter shall be of the same

accuracy class as the service connection meter or as specified by design.

The existing service connection meter needs to be replaced with a

bidirectional (import kWh and export kWh) service connection meter (the

“Solar Service Connection Meter”) for the purpose of net-metering.

Installation of the Solar Service Connection Meter is carried out by DESA.

It is not in the scope of the work of the Installer.

5.6 Connection to the Building Electrical System

The AC output of the solar grid inverter shall be connected to the building’s

electrical system after the service connection meter and main switch on the

load side.

The solar grid inverter output shall be connected to a dedicated module in

the Main Distribution Board (MDB) of the building. It shall not be connected

to a nearby load or socket point of the building.

The connection to the electrical system of the building shall be done as

shown in typical wiring diagram shown below .

5.7 Earthing

The PV module structure components shall be electrically interconnected and shall be grounded.

Earthing shall be done in accordance with IS 3043-1986, provided that

earthing conductors shall have a minimum size of 6.0 mm2 copper, 10 mm2

aluminium or 70 mm2 hot dip galvanized steel. Unprotected aluminium or

copper-clad aluminium conductors shall not be used for final underground

connections to earth electrodes.

A minimum of two separate dedicated and interconnected earth electrodes

must be used for the earthing of the solar PV system support structure with

a total earth resistance not exceeding 5 Ohm.

The earth electrodes shall have a precast concrete enclosure with a

removable lid for inspection and maintenance. The entire earthing system

shall comprise non-corrosive components.

5.8 Surge Protection :

Surge protection shall be provided on the DC side and the AC side of the

solar system.

The DC surge protection devices (SPDs) shall be installed in the DC

distribution box adjacent to the solar grid inverter.

The AC SPDs shall be installed in the AC distribution box adjacent to the

solar grid inverter.

The SPDs earthing terminal shall be connected to earth through the above

mentioned dedicated earthing system. The SPDs shall be of type 2 as per IEC

60364-5-53

5.9 Typical Wiring Diagrams for Grid-Connected Solar System

Fig 5.3 : Wiring Diagram for Grid-Connected Solar System

5.10 Power factor Requirements

The power factor of the inverter when considered as a load from the perspective of the grid should be maintained in the range 0.8 leading to 0.95 lagging for output

levels ranging from 20% to 100% of rating. Most inverters are configured to supply only active power and as such operate at unity power factor.

5.11 Grid Protection Requirements

The inverter specifies grid protection requirements. This part of the standard specifies the conditions under which an inverter must disconnect from the grid and specifies performance requirements for the equipment or other mechanisms which are used to accomplish this disconnection. The standard states that the inverter must disconnect from the grid:

• If supply from the grid is disrupted;

• If the grid goes outside present parameters (voltage and frequency limits);

• To prevent islanding.

It also describes the mechanisms by which inverters may re-connect to the grid after a disconnection.

5.12 Power Quality Issues Related to Solar PV Systems

Potential power quality issues related to high penetration of solar PV systems include increases in harmonic levels, deterioration in power factor and voltage rise.

5.12.1 Harmonic Distortion

Depending on the design of the inverter, there is potential for solar PV inverters to inject harmonic currents into the electricity network leading to increased harmonic voltage distortion. Square wave and quasi-sine wave inverters which have highly distorted output current waveforms are well known sources of harmonic distortion. However, the harmonic current output of modern inverters complying with STP 20000 TL is limited by the standard. Further, many modern inverters generally supply current waveforms which are nearly sinusoidal. As such, harmonic distortion due to modern inverters is expected to be negligible and to date there is little evidence of harmonic levels rising due to the influence of high solar PV inverter penetration. [31]

One area of concern with respect to harmonic distortion that has arisen recently is the contribution of inverters to what would be considered very high frequency harmonics. In order to produce a high quality output waveform, inverter systems switch at high frequencies (20 kHz or more). Harmonic voltages due to these

switching frequencies have been detected in distribution networks. The magnitude of these switching frequency harmonics and their impact on the distribution network is an area of ongoing research.

5.12.2 Power Factor

As detailed before, the inverter requires to operate at a high power factor. Further, most modern inverters operate at unity power factor. As such, the inverter itself does not constitute a problematic load with regard to power factor. However, one side effect of inverters operating at unity power factor is that solar PV systems may reduce power factor at distribution transformers. This is due to the fact that active load current is generated locally by the inverters while the upstream grid must supply all reactive load current. This results in a higher proportion of reactive to active load currents passing through distribution transformer resulting in reduction of the power factor at the transformer. However, this in itself does not present any operational problems for the network. In fact, local generation of active current reduces network losses as power does not need to be transported as far. Figure 12 illustrates graphically the mechanism by which power factor may be reduced at distribution transformers due to the interaction of PV systems. An example is shown in the figure :

Fig 5.4 : How PV Systems can Impact on Distribution Substation Power Factor

5.12.3 Local Voltage Rise

To date, by far the most prevalent power quality issue related to solar PV systems has been steady state voltage rise near inverter connection points. Traditional distribution systems were designed to deliver power in one direction only. Under

such a scenario, in a low voltage feeder, voltage levels were highest at the terminals of the distribution transformer and decreased along the length of the feeder due to voltage drops caused by load currents interacting with network impedances. In its simplest form, voltage rise can occur along a LV feeder due to the local generationsupplying all of the current required by local loads. As such, there is little to no voltage drop along the feeder and feeder voltage levels become close to the voltage at the transformer terminals. However, the nature of inverters compounds this problem by continuing to attempt to export power regardless of the feeder voltage. In such cases, local voltage levels may exceed the voltage level at the transformer terminals. In simplified form, the concept of voltage rise due to PV generation is illustrated in Figure 13.

Figure 5.5 : Simple Illustration of Voltage Rise due to PV Generation [14]

The degree of local voltage rise is directly influenced by the impedance or strength of the network. If the network to which the inverter is connected is weak (i.e. high impedance) the voltage at the inverter connection point will begin to rise. This has two potential consequences. The first impact is that once the voltage at the inverter connection point rises to the inverter pre-set overvoltage limit as prescribed in STP 20000 TL, the inverter will disconnect from the grid. If this occurs, no power can be exported and no income can be generated from feed-in tariffs. The second issue is that if the overvoltage limit on the inverter is set too high, the connection point

voltage may exceed the allowed maximum feeder voltage. Many utilities have specified that inverters should disconnect from the grid when the inverter connection point voltage exceeds 253 V. However, either by design, or other adjustment by installers, some inverters are not configured in this fashion and inverter connection point voltages of up to 270 V have been observed. These voltage levels are outside of the standard voltages and will likely damage or significantly reduce the lifespan of equipment connected at or near the inverter connection point.

The problem of connection point voltage rise has been observed in the field where loading levels are low and particularly where large rated power installations are being connected to weak networks. In these cases significant investment in solar PV systems is not being recouped due to the fact that the inverters are often switching off due to operation of overvoltage protection. Figure 14, below, gives an indication of the amount of PV generation that may be installed based on a given grid impedance and pre-connection voltage (shown in box on curves) before a switch off condition of 253 V is reached. This graph clearly illustrates the impact that grid impedance has on the capability of the network to accept generation before the above voltage limit is exceeded.[22]

Figure 5.6 : Graph showing PV Generation that may be Connected for a given Grid Impedance before Disconnect Voltage of 253 V is Reached.

5.12.4 Other Network Issues Related to Solar PV Systems

(i) Interference with Protection Operation

An important network issue related to high levels of solar PV system penetration is the potential to mask fault currents. Under normal network operating conditions, fault current is supplied by the upstream network and Real Power (kW)flows through upstream protection devices. Upon detection of this fault current, the protection device operates to clear the fault. Where solar PV systems are present, solar PV systems will supply a portion of the fault current. As solar inverter systems are inherently current limited, the inverter may not shut off under certain fault conditions.

The contribution of individual inverters to fault current may be small, but where penetration is high and fault current is low there is potential for the fault current supplied by the inverters to limit the fault current that flows through the upstream protection device to such an extent that it is not sufficient to cause the protection device to operate. In such a case, the solar PV systems are effectively masking the fault. This is a very dangerous situation with potential safety risk to people and the possibility of damage to equipment. Figure 15 shows diagrammatically how high penetration of solar PV systems may mask fault currents.

Figure 5.7 : How High Penetration of Solar PV Systems may Reduce Fault Currents

5.12.6 PV Systems and Stability

Where solar PV penetration is high, a significant amount of load may be supplied by the solar generation. If the solar generation is lost, large power swings may occur. If there is insufficient generation to supply the load upon loss of solar generation, this may lead to network stability issues and potential outages. Solar generation may be lost due to a transient fault. In such case, it may be preferable for the solar PV generation to ride through the fault so that power swings are limited. However, fault ride through is not dealt within STP 20000 TL and, at the present time, PV systems must disconnect on detection of network faults. The impact of high penetration of solar PV systems on network stability is an area of ongoing research.[24]

CHAPTER 6 : DESIGN AND CALCULATION

6.1 SYSTEM DESIGN

Grid connected PV system can be designed in various ways, like with battery, without battery, with or without transformer etc. Here without battery grid interconnected system is used, because of short life time, large replacement cost, and increased installation cost. A transformer is used for boosting the ac output voltage and feeding to grid. There are two meters connected-one is called the import meter, the other is called the export meter. Thus the difference between the two meter readings gives the power fed to the grid from solar photovoltaic power plant. So using these meters we can easily determine what amount of energy is fed to the grid from solar power.

6.2 Design Overview by Sunny Design Software

From the results obtained, we find that a 150 kWp solar photovoltaic power plant can be developed on 20600 ft² chosen rooftop area. Corresponding system sizing and specifications are provided along with the system design. By the evaluation of design done by “Sunny Design” software, we achieved the following overview:

Azimuth Angle: 0° , Tilt Angle: 30° , Mounting type : Roof

Total Number of PV modules 552 Peak Power 162.84 kWp Number of inverters 7 Nominal AC Power 140.00 kW AC Active Power 140.00 kW Active power ratio 86% Annual energy yield ( approx.) 263.22 MWh Energy usability factor 100% Performance ratio (approx.) 84.2 % Spec. energy yield (approx.) 1616 kWh/kWp Line losses ( in % of PV energy) N/A Unbalanced Load 0.00 VA

Table 6.1 : Overview of Simulation by Sunny Design Software

For the 150 kWp plant,

The required no. of PV modules = 552 which has to be accommodate within the free space of the rooftop of about 20600 ft²

The total number of PV modules are divided into two groups.

Group A

Group B

Group A design evaluation :

Peak Power 138.06 kWp Total number of PV modules 468 Number of inverters 6 Max DC power 20.44 kW Max. AC active power 20.00 kW Grid Voltage 220 V (220V/380 V) Nominal Power Ratio 89% Displacement power factor (Cos∅) 1

Table 6.2 : Overview of Simulation by Sunny Design Software

Fig 6.1: Block Diagram representation of Group A

Technical Specifications:

Input A Input B Number of strings 3 2 PV modules per string 18 12 Peak Power ( input) 15.93 kWp 7.08 kWp Typical PV voltage 584 V 789 V Min. PV Voltage 549 V 366 V

6×STP 20000 TL

Input A Input

B

Array of 18

Solar Panels Array of 18

Solar Panels

Array of 18

Solar Panels

Array of 12

Solar Panels

Array of 12

Solar Panels

Min. DC Voltage (Grid Voltage 220 V) 320 V 320 V Max. PV Voltage 862 V 575 V Max. DC Voltage 1000 V 1000 V Max. current of PV array 24.1 A 16.1 A Max DC current 33 A 33

Group B design evaluation :

Peak Power 24.78 kWp Total number of PV modules 84 Number of inverters 1 Max DC power 20.44 kW Max. AC active power 20.00 kW Grid Voltage 220 V (220V/380 V) Nominal Power Ratio 82% Displacement power factor (Cos∅) 1

Fig 6.2 : Block Diagram representation of Group A

1×STP 20000 TL

Input A Input

B

Array of 14

Solar Panels Array of 14

Solar Panels

Array of 14

Solar Panels

Array of 14

Solar Panels

Array of 14

Solar Panels Array of 14

Solar Panels

Technical Specifications:

Input A Input B Number of strings 3 3 PV modules per string 14 14 Peak Power ( input) 12.39 kWp 12.39 kWp Typical PV voltage 454 V 454 V Min. PV Voltage 427 V 427 V Min. DC Voltage (Grid Voltage 220 V) 320 V 320 V Max. PV Voltage 671 V 671 V Max. DC Voltage 1000 V 1000 V Max. current of PV array 24.1 A 16.1 A Max DC current 33 A 33 A

6.3 DESIGN LAYOUT BY AUOTOCAD

6.4 CALCULATIONS

(i) Plant Capacity Calculation :

For TSM PC-14 Solar Panel,

Peak power watts, Pmax= 295 Wp

No of solar panels =X

Y= X× Space factor

Here , Space factor is 0.9

So, The Plant Capacity = Y× Pmax

The Energy= ����� �������� ����� ����������

��������� ���� (unit : Kwh/day)

Here Operating Time =4.5

Plant Efficiency = 85 %

In our Design ,

X= 552

Y= X× Space factor

= 552×0.9

= 496.08

Plant Capacity = Y× Pmax

=(496.8 × 295 ��)

= 146.556 ���

≈ 150 ���

The Energy= ����� �������� ����� ����������

��������� ���� (unit : Kwh/day)

=��� �.��

�.� Kwh/day

= 28.3333 Kwh/day

(ii) DC Output Power Calculation :

Selected Utility Module of Solar panel is TSM PC-14

Peak Power watts , Pmax=295 Wp

Maximum Power Voltage, Vmp= 36.6 V

Open Circuit Voltage , Voc= 45.2 V

Maximum Power Current , Impp=8.07 A

Short Circuit Current , Isc =8.55 A

Group A :

No of Inverters=6

No of strings containing 18 Solar panels each=18

No of Strings containing 12 solar panels each=12

Total number of strings in group A = 18+12

= 30

So, The total number of panels in Group A = (18 × 18) + (12 × 12)

= 468

(i) Output Voltage of each string having 18 solar panels

= No of solar panels in each string × ���

=18× 36.6

=658.8 VDC

(ii) Output Voltage of each string having 12 solar panels

= No of solar panels in each string × ���

=12× 36.6

=439.2 VDC

(iii) Output Current of each string , Impp= 8.07 ADC

Since , the solar panels are connected in series with each other, the total

output current of A group

=(8.07 × 18) + (8.07 × 12)

=242.1 ADC

Group B :

No of Inverters=1

No of strings containing 14 Solar panels each =6

Total number of strings in group A = 6

So, The total number of panels in Group A =14 × 6

= 84

(i) Output Voltage of each string having 18 solar panels

= No of solar panels in each string × ���

=14× 36.6

=512.4 VDC

(ii) Output Current of each string , Impp= 8.07 ADC

Since , the solar panels are connected n series with each other, the total

output current of A group

=�� �� ������ × ����

=48.2 ADC

(iv) DC Output power of the string containing 18 solar panels

= � × ����

=658.8 × 8.07

=5.32 Kw

(v) DC Output power of the string containing 12 solar panels

= � × ����

=459.2 × 8.07

=3.54 Kw

(vi) DC Output power of the string containing 14 solar panels

= � × ����

=512.4 × 8.07

=4.14 Kw

(vii) Total DC output power of the inverters

=(Output power of the string containing 18 solar panels ×No of String

containing 18 Solar panels)+ (Output power of the string containing 12

solar panels ×No of String containing 12 Solar panels)+ (Output power

of the string containing 14 solar panels ×No of String containing 14 Solar

panels)

=(5.32 × 18) + (3.54 × 12) + (4.14 × 6)

=163.08 kW

(iii) Output AC power Calculation :

For Group A type inverters,

(i) For Input A ,

Number of strings =3

PV modules per string=18

So, the peak power (DC) of input A is

= ������ �� ������� × �� ������� ��� ������

=(3 × 18) ���

=15.93 ���

(ii) For Input B ,

Number of strings =2

PV modules per string=12

So, the peak power (DC) of input B is

= ������ �� ������� × �� ������� ��� ������

=(2 × 12) ���

= 7.08 ���

(iii) Total input DC power of each Group-A type inverter

=���� �� ����� �� �ℎ� ����� � + ���� �� ����� �� �ℎ� ����� �

=15.93 ��� + 7.08 ���

=23.01 ���

With 20 % Overload, the input DC power of each Group A type inverter

becomes

= Total input DC power of each Group A type inverter × 1.2

=23.01 ��� × 1.2

=27.612 ���

≈ 28 ���

(iv) In case of each inverter the output AC power would be 98 % of the input

DC power of that inverter.

Thus, the output AC power of each Group A type inverter becomes

= Input DC power of each Group A type inverter × 98%

=28 ��� × 98%

= 27.44 ���

For Group B type inverters,

(v) For Input A ,

Number of strings =3

PV modules per string=14

So, the peak power (DC) of input A is

= ������ �� ������� × �� ������� ��� ������

=(3 × 14) ���

=12.39 ���

(vi) For Input B ,

Number of strings =3

PV modules per string=14

So, the peak power (DC) of input B is

= ������ �� ������� × �� ������� ��� ������

=(3 × 14) ���

=12.39 ���

(vii) Total input DC power of each Group-B type inverter

=���� �� ����� �� �ℎ� ����� � + ���� �� ����� �� �ℎ� ����� �

=12.39 ��� + 12.39 ���

=24.64 ���

With 20 % Overload, the input DC power of each Group-B type inverter

becomes

= Total input DC power of each Group B type inverter × 1.2

=24.64 ��� × 1.2

=29.568 ���

≈ 30 ���

(viii) In case of each inverter the output AC power would be 98 % of the input

DC power of that inverter.

Thus, the output AC power of each Group-B type inverter becomes

= Input DC power of each Group B type inverter × 98%

=30 ��� × 98%

=29.4 ���

(iv) Output Current Calculation :

The formula is � = √3 �� ���∅

Here , For Group-A type inverters the Output AC power is , � = 27.44 ���

Per phase voltage is , � =230 V

For inductive load , Pf = ���∅ =0.8

So , the output current of each line of the inverter is ,

�= � ÷ � √3 ����∅�

=27.44 kWp÷(√3 ×230 V× 0.8)

≈ 87 �

Here , For Group-B type inverters the Output AC power is , � = 29.4 ���

Per phase voltage is , � =230 V

For inductive load , Pf = ���∅ =0.8

So , the output current of each line of the inverter is ,

�= � ÷ � √3 ����∅�

=29.4 kWp÷(√3 ×230 V× 0.8)

≈ 93 �

So, The total current going out of the MDB to Substation is

=( ������ ������� �� ���ℎ ����� � ���� �������� ×

�� �� ����� � ���� �������� ) +

( ������ ������� �� ���ℎ ����� � ���� �������� ×

�� �� ����� � ���� �������� )

=(4 × 87 × 6) + (4 × 93 × 1)

=2460 A

Circuit Breaker Rating Calculation :

(i) For each Group-A type inverter, the output AC current of each line is

=87 �

For circuit breaker design, taking 20% overcurrent margin, the output AC

current of each line becomes =( 87 × 1.2 ) �

=104.4 A

Due to the market availability , We took the cicuit breaker rating = 100 A

That means, We decided to use 100 A MCCB in each Group-A type inverter’s

output for the convenience.

(ii) For each Group-B type inverter, the output AC current of each line is

=93 �

For circuit breaker design, taking 20% overcurrent margin, the output AC

current of each line becomes =( 93 × 1.2 ) �

=111.6 A

≈ 112 �

Due to the market availability , We took the cicuit breaker rating = 125 A

That means, We decided to use 125 A MCCB in each Group-B type inverter’s

output for the convenience.

(iii) The output current of each line of the MDB toward s the substation is

=2460 A

For the circuit Breaker Design , taking 20% overcurrent margin,the output

current of MDB becomes

=(2460 × 1.2) �

=2952 A

For the market availability, We took the cuircuit breaker rating=3000 A

Tha means , We decided to use 3000A ACB in each line of the output of the

MDB towars the substation.

Fig 6.3 : System Design Illustration

(iv) Wire Length Calculation :

In the design , We have chosen 3 different size of cables. We chose,

1 × 4�� NYY DC Cable for the connection between the solar panels and

the Inverters.

1 × 6�� NYYF(Flexible ) Cable for the connection between the Inverter

output and the Bus Bars OF MDB.

1 × 16 �� NYYF(Flexible ) Cable for the connection of the MDB’s output

towards the Substation.

(i) Solar Panel String Wire Length Calculation :

No of full string containing 18 solar panels =18

Length of wire per string = 116 ft

So, the total amount of wire= (116 ft × 18 )

=2088 ft

≈ 2100 ��

No of full string containing 12 solar panels =12

Length of wire per string = 78 ft

So, the total amount of wire= (78 ft × 12 )

=936 ft

≈ 940 ��

No of full string containing 14 solar panels =6

Length of wire per string = 92 ft

So, the total amount of wire= (92 ft × 6 )

=552 ft

≈ 555 ��

Total amount of wire required to connect all 36 strings of solar

panel= (2100� + 940� + 555�)

=3595 ft

≈ 3600 �� ≈ ���� �����

(ii) Solar Panel strings to Inverter connecting Wire length

Calculation:

Inverter 01 :

Total length of the wire used in input:

=�����ℎ �� ���� �� ��� ����� × ������ �� ������

=220� × 5

=1100 ′

Inverter 02:

Total length of the wire used in input:

=�����ℎ �� ���� �� ��� ����� × ������ �� ������

=76′ × 5

=380′

Inverter 03 :

Total length of the wire used in input:

=�����ℎ �� ���� �� ��� ����� × ������ �� ������

=40� × 6

=240′

Inverter 04 :

Total length of the wire used in input:

=�����ℎ �� ���� �� ��� ����� × ������ �� ������

=30� × 5

=150′

Inverter 05 :

Total length of the wire used in input:

=�����ℎ �� ���� �� ��� ����� × ������ �� ������

=20� × 5

=100 ′

Inverter 06 :

Total length of the wire used in input:

=�����ℎ �� ���� �� ��� ����� × ������ �� ������

=100� × 5

=500 ′

Inverter 07 :

Total length of the wire used in input:

=�����ℎ �� ���� �� ��� ����� × ������ �� ������

=20′ × 5

=100 ′

Total amount of wire required at the input of all 7 inverters=

1100� + 380� + 240� + 150� + 100� + 500� + 100′

=2570 ft

≈ 783.336 ����� ≈ 790 �����

So, total length of 1 × 4 �� ��� �� ����� required

= Total amount of wire required to connect all 36 strings of solar panel+ Total

amount of wire required at the input of all 7 inverters

=2000 meter +790 meter

=2790 meter ≈ 2800 meter

(iii) Inverter output to Busbar (MDB) connecting wire length

calculation :

Inverter 01 :

Total length of the wire used in output:

=�����ℎ �� ���� �� ��� ������ × ������ �� �������

=125′ × 4

=500′

Inverter 02 :

Total length of the wire used in output:

=�����ℎ �� ���� �� ��� ������ × ������ �� �������

=150′ × 4

=600′

Inverter 03:

Total length of the wire used in output:

=�����ℎ �� ���� �� ��� ������ × ������ �� �������

=250′ × 4

=1000′

Inverter 04 :

Total length of the wire used in output:

=�����ℎ �� ���� �� ��� ������ × ������ �� �������

=125′ × 4

=500′

Inverter 05 :

Total length of the wire used in output:

=�����ℎ �� ���� �� ��� ������ × ������ �� �������

=375′ × 4

=1500′

Inverter 06 :

Total length of the wire used in output:

=�����ℎ �� ���� �� ��� ������ × ������ �� �������

=375′ × 4

=1500′

Inverter 07 :

Total length of the wire used in output:

=�����ℎ �� ���� �� ��� ������ × ������ �� �������

=250′ × 4

=1000′

Total length of the 1 × 6 �� ���� ����� required to connect

all 7 Inverter’s output to the busbar of MDB

=500� + 600� + 1000� + 500� + 1500� + 1500� + 1000�

=6600�

=2011.68 meter ≈ ���� �����

(iv) MDB to Substation Connecting wire length Calculation

Total length of the wire used in output:

=�����ℎ �� ���� �� ��� ������ × ������ �� �������

=25 ����� × 4

=100 meter

6.5 Financial Overview In Brief

(i) Solar Panel Cost :

Selected Model : TSM PC-14 Trina Solar

Total Number Required: 552 pieces

Price: 53 BDT per watt

Peak power watts ; 295 Wp

Total Price :

= ����� ��� ����� × ���� ����� ����� ×

����� ������ �� ����� ������ ��������

=(��× ���× ���) BDT

=86,30,520 BDT

(ii) Inverter Cost :

Selected Model : Sunny Tripower STP 20000 TL

Total Number Required: 7 pieces

Price: 3,40,000 BDT per piece

Total Price :

=����� ��� ����� × ����� ������ �� ��������� ��������

=(� × �,��,���) BDT

= 2380,000 BDT

(iii) Cable Cost :

Selected Model : 1 × 4 �� ��� �� �����

Total Length Required: 2800 meter

Price: 6000 BDT per 100 meter

So , Each 1 meter of cable costs=(6000 ÷ 100) ���

= 60 BDT

Total Price :

=����� ��� 1 � �����ℎ × ����� �����ℎ �� ����� ��������

=(��× ����) BDT

= 1,68,000 BDT

Selected Model : 1 × 6 �� ���� ( ��������) �����

Total Length Required: 2020 meter

Price: 9160 BDT per 100 meter

So , Each 1 meter of cable costs=(9160 ÷ 100) ���

= 91.6 BDT

Total Price :

=����� ��� 1 � �����ℎ × ����� �����ℎ �� ����� ��������

=(��. �× ����) BDT

= 1,85,032 BDT

Selected Model : 1 × 16 �� ���� ( ��������) �����

Total Length Required: 100 meter

Price: 23,300 BDT per 100 meter

So , Each 1 meter of cable costs=(23,300 ÷ 100) ���

= 233 BDT

Total Price :

=����� ��� 1 � �����ℎ × ����� �����ℎ �� ����� ��������

=(��� × ���) BDT

= 23,300 BDT

Total Price of the cable = (�,��,��� + �,��,��� +

��,���)���

=3,76,332 BDT

(iv) Circuit Breaker Cost

Selected Rating : 100 A MCCB

Total Number Required: 24 pieces

Price: 10,700 BDT per piece

Total Price :

=����� ��� ����� × ����� ������ �� �� ��������

=(��,��� × ��) BDT

= 2,56,800 BDT

Selected Rating : 125 A MCCB

Total Number Required: 4 pieces

Price: 10,700 BDT per piece

Total Price :

=����� ��� ����� × ����� ������ �� �� ��������

=(��,��� × �) BDT

= 42,800 BDT

Selected Rating: 3000 A ACB

Total Number Required: 4 pieces

Price: 3,50,000 BDT per piece

Total Price :

=����� ��� ����� × ����� ������ �� �� ��������

=(�,��,�� × �) BDT

= 14,00,000 BDT

Total Price Of Circuit Breaker

=(2,56,800 + 42,800 + 14,00,000)���

=16,99,600 ≈ ��,��,��� ���

(v) MDB Cost : 30,000 BDT

(vi) Earthing Cost : 1,00,000 BDT

Serial No. Component Quantity Value Unit

1. Solar Panel 552 pieces 86,30,520 BDT

2. Inverter 7 pieces 23,80,000 BDT

3. Cable 4920 meter 3,76,332 BDT

4. Circuit Breaker 32 pieces ��,��,��� BDT

5. MDB 30,000 BDT

6. Earthing 1,00,000 BDT

Total Cost: 1,32,16,852 BDT

Table 6.4 Financil Overview in short

Per Watt Cost = ����� ���� ÷ ����� ��������

=1,32,16,852 BDT ÷ 150000 ��

=88.11 BDT per ��

CHAPTER 7 : CONCLUSION

7.1 CONCLUSION

It is expected that with present acceleration in the efforts on the part of

manufacturers, designers, planners and utilities with adequate Governmental

support, PV systems will within the next two decades occupy a place of pride in the

country’s power sector, ensuring optimum utilization of the energy directly from

the sun around the year. It is clear that the Grid Connected SPV system can provide

some relief towards future energy demands. The outputs were calculated on the

basis of 20600 ft² area. Considering the average peak output is calculated from

where an estimate of the possible plant rating is made. The methodology adopted

seems satisfactory for determining the possible plant capacity for an arbitrarily

chosen area. The design described is based on the potential measured. System sizing

and specifications are provided based on the design made. Finally, cost analysis is

carried out for the proposed design. Total Estimated 150 KWp PV System Cost is

1,32,16,852 BDT . It costs 88.11 BDT per Wp Daily energy generation is also

calculated. The daily energy generation feed into the grid is approximately

estimated as 28 kwh/day

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BOOK [1]. “SOLAR PHOTOVOLTAICS FUNDAMENTALS, TECHNOLOGIES AND APPLICATION” by Chetan Singh Solanki, 2nd Edition 2012.