Design & estimation of rooftop grid tied solar pv system

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 2.5 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.
 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.

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/m2
insolation, 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 generation
supplying 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]

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