SOLAR TREE FOR STREET LIGHT

CHAPTER 1
INTRODUCTION

1.1 SOLAR TREE

• India is a highly populated country, so we should take the advantage of such an

energy which requires a very less space to produce energy efficiently.
• It can be applied in street lightening system, industrial power supply etc.
• It is much better than the traditional solar PV system in area point of view and
also more efficient.

1.2 WHAT IS A SOLAR TREE?

Fig.1.1 SOLAR TREE

A solar tree is a decorative means of producing solar energy and also electricity.
It uses multiple no of solar panels which forms the shape of a tree. The panels are
arranged in a tree fashion in a tall tower/pole.
• TREE stands for
• T= TREE GENERATING
• R=RENEWABLE
• E=ENERGY and
• E=ELECTRICITY
This is like a tree in structure and the panels are like leaves of the tree which produces
energy.

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Sustainable energy harnessed from restorable resources such as sun, wind, water,
geothermal, tides, waves etc. is the purest form of energy that helps in diminishing the
global warming problem. While numerous sustainable power source activities are
enormous scale, inexhaustible advances are likewise fit where clean energy is regularly
essential in human improvement. Solar power, that’s effulgent light-weight and warmth
from the sun, is controlled employing a vary of ever-evolving technologies like
photovoltaic, heating, thermal and artificial photosynthesis. It is considered as one of
the main sources of renewable energy in future. Solar technologies are broadly
portrayed as either passive solar or active solar relying upon the manner in which they
catch, convert and disperse solar energy.

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SOLAR TREE FOR STREET LIGHT

CHAPTER -2

LITERATURE SURVEY

2.1 INTRODUCTION
It is a form of renewable energy resource that is some measure competitive
with fossil fuels. Hydro power is the force of energy of moving water. It provides about
96% of the renewable energy in the United States. Hydroelectric power plants do not use
any resources to create electricity or they do not pollute the air. The sun is a hydrodynamic
spherical body of extremely hot ionized gases (plasma), generating energy by the process
of the thermonuclear fusion. The temperature of interior of sun is estimated at 8*10^6 k
to 40*10^6 k, where energy is released by fusion of hydrogen and helium.
Solar energy is available in abundance and considered as the easiest and cleanest means of
tapping the renewable energy. For direct conversion of solar radiation into usable form,
the routes are: solar thermal, solar photovoltaic and solar architecture. However the
main problem associated with tapping solar energy is the requirement to install large
solar collectors requires a very big space. To avoid this problem we can install a solar
tree in spite of a no of solar panels which require a very small space.
C. Bhuvaneswari, R. Rajeswari: He was publish the paper that is Idea to Design a
Solar Tree Using Nanowire Solar Cells in International Journal of Scientific and
Research Publications, Volume 3, Issue 12, December 20131 ISSN 2250-3153,To
introduces a new solar technology that emulates how trees convert sunlight into
energy. Trees, shrubs and plants use an inherent structural design to expose their
leaves, height dense to sunlight for photosynthesis. They do this determines their
survival. Based on this we describe the coconut tree growing u to 30m(98 feet) tall,
with pinnate leaves 4-6m(1320feet) long to design a solar tree. Pinnate refers to a leaf
resembling like a feather having the leaflets on each side of a common axis. It can be
either even or odd. By this structured pattern that leaves follow to arrange themselves
on a tree. With this arrangement we introduce a new idea to design a solar tree using
nanowire solar cell. Nanoparticles exhibit a number of special properties relative to
bulk material. A single Nanowire concentrates the sunlight upto 15 times of the
normal sunlight intensity. The solar new technology presented in this paper will

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SOLAR TREE FOR STREET LIGHT

provides nearly high efficiency. The number of papers and patents published in this
area has grown up exponentially over the last 10 years. However at the present,
research efforts have largely focused on solar trees. Nanowire can concentrate the
sunlight up to 15 times of the normal sunlight intensity and hence the surprising
results have the potential for developing a new kind of highly efficient solar cell. This
can be used to give a higher concentration efficiency of the sun’s energy [1].

Dr. Suwarna Torgal: She is publishing the paper that is Concept of Solar Power Tree
in International Advanced Research Journal in Science, Engineering and Technology
Vol. 3, Issue 4, April 2016. Demand for energy is increasing with each period, to
fulfill the required demand we must have to concentrate on utilizing non-conventional
sources of energy. Energy from the Sun is the best alternatives among the renewable
energy sources. . It is free, inexhaustible, nonpolluting, eco-friendly and continuous
source of energy. The paper detailed Solar Power Tree that generate large amount of
energy by capturing very small land area throughout the year. Silicon-crystalline
Photo-Voltaic (SPV) mounted on tall pole which direct convert solar energy in to
electrical energy by means of the photo voltaic effect. In the world, oil is running out
and it is estimated that 80% of the world’s supply will be consumed in our lifetimes.
Coal supplies appear to be very large but this stock is also stock out if rapidly uses.
Nuclear power having a dangerous aspect. Thus unconventional energy sources such
as geothermal, ocean tides, wind and sun is best option to meet future energy
requirements. Cultivable land is the greatest crisis of the earth rather it is already a
burning crisis in major countries, the cultivable land is god of the farmers, if used for
other than agriculture, it will be unpredictable loss to the society. Therefore Solar
Power Tree is very efficient to capture large amount of solar energy by utilizing a very
small surface area of valuable land [2].

Deepak M. Patil, Santosh R. Madiwal: He was publish the paper that is Design and
Development of Solar Tree For Domestic Applications in International Journal of
Engineering Sciences & Research Technology, August 2016 ISSN: 2277- 9655, he
work Flat or roof top mountings of PV systems require large area or land. Scarcity of
land is greatest problem in cities and even in villages in India. Solar Power Tree
provides better alternative to flat mounting of PV systems. For domestic lighting and
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SOLAR TREE FOR STREET LIGHT

other applications use of Solar Tree is more relevant when PV system is to be used. In
this article load or energy requirement of small house in India is estimated to
1.75kWhr/day. All the calculations are done considering solar radiation data at
Kolhapur, Maharashtra (16.760). The solar tree concept is very successful to fulfill the
increasing energy demand of the people, saving of land, and should be implemented
in India to provide electricity without the problem of power cut-off and reduce the
dependence on grid power. Daily average energy requirement of the small Indian
family is calculated about 3.5kW. Such systems can be mounted on the terrace, in front
of the house or near the wall avoiding shading areas. The initial investment cost of the
solar tree is also equal to same capacity PV systems as other system components are
similar [3].

Mr. A P R Srinivas: He was publishing paper that is Design and Development of a

SOLAR TREE in International Journal of Scientific & Engineering Research, Volume
7, Issue 10, October-2016, 1319 ISSN 2229-5518. a new product called, ‘solar tree’
has been designed to increase the power output by many folds by consuming solar
energy. It can be installed on the sides of heavy traffic roadways and on roof top
buildings. The tree consists of numerous solar panels connected to one another in
series and parallel connections. The solar tree consists of number of branches welded
to a stem and each stem has a solar panel mounted on it. It adds up voltage in series
and current in parallel connection. The paper calculates the sun earth angles at
different times of the day and designs solar tree based on these sun earth angles. The
panels are put on the structure in a spiral fashion. It proves to be a useful system to
meet the energy demands of the world and to use a given space more efficiently. The
present system of roof top solar systems can be replaced by solar tree and the roof top
space can be utilized for recreation purposes. The solar tree can be installed on ground
also in addition to roof top spaces. So, this solar tree proves to be advantageous in
saving space and increasing the power output by many folds. It saves a lot of energy
over the years to come. The number of solar trees that could be installed in a given
space depends on the wattage needed [4].

Sushma Gupta, Monish Gupta: She is publish the paper that is The Benefits and
Applications of Solar Tree with Natural Beauty of Trees in SSRG International
Journal of Electrical and Electronics Engineering (SSRG-IJEEE) – EFES April 2015,
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ISSN: 2348 – 8379. Now a days oil supply is decreasing therefore energy sources are
becoming limited throughout the world. In all this Solar Tree proves to be most
beneficial source of energy. This paper presents Solar Tree implementation as
alternate source of energy in urban cities. A new idea of a solar tree design us in Nano
wire solar cell is presented. Nano wires possess high physical light absorption
properties which can be improved tremendously Hence we can say that it is a
revolutionary urban lighting concept and these technologies lead to the development
of high efficiency solar energy. Keywords -- Solar Tree, Renewable Energy, Nano-
wire, solar cell, Solar Energy. To fulfill the increasing energy demand of the people,
saving of land, the solar tree concept is very successful one and should be implemented
in India to provide electricity without the problem of power cut and the extra energy
can be provided to the grid. India as the 2nd largest country of the world in the
increasing demand of the energy and try to find a way from which efficient and
abundant source of energy cab be available. Also a solar botanic tree is a
nonconventional source having many advantages of producing electricity as compared
to theother sources. It is therefore the responsibility on the shoulders of the youngsters
of the earth to think smartly and take the right decision. Everyone should starts as an
individual to co- operate with the government to make life favorable for mankind [5].

2.2 REVIEW OF SOLAR EFFICIENCY

Global warming and energy policies have become a hot topic on the international
agenda in the last years. Developed countries are trying to reduce their greenhouse gas
emissions. For example, the European union has committed to reduce their greenhouse
gas to at least 20% below 1990 levels and to produce no less than 20% of its energy
consumption from renewable sources by 2020. In this context, photovoltaic (PV) power
generation has an important role to play due to the fact that it is a green source. The
only emissions associated with PV power generation are those from the production of
its components. After their installation they generate electricity from the solar
irradiation without emitting greenhouse gases. In their life time, PV panels produce
more energy than that for their manufacturing. Also, they can be installed in places with
no other use, such as roofs and deserts. They can produce electricity for remote
locations, where there is no electricity network. The latter type of installations is known
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as off-grid facilities and sometimes they are the most economical alternative to provide
electricity in isolated areas. However, most of the PV power generation comes from
grid-connected installations, where the power is fed in the electricity network. In fact,
it is a growing business in developed countries such as Germany which is world leader
in PV power generation followed by Spain, Japan, USA and Italy. On the other hand,
due to the equipment required, PV power generation is more expensive than other
resources. Governments are promoting it with subsidies or feed-in tariffs, expecting the
development of the technology so that in the near future it will become competitive.
Increasing the efficiency in PV plants so as to increase the power generated is a key
aspect, as it will increase the incomes, reducing the cost of the power generated, cost
approaching the cost of the power produced from other sources.
Solar cells are the basic components of photovoltaic panels. Most are made from
silicon even though other materials are also used. Solar cells take advantage of the
photoelectric effect: the ability of some semiconductors to convert electromagnetic
radiation directly into electrical current. The charged particles generated by the incident
radiation are separated conveniently to create an electrical current by an appropriate
design of the structure of the solar cell.
The use of efficient photovoltaic solar cells has emerged as an important solution in
energy conservation and demand side management. Owing to their initial high costs,
they have not been an attractive alternative for users who are able to buy cheaper
electrical energy from the utility grid. However, they have been extensively used in
pumping and air conditioning in remote and isolated areas where utility power is not
available or too expensive to transport. Although solar cell prices have decreased
considerably during the last years due to new developments in the film technology and
the manufacturing process, PV arrays are still considered rather expensive compared
with the utility fossil fuel generated electricity prices.
After building such an expensive renewable energy system, the PV array has to be
operated at its highest conversion efficiency by continuously utilizing the maximum
available output of the array. The electrical system powered by solar cells requires
special design considerations because of the varying nature of the solar power generated
resulting from unpredictable changes in weather conditions which affect the solar
radiation level as well as the cell operating temperature.
The efficiency of a PV plant is affected mainly by three factors: the efficiency of
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the PV panel (in commercial PV panels it is between 8-15%), the efficiency of the
inverter (95-98 % ) and the efficiency of the maximum power point tracking algorithm
(which is over 98% ). Improving the efficiency of the PV panel and that of the inverter
is not easy as it depends on the technology available. It may require better components,
which can increase drastically the cost of the installation. Instead, improving the
tracking of the maximum power point with new control algorithms is easier, not
expensive and can be done even in plants which are already in use by updating their
control algorithms, which would lead to an immediate increase in PV power generation
and consequently a reduction in its price.
MPPT algorithms are necessary because PV arrays have a nonlinear voltage current
characteristic with a unique point where the power produced is maximum. This point
depends on the temperature of the panels and on the irradiance conditions. Both
conditions change during the day and are also different depending on the season of the
year. Furthermore, irradiation can change rapidly due to changing atmospheric
conditions such as clouds. It is very important to track the MPP accurately under all
possible conditions so that the maximum available power is always obtained. In the
past years numerous MPPT algorithms have been published. They differ in many
aspects such as complexity, sensors required, cost or efficiency. However, it is pointless
to use a more expensive or more complicated method if with a simpler and less
expensive method, similar results can be obtained.
In practice, the voltage dependency on the irradiation is often neglected. As the
effect on both the current and voltage is positive, i.e. both increase when the irradiation
rises, the effect on the power is also positive. More the irradiation, the more power is
generated.

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CHAPTER -3

PRESENT SCENARIO

3.1 SOLAR PROFILE

Sustainable energy harnessed from restorable resources such as sun, wind, water,
geothermal, tides, waves etc. is the purest form of energy that helps in diminishing the
global warming problem. While numerous sustainable power source activities are
enormous scale, inexhaustible advances are likewise fit where clean energy is regularly
essential in human improvement. Solar power, that’s effulge

nt light-weight and warmth from the sun, is controlled employing a vary of ever-
evolving technologies like photovoltaic, heating, thermal and artificial photosynthesis
. It is considered as one of the main sources of renewable energy in future. Solar
technologies are broadly portrayed as either passive solar or active solar relying upon
the manner in which they catch, convert and disperse solar energy.

3.2 Introduction to solar panel

A solar cell (photovoltaic cell or photoelectric cell) is a solid state electrical device that
converts the energy of light directly into electricity by the photovoltaic effect. The
energy of light is transmitted by photons-small packets or quantum of light. Electrical
energy is stored in electromagnetic fields, which in turn can make a current of electrons
flow.
Assemblies of solar cells are used to make solar modules which are used to capture
energy from sunlight. When multiple modules are assembled together (such as prior to
installation on a pole- mounted tracker system), the resulting integrated group of
modules all oriented in one plane is referred as a solar panel. The electrical energy
generated from solar modules, is an example of solar energy. Photovoltaic is the field
of technology and research related to the practical application of photovoltaic cells in
producing electricity from light, though it is often used specifically to refer to the
generation of electricity from sunlight. Cells are described as photovoltaic cells when
the light source is not necessarily sunlight. These are used for detecting light or other
electromagnetic radiation near the visible range, for example infrared detectors, or
measurement of light intensity.
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Solar cells, which largely are made from crystalline silicon work on the principle of
Photoelectric Effect that this semiconductor exhibits. Silicon in its purest form- Intrinsic
Silicon- is doped with a dopant impurity to yield Extrinsic Silicon of desired
characteristic (p-type or n- type Silicon). When p and n type silicon combine they result
in formation of potential barrier.

Working of Solar cells can thus be based on two crystalline structure

• Intrinsic Silicon
• Extrinsic Silicon

Pure Silicon (Intrinsic) Crystalline Structure

Silicon has some special chemical properties, especially in its crystalline form. An atom
of silicon has 14 electrons, arranged in three different shells. The first two shells- which
hold two and eight electrons respectively- are completely full. The outer shell, however,
is only half full with just four electrons (Valence electrons). A silicon atom will always
look for ways to fill up its last shell, and to do this, it will share electrons with four
nearby atoms. It's like each atom holds hands with its neighbors, except that in this case,
each atom has four hands joined to four neighbors. That's what forms the crystalline
structure. The only problem is that pure crystalline silicon is a poor conductor of
electricity because none of its electrons are free to move about, unlike the electrons in
more optimum conductors like copper

Fig 3.1 P-type and N-type Semiconductors

Extrinsic silicon in a solar cell has added impurity atoms purposefully mixed in with the
silicon atoms, maybe one for every million silicon atoms. Phosphorous has five

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electrons in its outer shell. It bonds with its silicon neighbor atoms having valency of 4,
but in a sense, the phosphorous has one electron that doesn't have anyone to bond with.
It doesn't form part of a bond, but there is a positive proton in the phosphorous nucleus
holding it in place. When energy is added to pure silicon, in the form of heat, it causes a
few electrons to break free of their bonds and leave their atoms. A hole is left behind in
each case. These electrons, called free carriers, then wander randomly around the
crystalline lattice looking for another hole to fall into and carry an electrical current. In
Phosphorous-doped Silicon, it takes a lot less energy to knock loose one of "extra"
phosphorous electrons because they aren't tied up in a bond with any neighboring atoms.
As a result, most of these electrons break free, and release a lot more free carriers than
in pure silicon. The process of adding impurities on purpose is called doping, and when
doped with phosphorous, the resulting silicon is called N-type ("n" for negative) because
of the prevalenceof free electrons. N-type doped silicon is a much better conductor than
pure silicon. The other part of a typical solar cell is doped with the element boron, which
has only three electrons in its outer shell instead of four, to become P-type silicon.
Instead of having free electrons, P-type ("p" for positive) has free openings and carries
the opposite positive charge.

Formation of Potential Barrier and Photoelectric Effect

The electric field is formed when the N-type and P-type silicon come into contact.
Suddenly, the free electrons on the N side combine the openings on the P side. Right at
the junction, they combine and form something of a barrier, making it harder and harder
for electrons on the N side to cross over to the P side (called POTENTIAL BARRIER).
Eventually, equilibrium is reached, and an electric field separating the two sides is set
up. This electric field acts as a diode, allowing (and even pushing) electrons to flow
from the P side to the N side, but not the other way around. It's like a hill -- electrons
can easily go down the hill (to the N side), but can't climb it (to the P side).

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Fig 3.2 Solar Cell

When light, in the form of photons, hits solar cell, its energy breaks apart electron-hole
pairs (Photoelectric effect). Each photon with enough energy will normally free exactly
one electron, resulting in a free hole as well. If this happens close enough to the electric
field, or if free electron and free hole happen to wander into its range of influence, the
field will send the electron to the N side and the hole to the P side. This causes further
disruption of electrical neutrality, and if an external current path is provided, electrons
will flow through the path to the P side to unite with holes that the electric field sent
there, doing work for us along the way. The electron flow provides the current, and the
cell's electric field causes a voltage.
The final step is to install something that will protect the cell from the external elements-
often a glass cover plate. PV modules are generally made by connecting several
individual cells together to achieve useful levels of voltage and current, and putting them
in a sturdy frame complete with positive and negative terminals.

Manufacturing Technology and process of Solar Cell

STEP 1 - PURIFICATION OF SILICON:

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Fig 3.3 Purification of Silicon

The basic component of a solar cell is intrinsic silicon, which is not pure in its natural
state. To make solar cells, the raw materials—silicon dioxide of either quartzite
gravel or crushed quartz—are first placed into an electric arc furnace, where a carbon
arc is applied to release the oxygen. A Graphite and Thermal insulator trap the heat
and maintain the furnace at required temperature for gangue (impurity) to form a
slag. The products are carbon dioxide and molten silicon. Silicon ingot is pulled
down from the molten silicon using seed silicon crystallization and floating zone
technique. Passing impure silicon in same direction several times that separates
impurities- and impure end is later removed. This process yields silicon with one
percent impurity, useful in many industries but not the solar cell industry. At this
point, the silicon is still not pure enough to be used for solor cells and requires further
purification. Pure silicon is derived from such silicon dioxides as quartzite gravel
(the purest silica) or crushed quartz.

STEP 2- INGOT AND WAFER PREPARATION:

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Fig 3.4 INGOT AND WAFER PREPARATION

Solar cells are made from silicon boules, polycrystalline structures that have the
atomic structure of a single crystal. The most commonly used process for creating
the boule is called the Kochanski method. In this process, a seed crystal of silicon is
dipped into melted polycrystalline silicon. As the seed crystal is withdrawn and
rotated, a cylindrical ingot or "boule" of silicon is formed. The ingot withdrawn is
unusually pure, because impurities tend to remain in the liquid. From the boule,
silicon wafers are sliced one at a time using a circular saw whose inner diameter cuts
into the rod, or many at once with a multi wire saw. (A diamond saw produces cuts
that are as wide as the wafer—. 5 millimeter thick.) Only about one-half of the silicon
is lost from the boule to the finished circular wafer—more if the wafer is then cut to
be rectangular or hexagonal. Rectangular or hexagonal wafers are sometimes used
in solar cells because they can be fitted together perfectly, thereby utilizing all
available space on the front surface of the solar cell. The wafers are then polished to

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remove saw marks.

STEP 3 - DOPING:

The traditional way of doping silicon wafers with boron and phosphorous is to
introduce a small amount of boron during the Czochralski process. The wafers are
then sealed back to back and placed in a furnace to be heated to slightly below the
melting point of silicon (2,570 degrees Fahrenheit or 1,410 degrees Celsius) in the
presence of phosphorous gas. The phosphorous atoms "burrow" into the silicon,
which is more porous because it is close to becoming a liquid. The temperature and
time given to the process is carefully controlled to ensure a uniform junction of
proper depth. These diffusion processes are usually performed through the use of a
batch tube furnace or an in-line continuous furnace. The basic furnace construction
and process are very similar to the process steps used by packaging engineers.

STEP 4 - SCREEN PRINTING:

Fig 3.5 SCREEN PRINTING

Electrical contacts are formed through squeezing a metal paste through mesh screens
to create a metal grid. This metal paste (usually Ag or Al) needs to be dried so that
subsequent layers can be screen-printed using the same method. As a last step, the
wafer is heated in a continuous firing furnace at temperatures ranging from 780 to
900°C. These grid- pattern metal screens act as collector electrodes that carry
electrons and complete the electrical continuity in the circuit.

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STEP 5 - STRINGING AND TABBING:

Fig 3.6 STRINGING AND TABBING

Electrical contacts connect each solar cell to another and to the receiver of
produced current. The contacts must be very thin (at least in the front) so as not to
block sunlight to the cell. Metals such as palladium/silver, nickel, or copper are
vacuum- evaporated After the contacts are in place, thin strips ("fingers") are
placed between cells. The most commonly used strips are tin-coated copper.

STEP 6 - ANTIREFLECTIVE COATING:

Because pure silicon is shiny, it can reflect up to 35 percent of the sunlight. To reduce
the amount of sunlight lost, an anti-reflective coating is put on the silicon wafer-
mostly titanium dioxide, silicon oxide and some others are used. The material used
for coating is either heated until its molecules boil off and travel to the silicon and
condense, or the material undergoes sputtering. In this process, a high voltage
knocks molecule off the material and deposits them onto the silicon at the opposite
electrode. Yet another method is to allow the silicon itself to react with oxygen- or
nitrogen-containing gases to form silicon dioxide or silicon nitride. Commercial
solar cell manufacturers use silicon nitride. Another method to make silicon absorb
more light is to make its top surface grained, i.e. pyramid shaped nanostructures that
yield 70% absorption that reaches the cell surface after passing through anti-
reflective coating.

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Fig 3.7 ANTIREFLECTIVE COATING

STEP 7 - MODULE MANUFACTURING

The finished solar cells are then encapsulated; that is, sealed into silicon rubber or
ethylene vinyl acetate. Solar module assembly usually involves soldering cells
together to produce a 36-cell string (or longer) and laminating it between toughened
glass on the top and a polymeric backing sheet on the bottom. The encapsulated solar
cells are then placed into an aluminum frame that has a Mylar or tedlar back sheet
and a glass or plastic cover. Frames are usually applied to allow for mounting in the
field, or the laminates may be separately integrated into a mounting system for a
specific application such as integration into a building.
Advantages of Solar Panels

Private home owners are discovering the benefits to our environment and a way to
live happily off the grid or are considering installing a grid-tied solar power system
to offset their electric bill or due to a belief in reducing their carbon emissions. These
are great reasons to "go solar"...

• Ecologically Friendly - For obvious reasons, the use of solar panels is Eco-
friendly and considered one of the most "green" electricity resources.
Because because they operate by interacting with a renewable energy
source, sunlight, there is no fear of depleting yet another natural resource.

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• Decreased Electrical Bill - By switching to solar energy, you will save money
on your electrical bills every month. Even if electricity bills continue raising
in the next few months you will have the peace of mind knowing that your
energy source is based on solar power.
• Low Maintenance - Solar panels have no moveable parts and are very
simple to use. After being set up properly, they do not need to be tinkered
with and will continuing working for many years. In fact, many
manufacturers have 25 year warranties on their panels.
• Efficiency - No matter where you live, the chances are that you can
successfully use solar panels for you electrical needs. They are rugged and
are very adaptable to climate conditions and the latest panel models are
efficient enough to work well without facing directly south and some will
even produce electricity under cloud cover.

Regardless of who you are or what type of home you have, solar power is one of the
best ways to provide you and your family with electricity without causing more
damage to our planet.

There are many ways to take advantage of the savings gained from solar panel
systems. Not only does it help you save by cutting your energy requirement from the
utility company, it may also allow you to lock in a lower solar power rate. By using
the electricity produced by your unit during the day, (when rates are at their highest),
and using the utility company's power in the evening, (when the rates are at their
lowest), you will lower your overall cost for all of your electrical use. There are also
many rebates available to help you save 40-60% on the cost of acquiring your system.
For more information on rebates and incentives for installing a solar power system on
your home or business look up "Energy Incentives" on the IRS website or check with
your local tax adviser for details

3.3 Solar Irradiation of the Site

Irradiance is a measurement of solar power and is defined as the rate at which solar
energy falls onto a surface. The sun- based irradiance is estimated by the power per
unit region, so irradiance is commonly cited as W/m². The National Renewable

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Energy Laboratory (NREL), situated in Golden, Colorado, specializes in sustainable

power and energy efficiency research and development. NREL is a government-
owned, contractor-operated facility, and is funded through the United States
Department of Energy.

Fig 3.8. Monthly insolation radiation.

According to the National Aeronautics and Space Administration (NASA)

atmospheric science data center, the monthly averaged insolation clearness index
and radiation incident on a tilted PV panel at the location of Bangalore, India is
6.25 KWh/m2/d [4]. Fig. 1 shows the monthly averaged radiation incident on
Bengaluru City.
Table3.1 -Voltage Profile of the panels output in a day
Time Average Outout
Voltage (V)
8 am-11 20.74
am
11 am-1 19.98
pm
1 pm-3 18.86
pm
3 pm-6 11.11
pm

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Table 1 shows the average voltage profile from 8 am to 6pm in a day, which is
required for analysis and for designing of the solar tree structure. The voltage profile
during a day from 8am to 6pm is represented.

Fig 3.9. Voltage profile plot during the course of the day.

3.4 Solar Tree

Sun based tree sounds like the ideal answer for our future energy needs. The sun is
always sending energy to the earth and we should simply to get it and after that utilize
it. Sun based energy is accessible in plenitude and considered as least demanding
and cleanest methods for tapping the sustainable power source. Solar trees were
introduced in 1998 as sun oriented fine art on streets and open spots. At that point this
innovation is embraced as sun powered trees. In Europe these are utilized from
numerous years. In 2006 in Europe the vitality utilization is 10%. 2000 billion kWh is
utilized from sun-oriented trees and 2900-million-ton carbon is killed. In October
2016 sun-based trees are utilized in Vienna, Austria. These are likewise utilized in
Graz, Austria. A sun-based tree is a brightening method for creating sunlight-based
energy and furthermore power. It utilizes different no of PV panels which structures
the state of a tree. The panels are masterminded in a manner in a tall pinnacle/shaft.
The measure of energy created by this tree is more than that of ordinary level cluster
of sun-based cells. This resembles a tree in structure and the panels resemble leaves
of the tree which produces energy. The trees are available in nature and they can
deliver their own sustenance material by the procedure called photosynthesis. Here
normal trees are considered for comprehension about the sun powered tree. The
sunlight-based tree is a tree where the stems associated go about as the parts of the
tree and the panels resemble the leaves. Green leaves are creating sustenance materials

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for individuals in like manner the sun-oriented tree leaves are delivering energy for
the general public. Thus, it is fitting to call it as a tree.

Fig 3.10. Solar tree structure side view.

Solar tree is a revolutionary urban lighting concept that represents a perfect symbiosis
between pioneering design and cutting edge eco-compatible technology. Solar tree opens
up new prospects for urban lighting in that it satisfies today’s most pressing environmental,
social, cultural and aesthetic demands.
The ability to combine innovative design with advanced technology along with an acute
sensitivity to environmental concerns make arsenide the ideal vehicle for the development
of this project conceived by Ross Love grove, with the collaboration of sharp solar, the
world’s leading manufacturer of solarcells.

Solar tree draws inspiration from the organic forms of nature, reinterpreting the morphology
of the tree and introducing the sensuality of the natural world into the urban context. In other
words of Ross Love grove, “this is a project that celebrates design, nature and art and
represents the DNA of our time”. A sinuously elegant tree with ecologically intelligent fruits-
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SOLAR TREE FOR STREET LIGHT

that is, the LED bubbles that light up at night powered by the sunlight accumulated during the
day by solarpanels.
The aesthetic refinement of the design is thus integrated with an extremely high
technological content, the result of the innovative research conducted by arsenide in
the deep conviction that a concrete solution to the problem of energy saving was needed.

3.5 Why We Called It As A Solar Tree

Fig 3.11 Solar Tree

As we know trees are present in nature and they can produce their own food material by
the process called PHOTOSYNTHESIS. It is the process by which the green plant collects
energy from sun and the water present in soil at the day time and can produces their own
food material. By this process they are indirectly providing food to the human society
because we are depending on the green plants for our food directly or indirectly.
Here we are considering the example for understanding about the solar tree. This is a tree in
which the stems connected acts as the branches of the tree and the solar panels are like the
leaves. Green leaves are producing food materials for human beings likewise this leaf are
producing energy for the society. So, it is appropriate to called it as a tree.

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SOLAR TREE FOR STREET LIGHT

3.6 Why It Is Needed

• Due to less land requirement.
• It can collect energy from wind.
• Efficient energy generation.

3.7 Construction

Fig 3.12 Construction

• The solar tree consists of some important parts in its design. They are as follows
• Solar panels
• Long tower
• LDEs
• Batteries
• Stems for connecting the panels

Solar Tree is a light fixture combining an innovative design with the technical
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SOLAR TREE FOR STREET LIGHT

performances of LED lighting system using solar energy supplied from photovoltaic
system.
Structure composed by curved steel poles of different diameters and heights with
a maximum total height of about 5.5m over road level. This system is composed by 10
“stems of grass”. On their extremity there is 1 LED protected by a diffuser screen in
PMMA and 10 poles supporting the heads.
The poles are painted with outdoor epoxy paint in light green color shading into
white. The 10heads, housing the photovoltaic cells in their upper part are supported
by poles;20 power LED’s are housed in the lower part of 4 of them, on an
aluminum dissipater and are provided with a screen in plastic material which ensures
protection against water and dusts. The base is made of hot-galvanized steel plate
to be fixed to the ground. Otherwise it is possible to use a base, always in galvanized
steel, with reinforced concrete parts forming a circular bench. In this case the base
can rest on the ground without need of further fixing systems. Benches in white
painted concrete, with second coat of anti-graffiti paint.

Fig 3.13 Solar tree in real life

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SOLAR TREE FOR STREET LIGHT

3.2 Working

Fig 3.14 Working

• Solar tree panels charge batteries duringthe day.

• At dusk the solar tree automatically switches on its LEDs.

• The internal control can also regulate the amount of light produced depending on how
much charge is left in the batteries.
• Solar Tree will produce light for three consecutive overcast days.

• Solar tree represents the DNA of our time and it shows it is possible to create beautiful
things using the most advanced technology.
• Batteries are also used to store the energy so that we can use it at night and in cloudy
days when no sunlight is there.

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SOLAR TREE FOR STREET LIGHT

3.2 Why It Is Better Than A Traditional System

Fig 3.15 Light emission

• For the traditional system we require large size of land to generate a small amount of
power. It requires about 1% land as compare to the traditional system.
• Example – To generate 2 MW power from a pv module we require 10 -12 acres of
land for housing of panels only.
• But for the same amount of energy we require only 0.10-0.12 acres of land in case
of solar tree.

3.3 SPIRALLING PHYLLATAXY

It is a technique used in designing of solar tree. It provides the way to help the lower
panels from the shadow of upper ones, so that it can track maximum power from
the sun.

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SOLAR TREE FOR STREET LIGHT

Fig 3.16 Spiralling phyllataxy

3.4 WHY IT IS UNIQUE

Fig 3.17 Solar tree facing Sun

• The unique technique is that flexible panels connected to the stem which can be
rotated as our desire.
• So that flexibility avoidance of wind pressure can be possible.
• Flexibility offers manual rotating so that maximum power can be obtained.

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SOLAR TREE FOR STREET LIGHT

CHAPTER -4

PROPOSED WORK

4.1 Proposed Model System

India being a developing country and highly populated requires a power plant where
maximum energy can be generated by using minimum land. Solar tree will be the best
option to avoid this problem. We must try to produce energy from sun by using solar tree in
our country to increase our per capita land and fulfil the growing energy demand.
In 2016, CSIR-Central Mechanical Engineering Research Institute, Durgapur, India
invented another model of Solar Tree for its application at villages, besides national
highway and conventional power grid system to fulfil the electricity crisis by increasing
the share of renewable energy in the country.

Fig 4.1 Proposed solar tree in India

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SOLAR TREE FOR STREET LIGHT

4.2 Conclusions

This paper has presented the design and construction of solar tree used for street
lightning. Sunlight based tree is a progressive urban lighting idea that speaks to an ideal
beneficial interaction between spearheading plan and front line eco-good innovation.
To satisfy the expanding energy request of the general population, sparing of land, the
sunlight-based tree idea is extremely effective one and ought to be executed in India to
give power without the issue of power cut and the additional energy can be given to the
network. Due to global warming, the temperature is always on a higher range usually
than assumption range so that can be used and generate electricity in large quantity.

To fulfil the increasing energy demand the people and saving of land this SOLAR TREE
is very successful one. This can provide electricity without any power cut problem. The
extra energy can be provided to the grid.

Fig 4.2 Solar system

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4.3 REFERENCES

1. Artemide. N.p... Web. 20 Feb 2013. Artemide Events Page.

2. Artemide. N.p. Web. 20 Feb 2013. Artemide Events Page.
3. Design Boom May 26, 2012 Article on Love Grove and solar trees
4. Solar Tree. Artemide. N.p. Web. 20 Feb 2013. Artemide
Brochure Archived 2011-01-05 at the Way back Machine.
5. Artemide. N.p.. Web. 20 Feb 2013. Artemide on Love Grove.
6. PR Web, announcement of Sandy Grove Middle School project completion.
7. Solar World Article on the Rams' solar projects
8. Dr. Harsh Vardhan launches the ‘Solar Power Tree’ – an Innovation aimed at
utilizing minimum land to harness maximum Solar Energy [1]
9. CSIR-CMERI, Durgapur: Solar Artifact [2] Solar Power Tree Artifact
10. strawberry tree (The Solar Energy Device)
11. CleanTechnica Feb 21, 2013 Clean Technica
12. Clean Technica May 30, 2011 General Electric goes solar
13. Rein Triefeldt. Princeton Green. N.p... Web. 20 Feb 2013. On Rein
Triefeldt[permanent dead link].
14. Projects. Solar Tree Foundation. N.p.. Web. 20 Feb 2013. Solar Tree
Foundation Projects.
15. Solar Tree Foundation accessed: Feb 20, 2013 Solar Tree Foundation site

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