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Sun is a star.
Sun is the centre of our solar system and all planets revolve around the sun.
About 75% of the sun is made up of hydrogen and most of the rest is helium.
As we wonder, sun is 5 billion years old. How the energy doesn’t get exhausted?
It is because of nuclear fusion reaction taking place inside the sun
Two hydrogen atoms fuses together to form a helium atom. This reaction releases
tremendous amount of heat and light energy.
The energy released from the sun is the source for all planets
, mainly for our earth, as it supports life.
Therefore, Sun is the primary source of energy for our world.
It provides energy to all living beings
This energy is used by the plant to prepare food by photosynthesis
and other creatures depend on it directly or indirectly
This energy is also used for cooking food, drying clothes etc:, in
But, sun today is not only used for preparing food.
It is used as an ALTERNATIVE SOURCE OF ENERGY
Solar energy is widely used all over the world as a source for generating
This energy is a renewable resource and pollution free. It can be utilized in
Here we are going to discuss about the solar energy- what? Uses, How it
can be used, advantages and disadvantages, applications etc:-
How much solar energy?
The surface receives about 47% of the total
solar energy that reaches the Earth. Only this
amount is usable.
The amount of solar energy received by one square meter area
of near earth space at an average distance between the sun
and the earth, is called solar constant.
Thus, solar constant tells us the amount of energy which falls in
1 second on a 1 square metre area of the near earth space at
an average distance between the sun and the earth.
The value of solar constant is
1.4kj/s/m2 (or) 1.4 kW/m2
SOLAR ENERGY- PRESENT SCENARIO
As solar energy is abundant for
our use we can use it for many
Therefore capturing heat energy
is easiest way to use solar
It can be used to heating
water, transport and
ventilation, water treatment
, architecture and horticulture .
Produce electricity through
The fossil fuels are non renewable
sources so we can not depend on
Though nuclear energy is a clean
and green energy ,as said by
Dr.A.P.J Abdul Kalam, there are
always some problems associated
So the only option we have is
solar energy because it is a
nonpolluting and silent source of
electricity and also low
maintenance and long lasting
USES OF SOLAR ENERGY
On an office building , roof areas can be covered with solar panels .
Remote buildings such as schools , communities can make use of solar energy.
Even on the highways , for every five kilometres ,solar telephones are used.
In developing countries , this solar panels are very much useful.
Putting Solar Energy to Use: Heating
Two methods of heating water:
passive (no moving parts) and
In both, a flat-plate collector is
used to absorb the sun’s
energy to heat the water.
The water circulates
throughout the closed system
due to convection currents.
Tanks of hot water are used as
Heating Water: Active System
Active System uses antifreeze so that the liquid does not
freeze if outside temp. drops below freezing.
Heating, cooling and
Solar heating, cooling and
ventilation can be used as
offset a portion of this energy.
A solar chimney is a passive
solar ventilation system.
As the chimney warms, the air
inside is heated
This causing an updraft that
pulls air through the building.
Solar distillation can be used
to make saline.
water disinfection (SODIS)
involves exposing water-filled
terephthalate (PET) bottles to
sunlight for several hours
Solar energy may be used in a
water stabilisation pond to
treat waste water.
Transport and reconnaissance
Development of a solar-powered car has
been an engineering goal since the
Some vehicles use solar panels for
auxiliary power, for air conditioning
To keep the interior cool, for reduced fuel
A solar balloon is filled with ordinary air.
As sunlight shines on the balloon, the air
inside is heated and expands causing an
upward buoyancy force.
Architecture and Horticulture
Agriculture and horticulture
optimises solar energy in
order to optimise plant
Planting cycles, tailored row
orientation, heights between
rows and the mixing of plant
varieties improves crop yields
Greenhouses converts solar
light to heat, enables yearround production and the
The solar cooker is a device which is used to cook food
by utilising the heat energy radiated by the sun.
What is solar cooker made of ?
A solar cooker consists of an insulated metal box or
wooden box which is painted all black from inside.
There is a thick glass sheet covering over the box and
a plane mirror reflector is also attached to the box.
The food to be cooked is put inside the solar cooker
box and covered with the glass sheet.
WORKING OF SOLAR COOKER
In order to cook food, the solar cooker is kept in sunshine.
The reflector of solar cooker is adjusted in such a way
that it faces the sun.
When the sun’s rays fall on the the reflector, the reflector
sends them to the top of solar cooker box in the form of a
strong beam of sunlight.
The sun’s heat rays pass through the glass sheet cover
and get absorbed by the black inside surface of the
Once the heat rays absorbed, then the glass sheet
doesn’t allow them to escape.
In this way, more and more heat rays of sun get trapped
in the box due to which the temperature rises upto 100
degree Celsius to 140 degree Celsius.
This heat the food materials kept in the black containers.
Solar cell is a device which converts solar energy into electrical energy.
SOLAR CELL IS MADE OF:
A solar cell is usually made from silicon.
A simple solar cell consists of sandwich of a silicon- boron layer and a silicon- arsenic layer .
The amount of boron and arsenic present in the two silicon layers is however very small.
A small piece of wire is soldered at the top of upper layer of cell and another piece of wire is
soldered at the bottom of the lower layer..
A solar cell is covered with a glass cover or transparent plastic cover protection.
WORKING OF SOLAR CELLS
When solar panels are placed in the
sunlight , photons will strike the surface
and emits electrons.
As a result electron hole pair is created
in the solar cell.
When external circuit is connected to
the solar cell , electrons flow in the
circuit and the current is generated.
When sunlight falls on the
surface of solar cell, it makes
the loosely held electrons in the
silicon atoms move due to
which, a current begins to flow
in the wires connected to top
and bottom of the cell.
Solar panel is a device which is collection of
Solar panel consists of a large number of solar
cells joined together in a definite pattern.
A solar panel can provide much more electric
power than a single solar cell.
The various solar cells in a solar cell panel are
joined together by connecting wires made of
This is because silver is the best conductor of
electricity. It increases the efficiency of solar
At many places, the solar panels are mounted
on specially designed inclined roofs so that
more solar energy is incident on them.
Use of solar panel- Water
The solar panel has hundreds of solar cells
The solar panel receive solar energy and is
converted into electricity.
The electricity produced is stored in battery .
This battery runs an electric motor .
And this motor finally drives a pump which
pumps out the underground water
This can be used to irrigate fields in villages.
Solar sail is a umbrella- like stretched
surfaces around the satellites or the ISS.
There are solar plants, which provide
energy to the objects in the flight.
It is a new technology, which uses the
pressure of the solar radiation to drive the
It has solar devices which capture energy
from sun and uses it.
The magnetic sail is a future based concept
going to be developed which uses the solar
wind, coming from the sun.
IS NUCLEAR ENERGY SAFE?
Today in present world, nuclear energy is considered as
important source of energy.
Even in India , nuclear energy has been given importance.
Recently, kudankulam project has also started functioning.
For the present world, nuclear energy seems to be as a
high yielding source for power and harm free too.
But nuclear energy has devastating effects on people.
Nuclear wastes produced during production cannot be
Radiation contaminates always even there is nuclear
accident- Around uranium mine, enrichment
facility, nuclear plants and nuclear wastes.
Impact of radiations.
Nuclear power plants has
radiation on plants animals
and humans too.
Impacts on vegetation Trees near jadugha uranium
mines have deformed
Impact on animals Radioactive boars on the
rise in Germany.
WHY? IN INDIA?
Still nuclear power plants are pushed in India.
Profit for MNC’S who will provide reactors to
nuclear power plants
Commisions for politicians, scientists and
SOLAR REPLACES NUCLEAR.
Recent researches say that only 10% of electricity demand
can be fulfilled by nuclear energy.
Electricity demand- 800,00,000 MW.
NUCLEAR POWER- 60000 MW
Why risk lives of humans for just 10% of electricity?
If not nuclear, then comes renewable sources of energy.
Wind energy, hydropower energy and SOLAR ENERGY.
Out of this, solar energy has the capability to feed the earth
1000 times than it’s demand.
The utilized solar energy can give more energy than
SOLAR ENERGY VS NUCLEAR
Have no effects on
Can feed more than
Radiation is more.
Have effects on
every living thing
Feed less than
Advantages and Disadvantages
• All chemical and radioactive
polluting byproducts of the
remain behind on the
sun, while only pure radiant
energy reaches the Earth.
• Energy reaching the earth is
incredible. By one
calculation, 30 days of
sunshine striking the Earth
have the energy equivalent
of the total of all the planet’s
fossil fuels, both used and
• Sun does not shine
• Solar energy is a diffuse
source. To harness
it, we must concentrate
it into an amount and
form that we can
use, such as heat and
• Addressed by
• 1) collection, 2)
conversion, 3) storage.
ENERGY STORING METHODS
Phase change materials such as paraffin wax and Glauber's salt are another thermal
These materials are inexpensive, readily available, and can deliver domestically
useful temperatures (approximately 64 °C). The "Dover House"
(in Dover, Massachusetts) was the first to use a Glauber's salt heating system, in
Solar energy can be stored at high temperatures using molten salts. Salts are an
effective storage medium because they are low-cost, have a high specific heat
capacity and can deliver heat at temperatures compatible with conventional power
systems. The Solar Two used this method of energy storage, allowing it to store
1.44 TJ in its 68 m3 storage tank with an annual storage efficiency of about 99%.[
Off-grid PV systems have traditionally used rechargeable batteries to store excess
electricity. With grid-tied systems, excess electricity can be sent to the
transmission grid, while standard grid electricity can be used to meet shortfalls. Net
metering programs give household systems a credit for any electricity they deliver to
A REPORT FROM IEA
The International Energy Agency has said that solar energy can make
considerable contributions to solving some of the most urgent problems
the world now faces:
Participants in a workshop on
inspect solar panels
at Monterrey Institute of
Technology and Higher
Education, Mexico City on
top of a building on campus.
The development of affordable, inexhaustible and clean solar energy
technologies will have huge longer-term benefits. It will increase
countries’ energy security through reliance on an
indigenous, inexhaustible and mostly import-independent
resource, enhance sustainability, reduce pollution, lower the costs of
mitigating climate change, and keep fossil fuel prices lower than
otherwise. These advantages are global. Hence the additional costs of
the incentives for early deployment should be considered learning
In 2011, the International Energy Agency said thatto be widely shared.
investments; they must be wisely spent and need solar energy
technologies such as photovoltaic panels, solar water heaters and power
stations built with mirrors could provide a third of the world’s energy by
2060 if politicians commit to limiting climate change. The energy from the
sun could play a key role in de-carbonizing the global economy alongside
improvements in energy efficiency and imposing costs on greenhouse
gas emitters. "The strength of solar is the incredible variety and flexibility
of applications, from small scale to big scale".
We have proved ... that after our stores of oil and coal are exhausted the
human race can receive unlimited power from the rays of the sun.
—Frank Shuman, New York Times, July 2, 1916
BETTER WAYS OF
Government should take measures and see that solar lights are used as street
lights in all the areas.
We can place solar panels in the barren lands instead of keeping it away uselessly.
We can also keep these solar panels in the deserts , where we can make use of
this energy with the help of a rechargeable battery.
Efficiency of solar panels depends on the range of frequencies of light that strikes
the surface . So they can give higher efficiency if we split the light into different
frequency ranges and direct the beams onto the cells tuned to these frequencies.
Building a new home is the best time to design and orient the home to take the
advantage of the sun’s rays.
A.A. AJIMEER ASLAM
M. KISHORE KUMAR
M.SAM ARUL RAJ