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[no dialogue].
Hi everyone, I'm Gowtham [unclear dialogue].
My name is Ram.
My name is Ashwini [unclear dialogue].
I'm Vinay.
(Gowtham). Our topic is solar cells.
Basically, what is a solar cell?
A solar cell is a device which converts light and
energy present in this light, not only sunlight,
every kind of light into electrical energy.
Electrical energy through a process of photovoltaic effect.
What does photovoltaic mean?
Photovoltaic means "light" and voltaic means "electricity," and
it converts light directly into electricity.
That is the basic meaning of photovoltaic.
The conversion of solar energy to electrical energy is done by
using a module of several groups of cells connected electrically
and packaged into a frame more commonly known as a solar panel.
I'll give you a basic idea of what happens in a solar cell.
When light from the sunlight touches the metal of the solar
panel or everything, the electrons present in the
metal will be ejected and these electrons will be
captured by the sum of the [unclear dialogue].
The moment the electrons called electricity, and we
captured the electricity from the moment of the electron.
That's what basically happens in the solar cell
and this is a very, around 400 B.C.
I think so, Greeks and Romans used this kind of technology.
There is no [unclear dialogue] but anyone
has no idea how they done it.
They used for heating buildings, water,
growing vegetables, and green houses.
And they say that Greek Archimedes used solar energy
to reduce the Roman army to ashes by
having soldiers reflect sunlight off their shields
towards Roman [unclear dialogue].
They say that, but I don't know exactly what,
it's written in books.
And the first solar cell was invented by American Charles
Fritts in 1883, and this one is only one percent efficient
and it can only convert the energy presented
in the light, only one person electrical energy.
The basic theme of, this thing is used by many others who will
have, sorry, this solar energy used by many other earlier
civilizations, not only Greeks and Romans like
Chinese, Anasazi, and Pueblo.
The idea was given by the French physicist Antoine-Cesar in 1839.
He observed by when a shining light on an electrode submerged
in a conductive solution would create an electric current.
This basic concept which gives an idea of solar energy.
We can convert energy and light to the electrical energy.
In 1941, Russell Ohl invented the silicon solar cell.
And in 1954, three Americans, Gerald Pearson, Calvin Fuller
and Darryl Chapin discovered the use of silicon as a
semiconductor, which semiconductor is a device made
by silicon which is used for capturing the light
and this thing is six percent efficient rather than
the one made by Fritz, which is one percent.
And in 1956, the first commercial solar cells
were made available to the public.
And it's very expensive, it's about a dollar 300 per watt.
So, remaining will be continued by Vinay.
(Mr. Vinay Kodiganti). What actually is, I will
continue with this, what actually is a solar cell.
A solar cell works on the principle
of photovoltaic effect.
Photovoltaic effect is carried on a special,
metal silicone and doping is some impurities.
Basically phosphorous or boron, it works like when a light or
some light energy hits the surface of the silicon material,
the electrons present on the other side of the shell
gets freed up with the energy, moves freely and
these moving free electrons produce a current.
As we all know that a current is nothing
but a motion of electrons.
The properties that silicon present, silicon has
14 free electrons in it and it's three differentials.
It's pure silicon, and it cannot, it forms a [unclear
dialogue] structure which is stable.
So when light energy hits the silicon surface,
the electrons doesn't get freed easily.
It needs much energy.
So to lose and these electrons, freed with phosphorous or boron.
For phosphorous, which has five free electrons is
[unclear dialogue] with silicon.
And we have some five free electrons in the
[unclear dialogue], so when the light energy hits these
surfaces, these electrons get free and
they move freely and electricity is generated.
The electricity is being stored into cells by [unclear dialogue]
pv cell, the pv cell is being [unclear dialogue]
contacts on the top and the bottom
and it is connected to a battery.
We can store it in a battery, or we can directly use it.
Solar cells can be made easily at home too
if we have the required materials.
The solar cell has p-type and n-type materials in that.
It has a junction in between those layers,
and the transfer of electrons is done from p to n.
It's like p electrons can flow from p to n,
but then electrons cannot flow from n to p.
So there is a junction in between,
and the electricity flows inside of the junction
[unclear dialogue] and it can be used.
The generation of electricity...[unclear dialogue]
alright it was actually a video of how solar cells works, and I
think it had some problem playing that.
Maybe I will find it in the end.
(Mr. Ashwini Pattem). I'm going to talk about
the applications of solar cells.
[unclear dialogue] to solar cell applications.
Alongside a [unclear dialogue] consumer products like
electronic watches, calculators, and power
off leisure equipment and tourism.
There is an extensive range of applications where
solar cells are already viewed as the best
option of electric [unclear dialogue].
And some of the advantages of solar [unclear dialogue],
there are no fuel costs or fuel supply problems,
and the equipment can usually operate unattended.
Solar cells are very reliable and require little maintentance.
And the applications are there are rural electrifications,
which means solar power, which provides rural areas
around the world with an efficient source of energy.
The provision of electricity to rural areas derives
important social and economic benefits to
remote communities throughout the world.
Power supplies to like remote [unclear dialogue]
electrification of the health care facilities, irrigation, and
water supply and the treatment are just
a few examples of such applications.
The UN estimates that 2 million villages with 20 percent
of the equator have neither great electricity
nor easy access to fossil fuel.
It is also [unclear dialogue] that 80% percent of all people
in the world do not have any electricity.
The large number of these peoples living in climates
ideally suited for the photovoltaic applications.
Even in Europe, several hundreds of thousands of families where
there [unclear dialogue] occupation do not
have access to grid electricity.
And the next one is domestic supply,
which we use in our home.
It can start with the source of electricity for the home.
Now it is intelligent concepts of housing
are being developed, which can sustain itself.
There is no need then to pay your monthly power bills.
In the photovoltaic areas mountain or the rooftops offers
the possibility of large scale power generation in
decentralized medium size grid connector units.
The main advantage of this distribution system [unclear
dialogue] as follows, there is no cost in buying the land and
preparing the site and the transmission uses are much
lower because the [unclear dialogue] is on the
same side as the supply.
And the next application is the healthcare one.
In the whole world, the whole world is fighting the
common diseases like vaccinations something.
And to be effective, the program must provide
immunization for the people in the rural areas.
If in the service, all vaccinations have to be
kept in a strictly temperature arranged
through transportation and storage.
The provision of refrigerators from this aim is
known as the Vaccination Cold Chain.
We have to use a refrigerator, which
works with the solar energy.
And the next one is lightning.
In terms of number of installations,
lightning is presently the biggest application
of photovoltaic [unclear dialogue].
Within some thousands of units installed worldwide,
they are mainly used to provide lightning for
domestic or community buildings such as schools,
health centers, and community buildings, offices.
The photovoltaic also being increasingly used
for the lightning streets and tunnels also for
the security purpose lightning.
And the last one is electric power generated in space.
The photovoltaic solar generator have been and will retain the
best source for providing the electric power
to satellite in an orbit around the earth.
[unclear dialogue] the user of solar cells on the U.S.
satellite, Vanguard 1, in 1958 demonstrated beyond the doubt
the first practical application of photovoltaic.
And these are some of the applications of the solar cells,
thank you and Vinay.
(Vinay). This is how a pv cell,
the photovoltaic cell or the solar cell, works.
(male narrator). Solar cells convert sunlight
directly into electricity.
We start with sand, which is processed
into highly purified silicon.
In a process called doping, trace amounts of
special impurities are added to this purified silicon.
For example, when silicon is doped with boron,
the resulting material is called p-type.
When silicon is doped with phosphorus,
the resulting material is called n-type.
When pure silicon is doped with both boron and phosphorus in
just the right way, a p-n junction is formed.
This process establishes a permanent
electric field in the crystal.
When a p-n junction is made, light can strike it's top
surface and metal conductors are attached to the
p and n type sides, a solar cell is formed.
When sunlight strikes the solar cells, electrons are ejected
from the atoms and the permanent electric field in the junction
steers them to the n-type side.
If a wire is connecting both sides of the solar cell,
electric current can flow whenever sunlight
is striking the solar cell.
(Dr. Wafeek Wahby). I have a question for you,
you say that 80%, eight zero percent, of the
people if the world don't have...
(Ashwini). Eighty percent of people
do not have electricity.
(Dr. Wafeek Wahby). So worldwide globally,
80% of people...
(all presenters). Solar, solar, solar,
not regular electricity, we are talking
about solar power.
(Dr. Wafeek Wahby). Solar, solar, so we have
electricity, not solar.
(Ram Mahidara). Yeah, what we want to
say is the reach of this technology, what
we want in turn is that this technology, though it is so
promising and though it gives a cheap source and renewable
source which could displace our crisis now, it is only reaching
20% of, not even 20% of the whole population.
(Vinay). It's mainly because of
the initial cost to get this technology.
(Ram). I would like to conclude
this presentation with by talking
about the future of this technology.
The future actually seems very promising though just like
any other technology, it has many hurdles in front of it,
and the main hurdle being cost.
About a decade ago, it would have costed a kilowatt of power,
approximate cost of 350 dollars.
So it is not what every common man can afford, so the main
thing which I would suggest is subsidies provided by the
government and local companies which are into this
business, without which I don't think it will ever be able
to hit the streets, you know.
In the pictures, we see solar panels lining the rooftops of
houses but this is just a conceptual house.
Maybe these we could count them on fingers, but we
could imagine the whole city being lined up
like that, but it's really costly.
This is a photo actually of a small town in Japan where the
researchers started experimenting by just building a
row of houses with these on the rooftops.
And this is what he said, this is the refrigerator and the
mobile unit and how the solar panels are
being used in the mobile units.
So actually we are living in a world where information
technology rules everything.
Whatever we want can be achieved on the web, so those types of
technologies connect more often and, you know, much easily to
the public than these ones.
The only thing which we see in the news is that some researcher
has a breakthrough in this technology, and a new
type of silicon, maybe nanoscale silicon are used,
nanotechnology is being used everywhere.
But it never connects to the public.
The only thing that connects are marvels like the iPhones, the
iPads, only stuff that is more catchy to the eye.
These are the ones, which take a longer time,
which is much difficult to accomplish.
If governments invest in this kind of technology,
it would be a gift for the next generation.
Because if we do not act now all of our
resources will get depleted soon.
Soon there will be nothing left for our children to come.
This is a one-liner, which I wrote, this is my impression.
This was the rock that fell on my face when I did this,
the future is cloudy but clouds with a silver lining, so...
(Dr. Wahby). We clap our hands for this.
(Ram). Thank you.
[audience applause].
We are open for any doubts, comments, discussion, whatever.
[unclear dialogue].
(Dr. Wahby). I have a question regarding
what Ashwini, I think, you mentioned
about vaccination.
What vaccination has to do with...
(Ashwini). No, it's not about
the vaccination.
The refrigerators are run by the solar cells.
(Dr. Wahby). Run on the solar cells.
(Vinay). There are some places in
India where we can't have electricity
and some places in [unclear dialogue] where
we don't have electricity, it's all sunlight.
So the medicine should be maintained at a particular
temperature, so to maintain the temperature,
we don't have electricity there to keep it refrigerated.
(Dr. Wahby). Very good.
(Vinay). So they use, you can
see it in the picture, they use camels to
move around the places, so they use the solar cell
technology to refrigerate the medicines.
(Dr. Wahby). To keep the refrigerators
working, to keep the vaccines.
[unclear dialogue].
(Ram). This one is from
[unclear dialogue], we just wanted to put
one of the pictures from India.
So this is a picture, this is from [unclear dialogue] that
we actually searched for.
And this is from [unclear dialogue].
(Dr. Wahby). Very good, let's
clap our hands for this also.
[audience applause].
(female speaker). My question is does
these [unclear dialogue] cells will
they save the energy and later...
(Vinay). It just produces electricity
and it makes the flow of electrons
and the current [unclear dialogue] in the
junction there and it's being transferred.
You can use it directly or you can store it in
capacitors or something.
(female speaker). It's instant, but then
it has a capacitor or something?
(Vinay). We can store it in batteries.
(female speaker). Oh, okay.
(Vinay). You can use in
[unclear dialogue] batteries or to manage
power supply in the house.
(female speaker). So what about winter?
(Gowtham). We can use any
light, not only sunlight.
On a cloudy day, we'll use ten meters of the cells on your top,
we'll get 800 watts of energy on a cloudy day,
sufficient for a three-story building.
(Dr. Wahby). Other questions, comments?
If not, let's give them a hand.
[audience applause].