Solar cells convert sunlight directly into electrical energy. They work as a semiconductor that produces electricity when exposed to light, functioning similarly to how a battery produces electricity. The key components are a photovoltaic material like silicon that produces electrons and holes when struck by photons, and electrical conductors that carry the current. Solar cells have many applications and benefits like being renewable, clean, and able to provide off-grid power, but their initial costs remain high and they require large surface areas for average efficiency.

1. MSc/Chem/03
2017-19, IGIT, Saranga
Under the Guidance of :
Dr. B.B PANDA

2. * Introduction.
* Historical background
* working Principle.
* Types of solar cell.
* Benefits.
* Application.
* Disadvantages.
* Conclusion

3. ● A solar cell is a that converts solar energy(energy obtained from the
sun) directly into electrical energy.
● Also known as .
● It is like a battery because it supplies power.
● It is different from a battery in the sense that the voltage supplied by the cell
changes with changes in the resistance of the load.

4. ● The term “ ” comes from the Greek meaning “ ”
and “ ” from the name of the Italian physicist “ ”.
●The photoelectric effect was first recognized in 1839 by
French Physicist .
● explained the photoelectric effect in 1905
for which he received the Nobel prize in Physics in 1921.
● The modern photovoltaic cell was developed in 1954 at
● The highly efficient solar cell was first developed by
in 1954
using a diffused silicon p-n junction.
● Solar Cells were first used in satellite,
launched in 1958.

5.  The outer shell of Si has 4 e- . So to fill up , it will share electrons with 4 nearby atoms.
 When phosphorus(5 e- in its outer shell) combines with silicon , one electron remains free.
 Impure silicon with phosphorus atoms takes less energy to loose one of its “extra” electron
because they are not tied up in a bond with any neighbouring atoms.
 The other part of solar cell is doped with the element Boron (with 3 e- in its outer shell ) to
become P-type silicon.
 when this 2 types of silicon interact, an electric field forms at the junction which prevents
more electrons to move P-side.
 When photon hits solar cell, its energy breaks apart electron-hole pairs. Each photon normally
free exactly one electron, resulting in a free hole as well. If this happens close to the electrical
field, causes disruption of electrical neutrality.
 If we provide an external current path, electrons will flow through the P-side to unite with
holes .The electron flow provides the current and electric field causes a current flow.
 The single solar cell constitute the N-type layer sandwiched with P- type layer.

6. Based on the types of crystal used, solar cells can be classified as :-
1. The is produced from pure silicon (single
crystal). Since the mono crystalline silicon is pure and defect free, the efficiency of
cell will be higher.
2. In , liquid silicon is used as raw material and
polycrystalline silicon was obtained by solidification process .The material contain
various crystalline sizes. Hence the efficiency of this type of cell is less than mono
crystalline cell.
3. is obtained by depositing silicon film on the substrate like
glass plate. The layer thickness amounts to less than 1m.The efficiency of
amorphous
cells is much lower than that of the other two cell types.
As a result they are used mainly in low power equipment, such as watches and
pocket calculators.

7. ● It is based on a substrate with a coating of
nanocrystals.
●The nanocrystals are silicon, CdTe and substrates
are generally silicon or various organic conductors.
● It is a solar cell made by using a combination of
organic matter and inorganic matter.
● It is made by using multiple layers of photo system
and many of the same inorganic materials that are
found in other solar cells.
● It is based on the use of Cadmium Telluride, a
thin semiconductor layer.
● CdTe : Band gap 1.5 ev ; Absorption coefficient
10 times that of Si.
● It is based on a semiconductor formed
between a photo sensitized anode and an
electrolyte.
● Its modern version is known as Gratzel cell.
● Produced from cheaper polycrystalline
materials and glass.
● High optical absorption coefficient.
● Uses quantum dots as the absorbing
photovoltaic material.
● It can replace silicon , CdTe.
Made Most Popular Types are :-

8. ● The very first benefit of using this technology is that solar energy is renewable.
● This is a 100% environment- friendly. Contrary to fossil fuels, this technology is not going
to release any greenhouse gases, harmful agents, volatile material or CO to the environment.
● Solar panels are highly durable and reliable. These systems don’t have any moving
systems and hence they don’t require any replacement.
● We can use solar cell technology to generate thousands of hours of electricity with
minimal maintenance. Solar cells and panels don’t create any noise and they are totally
silent.
● Solar cells provide cost effective solutions to energy problems in places where there is no
mains electricity.
● It enhances the clean and emission free power production.
● Solar energy systems have a 25 yr. warranty but can last 40+ yr. with occasional
maintenance.

9. ● The provision of electricity to rural areas derives important
social and economic benefits to remote communities throughout the world like
power supply to remote houses , electrification of health care facilities, irrigation and
water supply and treatment.
● Many lighthouses are now powered by solar cells.
● Radio transceivers on mountain tops are often solar
powered.
● Solar cells are often electrically connected as a module. These modules often have
a sheet of glass on the front, allowing light to pass while protecting the
semiconductor wafers from climate conditions. Solar cells are also usually connected
in series in modules, creating an additive voltage.
● Photovoltaic solar generators have been and will remain the best choice for
providing electric power to satellites in an orbit around the earth.

10. ● The main disadvantage of solar cell is the initial cost. Most types of solar cell requires
large areas of land to achieve average efficiency.
● Air pollution and weather can also have a large effect on the efficiency of cells.
● The silicon used is also very expensive and the solar cells can only ever generate
electricity during the day time.
● The efficiency level of this technology is low.
● The most efficient solar power system gives an efficiency of not more than 40%. This
means that the rest of the 60% power of sunlight is not harnessed .
● The most important thing is that the sky should be clear so that sunlight can fall on the
solar cell and we can get electricity.

11. ● Solar cell can be used in .
● could power their pumps through the use of solar cells.
● Anything that requires electricity could utilize photovoltaic energy as it
● Solar cell is mainly used as a voltage generator.
● It can be also used as a .
● It can also used to .