About Solar Renewable Energy

1. By:
Charan S Devaraj
10th A
AMRIT VIDYALAYAM

2.  Solar energy Originates with the thermonuclear fusion
reactions occurring in the sun.
 Represents the entire electromagnetic radiation.
 This energy consists of radiant light and heat energy
from the sun.
 Out of all energy emitted by sun only a small fraction
of energy is absorbed by the earth.
 Just this tiny fraction of the sun’s energy is enough to
meet all our power needs.

3. The surface receives about 47% of the total solar
energy that reaches the Earth. Only this amount is
usable.

4. • Using present solar techniques some of the solar energy reaching
the earth is utilized for generating heat, electricity etc….
• Even then the energy demand met by using solar energy is very
less.
Fossils
1st Qtr
Bio-fuels
2nd Qtr
3rd Qtr
Hydro-based
4th Qtr
Nuclear
SOLAR(0.8%)
Windmills

5. • The fossil fuels are non renewable sources so we can
not depend on them forever.
• Though nuclear energy is a clean and green energy ,as
said by Dr.A.P.J Abdul Kalam, there are always some
problems associated with it.
• 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 energy.

6.  Solar Thermal Energy
 Solar cooker
 Electricity Generation Using Solar Concentrators
 Solar street lights or home lights
 Solar water pumps etc..

7.  Solar thermal technologies involve harvesting energy from the sun
for heating water or producing electrical power.
 Solar collectors are used for this purpose.
 Three Types:
 Flat-plate collectors
 Evacuated-tube collectors
 Integral collector-storage systems(Batch or Bread Box)

8. A solar cooker is a device which uses the energy
of direct sunlight to heat, cook
or pasteurize food or drink. Many solar cookers
presently in use are relatively inexpensive, low-tech
devices, although some are as powerful or
as expensive as traditional stoves, and
advanced, large-scale solar cookers can cook for
hundreds of people.

9. Because they use no fuel and cost nothing to
operate, many nonprofit organizations are
promoting their use worldwide in order to help
reduce fuel costs (for low-income people) and
air pollution, and to slow down
the deforestation and desertification caused by
gathering firewood for cooking. Solar cooking is
a form of outdoor cooking and is often used in
situations where minimal fuel consumption is
important, or the danger of accidental fires is
high, and the health and environmental
consequences of alternatives are severe.

10. Concentrated solar power (CSP) systems use mirrors or lenses to
concentrate a large area of sunlight, or solar thermal energy, onto a
small area. Electrical power is produced when the concentrated
light is converted to heat, which drives a heat engine (usually
a steam turbine) connected to an electrical power generator or
powers a thermo chemical reaction.

11. Solar street lights are raised light sources which are powered
by photovoltaic panels generally mounted on the lighting
structure. The photovoltaic panels charge a rechargeable
battery, which powers a fluorescent or LED lamp during the
night.

12. A solar-powered pump is a pump running on electricity
generated by photovoltaic panels or the thermal energy available
from collected sunlight as opposed to grid electricity or diesel run
water pumps. The operation of solar powered pumps is more
economical mainly due to the lower operation and maintenance
costs and has less environmental impact than pumps powered by
an internal combustion engine(ICE). Solar pumps are useful where
grid electricity is unavailable and alternative sources (in
particular wind) do not provide sufficient energy.

13. • Converting solar energy directly into electrical
energy.
• Devices used are called solar panels.
• Solar cells work on the principle of
photoelectric effect.

14. Solar panel is a group of solar cells.

15.  A typical solar cell is a multi-layered unit consisting of a:
 Cover - a clear glass or plastic layer that provides outer
protection from the elements. Transparent Adhesive - holds
the glass to the rest of the solar cell.
 Anti-reflective Coating - this substance is designed to
prevent the light that strikes the cell from bouncing off so
that the maximum energy is absorbed into the cell.
 Front Contact - transmits the electric current.
 N-Type Semiconductor Layer - This is a thin layer of silicon
which has been mixed (process called doping) with
phosphorous.
 P-Type Semiconductor Layer - This is a thin layer of silicon
which has been mixed or doped with boron.
 Back Contact - transmits the electric current.

17. • Photoelectric effect
 When a light of certain frequency falls on the
surface of a metal
 Electrons will absorb the energy
 If incident light energy is greater than the work
function (minimum energy required to remove the
loosely bound valence electrons) of the metal
 Then the photo electrons will be emitted and
 The excess energy is converted to the kinetic energy
of electron.

18. • 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.

19. 1. Solar energy is free although there is a cost in the building
of ‘collectors’ and other equipment required to convert solar
energy into electricity or hot water.
2. Solar energy does not cause pollution. However, solar
collectors and other associated equipment / machines are
manufactured in factories that in turn cause some pollution.
3. Solar energy can be used in remote areas where it is too
expensive to extend the electricity power grid.
4. Many everyday items such as calculators and other low
power consuming devices can be powered by solar energy
effectively.
5. It is estimated that the worlds oil reserves will last for 30 to
40 years. On the other hand, solar energy is infinite (forever).

20. 1. Solar energy can only be harnessed when it is daytime and
sunny.
2. Solar collectors, panels and cells are relatively expensive to
manufacture although prices are falling rapidly.
3. Solar power stations can be built but they do not match
the power output of similar sized conventional power stations.
They are also very expensive.
4. In countries such as the UK, the unreliable climate means that
solar energy is also unreliable as a source of energy. Cloudy skies
reduce its effectiveness.
5. Large areas of land are required to capture the suns energy.
Collectors are usually arranged together especially when
electricity is to be produced and used in the same location.
6. Solar power is used to charge batteries so that solar powered
devices can be used at night. However, the batteries are large
and heavy and need storage space. They also need replacing from
time to time.