Solar energy originates from thermonuclear fusion reactions in the sun. It is harnessed through photovoltaic cells, which use sunlight to free electrons and create electricity. There are two main types of solar power plants - solar thermal plants that use mirrors to heat liquid and create steam to power generators, and photovoltaic plants that directly convert sunlight to electricity using solar cells. While solar energy has advantages of being renewable, non-polluting and having low operating costs, its disadvantages include high initial installation costs and lower efficiency compared to energy from fossil fuels. The maximum theoretical efficiency of solar cells is around 77% but current cells only operate at 10-14% efficiency due to energy lost as heat and light reflection

1. SOLAR ENEGY

2. CONTENTS
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Important Facts on solar
Introduction
Working
Solar Electric Power Plants
Direct Conversion into electricity
Advantages
Disadvantages
Efficiency
References

3. Fast Facts on Solar
• The sunlight that reaches the earth is about 200,000
times the total electrical energy generated by humans
everyday!
• The first working solar cell was invented by Charles Fritts
in 1883 and operated at 1% efficiency.
• The word photovoltaic, the proper name for solar cell,
comes from the Greek word for light, which is combined
with the name Volta, the last name of the scientist after
whom the measurement unit volt is named. All together
the word photovoltaic means light electrical or electricity
from light.
• Every minute, enough solar energy reaches the Earth to
meet global energy demands for a year.

4. What is Solar Energy?
• Originates with the thermonuclear
fusion reactions occurring in the sun.

5. How much solar energy?
The surface receives about 47% of the total
solar energy that reaches the Earth. Only this
amount is usable.

6. How It Works
• Solar energy is harnessed and used through a process
using photovoltaic cells, also known as solar cells. These
cells or panels are usually made up of two types of
silicon.
• Sunlight is made up of little units of energy called
photons.
• The solar cell is made up of negative and positive layers,
which create an electrical field.
• When the photons hit the surface of the solar cell, the
electrons inside the energy from the sun are freed, pass
to the bottom of the cell, and flow through to whatever
requires power. This flow of electrons is what we know
as electricity.

8. Solar Electric Power Plants
•
• Harness solar power to
Efficiency is fargenerate electricity spectrum
lass than the 77% of solar
with usable wavelengths.
43% of photon energy is used to warm the crystal.
• Main types:
•
• Efficiency drops as temperature increases (from
– Solar thermal energy
24% at 0°C to 14% at 100°C.)
Has mirrored surface that
• Light is reflected off •the front face and internal
Array of mirrored electrical resistance are othersunlight to heat up
solar collectors at
reflects factors.
• site
is about 10-14%.
FPL Energy Overall, the efficiencyliquid to make steam to
generate electricity
– Photovoltaic
• Uses photovoltaic cells
that absorb direct sunlight
(as discussed previously)

9. Direct Conversion into Electricity
•
•
•
•
•
• Photovoltaic cells are capable of
directly converting sunlight into
Efficiency is far lass than the 77% of solar spectrum
electricity.
with usable wavelengths.
A simple wafer of silicon with
43% of photon• energy is used to warm the crystal.
wires attached to the layers.
Efficiency drops as temperature increases (from
Current is produced based on
24% at 0°C to 14% at 100°C.)
Light is reflected types of silicon (n- and p-types)
off the front face and internal
used for the layers.
electrical resistance are other factors. Each
cell=0.5 volts.
Overall, the efficiency is about 10-14%.
• Battery needed as storage
• No moving partsdo no wear
out, but because they are
exposed to the weather, their
lifespan is about 20 years.

10. Advantages
1. Non polluting: no noise, no harmful or unpleasant emissions or
smells.
2. Very reliable: most solar panels have a 25 year warranty and even a
longer life expectancy (the theory is they could last 100 to 125
years).
3. Although we cannot utilize the power of the sun at night or cloudy
days, we can count on the sun being there the next day, ready to
give us more energy and light.
4. Solar modules over their lifetime produce more power per gram of
material than nuclear power but without the problem of large
volumes of environmentally hazardous material.
5. Solar panels produce more power within 5 years than the power
consumed in their production.
6. Solar Power is a renewable energy source. It is a resource that
cannot be used up by us using it.
7. Although solar panels may be expensive to buy, you will save money
and our environment in the long run.

11. Disadvantages
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Cost of electricity from coal-burning plants
is anywhere b/w
8-20 cents/kWh, while
photovoltaic power generation is anywhere
b/w $0.50-1/kWh.
Does not reflect the true costs of burning
coal and its emissions to the nonpolluting
method of the latter.
Underlying problem is weighing efficiency
against cost.
 Crystalline silicon-more efficient, more
expensive to manufacture
 Amorphous silicon-half as efficient, less
expensive to produce.

12. Efficiency
Efficiency is far than the 77% of solar spectrum
• Efficiency is far lass lass than the 77% of solar
spectrum with usable
with usable wavelengths. wavelengths.
• 43% of photon energy is used used tothe crystal.
43% of photon energy is to warm warm the
• Efficiency drops as temperature increases (from
crystal.
24% at 0°C to 14% at 100°C.)
 Efficiency drops as temperature increases
• Light is reflected off the front face and internal
(from 24% at 0°C to 14% at 100°C.)
electrical resistance are other factors.
• Overall,is reflected off the front face and
Light the efficiency is about 10-14%.

internal electrical resistance are other
factors.
Overall, the efficiency is about 10-14%.

13. The End