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Solar Power
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Contents
1.Introduction 2.History 3.Applications 4.Solar
Panels 5.How PV cells work 6.Other
applications 7.Top Countries 8.EXIT
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1. Introduction
Solar energy is a type of renewable energy which
comes directly from the Sun. This energy drives
the climate and weather and supports virtually
all life on Earth. Solar energy technologies
harness the sun's energy for practical ends.
These technologies date from the time of the
early Greeks, Native Americans and Chinese, who
warmed their buildings by orientating them toward
the sun. Modern solar technologies provide
heating, lighting, electricity and even
flight. Solar power is used synonymously with
solar energy or more specifically to refer to the
conversion of sunlight into electricity. This can
be done either through the photovoltaic effect or
by heating a transfer fluid to produce steam to
run a generator.
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2. History
The photovoltaic effect was first recognised in
1839 by French physicist Alexandre-Edmond
Becquerel. However, it was not until 1883 that
the first solar cell was built, by Charles
Fritts, who coated the semiconductor selenium
with an extremely thin layer of gold to form the
junctions. The device was only around 1
efficient. Russell Ohl patented the modern solar
cell in 1946. Sven Ason Berglund had a prior
patent concerning methods of increasing the
capacity of photosensitive cells. The modern age
of solar power technology arrived in 1954 when
Bell Laboratories, experimenting with
semiconductors, accidentally found that silicon
doped with certain impurities was very sensitive
to light.
Russell Ohl
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3. Applications
Solar cells have many applications. Individual
cells are used for powering small devices such as
electronic calculators. Photovoltaic arrays
generate a form of renewable electricity,
particularly useful in situations where
electrical power from the grid is unavailable
such as in remote area power systems,
Earth-orbiting satellites and space probes,
remote radiotelephones and water pumping
applications. Photovoltaic electricity is also
increasingly deployed in grid-tied electrical
systems.
Solar cells
The first spacecraft to use solar panels was the
US satellite Explorer 1 in January 1958. This
milestone created interest in producing and
launching a geostationary communications
satellite, in which solar energy would provide a
viable power supply. This was a crucial
development which stimulated funding from several
governments into research for improved solar
cells.
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4. Solar panels
Photovoltaics, or PV for short, is a solar power
technology that uses solar cells or solar
photovoltaic arrays to convert light from the sun
directly into electricity.
Solar cells produce direct current electricity
from light, which can be used to power equipment
or to recharge a battery.
A new photovoltaic "thin film" technology is
being pioneered by a Californian company that
allows cells to be mass produced by printing them
on to aluminium film at a fraction of the cost of
existing techniques. At December 2007 the company
claims it can achieve costs of USD 0.99 a watt
which is comparable to coal produced electricity.
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5. How PV cells work
Photovoltaic (PV) cells are made of special
materials called semiconductors such as silicon,
which is currently the most commonly used.
Basically, when light strikes the cell, a certain
portion of it is absorbed within the
semiconductor material. This means that the
energy of the absorbed light is transferred to
the semiconductor. The energy knocks electrons
loose, allowing them to flow freely.
PV cells also all have one or more electric
fields that act to force electrons freed by light
absorption to flow in a certain direction. This
flow of electrons is a current, and by placing
metal contacts on the top and bottom of the PV
cell, we can draw that current off to use
externally.
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6. Other applications
Solar thermal energy
Is a technology for harnessing solar energy for
heat. This is very different from solar
photovoltaics, which convert solar energy
directly into electricity.
Solar thermal collectors are characterized by the
US Energy Information Agency as low, medium, or
high temperature collectors. Low temperature
collectors are flat plates generally used to heat
swimming pools. Medium-temperature collectors are
also usually flat plates but are used for
creating hot water for residential and commercial
use. High temperature collectors concentrate
sunlight using mirrors or lenses and are
generally used for electric power production.
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Solar power tower
The solar power tower (also known as 'Central
Tower' power plants or 'Heliostat' power plants
or power towers) is a type of solar furnace using
a tower to receive the focused sunlight. It uses
an array of flat, movable mirrors (called
heliostats) to focus the sun's rays upon a
collector tower (the target). The high energy at
this point of concentrated sunlight is
transferred to a substance that can store the
heat for later use.
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Solar vehicles
Development of a practical solar powered car has
been an engineering goal since the 1980s. Solar
cars are generally powered by PV panels
positioned on the vehicle. The center of this
development is the World Solar Challenge, a
biannual solar-powered car race in which teams
from universities and enterprises compete over
3,021 km across central Australia from Darwin to
Adelaide.
In 1987, when it was founded, the winner's
average speed was 67 km/h. The 2007 race included
a new challenge class using cars with an upright
seating position and which, with little
modification, could be a practical proposition
for sustainable transport. The winning car
averaged 90.87 km/h .
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7. Statistics
Top contries using solar power
Germany-gt2,863MV
France
Japan
South Korea
USA
Thailand
Switzerland
Spain
Austria
China
Luxembourg
Australia
World -gt5,862MV
the Netherlands
EU-gt3,220 MV
Italy
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made by
Isac Bianca-Mihaela Voda Dragos-Ioan
Coordonated by Mr.Schnabel Dieter