Energy from the sun travels to the earth in
the form of electromagnetic radiation similar to radio waves, but in a
different frequency range. Available solar energy is often expressed
as energy per time per unit area, Joules per second per square meter, or watts per
square meter (W/m2). The
amount of energy available from the sun outside the Earth’s atmosphere is
approximately 1400 W/m2; that’s nearly the same as a high power hair
drier for every square meter of sunlight! Some of the solar energy
is absorbed as it passes through the Earth’s atmosphere. As a
result, on a clear day the amount of solar energy available at the Earth’s
surface in the direction of the sun depend of the angle of elevation and is
typically only about 400 W/m2 in Canada. At any particular
time, the available solar energy is primarily dependent upon how high the sun
is in the sky and current cloud conditions. On a monthly or annual
basis, the amount of solar energy available also depends upon the
location. Furthermore, useable solar energy depends upon available
solar energy, other weather conditions, the technology used, and the
There are many ways that solar energy
can be used effectively. Applications of solar energy use can be
grouped into there are three primary categories:
Electricity production, and
The most widely used applications are for water
and space heating. Ventilation solar air heating is also growing in
popularity. Uptake of electricity producing solar technologies is
increasing for the applications photovoltaics (primarily) and concentrating
solar thermal-electric technologies. Due to recent advances in solar
detoxification technologies for cleaning water and air, these applications hold
promise to be competitive with conventional technologies.
Fig. 1: The energy budget of the Earth
using Solar Energy & description in working: –
Fig. 2: The French
chemist Lavoisier experimented with concentrating
solar energy using a
large parabolic mirror.
Combustion, generated by focusing sunlight over flammable
materials using lenses, experiment conducted by Lavoisier circa 1770s.
Fig. 3: In 1866, Auguste Mouchout used a parabolic trough to
steam for the first solar steam engine.
Auguste Mouchout, inventor of the
first active solar motor, questioned the widespread belief that the fossil
fuels powering the Industrial Revolution in the 19th century would never run
out. Prophetically he said:
Eventually industry will no longer find in Europe
the resources to satisfy its prodigious expansion. Coal will undoubtedly be
used up. What will industry do then?
1861, Mouchout developed a steam engine powered entirely by the sun. But its
high costs coupled with the falling price of English coal doomed his invention
to become a footnote in energy history. Nevertheless, solar energy continued to
intrigue and attract European scientists through the 19th century. Scientists
developed large cone-shaped collectors that could boil ammonia to perform work like
locomotion and refrigeration. France and England briefly hoped that solar
energy could power their growing operations in the sunny colonies of Africa and
Fig. 4: 1901 “solar motor” in operation in California.
The solar furnace in Mont Louis, built in 1949 by Professor Félix Trombe, was the first
solar furnace in the world. This dual reflection solar furnace has been in
steady evolution over the past 50 years and in 1993, was taken over by the
limited liability company “Solar Furnace Development” who, along with
continued scientific research, is the first company to use a solar furnace for
industrial and manufactured products such as the firing of ceramics, and bronze
and aluminum products.
Trombelater (1969-1971) directed the design and the construction of the largest
solar furnace in the world that we will discuss in detail.
Fig. 5: The solar furnace in Mont Louis.
Sun power in the Pyrenees: –
In 1972 Time magazine’s Science
section described the world’s largest solar furnace in sufficient technical
detail to allow the setting for an investigation that involves a great deal of
students’ knowledge of physics and, with some guidance, can lead to her asking
a series of questions that lead to problems and experimentation that go beyond
the textbook. These questions eventually lead to the discussion radiation,
optics, wave motion, thermodynamics, solar energy, quantum mechanics and
thermonuclear reactions. It should also be mentioned that the Mont-Louis solar
furnace in the Pyrenees is still the largest in the world.
Fig. 8: The Solar Furnace of Odeillo in the French
(This is the largest
solar furnace in the world)
Perched high in the
powerful new solar furnace (1970) harnesses the almost limitless energy of the
sun. Eight stories tall, the furnace’s
gleaming reflector dwarfs the ancient buildings nearby and turns the
surrounding hillsides topsy-turvy on its curved surface. Lined up in tiers on a
pasture in front of the big reflector stand 63 smaller mobile mirrors. These heliostats, as they are called, can be
individually adjusted so that each one reflects the sun’s rays directly into
the big parabola, thereby creating striking flare-ups of light. Focusing these rays at the oven building only
a short distance from its base, the giant mirror concentrates the sun’s
radiation on the small target area. The
converged beams, which are no wider than a foot at their target, can create
temperatures as high as 6,300° F (3500 °C.)
Fig. 9: Three commonly used reflecting
schemes for concentrating
solar energy to attain high
The description of this context is based on an article
in Time magazine’s Science section that appeared in the May 18. 1970 issue. The
Time article describes the world’s largest (1970) solar furnace in sufficient
detail for an investigation that involves a great deal of the young physics
student’s knowledge of physics. The situations described below move from the
practical aspects of the furnace to a discussion of geometric optics,
radiation, quantum theory, and thermonuclear reactions. The
following is the content of the article as it was given in Time magazine.
A simple magnifying glass, focusing the
sun’s rays, can scorch a piece of wood or set a scrap of paper on fire. Solar radiation can also be concentrated on a
much more awesome scale. It can burn a
hole through thick steel plate, for example, or simulate the thermal shock of a
nuclear blast. It can, that is, with the
aid of a super reflector of the sort that has been set up by French scientists
high in the Pyrenees. Ten years in the building, the world’s
largest solar furnace is a complex of nearly 20,000 mirrors and can concentrate
enough sunlight to create temperatures in excess of 6,000° F, or 3500°C.
Harnessing solar energy is hardly a new
accomplishment. Nearly 22 centuries ago,
the Greek mathematician Archimedes is said to have temporarily saved Syracuse from Roman
conquest by setting the invading fleet aflame with numerous large mirrors. In the 18th century, the pioneer
French chemist Lavoisier produced enough heat with 52-inch-wide lenses to power
his experiments. Though Lavoisier’s work was cut short by the French Revolution
(he was guillotined in 1794)), his history has not discouraged contemporary
French scientists—notably Physical Chemist Felix Trombe, a research director of
France’s National Center for Scientific Research and its premier experimenter
with the sun’s energy.
For more than 20 years, Trombe has
championed solar furnaces as an ideal source of intensive heat for both
industrial uses and scientific experimentation.
In 1946 he fashioned his first sun stove out of a captured German
antiaircraft searchlight mirror at an observatory near Paris.
Moving to the old Pyrenean citadel town of Mont-Louis where the sun shines as many as
200 days a year, he has since built five larger solar furnaces. Now, in masterly style, he has created his pièce de résistance on a hillside in the
nearby ski resort of Odeillo. Compared
with similar devices in several other countries, such as the U.S. Army’s
30-kilowatt stove at Natick, Mass.,
Odeillo’s 1,000-kilowatt structure is easily the Mount
Palomar of solar furnaces.
10: The Solar Furnace of Odeillo; The
parabolic shape of the
solar collector is evident here.
Fig. 11: The array of mirrors is controlled by a computer and turn with
Rays come from reflectors
Fig. 12: The geometry of reflection depend on the law of reflectivity
Fig. 13: The furnace is located at the focus of the parabolic mirror
14: The array of solar collector and the mirrors in perspective.
Only recently, however, have we developed the ability to harness
the sun’s awesome power. The resulting technologies have promising implications
for the future of renewable energy and sustainability. Below, we’ve given a
brief on solar power, how it works, and what may be in store for the future of
What is Solar Power?
Solar power is a form of energy harnessed from the power and
heat of the sun’s rays. It is renewable, and therefore a “green” source of
How Does It Work?
The most common way of harnessing energy from the sun is through
photovoltaic (PV) panels – those large, mirror-like panels you’ve likely seen
on rooftops, handheld solar devices, and even spacecraft’s. These panels
operate as conductors, taking in the sun’s rays, heating up, and creating
energy (and electricity).
On a larger scale, solar thermal power plants also harness the
power of the sun to create energy. These plants utilize the sun’s heat to boil
water and, in turn, power steam turbines. These plants can supply power to
thousands of people.
. How is Solar Power a “Greener”
Just like wind power (link to blog), solar power is a virtually
unlimited and inexhaustible resource (unlike power produced from expendable
fossil fuels). As technologies improve and the materials used in PV panels
become “greener,” the carbon footprint of solar power becomes smaller and
smaller and the technique becomes more accessible to the masses.
What’s the Holdup? Why Isn’t
Solar Power More Prevalent?
Similarly, to wind power, solar power is contingent upon the
weather and the amount of sunshine present in a specific location. This means
that geographical areas lacking in sunlight, or areas that frequently
experience cloudy weather, may have difficulty utilizing solar power
Additionally, solar power is an expensive endeavor. The
technologies often require a large amount of land, and they can be extremely
costly. Scientists are hard at work to find an affordable, efficient solution
for harnessing solar power.
Did You Know?
§ Every hour, the sun beats down with enough power to provide
global energy for an entire year.
§ It takes an average of eight minutes for energy to travel
from the sun to the Earth.
§ Scientists have used solar energy to power spaceships since 1958.
§ Most solar panels used today have an average life expectancy
of between 20-40 years.
Let the sunshine in! Interested in solar power for your home?
There are a number of resources, projects, and products available online for
families interested in going solar. To get the best bang for your buck, be sure
to conduct thorough research before beginning any new effort.
Solar Energy Advantages: –
Ø Saves you money
Ø After the
initial investment has been recovered, the energy from the sun is
incentives are available from the government that will reduce your
Ø It’s not
affected by the supply and demand of fuel and is therefore not subjected to the
ever-increasing price of gasoline.
Ø Solar energy is
clean, renewable (unlike gas, oil and coal), sustainable and helping to protect
Ø As we see
previously, it does no pollute air.
Ø Therefore, Solar
Energy does not contribute to global warming, acid rain or smog. it actively
contributes to the decrease of harmful greenhouse gas emissions. By not using
any fuel, solar energy does not contribute to the cost and problems of the
recovery and transportation of fuel or the storage of radioactive waste.
Ø Solar Energy
systems are virtually maintenance free and will last for decades.
Ø Once installed, there are no
recurring costs. They operate silently, have no moving part, do not release offensive
smalls and do not require you to add any fuel. More solar panels can easily be
added in the future when your family’s needs grow.
Solar Energy: –
Ø Initial cost: the
initial cost of purchasing and installing solar panels always become the first
disadvantage. Although subsidy programs, tax initiatives and rebate incentives
are given by government to promote the use of solar panels we are still way
behind in making full and efficient use of solar energy.
Ø Location: the location of solar panels is of
major importance in the generation of electricity. Areas which remains mostly
cloudy and foggy will produce electricity but at a reduced rate and may require
more panels to generate enough electricity homes. Houses which are covered by
trees, landscapes or other building may not be suitable enough to produce solar
Ø Pollution: Most of the photovoltaic panels are
made up of silicon and other toxic metal like mercury, lead and cadmium.
Pollution in the environment can also degrade the quality and efficiency of
photovoltaic cells. New innovative technologies can overcome the worst of these
Ø Reliability: Unlike other
renewable source which can also be operated during night,
solar panels prove to be useless during night which means you have to depend on
the local utility grid to draw power in the night
Ø Inefficiency: Since not all the light from the sun
is absorbed by the solar panels therefore most solar panels have a %40
efficiency rate which means %60 of the sunlight gets wasted and is not
Ø Installation: For home users, a
solar energy installation may not require huge space but for big companies, a
large area is required for the system to be efficient in providing a source of
Uses of Solar Energy: –
§ Heaters Green houses
§ Cars Water pumps
§ Light Desalination
§ Satellite chilling
§ Dryers Solar ponds
§ Calculators Thermal
§ On an office
building, roof areas can be covered with solar panels
§ Remote building
such as school, communities can make use of solar energy.
§ In developing
countries, this solar panels are very much useful.
§ Even on the highways,
for every five Kilometers, solar telephones are used
?????? ?? ????
ways of usage:
should take measures and see that solar light are used as street light in all the
can place solar panels in the useless lands instead of keeping these solar it
can also keep these solar panels in the deserts, where we can make use of this
energy with the help of a rechargeable battery,
of solar panels depends on the range of frequencies of light that strikes the
surface. So they can give higher efficiency if we spilt the light into
different frequency ranges and direct the beams on to the cells tuned to these
a new home is the best time to design and orient the home the to take the
advantage of the sun’s rays.