There are two ways of capturing solar energy.
direct means, and
1.By direct means:
Many scientists have come up with two main kinds of artificial
collectors to directly capture and utilize Solar Energy:
flat plate collectors
Flat plate collectors are
basically flat, thin boxes with a transparent cover that are
placed on rooftops facing the Sun. The heat radiations from the
Sun heats a blackened metal plate inside the box, called the
absorber plate, that in turn the heats fluid (air or water)
running through tubes within the collector. These collectors are
able to heat the carrier fluids up to 180°F (82°C). These kind
of collectors are usually used for water heating and for space
§For applications such
as central power generation, air conditioning, and many
industrial heat requirements, flat plate collectors are
incapable of providing carrier fluids at very high
temperatures to be effective. They can be used as
first-stage “primitive” heat input devices; the temperature
of the carrier fluid is later increased by other ways of
more sophisticated, complex and expensive concentrating
collectors can be used. These devices reflect the Sun’s
powerful rays from a large area and focus it onto a small,
blackened light-heat receiving area. The light intensity is
concentrated to produce temperatures of several hundred or
even several thousand degrees Celsius! These concentrators
move to track the Sun using devices called heliostats.
(Heliostat is an instrument with an automatically rotated
mirror that reflects the Sun's light in a constant
direction, used to measure the Sun's radiation.)
§Concentrators use curved
mirrors with aluminum or silver reflecting surfaces that
coat the front or back surfaces of glass or plastic.
Researchers are developing cheap polymer films to replace
the more expensive glass. One new technique uses a pliable
membrane stretched across the front of a cylinder and
another across the back with a partial vacuum between. The
vacuum causes the membranes to form a spherical shape ideal
for concentrating sunlight
§Concentrating solar energy
is the least expensive way to generate large-scale
electrical power from the Sun’s energy and therefore has
the potential to make solar power available at a
competitive rate. Consequently, government, industry,
and utilities have formed partnerships to reduce the
manufacturing costs of concentrators.
§Another type of concentrator
called a central receiver, or 'power tower' uses an
array of sun-tracking reflectors mounted on
computer-controlled heliostats to reflect and focus the
Sun’s rays onto a water boiler mounted on a tower. The
steam thus generated can be used in a conventional
power-plant cycle to produce electricity.
2.By indirect Means:
solar energy by indirect means is nothing but collecting
solar energy that has been naturally collected.
Well, most importantly solar energy is used by all the
living beings in the form of heat and light energy. This
passive solar heating.
The Solar energy, acting on the oceans and the atmosphere,
creates winds that for years and years have turned windmills
and driven sailing ships.
Approximately 30% of the total solar energy reaching the
earth is used up in the hydrological cycle, i.e., the water
cycle. Hence it is a main element in water cycle.
Sunlight is also a major requirement for the process of