J DAYAKAR
Solar Energy and Its Uses
Utility scale solar energy facilities generate
electricity that is sent to energy consumers via electric transmission
systems. On a smaller scale, solar energy facilities can be used to
generate electricity or hot water for use in individual buildings.
What is Solar Energy?
Solar energy is the radiant (light and heat) energy produced by the sun.
The solar energy that reaches the earth can be used to produce
electricity or heat through the use of solar collectors. As an example, a
closed car can be viewed as a solar collector—the light energy that
passes through the window glass is absorbed by the car's interior and is
converted into heat energy, which becomes trapped inside the vehicle.
In optimal areas, the amount of solar energy falling on an area the size
of a basketball field, in thermal energy terms, is equivalent to about
650 barrels of oil a year. Solar energy is a renewable resource whose
use does not affect its future supply.
Conventional power plants use fossil fuels or nuclear energy as a heat source to boil water. The steam from the boiling water rotates a turbine, which activates a generator to produce electricity. Solar energy facilities
use concentrating solar power (CSP) as the heat source to boil water,
or they convert sunlight directly into electricity using solar cells,
also known as photovoltaics (PV). The CSP technologies are also referred
to as solar thermal or thermoelectric technologies, while PV
technologies are also referred to as solar electric or photoelectric
technologies.
The main types of CSP systems are linear (i.e., parabolic trough and
compact linear Fresnel reflector), power tower, and dish engine. CSP
plants consist of two parts: one that collects solar energy and converts
it to heat, and another that converts the heat energy to electricity.
More information about CSP technologies is available through the U.S.
Department of Energy's (DOE's) Solar Energy Technology Web site CSP page.The two types of PV technologies are flat plate and concentrating PV. Both PV technologies use solar cells that are made of semiconductor materials to absorb sunlight. The solar energy knocks electrons loose from their atoms, allowing electrons to flow through the material to produce electricity. A brief animation titled "Sunlight to Electricity" that shows how a solar cell works is available on the Animations page of the DOE Solar Energy Technologies Program Web site. More information about PV technologies is available through the DOE's Solar Energy Technology Web site PV page.
http://www.youtube.com/watch?v=x4CTceusK9I