Technologies Associated With Solar Power
Author: J.R. Ferrara

There are various technologies associated with solar power, but
all of them come under two major groups. The solar thermal
technology--which includes passive solar heating and solar
concentrator power systems-- use the sun to generate heat.
Solar power technology, the second group, converts solar
radiation into electricity through photovoltaics--a technology
capable of producing electricity when exposed to light.

Group 1: Solar Power Through Solar Thermal Technology

Solar thermal technologies vary from small—in which a parabolic
disk cooks food and boils water--to large, in which centralized
solar power plants use many acres of mirrors to collect the
sun's power, focus it and heat water to steam that will power
generators. Solar concentrator power systems use mirrors and
lenses to concentrate sunlight onto a receiver, which converts
the sunlight into heat. This heat is used to heat fluid, which
is led through pipes to a steam generator, where it is
converted into electricity.
Power plants with a capacity of 10 megawatts can power 10,000
households, and future power plants with capacities ranging
from 30 to 200 megawatts are possible.

Flat-plate solar collectors are large, flat boxes dark-colored
metal plates inside that absorb heat. This system is great for
providing heated water for household use by passing water
through pipes that are heated by the heat absorbed in these
plates. Passive solar heating like this uses the sun's thermal
power to heat the buildings. The south facing windows in the
northern hemisphere invite the sun's warm rays in, helped by
building materials that absorb the sun's thermal energy.

Another benefit of solar thermal technology, which isn't very
apparent, and even seems oxymoronic, is its ability to cool
buildings. This is done with absorption-cooling devices and
desiccant cooling systems.

Group 2: Solar Power Through Photovoltaics

Photovoltaics is another way of collecting the sun's energy.
Solar cells made of semi-conductors convert the energy in
sunlight into electricity. Sunlight, which is a stream of
energy particles known as photons, hits the semi-conductors and
transfers its energy into them. These photons generate
electricity as they hit the silicon atoms in the solar cells.

Mirrored dishes and fresnel lenses, which consist of concentric
rings of segmental lenses, and are used to help concentrate the
sunlight onto a small area of photovoltaic cells. Concentrated
photons cause a photoelectric effect as they hit one of the
pairs of negatively charged plates and liberate the electrons.
These liberated electrons are attracted to the other negatively
charged plate. This flowing of electrons from one plate to the
other is an electric current.


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