Solar
energy is the cleanest and most inexhaustible of all known
energy sources. Solar radiation is the heat, light and other
radiation that is emitted from the sun. Solar radiation contains
huge amounts of energy and is responsible for almost all the
natural processes on earth. The suns energy, although plentiful,
has been hard to directly harness until recently.
Solar
Energy can be classified into two categories, Thermal and
Light. Photo-voltaic cells (PV) use semiconductor-based technology
to convert light energy directly into an electric current
that can either be used immediately, or stored in a battery,
for later use. PV panels are now becoming widely used as they
are very versatile, and can be easily mounted on buildings
and other structures. They can provide a clean, renewable
energy source which can supplement and thus minimize the use
of mains electricity supply. In regions without main electricity
supply such as remote communities, emergency phones etc, PV
energy can provide a reliable supply of electricity. The disadvantage
of PV panels is their high cost and relatively low energy
conversion rate (only 13-15%). Thermal solar on the other
hand has average efficiency levels 4-5 times that of PV, and
is therefore much cheaper per unit of energy produced.
Thermal
energy can be used to passively heat buildings through the
use of certain building materials and architectural design,
or used directly to heat water for household use. In many
regions, solar water
heaters are now a viable supplement or alternative to electric
or gas hot water production.
Thermal
energy obtained from the sun can be used for a number of applications
including producing hot water, space heating and even cooling
via use of absorption chilling technology.
Using
solar and other forms of renewable energy reduces reliance
on fossil fuels for energy production, thus directly reducing
CO2 emissions. CO2
emissions contribute to global warming, an environmental issue
which is now of great concern. The average household can reduce
CO2
emissions by as much as 20% by installing an
solar collector.
Flat plate thermal solar collectors have been in use for several
decades, but only in relatively small numbers, particularly
in Western countries. Evacuated tubes have also been in use
for more than 20 years, but have been much more expensive
than flat plate, and therefore only chosen for high temperature
applications or by those with money.
In recent years the production volume of evacuated tubes has
exploded, resulting in greatly lower manufacturing and material
costs. The result is that evacuated tubes are now similar
in price to flat plate, but with the insulating benefits of
the evacuated tube, they are set to become the default choice
for thermal solar applications worldwide.
The days of a 15 year payback time for a solar collector are
over - we can now achieve payback times of less then half
that!
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