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SOLAR ENERGY USE IN SOUTH AFRICA - INTRODUCTION
‘The sun
is a constant source of energy. Everyday it provides us with 5000 times as
much energy as the whole world needs.’ (Unknown)
In the 1950s
and '60s efficient energy use was often neglected in constructing buildings
and houses, but the high energy prices of the 1970s changed that. Some new
office buildings built in 1980 use only a fifth of the energy used in
buildings constructed just ten years earlier. Techniques to save energy
include designing and siting buildings to use passive solar heat, avoiding
overlighting, and using better insulation. A “life-cycle” approach, which
takes into account the total costs over the entire life of the building,
rather than merely the initial construction cost or sales price, is
encouraging greater efficiency
Solar energy
is not a single energy technology but a term that covers a diverse set of
renewable energy technologies. Their common feature is that, unlike oil,
gas, coal, and present forms of nuclear power, solar energy is
inexhaustible.
SOLAR
ENERGY IN SOUTH AFRICA
Climate
South
Africa is one of the areas in the world with the highest count of sunny days
per year in the world therefore making it also one of the most appropriate
places in the world to use solar power energy should that be the only reason
for using them.
A
photovoltaic sell uses the sun’s light to create an electric current and not
the heat of the sun as is commonly thought. A photovoltaic sell actually
decreases in efficiency when the sell is heated extremely because of the
resistance building up in the material. Because of the above fact, one can
see that these photovoltaic panels is actually less efficient in very warm
climates. South Africa, in summertime, can be extremely hot and could cause
a photovoltaic panel on certain summer days to work less efficient although
not as significantly as 25% less efficient as it is said can be lost in
desert-type climates.
Cost efficiency &
economy
Eskom
South Africa provides our country with some of the cheapest conventional
unsustainable electricity costs in the world, and that is the main reason
for solar energy technology not taking off in South Africa. Although a
number of solar thermal panels is in operation, even in residential
buildings in the country, photovoltaic panels was up to date just not cost
effective enough to justify the money saved using conventional electricity
for manufacturers making them available on a large scale. Because of the
uncommonness and unavailability of these panels the prices of theses panels
has not significantly decreased in South Africa as it has in other more
technologically advanced and environmentally aware
countries.
Also,
because the electricity has been so inexpensive in SA, the cost of paying
off a solar electricity system that provides the same amount (or sufficient
amount) of electricity as a conventional system, will take an extremely long
time to pay off with the money saved without using conventional electricity,
and most home owners in South Africa doesn’t stay long enough in one home to
justify the cost saving.
Another
factor is that the technology is becoming more advanced day by day, and one
might purchase a system today which will reach the end of it’s life before
the system has paid for itself with money saved from not using conventional
electricity is over.
Sustainability &
the environment
Eskom
might well be one of the cheapest electricity providers in the world, but it
is also a fact that eskom releases some of the most pollution in the
atmosphere by burning coal to generate electricity. Although air pollution
doesn’t seem to be that big a problem here than in other countries where
acid rain etc. is huge concerns for the community, it would be wise to
sooner rather than later start to concentrate on the environment in South
Africa and that is when solar power could start playing a big role as an
energy provider.
Appropriate for us?
Solar
panels can be used very effectively and appropriately in the remote areas
around the country because the cost of connecting to the conventional power
grid by laying cables might be even more expensive and once a solar PV
system is installed one does not need any tools or technicians to maintain a
PV panel regularly.
There
are a number of places in our environment where solar power could be (and
are already) used very effectively for example water pumps to dams in nature
reserves. PV panels have also been used to power electric fencing in game
reserves very successfully for interruptions in electricity is eliminated
and big mammals like elephants has no chance of breaking through a fence as
could be the case in an normal power interruption.
In
conclusion, the use of solar power in South Africa isn’t that far fetched
when one look at the very appropriate weather conditions and the need to
look at a more sustainable and renewable energy source for the future.
SOLAR ENERGY GENERATION
Solar power to
produce electricity is not the same as using solar to produce heat. Solar
thermal principles are applied to produce hot fluids or air. Photovoltaic
principles are used to produce electricity. A solar panel (PV panel) is made
of the natural element, silicon, which becomes charged electrically when
subjected to sun light
Solar
electricity
The four
primary components of a typical solar power electrical system which produces
common 110/220 volt power for daily use are: Solar panels, charge
controller, battery and inverter. Solar panels charge the battery. The
charge regulator insures proper charging of the battery. The battery
provides DC voltage to the inverter, and the inverter converts the DC
voltage to normal AC voltage.
Simply put,
a solar or photovoltaic panel converts light into electricity. It is
basically a battery charger that gets it’s power from the sun. A
photovoltaic panel refer to a physically connected collection of
photovoltaic modules used to achieve a required voltage and current. A
photovoltaic module in turn is the smallest environmentally protected,
essentially planar assembly of solar cells and ancillary parts, such as
interconnections, terminals, [and protective devices such as diodes]
intended to generate dc power under unconcentrated sunlight. A photovoltaic
(PV) cell is the smallest semiconductor element within a PV module to
perform the immediate conversion of light into electrical energy.
Because
there are no moving parts in PV solar cells, they are very easy to keep
running. In general, regular dusting is all that a PV panel needs to keep it
operating smoothly for up to thirty years.
Photovoltaics
are thus perfectly suited for remote locations, far from technicians and
tools.
Solar
Heating
Solar water
heaters are made up of collectors, storage tanks, and, depending on the
system, electric pumps.
There are
basically three types of collectors: flatplate, evacuated-tube, and
concentrating. A flatplate collector, the most common type, is an insulated,
weather-proofed box containing a dark absorber plate under one or more
transparent or translucent covers.
Evacuated-tube
collectors are made up of rows of parallel, transparent glass tubes. Each
tube consists of a glass outer tube and an inner tube, or absorber, covered
with a selective coating that absorbs solar energy well but inhibits
radiative heat loss. The air is withdrawn ("evacuated") from the space
between the tubes to form a vacuum, which eliminates conductive and
convective heat loss.
Concentrating collectors for residential applications are usually parabolic
troughs that use mirrored surfaces to concentrate the sun's energy on an
absorber tube (called a receiver) containing a heat-transfer fluid.
Most
commercially available solar water heaters require a well-insulated storage
tank. Many systems use converted electric water heater tanks or plumb the
solar storage tank in series with the conventional water heater. In this
arrangement, the solar water heater preheats water before it enters the
conventional water heater.
Some solar
water heaters use pumps to recirculate warm water from storage tanks through
collectors and exposed piping. This is generally to protect the pipes from
freezing when outside temperatures drop to freezing or below.
Solar water heaters
can be either active or passive. An active system uses an electric pump to
circulate the heat-transfer fluid; a passive system has no pump. The amount
of hot water a solar water heater produces depends on the type and size of
the system, the amount of sun available at the site, proper installation,
and the tilt angle and orientation of the collectors.
Solar water
heaters are also characterized as open loop (also called "direct") or closed
loop (also called "indirect"). An open-loop system circulates household
(potable) water through the collector. A closed-loop system uses a
heat-transfer fluid (water or diluted antifreeze, for example) to collect
heat and a heat exchanger to transfer the heat to household water.
TROMBE WALL SYSTEMS
 
A Trombe wall is
a masonry or concrete wall with a dark heat absorbing surface covered
externally with a glass skin. A small air space is left between the wall and
the glazing. Solar radiation passes through the glass and is absorbed by the
mass wall. The glazing should have exterior insulating shutters for
nighttime use in order to prevent the heat gained from being returned back
to the outside. The mass is heated during the day and releases its warmth to
the interior during the evening and night hours. Vents may also be placed in
the wall to permit heat to flow directly into the room during the day and
thus can be used to draw cool air through the house in the hot season.
Compiled by HJ Botes, Architect & founder of Dreamhouses.co.za
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