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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 JB, Architect & founder of Dreamhouses.co.za
 
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