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Solar Energy Disadvantages |
The two primary forms of solar energy that are of practical use for the home are the production of electricity by the use of photovoltaic panels, and the use of thermal panels for water heating. Both systems have their pros and cons assiociated with functionality, maintenance and cost. It has been estimated that the energy shining onto the planet from the sun every twenty days is equivalent to the total reserves of oil, coal and gas on the earth!Of course, all energy is solar energy, as it was the sun the provided the nergy to grown plants in the first place - by solar energy, we normally refer to that renewable resource that shines on us every day. One of the more sustainable and sensible uses of solar energy is the design of buildings that passively store and manage this energy in a way that reduces traditional energy needs. For existing buildings, it's mostly the use of photovoltaic and thermal water heating systems that are dominant ... |
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Thermal water heatng systems consist of distinct elements, namely, the solar collectors and water distribution system, a storage vessel and a control system. A basic collector may consist of a grid of small bore copper piping painted black and housed under a tough glass cover. The arrangement is normally inclined (or installed on an inclined roof) and connected to the storage tank. A small pump circulates the hot water into a heating coil located in the bottom of the storage cylinder before returning to the collector on the roof, and an electronic control system ensures that the pump doesn't operate until the water in the collector is hot. Many systems operate at a higher pressure, and also contain a mixture of food quality antifreeze so that the system can be used all year round. A relatively small system with collectors of around 4 square metres will be sufficient to provide up to 80% of a family's hot water needs, depending on location. Thermal solar panels are approximately 75% efficient, which is far higher than photovoltaic panels. This means that for every 1000 watts of sunshine energy per square meter (the average in the Western hemisphere) we can draw up to 75% of water heating energy. Large systems with collector areas of up to 25 square metres can be used to provided a useful space heating supplement, particularly if used with low temperature under floor heating systems. Although quite efficient, there is a downside. First of all, compared to the amount of money saved in water heating costs, even a small system is relatively expensive. That said, the cost of manufactured systems is very rapidly coming down, and thermal solar panels can easily be constructed by the practically minded, basically being constructed out of copper pipes and a few other things. Unlike photovoltaic panels, thermal installations will not perform unattended forever, and need a maintenance check every two years or so. In addition, the water/anti-freeze mixtuire shouldbe changed as well to ensure adequate protection.
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