SOLAR WATER HEATING SYSTEMS - Frequently asked questions

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   nick01posted 15 years ago

   Before you decide to install a solar water heating system, there are a number of questions that you will have to clarity about. Some more general questions are:
   
   HOW DOES A SOLAR HEATING SYSTEM WORK?
   
   A solar heating system consists of a number of components such as a solar collector (flat plate or evacuated tubes), a pump, a controller and a hot water storage tank or geyser.
   The solar collector is installed on the roof and collects the sun’s energy which in turn heats the water. The hot water is then transferred by means of a thermosyphon process or a solar pump to the storage tank or geyser.
   
   HOW MUCH CAN I SAVE ON ELECTRICITY?
   
   It is generally accepted that the heating of water takes up about 30 to 50 % of your electricity bill. At current electricity prices a solar water heater will pay itself within 2 to 5 years. After that you then have free hot water for the next 18 to 20 years. With the rapid increase in the price of electricity, this is one investment that you will never regret.
   
   FLAT PLATE COLLECTOR OR EVACUATED TUBES?
   
   Both collectors can be used with good results. The flat plate collector will cost less than the evacuated tubes, but the latter has some clear advantages such as:
   •    Heat absorption is superior to that of a flat plate collector, especially on cloudy days and during winter
   •    The vacuum in the tubes acts as heat insulator and retains heat even under extreme environmental conditions like cold winter temperatures and wind. Flat plate collectors lose a considerable part of the heat energy collected back to the environment.
   Benefits of flat plate collectors are:
   •    Simple technology that can easily be built by anybody with basic knowledge
   •    DIY guides are readily available to help you build your own solar water heater
   •    Virtually no maintenance required. No vacuum that can be lost due to breaking of a glass tube.
   •    Flat plate collectors can be produced at a much lower cost than evacuated tubes.
   
   WILL A SOLAR HOT WATER HEATING SYSTEM WORK ON A CLOUDY DAY?
   
   Yes. Although the heat output of the solar collector is reduced on overcast days it will still be able to provide heating. Approximately 25-30% of the sun’s energy actually gets through the clouds.
   
   DO I HAVE TO REPLACE MY EXISTING GEYSER?
   
   No. Most suppliers have a conversion kit available so that you can convert your old geyser into a solar system.
   
   WILL I SEE THE GEYSER ON THE ROOF?
   
   No. You have a choice to install the geyser on the roof or inside the roof. With a solar pump system your geyser can be installed wherever you choose.
   
   CAN I INSTALL A SOLAR ON A FLAT ROOF?
   
   Yes. A specially designed steel frame can be supplied to install the solar collector on a flat roof.
   
   WHAT WILL IT COST?
   
   On average an evacuated tube system will cost between R12 000 and R15 000. You may also qualify for a rebate from ESKOM or your local municipality.
   If you build your own flat plate collector you will save about 70% of the cost. You will not be eligible for a rebate.
   
   WHAT DO I NEED TO BUILD MY OWN FLAT PLATE COLLECTOR?
   
   There are a number of DIY guides available. This will give you step by step instructions and show you in detail how to build your solar water heater.

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