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Solar Knowledge

Aug 29, 2012

Solar Engery FAQ (I)

Solar Engery FAQ (I)
Category: news
Posted by: jarryq

1-1. Is solar water heating a viable alternative to gas or electricity?
Solar should not be seen as a alternative to gas or electricity, but rather a supplement. Solar cannot totally replace the need for gas or electric heating as there are sometimes days when there is little sunlight. When averaged over a year, a correctly sized solar system can provide 60%-70% of a household's hot water needs. Providing more than this is unadvisable, as too much heat will be produced in the summer. The hot water system can easily be automated,so hot water is guaranteed regardless of sunlight levels.

1-2. How long will it take to recoup my investment?
Solar collectors are much more affordable than many other solar hot water heaters. For a household of 4, the price of a full system may not be too much more than a new electric or gas system. Depending on your location (solar levels) and current hot water usage the annual electricity or gas saving will differ. However in a normal household that spends 25% of its electricity bill on hot water heating, the full cost of the purchase may be recouped as quickly as 4-5 years in reduced bills. You will definitely make considerable savings during the life of the solar hot water heater.

1-3. Can solar collectors be used in cold conditions?
Yes. collectors can be used in temperatures as low as -30oC, although performance is greatly reduced in such extreme conditions. Good heat output is still achieved in mild sub-zero conditions.

1-4. What happens if one of the solar tubes is broken?
Firstly, tubes are very strong and not easily broken, but if the worst should happen, solar tubes can be replaced very easily. They are inexpensive and available though your local distributor. The solar collectors can operate with several broken tubes, but the efficiency will be reduced, so it is recommended that broken tubes be replaced immediately.

1-5. Will water be heated on a cloudy day?
Although the heat output of the solar collector is reduced on overcast days,it will still be able to provide heating. If it is a heavily clouded day or raining, then more gas or electric boosting may be required to maintain water at the required temperature. This system will be automated so you don't have to worry about running out of hot water on a rainy day.

1-6. Can I use a solar collector with my existing hot water system?
Normally yes. Simple retrofit valves can often be used to allow solar to connect to your existing cold water inlet. If your tank cannot accept the solar input directly an additional storage tank can be installed to pre-heat the cold water prior to entering the existing tank.

1-7. Are the solar collectors noticeable on the roof?
If only the collector is mounted on the roof it should blend into the roof design quite well. Our solar collectors are very thin and can be flush mounted on a roof. From a distance they look somewhat like a skylight. You may have to check with your local council regarding building restrictions when installing your solar collector.

1-8. Can solar collectors be mounted on a flat surface?
Yes they may be mounted on a flat roof, or on the ground by using a stainless steel Flat Roof Frame. The collector should be installed at a minimum of 20o angle to ensure optimal heat pipe operation.

1-9. How do I protect my solar system during subzero temperatures?
If you have a system that is operating in areas with subzero temperatures then freeze protection must be implemented. The easiest means of preventing freezing is to use a controller with a low temperatures setting, so when the manifold temperature drops below a certain pre-set temperature (5oC/40oF), the pump will circulate, warming the collector with water from the bottom of the storage tank. The pump will not run continually, just periodically, the frequency of which will depend on the outside temperature. In extremely cold areas, a closed loop using a glycol/water mix may be appropriate.

1-10. Will the solar collector be a fire hazard during hot, dry weather?
No. The solar collector's components are all high temperature rated and non-flammable so even during strong sunlight with the circulation pump turned off (stagnation), the system will not catch alight or give off any sparks. The majority of the solar collector's components are stainless steel, aluminium, glass or glass wool. The manifold outlet should be fitted with a temperature relief valve, which will prevent the manifold temperature from exceeding 99oC / 212oF.