Solar Energy Facts

Solar energy is the cleanest and most inexhaustible of all known energy sources. Solar radiation is the heat, light and other radiation that is emitted from the sun. Solar radiation contains huge amounts of energy and is responsible for almost all the natural processes on earth. Energy from the sun, although plentiful, has been hard to directly harness until recently.

Solar Energy can be classified into two categories, Thermal and Light. Photovoltaic cells (PV) use semiconductor-based technology to convert light energy directly into an electric current that can either be used immediately, or stored in a battery, for later use. PV panels are now becoming widely used as they are very versatile, and can be easily mounted on buildings and other structures. They can provide a clean, renewable energy source which can supplement and thus minimize the use of a conventional electricity supply. In regions without grid power such as remote communities, emergency phones etc, PV energy can provide a reliable supply of electricity. The disadvantage of PV panels is their high cost and relatively low energy conversion rate (only 13-15%). Thermal solar on the other hand has average efficiency levels 4-5 times that of PV, and is therefore much cheaper per unit of energy produced.

Thermal energy can be used to passively heat buildings in conjunction with certain building materials and architectural design, or used directly to heat water for household use. In many regions, solar water heaters are now a viable supplement or alternative to electric or gas hot water production. Thermal energy obtained from the sun can be used for a number of applications including producing hot water, space heating and even cooling via use of absorption chilling technology.

Using solar and other forms of renewable energy reduces reliance on fossil fuels for energy production, thus directly reducing CO2 emissions. CO2 emissions contribute to global warming, an environmental issue which is now of great concern. The average household can reduce CO2 emissions by as much as 20% by installing a Solar Panels Plus collector system.

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Frequently Asked Questions about Solar Collectors:

What is the difference between flat plate collectors and evacuated tubes? Flat plate thermal solar collectors have been in use for several decades, but only in relatively small numbers, particularly in Western countries. Evacuated tubes have also been in use for more than 20 years, but have been much more expensive than flat plate, and therefore only chosen for high temperature applications or by those who could afford their high price. In recent years the production volume of evacuated tubes has exploded, resulting in greatly lower manufacturing and material costs. The result is that evacuated tubes are now similar in price to flat plate, but with the insulating benefits of the evacuated tube, they are set to become the default choice for thermal solar applications worldwide. When comparing peak efficiency levels it may seem that there is little difference between flat plate and evacuated tubes, and in fact flat plate may actually be higher, but this is during minimal heat loss conditions. When averaged over a year, evacuated tube collectors have a clear advantage.

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 inadvisable, 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.

How long will it take to recoup my investment? Solar Panels Plus 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 savings 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 energy costs. You will definitely appreciate considerable savings over the life of the solar hot water heater.

Will water be heated 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. 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.

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 it entering the existing tank.

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 temperature setting, so when the manifold temperature drops below a certain pre-set temperature (50C/40F), 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.

Can Solar Panels Plus solar collectors heat water to a high enough temperature? Yes, in good weather these solar collectors can bring water to boiling point. Generally this is not necessary and so the system should be designed to provide a daily temperature rise of around 25-30C (45-54F) in the summer. Sizing a domestic system that can bring the cold water up to 60C/141F in a single day is not logical, because if hot water is not used for one day, the following day the system will be boiling and dumping hot water via the temperature relief valve. This is both a waste of energy and water! We recommend sensibly sizing solar water heating systems to ensure optimal performance and minimal wastage of water.

What maintenance of the solar collector is required? Under normal circumstances no maintenance of the system is required. Due to the shape of the tubes, regular rainfall and wind should keep the tubes clean. Should a tube ever be broken it should be replaced. This, however, is an inexpensive and easy job. Any "handy" person can install a new tube (while adhering to local health and safety regulations). These collectors can operate with several broken tubes, however the efficiency will be reduced slightly.

Can I heat my swimming pool or spa using a Solar Panels Plus collector? Yes, these collectors are high temperature collectors, and are therefore ideal for spas, as the volume of water is small and temperature requirements high. For swimming pools, however, the volume of water is large and the temperature rise required is only several degrees. The cost of heating a pool using solar tube collectors (for domestic purposes) may be prohibitively high. But for large scale swimming pools, Solar Panels Plus collectors may be an extremely viable supplement to gas or electricity.

For more information about using solar power or help with designing a system, please contact us.