Choosing a Solar Air Conditioning System
Last Updated Nov 4, 2011 · Written by Rob Schneider
As they look for more efficient and environmentally friendly forms of energy, researchers are increasingly turning to new ways to utilise solar power. Since the summer months are when the most solar power is available and are also the months when we use air conditioning the most, solar air conditioning systems have the potential to reduce our conventional energy consumption enormously. There are now many commercially available solar air conditioning systems available. What should you look for when choosing a solar air conditioning system?
Types of Solar Air Conditioning Systems
How do you use hot air to create cool air? Most solar air conditioning systems do this a little differently than refrigerators and conventional air conditioners. The principle behind solar air conditioning is called sorption. There are two kinds of sorption:
- Absorption is a term we are all familiar with and absorption chilling has been widely used since the mid-20th century. Basically, a solar air conditioner using the absorption technique contains a heat absorbing material that stores the heat needed in the heat transfer process.
- Adsorption is a process by which a chemical agent (often silica gel) attaches water molecules to its surface. The adsorbed moisture is then used to cool air that is passed over it. Solar energy is used in two ways in this method; first in the collection process and then to reactivate the adsorbent.
Both of these systems are known as "closed systems" because they operate in a continuous loop. In both systems, a liquid is converted into a gas and then reconverted back into a liquid. Advocates of adsorption solar air conditioning systems believe that since an electrically powered condenser is not required, adsorption systems are potentially the most energy efficient. Absorption systems are believed to be more efficient than normal refrigeration and air conditioning systems because they "superheat" the refrigerant.
As research continues, both of these sorption methods are continually being improved and incorporated into solar air conditioning systems. Because of the complexities of direct solar absorption, adsorption is usually the technique used for residential purposes.
Choosing a Solar Air Conditioning System
While understanding a little bit about the basics of solar air conditioning helps, it doesn't really answer the question, "Which solar air conditioning system should I choose?" That will depend on whether or not you are already utilising solar energy in your home and how much you want to invest in your system.
These are some of the available options:
- A conventional water evaporative cooler uses very little electricity and your PV system may be able to generate all of the power needed to operate it. The drawback to some of these coolers is that they are only suitable for use in very dry climates.
- Your solar panels can assist a conventional air conditioning system, supplying 10-30% of the power needed to run the system.
- Solar absorption air conditioners are much cheaper to run that conventional air conditioners, but require a separate solar energy collector. Flat solar panels will not work with these. Most of these are also only available for commercial applications.
- Desiccant (such as silica gel) adsorbent air conditioning systems are very energy efficient, but they are expensive to buy in comparison to other greenhouse gas reduction systems. However, solar credits and rebates may reduce the cost of purchase and/or installation.
Also, don't forget about passive solar air conditioning. Your choice of home insulation
and other products will greatly reduce your dependence on cooling devices.
The best way to ensure you choose the best solar air conditioning system is to contact a solar power specialist in your area and discuss your needs with them. As a local dealer, they will know what is best for your climate and will be able to come to your home and assess all of your solar power options. Having them in your neighbourhood is your assurance, too, that they will always be there to help you with all your solar needs.