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. It can also be used to lengthen the effective season for an outdoor pool and reduce the cost of heating an indoor pool.

Thermal energy can be used to passively heat buildings through the use of certain building materials and architectural design, or used directly to heat water for household use. In many regions solar water heaters are a viable supplement or alternative to electric or gas hot water production.

In recent years the production volume of evacuated tubes increased significantly resulting in lower manufacturing and material costs. Evacuated tubes are now competing in price to flat plate. With the insulating benefits of the evacuated tube, they are set to become the default choice for thermal solar applications worldwide.

Evacuated tubes absorb the solar energy converting it into heat for use in water heating. Each evacuated tube consists of two glass tubes made from extremely strong borosilicate glass. The outer tube is transparent allowing light to pass through with minimal reflection. The inner tube is coated with a special selective coating (Al-N/Al) which features excellent solar radiation absorption and minimal reflection properties. The top of the two tubes are fused together and the air contained in the space between the two layers of glass is pumped out forming a vaccum chamber between the two glass tubes.

Heat pumps

Heat Pumps are methods by which energy can be transferred from one medium to another by removing excess heat from one source and storing it elsewhere. In the same way that a refrigerator can remove heat from stored items and produce hot air, an air or ground source heat pump can take heat from its surroundings and heat water.

A heat pump works by pumping a fluid around a refrigeration circuit via an evaporator, a compressor, a condenser and an expansion valve. The fluid changes from a liquid to a gas (evaporates) as heat is extracted from the heat source. As the cycle continues the fluid condenses back to a liquid as the heat is then transferred to where it is needed.

The heated water can either be supplemented by other forms of renewable heat source, such as solar panels, or a biomass boiler, or conventional heating systems such as condensing boiler.

Heat pumps can be very efficient delivering up to 5 times the energy they use during operation. The level of efficiency will depend on the ambient conditions in which they operate, although under all conditions they consume far less energy than they generate.

Historically ground source heat pumps have out-performed their air source equivalents. Today using the very latest technological advances, air source heat pumps can achieve performance ratios of 4:1 and benefits from being simpler to install either outside the house or in a garage or even a loft space.

A heat pump can also be used in reverse mode to provide cooling and with global warming the perfect combination is likely to be the combination of pre-heated water and cooling during the summer months.

| 01.01.2009 | Read more | Print |