Heating Service » Solar Systems
Solar thermal collectors are used to receive heat energy from the sun and transmit it via a medium and heat exchanger to a water storage tank.
Solar thermal collectors can be used anywhere, in any configuration. They can be installed on the roof, the ground or on a rack.
To obtain the best results, we suggest the following:
- Collectors should face south.
- Collectors should be installed in a location not shaded by trees or bushes, etc.
The collectors are the most important part of a solar heating system. Solar heating systems are most often used for:
- Hot water heating
- Pre-heating of water to assist central heating
- Pool heating and water systems.
In practice solar heating systems can feed any heating emitter/load
Direct and Diffuse Radiation:
Solar radiation is composed of two components: direct radiation/sunshine that comes in a straight line from the sun through the atmosphere to the ground and a diffuse component that arrives after being reflected from clouds/ground or scattered by dust, water vapour or air molecules in the atmosphere.
Ireland and Britain have an Atlantic maritime climate that often yields high relative levels of diffuse radiation, particularly on overcast days. The climate also delivers many days of broken sunshine, where radiation values can briefly rise above a level of 1200 W/m2 on the collector’s surface. Fortunately, the showery rain that often accompanies these conditions has little effect on performance
Flat Plate Collectors
Sunlight passes through the glazing and strikes an absorber plate, which heats up, changing solar energy into heat energy. The heat is transferred to a liquid passing through pipes attached to the plate. Absorber plates are commonly painted with “selective coatings”. These coatings absorb UV and visible radiation, but are poor emitters of longer wave infrared radiation so that they retain heat much better than ordinary black paint would. Absorber plates themselves are made from copper, aluminium or stainless steel ultra-sonically welded to copper pipe.
Vacuum Tube Collectors
There are two main types:
- The first is a clear single-walled tube with a conventional plate absorber inside.
- The second is a double walled glass tube with an absorber coating sprayed onto an inside wall.
A clear single-walled tube contains a selective absorber plate; the tube is evacuated down to a vacuum-level normally encountered only in outer space. This virtually eliminates the conduction and convection and convection heat losses, leaving only the radiation heat losses. These losses are minimised through the use of a selective coating which hinders the emission of infra-red heat radiation. This makes this type of collector very efficient at retaining heat and hence it is very good for high temperature applications.
In the double-walled glass tube, the top of the two tubes are fused together and the space between the two layers of glass is evacuated, giving a vacuum-tube jacket. The insulating properties (thermal efficiency) are generally not as good as the high efficiency single-walled tube but are a lot better than those of flat plate collectors.
We supply a wide range of solar water heating systems from flat plate to evacuated tube solar panels suitable for any building and at prices to suit every budget. We cover all work required for total system installation. We replace your cylinder and recycle the old one. We can perform electrical work to make any required mains connection. We do all related roof and plumbing work.
Grants through www.sei.ie for solar water systems under Phase III of the Greener Homes Scheme have been re-introduced. To download an Application forms please click here. Both the product and the installer must be registered with SEI to avail of this grant. We can help you with your application.
