The sun drives our weather system, powers plant photosynthesis and is such a reliable source of heat and light that we sometimes take it for granted. Generations have used glass and other materials and structures to capture and magnify the sun’s energy and these systems have gradually evolved to form the basis of techniques employed today to harness solar energy.
Harnessing Solar Energy in the home,
Three basic approaches are used today to gain maximum benefit of solar energy in buildings.
The first is known as passive solar which is an architectural approach that uses the building material, orientation and general design to ensure that solar gains are maximised. Therefore, the approach is of most applicability to buildings that are in the design and planning stage, although minor retrofits, for example the addition of a south facing conservatory, can be made to existing buildings. Passive solar design can significantly reduce the need for auxiliary heating and lighting, it need add nothing to the cost of the building and generally produces a pleasant and healthy living environment, which will increase the amenity value of the building.
A second type of solar system, sometimes known as active solar technology, involves the installation of a solar collector device, which is typically a metal box structure containing an absorber. The solar collector absorbs the sun’s heat to provide space or, more commonly, water heating. For water heating, three basic types of solar collector are available - flat plate, evacuated tube and air - based systems. For Space Heating, it is possible to use air rather than water as the heat transfer fluid for applications where space heating is the main requirement. A whole house system currently being marketed in Ireland incorporates triple glazed solar collectors, an air handling unit and a ducted warm air ventilation supply. Heat is reclaimed from returned air by a heat exchanger system. During the summer, the system provides the bulk of hot water, and a conventional boiler provides back up in cloudy, winter weather.
The third approach is solar photovoltaic systems which use semiconductor materials to convert solar energy to electricity. Photovoltaic cells are used widely n consumer products such as solar calculators, watches and other electronic systems, and standalone photovoltaic systems are being used increasingly in regions where small amounts of electricity are required in areas remote from the grid. In buildings, there is potential to integrate photovoltaic materials into roof and wall structures with minimum visual impact. The photovoltaic system can then be linked to the electricity distribution network through an inverter. When the sun shines, the installation provides the building with electricity and any surplus power is fed into the network; when sunshine is insufficient, electricity is supplied from the grid.
When solar energy is used instead of traditionally generated electricity or fossil fuels such as oil, coal and gas, the release of gases that cause global climate change, acid rain and air pollution is reduced.
In addition to helping protect the environment, maximising the use of solar energy in a house through passive solar design can make economic sense through reduced fuel and electricity bills.
For further information, contact
Irish Energy Centre, Shinagh House, Bandon, County Cork.