Solar energy is a renewable energy source that is available to us more or less continuously (with approximately 2,100 hours of sunshine a year in Hungary) and is regarded as easy to harness. Its use can lead to reductions in CO2 emissions.
The energy of the Sun can be harnessed actively and passively. In the passive utilisation of solar energy, the building functions similarly to a greenhouse. It is important to use the appropriate building materials and when constructing the building to orientate it so as to receive the most sunshine. Besides this, it is essential that the building’s insulation is designed to keep heat loss to a minimum during the winter. Blinds can provide protection against overheating during the summer months, and it is advisable to ensure that the layout of the building is appropriate.
The active utilisation of solar energy means the conversion of solar energy into heat energy using solar collectors. These generate heat energy directly from the sun`s light energy for heating or to produce hot water, or possibly for the heating of a swimming pool. The coating on the solar collector`s outer layer absorbs light and warms the heat exchange medium, usually a fluid, which is circulated in the system (by a pump). The heat energy is then transferred to the water that is stored in a large tank for later use. The solar collectors should be located on the roof, but the tank can be situated anywhere in the building. A solar collector with a surface area of 1-1.5 m2 can supply the daily hot water requirements of one person. Their use for heat generation is not limited to the summer months; heat can also be generated during the winter, albeit at lower efficiency.
Solar collectors can be used cost-effectively not only in the case of single houses, but also on a larger scale for apartment buildings or institutions. In this case, the payback period of the investment will be significantly shorter (approximately 4-5 years). The use of solar collectors can result in an average annual energy saving of 60-70%.