Five million homeowners want to modernize their own four walls in the next three years. Nine out of ten pursue a goal: Reduction of energy costs. Why not use an energy, which costs nothing?
Reducing energy requirements is particularly important for the younger generation of homeowners, was the result of a representative survey by Emnid on behalf of the financial partner BHW. And seventy percent of those surveyed also attach great importance to ecology. Good opportunities for solar energy.
Popular in refurbishment, almost standard in new buildings: the heating of domestic water with solar collectors. The principle is very simple. Per person in the household will be about 1,5 sqm collector area, mostly flat-plate collectors, mounted on the south side of the roof. The heart of this collector is the absorber, which absorbs solar radiation and converts it into heat. Is
is traversed by a heat transfer fluid – usually a mixture of water and antifreeze -, which heats up, is pumped to the solar storage tank, where it transfers its energy to the cold service water via a heat exchanger, with which you can then take a comfortable shower. No hot water is needed in the household at the moment, the solar storage tank can store them for several days. More hot water is needed, than the solar collectors can heat, the conventional boiler additionally heats the service water. This is usually the case in the winter months. On an annual average, a precisely designed solar collector system can 60 percent of the custom-
heat the water. It is also well suited for retrofitting a conventional heating system, as modern service water storage tanks often already have connections. Costs for a four-person household: from about 4000 euros including installation. DIY systems are from about 2500 to have euros.
For particularly well-insulated houses, characterized by a correspondingly low heating energy requirement, the power of the sun extends even further: In spring and autumn, it can also supply the heat for the heating circuit and relieve the workload of the conventional boiler in winter. This is where vacuum collectors come into play, the ones by up to 20 percent better efficiency, however, are also significantly more expensive.
systems, which should also take over part of the space heating, cannot, of course, be retrofitted, they can only be installed in new buildings or in the case of a complete heating renovation of an older house. However, is it worth it?, should be calculated by a plant engineer or energy consultant.
All these systems are technically mature and have a service life of 20 years and more. And thanks to state funding from the federal government, they pay off, countries and communities. Finally, there is also photovoltaics, which converts sunlight directly into electricity. The amount of electricity generated depends on the number of solar cells and the orientation of the cells to the sun. More and more devices are being offered, who obtain their electricity solely from the sun: outdoor lights, Systems for the supply of mobile homes, from garden- or weekend homes.
So that solar power can be used on a larger scale, you need more technology – especially powerful batteries – and ends up with considerable investment costs. They only count, when the electricity is fed into the public grid. Will the plant 2004 put into operation, there are per kW/h 20 for years 43,4 Cent.