9 Answers about solar thermal energy

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Using free and sustainable solar energy – an excellent reason to choose an economical, environmentally friendly system like this one. But when is solar thermal suitable for one's own use and what needs to be taken into account? Hoval provides answers.

1. How important is the alignment of the roof for the best possible solar yield?

In order to fully exploit the performance potential of thermal solar collectors, the roof should be oriented in the direction of the strongest solar radiation. This means that in the best case the roof faces south. However, good results can also be achieved with an eastern or western orientation – although the west-facing is even more suitable than the east-facing. This is due to the fact that the outside temperatures rise in the afternoon and therefore the absorption coefficient is better in a westerly direction.


2. Do solar collectors also work in cloudy conditions?

Thermal solar collectors not only use direct solar radiation to generate energy, but also diffuse light. Therefore, they also heat the water on cloudy days, although not so strongly. While the largest amount of energy is generated in the summer months, a heating system can normally also contribute to meeting a household's energy needs in spring, autumn and winter. It is estimated that such a system can cover between 50% and 70% of the annual energy demand for the hot water supply of a single family home. Of course, the heat transfer yield increases at higher outside temperatures.

3. Can solar heating systems also be used for larger buildings?

In general, solar heating systems can meet the majority of the hot water needs of apartment buildings, villas, businesses, hospitals, office buildings, industrial plants and factories, as well as other commercial facilities. In these applications, large quantities of hot water are usually consumed, so that solar heating systems offer considerable advantages here. Since a supply rate of 20-40% can be achieved in these cases, the costs for hot water consumption can be reduced.

4. Do solar collectors need special protection in very cold winters?

Solar collectors are safely protected from frost if the heat transfer from the hot water storage tank to the solar collectors is reversed. This means that during maintenance of the maintenance the antifreeze agent is checked and the frost protection temperature is set correctly in the controller.


5. Do solar collectors need special protection in very hot weather?

Some time ago it was important not to oversize the solar collectors so that they would not overheat. This was all the more true when no water was consumed. However, this is not a factor with Hoval.
A good example are solar collectors installed on holiday homes. The stagnation temperature is the temperature at which no consumption takes place and the collector is exposed to the sun. This is the highest temperature that the collector reaches when no heat is being dissipated. Hoval has lowered the stagnation temperature to avoid problems with the solar fluid and other components. Thanks to the lower stagnation temperature, more stable operation can be ensured.

6. Is it possible to heat a swimming pool?

Pool heating requires a lot of heating energy, which is why the savings potential is particularly high. Due to their high yield, thermal solar collectors are therefore ideal for the ecological, efficient and economical heating of swimming pools. The net area of the collectors refers to the water area of the pool. In indoor pools, the absorber area is half the water area. With outdoor pools, this value increases to 2/3 of the water surface due to the outside temperature.

7. How long does it take to commission a solar heating system?

The commissioning of the solar heating system on a single family home can take up to half a day. But it doesn't have to. Hoval has reduced the job to four minutes. This is a huge time saving made possible by the new SolKit® aqua hot water tank and the proven UltraSol® solar collector.

8. Is it possible to install solar heating systems on old buildings?

Yes – but there are various points to consider, such as the type of roof, the material the roof is made of and the selection of the optimum fastening system. The condition of the roof must also be checked to ensure that it can support the weight of the solar heating system. The UltraSol® solar collector from Hoval weighs only 39 kg and is therefore one of the lighter models. However, the most important aspect to consider when installing a solar system is solar radiation.

9. What is the system service life of a solar heating system?

With proper operation and regular maintenance, a minimum of 20 years can be assumed.

However, a modern solar heating system consists of several different components. In order to achieve an efficient and sustainable solution, only high-quality components should be used and the entire system should be professionally installed.

Alexandra Dragoi

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