Using the sun as a source of energy

Martin Ellwanger, Project Manager

It's not only new buildings that should meet part of their energy requirement themselves in future. This is also a desirable objective in existing buildings. As well as optimising the building shell insulation and renovating the heating technology, we also aim to focus more attention on utilising solar energy.

Every day, the sun supplies us with an inexhaustible potential of free energy. More use should be made of this gigantic power source, and it should be incorporated into planning for future building reconstructions.

Two basic methods of actively utilising solar energy are available: solar thermal systems, which heat domestic hot water and assist with heating the water in the heating system via collectors. Photovoltaic systems, which use solar cells to convert the sun's energy directly into electric power. For a long time, both these technologies were viewed as costly playthings, and they were only used in special applications or by enthusiasts. This is no longer true. Production and installation costs have been drastically reduced in recent years. 

Solar thermal systems are losing ground to photovoltaic systems, which are becoming cheaper as time goes on. It is often more advantageous to produce electrical energy on large areas that are linked together. Processing hot water may make sense where only small areas are available for use. On average, at least 70% of the annual domestic hot water requirement can be met with solar energy. With heating support systems, the solar coverage quota is about 25%.
Moreover, building technology specialists can easily integrate solar thermal systems into existing heating systems. In the canton of Bern, installation of solar thermal systems is promoted by an upgrade of the efficiency class on the cantonal building energy certificate (GEAK®).

Modern solar power systems should be designed for high levels of own consumption. Power is used at the location where it is produced. This works best if solar power is used not only for household purposes, but also for heating, water heating and mobility. A communal consumer cooperative is set up so that tenants in apartment buildings can use the power produced on site to meet their own individual power requirements. Energy suppliers bill the plant operator for the energy obtained. Excess energy fed into the grid is also reported. Internal billing arrangements are left up to the consumer cooperative on the basis of negotiations with the plant owner.