Solar energy, which reaches the earth's surface in the form of light and heat, can be actively utilised with the aid of solar collectors for heat production (hot water and auxiliary heating), through the use of concentrating systems for chemical processes and electricity production, and through the use of photovoltaic systems for electricity production.
The solar cells used in photovoltaic systems consist of semiconductors similar to those used for the manufacture of computer chips. When exposed to light, these semiconductors produce electricity or direct current, which is then converted into alternating current with the aid of an inverter and subsequently fed into the public grid. Photovoltaics is an important technology for securing the sustainable supply of electricity in the future. Solar power has enormous potential: by 2050 it would be possible to meet around 20 percent of the current level of electricity demand in Switzerland through the use of photovoltaic systems.
Thanks to the development of standardised systems for hot water and auxiliary heating, the use of solar heat is an attractive option, and suppliers of conventional heating equipment are also offering efficient systems to an increasing extent. Solar heat can be ideally combined with any other energy carrier. Although the proportion of solar heat to overall consumption in Switzerland is still relatively low, its potential is considerable. If all existing buildings were to be optimally improved in terms of energy efficiency, it would be possible to meet the heating requirements of all Switzerland's households through the use of solar collectors.
Solar energy can also be utilised very effectively in solar thermal power plants. This is not possible in Switzerland, but power plants of this type can be operated very economically in the earth's sun belt. In theory, only around one percent of the surface area of the Sahara would be required in order to meet the entire electricity demand of our planet with solar thermal power plants equipped with concentrating reflector systems.
Solar energy can also be stored with the aid of solar-chemical processes. The process and reactor technologies that are required for this long-term option for the chemical storage and for the transport of solar energy are currently the subject of intensive research and development activity, in which the main focus is on hydrogen production via the ZnO/Zn cycle.