Solar energy that reaches the earth's surface can be utilised with the aid of the two established solar technologies, photovoltaics (electricity) and solar thermal energy, for the production of renewable energy. The potential of solar electricity is considerable: by 2050, around 20 percent of the current level of electricity demand could be met through the use of photovoltaics. Solar thermal energy is an attractive option for the production of hot water and heat thanks to the existence of standardised systems. From the suitability map the degree of suitability of a particular roof for the use of solar energy can be deduced, as well as the anticipated yield. The calculations are based on a simulation of the path of the sun throughout the year, and the amount of sunlight that falls on each roof surface.At present, 50% of Switzerland's buildings have been recorded. The data for the roofs of all buildings in the country will be available by the beginning of 2018.