The SFOE study , published in mid April, is based on the solar potential cadaster that the Swiss Federal Office of Topography (Swisstopo), the Swiss Federal Office of Meteorology and Climatology (MeteoSchweiz), and the Swiss Federal Office of Energy (SFOE) provide in conjunction with the application sonnendach.ch . The SFOE leveraged this cadaster to accurately estimate the solar potential of rooftops and façades. Back in September 2018, the potential of rooftops was estimated at an annual output of approximately 50 billion KWh (50 TWh). The SFOE has now set the potential of façades at 17 TWh per year. In both cases, this is the useable potential of large connected surface areas with economically useful irradiation.
In addition, Swiss solar trade association Swissolar has calculated that a further 15 TWh per year could be generated on parking lot roofs and street surfaces, as well as in ski resorts in the Alps and on other non-protected areas with infrastructures. According to Swissolar, when combined with existing hydropower output (35 TWh) and other renewable energies, this energy could make Switzerland 100% nuclear power and fossil fuel-free (including for mobility and heating) by 2050.