Efficiency of photovoltaics at altitude


With its Energy Strategy 2050, Switzerland has decided to phase out nuclear energy in the medium term. The electricity that will no longer be produced by nuclear power plants will have to come from other energy sources in the coming decades. To ensure that the climate is not affected by additional carbon dioxide emissions, the sun, wind and geothermal energy must be used first.

Photovoltaic energy in high mountains

In a study published on 7 January 2019 in the prestigious journal Proceedings of the National Academy of Sciences (PNAS), Annelen Kahl and her colleagues from the "Snow Process research group" at WSL Institute for Snow and Avalanche Studies SLF and the Cryospheric Sciences Laboratory (CRYOS) at EPFL are investigating whether more photovoltaic energy could be produced in winter with facilities located in high mountains rather than on the Plateau. To answer this question, they use, among other things, satellite remote sensing data to assess solar radiation for the entire Swiss territory. The researchers deduced the potential photovoltaic electricity production from this. The study shows that photovoltaic installations in high mountains can significantly reduce the winter power deficit, as solar radiation is higher in winter than in regions often enveloped in the fog of the Plateau.

Snow increases power generation

In addition, the researchers studied how snow-covered soils and the inclination of solar modules could influence electricity production. Annelen Kahl confirms it: "When photovoltaic installations are installed in the mountains, the solar radiation reflected by the snow can contribute to production." According to the study, maximum efficiency is achieved when the modules are installed at a steep angle, which increases power production in winter. "Our work shows that the production deficit that will result from the phase-out of nuclear power can be better compensated by the construction of photovoltaic installations in the mountains than by modules on the roofs of the Plateau because each square meter produces not only more electricity, but also at a better time" add Annelen Kahl.

A test facility above Davos

With a test facility on the Totalp in the Parsenn ski area in Davos (Graubünden), SLF and EPFL are now studying, together with the Zurich City Electricity Authority (EKZ) and the University of Applied Sciences Zurich (ZHAW), the practical and technical issues that can arise from the photovoltaic installations in the mountains, including the inclination that solar panels must have in order for the snow to slide on its own.

Source: EPFL press release