Photovoltaics in the Alps deliver up to four times more electricity in winter

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Alpine Solaranlagen befinden sich im Winter normalerweise über der Hochnebel-Dec
Alpine Solaranlagen befinden sich im Winter normalerweise über der Hochnebel-Decke und können deshalb auch dann hohe Erträge liefern. ©ZHAW

Alpine solar plants can produce up to four times as much electricity in the winter half-year as plants in the Central Plateau. This is shown by measurements with a test system in the Davos-Parsenn ski area, which were carried out by the ZHAW over the last five years.

Tuesday, October 10, 2023 Currently, many large-scale alpine plants are being planned as part of the so-called "Solar Express", which is to be funded by the federal government. With regard to the planning of these plants, ZHAW researchers have summarized the most important findings from measurements at the Davos-Totalp alpine test facility in a report. Above Davos at 2500 meters above sea level, the ZHAW Renewable Energy Research Group has been operating this alpine photovoltaic test facility together with the EKZ for more than five years.

Alpine solar plants conserve reservoirs

The yield of an alpine solar plant is divided roughly equally between the winter and summer half-years. The electricity yield in the winter half-year, i.e. from October to March, is three to four times that of a plant on the Central Plateau. According to ZHAW researcher Jürg Rohrer, the particularly high yields in April and May are also a major advantage. In these months, alpine solar plants achieve their highest monthly yields and the levels of the reservoirs are relatively low in each case. "This means they can make a significant contribution to the security of electricity supply," says Jürg Rohrer. "The construction of alpine solar plants can conserve the reservoirs and therefore also make fossil reserve power plants superfluous, for example."

The measurement results give practical instructions to the planners of alpine solar plants. These plants are sensibly built on south-facing slopes with the modules oriented to the south. If the modules are inclined between 60 and 90 degrees, the losses due to any snow cover can be practically neglected, since the snow slides off quickly. The tilt angle of the modules influences when the yield is highest: vertical modules with a 90 degree tilt angle achieve higher yields in the months of December and January than modules with a 60 or 70 degree tilt angle. However, the latter are more productive in the months of March to May and in summer.

According to Jürg Rohrer, Alpine solar plants are intended to supplement photovoltaic expansion on existing infrastructures in the Central Plateau and can in no way replace it. "We have overslept the energy turnaround and need to expand electricity generation with photovoltaics at least twice as fast as last year in the next ten years. But we also need more wind energy and, above all, the huge savings potential should be better exploited." With further research, ZHAW researchers are currently systematically investigating the influence of distances between module rows on the electricity yield of large-scale alpine plants. Corresponding results are expected in summer 2024.