The 2.2 megawatt solar plant will produce around 3.3 gigawatt hours of electricity per year. "Those solar panels that were already in operation in the winter of 2021/22 achieved a very high solar yield, proving the value of alpine photovoltaics," says Christian Heierli. He is the overall project manager for Alpinsolar at Axpo. Winter electricity is also very much in demand in the Swiss electricity mix, because much greater amount of green electricity is needed in the cold months of the year. However, the legal basis for the approval of solar plants outside of building zones is still lacking today. "Since July 2022, there have been minor improvements with the revision of the Spatial Planning Ordinance with regard to construction on facades, dams and noise barriers," Axpo explains.

PPA agreement with discounter supermarket Denner

The pioneering project was built by the utility Axpo together with IWB, the energy supplier for the city of Basel. Last autumn, the plant in the Glarus Alps was able to produce electricity for the first time. Now the plant is fully operational. For the first 20 years of operation, the discount retailer Denner will purchase all the solar power under a power purchase agreement and use it in its shops.

See also: Solar plant in Switzerland has been supplying solar power for 40 years

In order to make the best possible use of the available surface area, Megasol uses two different module types with outputs of 460 watts and 385 watts respectively. Installers prepare them on 14.5-metre-wide module tables for final placement on the dam wall. 4,872 bifacial glass-glass modules from the Swiss manufacturer Megasol were installed. Their wide frame of 40 millimetres meets the requirements for the expected snow load. In module areas where the highest load is expected, additional support must therefore be provided centrally from behind at one point. This is the only way the glass can withstand the load and not bend too much.

Completely new mounting system

The vertical primary substructure consists of steel trusses, but the tools for the aluminium profiles had to be made especially for Alpinsolar. The mounting system itself was completely redeveloped in six months by the general contractor Planeco and its project partners Megasol and Crestageo. Put simply, it is a commercially available insertion system for modules, but one that has never been built before on this scale