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Construction Begins on a “Solar Dam” in Swiss Alps

published: 2021-06-22 9:30

Swiss companies Axpo and IWB announced on June 1 that they have begun construction on a 2.2MW vertical PV project in the Swiss Alps. The project is located 2,500m above the sea level at the Muttsee Reservoir in the Canton of Glarus, Switzerland. It is “vertical” because PV modules (or solar panels) will be covering the dam wall of the reservoir. Designated as “PV Muttsee”, the project will produce 3.3 million of kWh of electricity annually. Axpo is a developer of renewable energy projects and an energy trader, whereas IWB involves in various utilities and telecommunications.

After obtaining the building permit for the project in late May, the joint development team of Axpo and IWB is now using helicopters to airlift a crane and other types of construction equipment to the project site. The Muttsee Reservoir is the highest of its kind in Europe and not accessible via road transport. Axpo stated that it has formulated a special flight schedule in order to minimize the disturbance to the local environment and community. The company also asserted that the carbon emissions from the construction will be more than offset by the operation of the PV project. According to Axpo’s factsheet on the project, 4,872 PV modules will be installed on a surface of 10,000 square meters. The company also said that it had conducted a study on the effect of snow load on modules. The risk of snow and ice pulling down modules from the dam wall has been thoroughly addressed. Actually, the angle of the dam wall allows the snow to slide off the modules on its own. 

The development of PV Muttsee was initiated in 2019. The installation of PV modules has just started and is expected to finish within four months. The whole project should enter operation sometime in the autumn of this year. Denner, a Swiss supermarket chain, will be buying power from PV Muttsee under a 20-year PPA.

Axpo estimates that half of the electricity that PV Muttsee will be providing annually will be generated during the winter months, when Switzerland consumes more power than it produces. The alpine region of the country seems to be a very unlikely place for setting up PV generation assets. However, the Muttsee Reservoir has many advantages. First, the project will be above the fog line and therefore receive plenty of sunshine. Second, the dam wall faces south, so the modules that cover it will get sunlight all day. Third, the snow that exists in the surrounding landscape offers high albedo and low temperature. These two conditions raise the performance of individual modules. Fourth, the reservoir is part of the Limmern Pumped Storage Plant. This means that the PV project can be easily integrated into the existing power infrastructure at the location. And finally, by cladding PV modules on the dam wall, little to no additional land is required for the whole project. After all, Switzerland does not have a lot of open spaces for building ground-mounted PV power plants.

Since PV Muttsee will generate around 50% of its annual electricity production in winter, it fits perfectly with Switzerland’s demand pattern. Christian Hiereli, project lead for PV Muttsee, said that Switzerland will experience more acute electricity shortages during the winter season in the next several years due to the decommissioning of older power plants. Many small-scale PV systems have been deployed around Switzerland, but they are not enough to meet the peak winter demand. Axpo believes that more vertical PV projects in the alpine region could make a significant contribution to the domestic power supply and thereby helping Switzerland achieve the goals under its 2050 Energy Strategy.

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