The largest alpine solar plant in Switzerland

Pioneer project at a glance

Together with IWB, Axpo has realised Switzerland's largest alpine solar plant at 2500 metres above sea level. The plant has been fully operational since the end of August 2022. The pioneering AlpinSolar project produces 3.3 million kilowatt hours of electricity per year - half of it in winter. In this way, we use solar energy at any time of year and despite the sea of fog. 

Impressions from the construction period

We use the sun where it is the closest

The Muttsee dam is extremely well suited for a photovoltaic plant thanks to its existing infrastructure, its orientation and its altitude:

  • Owing to the alpine location at 2500 m.a.s.l., solar power is particularly effective and generates lots of power in the winter thanks to snow reflection and a lower incidence of fog.
  • The Muttsee dam faces the south and, as a result, has sun all day.
  • The Muttsee dam has an optimal angle – snow slides off the surface on its own.
  • Part of the infrastructure (e.g. 16 kV grid connection) could be used for the installation. 
Local, renewable power for Denner

Denner, Switzerland's largest discounter, purchases the alpine solar power from Axpo under a power purchase agreement (PPA) for the first 20 years after commissioning. Denner is thus consistently pursuing its ambitious sustainability goals and is supplying its retail outlets and offices with 100% renewable and local electricity. 

Politics

The energy transition requires additional large-scale plants, but...

In order to achieve the energy transition, many large-scale plants like AlpinSolar must be built in the next few years to produce renewable electricity. Unfortunately, however, the construction of new plants is proceeding slowly. This is due to the current subsidy framework, which is designed for small plants with self-consumption. Today, large-scale plants are a major economic risk.

The Energy Act must improve the subsidy framework

However, the success of the energy transition must not depend on whether companies can be found to accept uneconomic projects. Switzerland must improve the political framework for large-scale plants. The current revision of the Energy and Electricity Supply Act offers an opportunity to do so. It will come before the Federal Parliament in the second half of 2022. Axpo and IWB, together with the majority of the industry, have introduced proposals into the discussion on how this could be achieved most efficiently: for example, with a sliding market premium based on the international model. In addition to the subsidy framework, the approval procedures must also be accelerated and the possibility created that free-standing plants can be approved at suitable locations. Today, this is basically only possible within building zones and on existing infrastructure.

Alpine solar power in winter

Switzerland produces significantly less electricity in winter than it consumes. So there is a shortage of electricity in winter, which has to be imported. And this fact is likely to increase significantly over the next few years as nuclear and coal-fired power plants are taken off the grid at home and abroad.

It is therefore important to find solutions to produce additional electricity from renewable sources in winter. The large-scale alpine solar plant in the Glarus Alps makes a contribution to this: it produces around three times more electricity in the winter months than a comparable solar plant in the Swiss midlands.

Solar panels in the Swiss midlands are often under a blanket of fog during the winter months - at high altitudes there is much less fog and thus more solar radiation. In addition, solar panels like it cold. The efficiency of solar modules is higher at low temperatures than when it is hot. And finally, the sunlight is reflected by the snow cover, which leads to a higher solar power yield. This is called the "albedo effect". In addition, the angle of inclination of the dam is optimal for solar power production in winter.

Winter power from a dam

Project manager Christian Heierli in an interview on winter power and profitability.

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Data for research

The full operation of AlpinSolar also marks the start of scientific research work by the Snow and Avalanche Institute (SLF) and the EPFL technical university. Over a period of four years, empirical values and data on the system will be collected, which can serve as a basis for future systems in the alpine region. The testing of different panel types, the comparison of different panel inclination angles on the dam and data on wind and snow loads are also part of the research.

Solar researcher Annelen Kahl on the pioneer project in the Glarus Alps

The largest alpine solar plant at the Muttsee dam at 2,500 metres above sea level has also been of interest to the Federal Institute of Technology Lausanne (EPFL) and the Institute for Snow and Avalanche Research (SLF) since the beginning of the project. Annelen Kahl has been researching the behaviour of solar plants in the high alpine region for several years. In this interview she reveals what opportunities she sees in the 2-megawatt pioneer project.

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10.08.2022

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21.01.2021

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21.01.2021

Axpo and IWB to build Muttsee solar plant; Denner to use the electricity

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