01.04.2022 | Large-scale solar plants make a significant contribution to the prevention of a winter power gap

Off into new heights

Jeanette Schranz




The discussion on the feasibility of the energy transition in Switzerland is more urgent than ever: If Switzerland wants to be more independent in terms of energy, we must move forward. By 2050, up to 50 TWh of electricity will be lacking each year. What's important: A balanced power mix is needed and must also include alpine solar power, especially because of its high proportion of important winter electricity. Alpine solar power has great potential. Here, a summary of the advantages and obstacles of alpine solar plants.

Standing in the landscape on a few stilts they look up to the sun – ground-mounted solar plants. We have all seen them when driving through Spain or in documentation on the topic of sustainability.

In Switzerland, there are few to be found because large-scale solar plants on open land are not widespread or even prohibited.

This situation must change quickly. The electricity they produce is urgently needed in our power mix. With the phase-out of nuclear energy and the clear trend of increasing power consumption, some 50 TWh of electricity will be lacking by 2050.  

Graphic: Swiss power production today and in 2050. Source: Axpo

Particularly in the mountains, large-scale solar plants could make a major contribution because the solar power yield is very high. This is due to the fact that solar radiation in the Alps is more intense and electricity production in the winter months is up to three times higher than a comparable plant in the  Midlands.

The advantages and obstacles of alpine solar plants in summary: 

Around three times more solar energy is produced in the winter half-year

  • because alpine solar plants are often located above the fog line,
  • the sun reflects off the snow,
  • solar panels like cold temperatures,
  • and so overall much more electricity is produced as a comparable plant in the Midlands.

As a comparison: A solar plant in the lowlands produces only about 25-30% of its electricity during winter.


Production profile for a year: Midlands solar versus alpine solar
Graphic: Alpine solar plants generate significantly higher power volumes during the winter months as compared to solar plants in the Midlands. Source: ZHAW
Ground-mounted: More large-scale solar plants needed

All the opportunities offered by alpine locations should be utilised in order to benefit from the advantages mentioned above. This also includes the installation of solar plants on existing infrastructure, as recently seen in the pioneer project AlpinSolar. The largest alpine solar plant in Switzerland is located on the Muttsee dam at the Limmern pumped storage plant. However, these types of solar plants are currently the exception to the rule. This should definitely be changed. At the same time, existing infrastructures in the alpine region with a grid connection is limited, which is why large-scale, ground-mounted solar plants should also be introduced. 

Over 16 TWh of solar power from the Alps

In a 2019 study, Swissolar/Meteotest estimate the potential of alpine solar plants at 16.4 TWh and forecast a possible power production of 3.3 TWh per year in the short term.

A huge potential, that is not yet being used. However, there are various obstacles to the construction of large-scale solar plants. All too often, construction fails today because of the permit process.

AlpinSolar: The solar plant generates important winter power on the Limmern pumped storage plant dam at 2,500 metres, with an ideal southern exposure.
Depending on the building zone: Approval or not?

In contrary to alpine solar installations, installations within the building zones usually have a better chance of being approved. This is due to the fact that there is currently no legal basis for the approval of solar installations outside the building zones. According to the Spatial Planning Act (SPA), a plant outside the building zone must be "location-bound" in order to make an exemption permit possible. Solar plants – in contrast to wind and hydropower plants – are, however, never considered location-bound because it can always be argued that the panels could be installed at a different location. Through this requirement, large-scale solar plants near existing infrastructure are de facto prohibited.

The development of renewables and ensuring long-term energy supply in Switzerland is contingent upon the possibility to approve these types of plants. This can be achieved by defining suitable criteria for the location-bound requirements (e.g. infrastructure proximity or earmarking suitable locations through the federal government/cantons).

It is not enough to only install solar plants on the rooftops of new or renovated buildings. In the medium to long term we will run out of electricity.
Solar plants favour biodiversity 

Several studies indicate that at our latitude, the advantages of ground-mounted solar plants prevail and the impact on nature is limited. Thanks to partial shading through the solar panels, small-scale, side-by-side habitats can be established and, thanks to different microclimates they offer space for more diverse species than uniform habitats.

The decisive factor is always support in terms of spatial planning and the balanced consideration of protection and use. In any case, locations for large-scale solar plants are selected because they are well accessible – in particular, when it comes to a grid connection. Road access is also a major advantage. Additional specifications regarding the dismantling of plants at the end of their service life could be integrated in the building permit.

Energy transition and security of supply

For the energy transition, and, in particular, to ensure the security of supply in Switzerland, power plant construction must gain momentum. Solar panels on roofs in new construction and remodeling projects are important, but not enough. In the medium to long term we will run out of electricity.

Solutions exist and we can implement them. Axpo developed a scenario that demonstrates how this can be done. Create your own power mix for tomorrow on https://powerswitcher.axpo.com/. More on the energy transition here

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