The results of the flights are transmitted directly to the authors of the projects – or to Stefan Margreth, head of the protective measures research group at the SLF. This uses them for assessments which allow designers to know whether particular measures are necessary and, if so, which ones. “Before, we only had approximate data from maps representing the average snow depth over the whole of Switzerland, there was perhaps still a measuring station nearby, this gave us an idea of the situation on place, but not the details”, explains Stefan Margreth. In practice, a relatively small basin can already cause large local snow depths. This is why topographical flights provide important information.
Because snow doesn’t just fall and stay until spring. The wind moves it, resulting in cornices and free-blown surfaces, places with a lot of snow and others with little, the differences are enormous in the mountains. “The distance to the ground of the PV modules must be calculated based on the local snow depth,” explains Margreth. If the base is too low, the modules disappear under a white cover and the solar park does not produce electricity. Additionally, damage can be caused by snow pressure.
However, the installation itself also has an impact on the situation on site. “In principle, solar parks reduce local wind speed, which should lead to greater snow deposition,” explains Margreth. Due to this effect, it may be distributed differently compared to the initial state before construction. Margreth compares this to protective structures such as column crossings and mosquito fences, which optimize the distribution of snow or reduce the risk of avalanches by allowing the wind to deposit the snow in a controlled manner in certain locations.
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