Solar panels on mountain tops generate more electricity in winter than those on the roofs of buildings at lower altitude. By having them on mountain tops, many countries could reduce the power deficit that exists during the winter months. Specifically, the power deficit experienced by this particular type of renewable energy (solar energy).
This is what researchers from the École Polytechnique Fédérale de Lausanne and the WSL Institute for Snow and Avalanche Research have concluded. Both academic institutions are in Switzerland.
The researchers wrote about their study and findings in Proceedings of the National Academy of Sciences (citation below). The authors were Annelen Kahl, Jérôme Dujardin, and Michael Lehning.
Solar energy and solar power both refer to capturing the energy from the Sun and converting it into electricity.
Solar power generation fluctuations
Electricity generation from solar energy fluctuates considerably during the year. Typically, PV systems generate more electricity than the market needs in the summer. PV stands for photovoltaic. Solar panels that can produce electricity from sunlight are photovoltaic devices.
During the winter months, on the other hand, the system generates less than the market requires. This is because there is less solar radiation in winter, i.e., less sunlight. The sun is lower in the sky, there are fewer daylight hours, and there is more fog as well as low stratus clouds.
For PV systems, the difference between summer and winter is greater at low altitude compared to mountain tops.
Storing the energy
The only way to overcome this disparity between summer and winter electricity supply is to store the energy. If utility companies can store the energy, they can subsequently make it available in the winter.
We can only do this by pumping water uphill so that we can generate hydroelectricity at a later date.
However, there is not enough available capacity to make up for the winter shortfall. Pumping water uphill is also inefficient, i.e., the process wastes a lot of energy.
It would, therefore, make more sense to be able to generate more solar energy in winter.
PV systems on mountain tops
In this latest study, researchers examined what would happen if there were PV systems on mountain tops.
They gathered and analyzed data from remote sensing satellites. These satellites can provide an estimate of solar radiation that strikes the ground throughout the whole of Switzerland.
Thanks to these satellites, the researchers were able to calculate the potential for generating power with PV systems.
More sunlight on mountain tops
Their findings showed that PV systems on mountain tops generated more electricity in wintertime than at low altitudes. Therefore, installing them high up in the Alps would significantly reduce the seasonal shortfall.
The Swiss Plateau (low altitude) is frequently shrouded in fog during the wintertime. Mountain tops, on the other hand, are relatively ‘fog-free.’
Snow boosts power generation
There is something else that mountain tops always have during the winter months – snow. The researchers also tried to determine whether solar panels generated more electricity when snow covered the ground.
Annelen Kahl, a Post-Doctoral Researcher at the École Polytechnique Fédérale de Lausanne, explained:
“When PV systems are installed in the mountains, solar radiation reflected by the snow can be used additionally to produce electricity.”
Install panels at a steep angle
It is best to install the solar panels at a steep angle. Then they can fully exploit the sunlight that bounces off the snow. This further boosts power generation during the winter months.
Dr. Kahn added:
“Our study shows that PV systems in the mountains, compared with installations on the roofs of buildings in the Swiss Plateau, are much more capable of overcoming the supply shortfall that will arise as a consequence of abandoning nuclear power because, per square meter, solar panels at high altitudes produce electricity not only in larger quantities, but also when it is needed.”
Energy from mountain tops – system trials
Above Davos, in Switzerland, is the Parsenn ski resort. The Totalp, a mountain, is located at Parsenn. With the aid of an experimental system on the Totalp, the researchers are currently examining the practical and technical issues arising from the installation of PV systems on mountain tops.
The researchers are also trying to determine the best angle to position the solar panels so that snow does not settle on them.
The research team is working together with Elektrizitätswerke des Kantons Zürich (EKZ), a leading Swiss power utility company.
“The bright side of PV production in snow-covered mountains,” Annelen Kahl, Jérôme Dujardin, and Michael Lehning. Proceedings of the National Academy of Sciences (PNAS), published ahead of print January 7, 2019. DOI: https://doi.org/10.1073/pnas.1720808116.