The Zurich University of Applied Sciences (ZHAW) says alpine solar PV plants can generate up to 4 times more electricity than their counterparts at lower altitudes in winter months. It makes the observation based on the results of an experimental solar PV plant it installed in the alpine region 5 years back.
At 2,500 meters, the alpine test facility in the Davos-Parsenn ski area has been operational since October 2017. ZHAW built it in collaboration with renewable energy company EKZ. It is equipped with 6 framed and frameless monofacial and bifacial solar modules, tilted at varying degrees of 30° to 90°. All of these are at least 2 meters above the ground.
According to the findings, power generation during the winter months of October to March for the alpine solar plant was seen to be 3 to 4 times higher than a similar system in the mainland.
Even during the high yield months of April and May, alpine solar systems can supplement power generation from hydropower when the reservoir levels are relatively low. Analysts argue that alpine solar systems can protect the reservoirs.
What's important is to install the alpine solar systems on southern slopes with modules facing south. The angle of the inclination is significant here since vertical modules with a 90° incline achieve higher yields in the months of December and January. With this incline, bifacial solar modules generated the highest winter electricity yield of 878 kWh/kW to 949 kWh/kW.
In comparison, those with a 60° or 70° tilt are more productive in the months of March to May and in the summer. Bifacial modules with a 60° tilt generated a high of 1,977 kWh/kW in 2021 calendar year, according to the report.
If the modules are tilted between 60° and 90°, the losses caused by snow cover will be minimal since the snow will slide off quickly.
The main argument in favor of alpine solar plants is the increased power generation with low temperatures and high levels of radiation at a high altitude. Using bifacial modules just complements the system. A similar conclusion was drawn by the EPFL in a May 2021 study wherein it stated that to become energy self-sufficient, Switzerland can hugely benefit from solar PV deployment in the Alps (see EPFL Study Recommends Solar & Wind In Swiss Alps).
As if taking a cue, the Swiss government launched a solar offensive and offered special bonus for solar arrays in the alpine region via competitive auctions (see Switzerland To Launch Solar Auctions For 150 kW & Above).
Since then, several small alpine solar projects have been announced in Switzerland; however, the plans are not always welcomed by the denizens. For instance, people in Valais Canton voted against a large solar power project in the alpine region (see Another Alpine Solar Power Plant In Switzerland).
Nonetheless, ZHAW's Jürg Rohrer believes alpine solar plants are intended to complement the ongoing PV expansion in the mainland and not replace it. The institute is now investigating the impact of distance between rows of modules on large-scale alpine PV projects.
The complete report stating the findings from 5 years of operation of the Alpine PV test facility is available on ZHAW's digital collection.