Researchers from the Ecole Polytechnique Fédérale de Lausanne (EPFL) and WSL Institute for Snow and Avalanche Research SLF in Switzerland have modelled snow patterns to identify some best practices for PV installations built with Helioplant, a patented Austrian vertical PV framing structure.

“Alpine PV systems have demonstrated strong potential for electricity production during winter, notably due to the reflection of incoming solar radiation by the snow cover. While this reflection helps improve energy capture, snow can also create problems by covering or burying the solar panels, which induces losses or damages,” Océane Hames, co-first research author, told pv magazine.

The optimal design for alpine solar PV systems remains to be established, not only for individual installations but also for larger clusters comparable in scale to future commercial alpine power plants, according to Yael Frischholz, co-first author of the research.

“Helioplant structures have shown significant potential in terms of snow accumulation mitigation, which is why we investigated this design,” Frischholz told pv magazine.

Helioplant is a patented vertical PV framing structure developed by Ehoch2, an Austrian PV engineering company, to mitigate snow accumulation. It has a cross-shaped load-bearing structure with four solar wings designed to passively prevent snow accumulation within the wing area.

The researchers used a computational fluid dynamics (CFD) modelling tool known as Snowbedfoam to simulate snow transport and examine the snow-drifting impact of Helioplant structures. According to the research, Snowbedfoam is an Openfoam-based Eulerian-Lagrangian solver for modelling snow transport.

“It is the first time that such a detailed snow transport model is applied to solar panel structures. The simulations of the sensitivity analysis were specifically designed to provide practitioners with key messages, or guidelines, on how to plan with this type of structure,” explained Hames.

The study used simulations and field observations from an identical test site. Some of the parameters considered were azimuth, height-above-surface, spatial arrangement of multiple units, interspace, size of the group and alignment.

Several initial best practice recommendations emerged from the analysis. For example, the height above the bare surface, ground gap, should be greater than 0.6 m, and the orientation of the Helioplant units relative to prevailing wind directions should be as close to 0° as possible. “If set to 45°, an undesired erosion-free area will form in the inner lee of the structures. Locations with primary wind directions that are perpendicular or opposite to each other are therefore preferable,” said the researchers.

Further guidelines are described in their paper, “Optimizing snow distribution in alpine PV systems: CFD-based design guidelines for power plant layout,” published in Cold Regions Science and Technology.

In the conclusion, it was noted that the results “validated the importance of using CFD-based studies alongside small-scale test sites,” particularly when scaling up from smaller installations to larger-scale alpine power PV plants.

The technology is not limited to any particular type of solar PV mounting solution. “The methods developed for this study can be used for any type of structure. Simulations on more conventional row-based layout were already done,” said Frischholz.

The team is continuing the research towards developing yield simulations that compare snow deposition patterns to actual PV electricity losses, and modelling more complex, non-flat terrain.