Created by E.Ö., SUPSI, on 27.11.2025
PV modules installed in cold, snowy, and high-altitude environments are exposed to significant mechanical stresses from snow accumulation, ice formation, and wind loading as highlighted in Alpine PV Stressors. Heavy or uneven snow buildup increases bending forces on the module surface, while strong winds introduce both static and cyclic mechanical loads across the laminate. At low temperatures, module materials become stiffer and less able to absorb deformation. This shift in material behavior increases the likelihood that mechanical stress will be transferred directly into silicon cells. These stressors can lead to several damage modes, including reduced mechanical stability and glass breakage, cracks in the solar cells that may develop into performance-limiting defects, and shading losses caused by snow accumulation that reduce energy yield and create electrical mismatch across the module. Understanding how snow and wind interact with module design and installation configuration is essential for minimizing damage and maintaining long-term system performance in cold-climate regions. The main damage modes caused by snow and wind load stresses are described in more detail below.
Mechanical Stability and Glass Damage in Solar Modules
High mechanical loads, whether unevenly distributed or uniform and heavy, place significant mechanical stress on photovoltaic modules (Figure 1). Uneven accumulation on tilted arrays can create localized pressure points that increase bending and deflection, while uniformly deep snow can generate high static loading across the entire module surface. Large modules are particularly susceptible because their greater surface area allows more deflection under the same load. At low temperatures, the module materials become more rigid, reducing their ability to absorb and distribute stress. Once the stress exceeds the module’s structural capacity, the glass may fracture, sometimes catastrophically. Mechanical stability depends on design parameters such as glass thickness, frame rigidity, module size, clamp placement, and support configuration.
Figure 1: PV-system at Wildkogel/Austria; wrong site-selection: every winter, a snow roll always covers the PV fields and causes severe damage; the PV plant must be relocated [1].
Cell Cracking
Cell cracking occurs especially when mechanical stress is transferred directly to the brittle silicon cells at low temperatures. As temperature decreases, the encapsulant layers lose flexibility and are less able to buffer mechanical loads from snow or wind [2]. EVA begins to lose elasticity as it approaches its glass-transition range around −20 °C and becomes significantly more brittle near −30 °C. EPE, which consists of layers of EVA and POE, exhibits two distinct transitions, with mechanical property changes beginning around −20 °C and again near −40 °C. POE remains flexible to much lower temperatures, with the transition beginning near −40 °C and mechanical stability maintained even below this point (Figure 2) [3]. When the encapsulant stiffens, stress is transferred into the silicon wafers, where microcracks can form. These cracks are often not visible immediately but may propagate over time, reducing active cell area, increasing electrical resistance, lowering module output, and in severe cases leading to localized hot spots. This effect has been confirmed to predominantly affect glass/backsheet module constructions in [3].
Figure 2: (left) Curves resulting from tensile stress tests: Stress at 10% elongation of encapsulants at varying temperatures. (right) EL images of full-size Glass/EVA/Backsheet modules after the Mechanical Load (ML) test sequences at -40C and +25C. Difference in severeness of cell cracking is visible [3].
Shading losses
Snow accumulation leads to shading that reduces PV module energy output and can cause electrical mismatch within the string. Snow commonly builds up along the lower frame edge, forming a snow bridge that blocks irradiance to the lower cell rows and forces current mismatch through the affected string. This partial shading may cause local heating and can intensify pre-existing microcracks by creating localized hot spots. The rate at which snow sheds from a module depends on several factors, including module tilt, frame geometry, row spacing, ground clearance, and whether the module is bifacial.
Mitigation Strategies
- Glass/glass module configuration: Dual-glass designs offer additional structural rigidity and help distribute mechanical stress more evenly across the module.
- Use of thicker, fully tempered glass: Modules benefit from fully tempered and thick glasses, which provide enhanced mechanical strength and improved resistance to snow and wind loads. Regarding thickness, it is important to know what is minimum thickness to be able to get a fully tempered glass.
Figure 3: Fracture strength probability graph of fully tempered, heat-strengthened, and annealed glasses [3].
- Reinforced frames: Using stronger frame materials (e.g., steel), special frame geometries, thicker frame profiles, or increasing the contact area between the glass and frame can significantly reduce bending stress [1].
- Optimized frame geometry: Special frame designs that prevent snow accumulation, facilitate meltwater drainage, and feature smooth edges to minimize snow adhesion contribute to better long-term performance [5].
- Adhesively bonded frames: Frames glued with silicone-based adhesives can provide additional structural integrity, increase load resistance, and enhance humidity diffusion—reducing moisture-related stress.
- Reduced module size: Smaller module formats limit deflection under load, thereby lowering the risk of glass fracture.
- Frameless module designs: Frameless modules promote faster snow shedding, reducing both snow load and shading by allowing snow to slide off more easily [6, 7]. However, effect on mechanical stability of not having a frame must be considered.
- Use encapsulant materials rated for cold operation: Select encapsulants with low glass-transition temperatures (Tg) that remain flexible at sub-zero conditions, ensuring mechanical integrity and reducing the risk of cracking or delamination during thermal cycling.
- Optimized mounting configuration: Proper selection and placement of clamps, mid-bar supports, and mounting systems can minimize bending stress under mechanical loads [1].
- Sloped installation with adequate ground clearance: Installing modules at an appropriate tilt angle and ensuring sufficient ground clearance helps prevent excessive snow buildup, especially near module edges, and facilitates natural snow shedding.
- Enhanced mechanical testing: Performing mechanical durability tests under cold and high snow-load conditions ensures that modules can withstand stresses beyond standard certification requirements.
- Implement snow-removal technologies: Implementing various snow-removal technologies could help prevent snow and ice accumulation; however, their long-term reliability and performance still need to be demonstrated in real operation.
- Passive methods: surface coatings (e.g. ice-phobic or hydrophobic), nano-textured or micro-textured glass to reduce snow adhesion and promote sliding [8,9].
- Active methods: thermal snow-removal systems such as reverse-bias current heating or embedded/attached resistive heaters to melt snow when needed.
References
[1] IEA Task 13, Optimisation of Photovoltaic Systems for Different Climates, International Energy Agency, 2025.
[2] E. J. Schneller, H. Seigneur, J. Lincoln, and A. M. Gabor, “The Impact of Cold Temperature Exposure in Mechanical Durability Testing of PV Modules,” Proceedings of the IEEE Photovoltaic Specialists Conference (PVSC), Cocoa, FL, USA, 2019.
[3] A. Gassner, G. C. Eder, E. Özkalay, G. Friesen, M. Feichtner and V.‑M. Archodoulaki, “Enhanced mechanical load testing of photovoltaic modules for cold and snowy climates,” EES Solar, vol. Advance Article, 2025. doi:10.1039/D5EL00125K.
[4] D. M. Roberts, M. Owen-Bellini, C. W. Hansen, A. Jain, D. C. Miller, M. Springer, J. L. Braid, and T. M. Barnes, “Reliability forecasting for new modules with new technology and new problems: How can you know if it will last?,” Presentation at the 42nd European Photovoltaic Solar Energy Conference and Exhibition (EU PVSEC), 2025.
[5] ReneSola, “Subverting tradition and pioneering innovation–ReneSola’s high-strength alloy steel frame photovoltaic modules open a new chapter.” Accessed: Nov. 5, 2025. [Online]. Available: https://www.renesola-energy.com/news_detail/1750789837987926016.html
[6] P.-O. A. Borrebæk, B. P. Jelle, and Z. Zhang, “Avoiding snow and ice accretion on building integrated photovoltaics – challenges, strategies, and opportunities,” Sol. Energy Mater. Sol. Cells, vol. 206, p. 110306, Mar. 2020, doi: 10.1016/j.solmat.2019.110306.
[7] J. P. Aubell and A. Gebremedhin, “Framed-or Frameless Photovoltaic in Snow Experiencing Climates,” Int. J. Innov. Technol. Interdiscip. Sci. www .IJITIS.org, vol. 4, no. 3, pp. 742–753, 2021, [Online]. Available: https://doi.org/10.15157/IJITIS.2021.4.3.742- 753
[8] M. Manni, M. C. Failla, A. Nocente, G. Lobaccaro, and B. P. Jelle, “The influence of icephobic nanomaterial coatings on solar cell panels at high latitudes,” Solar Energy, vol. 248, pp. 76–87, 2022. doi: 10.1016/j.solener.2022.11.005.
[9] A. Dhyani, C. Pike, J. L. Braid, E. Whitney, L. Burnham, and A. Tuteja, “Facilitating large-scale snow shedding from in-field solar arrays using icephobic surfaces with low-interfacial toughness,” Advanced Materials Technologies, 2021. doi: 10.1002/admt.202101032.
