Solar industry cost-cutting sparks record wave of spontaneous glass breakage
From the magazine (https://www.pv-magazine.com/issue/05-2026/)
Solar glass has traditionally been engineered to withstand environmental stress, but recent trends show a surprising shift toward spontaneous breakage. Since 2021, scientists and operators have reported that many solar modules experience glass failure without warning, raising concerns over reliability and safety. This phenomenon, termed 'spontaneous glass breakages,' has sparked debates among experts about the causes and implications of this unexpected trend.
Kiwa PVEL, a global solar manufacturer, attributes this issue to the industry’s evolving cost strategies. “We are aware of it occurring in multiple countries, with multiple module model types, mounted to multiple tracker/racking solutions,” the lab wrote in its 2025 PV scorecard. As manufacturers prioritize efficiency, they have increasingly reduced glass thickness and optimized mounting techniques, which may not fully address the underlying risks of microscopic defects and improper adhesion.
Tristan Erion-Lorico, vice president of sales and marketing at Kiwa PVEL, emphasized that the phenomenon is directly tied to these changes. “Generally speaking, we have thinned the glass, frames, and encapsulant and gone to more aggressive mounting,” he explained. However, eroded safety margins mean that even minor imperfections can lead to catastrophic failures. Microscopic defects along the edges or surface stress imbalances, combined with pressure from busbars, can cause modules to break during testing, indicating that traditional mechanical stress tests are insufficient for predicting real-world performance.
In 2025, Kiwa PVEL recorded a historic high in spontaneous breakage rate, with one-third of modules failing during testing. The results were better than expected for the last quarter, though still unprecedented. This suggests that while the test does not replicate field conditions, it highlights the growing vulnerability of modules to environmental factors beyond just physical stress. The shift to thinner glass, driven by demand for cost savings, has led manufacturers to invest in specialized equipment, yet the resulting compromises may undermine long-term reliability.
Notable examples include larger modules being designed to reduce weight. With glass representing over half of a module’s weight, thinner glass modules require more robust installation support. Pradeep Kheruka, chairman of Borosil and Borosil Renewables, noted that this change is primarily customer-driven. “Glass manufacturers have had to invest significantly in new equipment to cater to this changed demand,” he said. While thinner glass is safer, the increased complexity of large, heavier modules raises questions about how responsibility for breakage is distributed across stakeholders.
The US National Laboratory of the Rockies (NLR) surveyed potential causes, identifying factors such as reduced thermal strengthening, edge microdefects, lamination-induced stresses, and contact between the glass and frame. A 2026 study focused on the first cause and developed a non-destructive method to measure surface stress directly on finished panels. Researchers found that 2.0 mm glass is still weaker than traditional 3.2 mm glass, though surface stress levels correlate strongly with susceptibility to breakage. This discovery underscores the importance of maintaining sufficient safety margins in both design and production processes.
Investors are concerned about this trend, as smaller, more nuanced factors become critical in assessing module reliability. Henry Hieslmair, principal engineer for solar at DNV, highlighted that investors often overlook the fragility of glass, especially when safety margins are reduced. Farid Samara, senior engineer at DNV, stressed that projects involving thinner glass and larger modules require a deeper review of the module’s design. “Module manufacturers often argue that structural testing should be the responsibility of tracker suppliers, while tracker manufacturers claim otherwise,” he said.
This debate highlights a growing issue: a lack of a unified standard for PV glass. Without clear definitions for surface stress and material properties, manufacturers struggle to communicate their progress effectively. “Having the community align on definitions for glass surface stress would be a huge step,” NLR researcher Elizabeth Palmiotti concluded. This reflects a broader concern about ensuring consistent quality and safety in the rapidly evolving solar industry.
