Thinner Glass, Larger Sizes Linked to Solar Panel Glass Breakage, Says NREL

The latest report by the National Renewable Energy Laboratory (NREL) has shown concerns over glass breakage in photovoltaic (PV) modules as the industry shifts toward using thinner glass to accommodate larger modules.

The report titled 'Tough Break: Many Factors Make Glass Breakage More Likely' delves into the increasing occurrences of glass breakage in photovoltaic (PV) modules used in utility-scale solar power plants. The findings suggest that while thinner glass is cost-effective, it compromises the durability of PV modules, making them more susceptible to damage during manufacturing, transportation, and installation. With a lower compression threshold, thinner glass is more prone to cracking, raising concerns about the long-term reliability of PV systems.

The report says that the recent trends show a rise in spontaneous breakage, with fractures appearing without any apparent external cause. Unlike past instances of damage caused by hailstones or manufacturing flaws, these recent breaks often exhibit large cracks with minimal branching, indicating a deeper underlying issue.

As per the report, a significant factor contributing to this increase in glass breakage is the shift to thinner glass in PV modules, with many manufacturers using 2-mm glass rather than the traditional 3.2-mm glass. While this change helps reduce costs and weight, it has also made the glass more susceptible to breakage, even with heat treatment techniques designed to strengthen it.

NREL's report notes that fully tempered glass, typically used in PV modules, undergoes a heat treatment process to add surface compression and prevent small flaws from spreading. However, the thinner 2-mm glass has a smaller compression zone, making it more vulnerable to failure when faced with microscopic defects. The report also highlights that the new fracture patterns observed in broken modules suggest that flaws at the edges and surfaces of the glass are critical to its overall strength, as even minute imperfections can drastically reduce its durability.

Furthermore, the increasing size of PV modules, driven by the demand for higher power outputs, is exacerbating the issue. Larger modules, combined with thinner glass, are under greater stress due to environmental factors like temperature fluctuations and wind loads, further amplifying the risk of spontaneous breakage. The report stresses that there is no single factor behind this rise in breakage; rather, it is the result of a combination of material choices, design changes, and manufacturing practices.

NREL is continuing its research into potential solutions to address these challenges, such as optimising module designs, enhancing heat treatment processes, and improving installation practices to ensure the long-term reliability and safety of solar installations. This report provides valuable insights for manufacturers, researchers, and policymakers working to enhance the durability of solar technologies.

The report further suggests that to address the issue of glass breakage in photovoltaic (PV) modules, the community should develop tools to measure the key risk factors. Suppliers and customers need to enhance communication about factors such as reduced glass strengthening, flaws at edges and surfaces, edge pinch, larger module areas with thinner glass without re-evaluating frame and mounting points, and contact between the glass and frame, with or without sand. Manufacturers should focus on reducing or eliminating these factors, while module buyers can mitigate risks by selecting products with fewer of these issues.

In conclusion, the cause of the recent glass breakage issue in photovoltaic (PV) modules is  likely due to a combination of several factors that may vary across different sites and products. Researchers are working on tests and characterisation methods to identify modules susceptible to breakage under low loads and continue collecting modules from affected plants to track any changes.