GroundWork® Identifies Direct Correlation Between Larger PV Modules and Increased Breakage: The Risks of Thin Glass and Frames
The demand for larger photovoltaic (PV) modules in solar energy systems has been steadily rising, with the expectation that these modules would provide enhanced efficiency and power output. However, as module size increases, an unintended consequence has surfaced, increased fragility. Recent findings from GroundWork® research suggest a direct correlation between larger module sizes and a significant reduction in mechanical strength, especially due to the thinning of glass and frame materials, leading to higher failure rates under mechanical stress.
The Shift in Design: Larger Modules, Thinner Frames, and Glass
As module designs have evolved with time, they have increased by 40% to 60% in size, and the materials used to construct them have become thinner. Frames have been reduced from 40mm to 30mm, and in some cases, as small as 25mm. The glass, once 3.2mm thick and tempered, has been reduced to 2.0mm heat-strengthened glass. While these design changes allow for larger modules, they also compromise structural integrity.
This shift is showing a clear impact. Failures have risen from 0% in 2018 to approximately 30% between 2021 and 2024. Not only has the failure rate increased, but fielded mechanical failure related projects are up 300% since 2018, underscoring a troubling trend in module durability.
Understanding the Test Results
As modules continue to grow in size and glass and frame thicknesses decrease, the rate of breakage pressure in laboratory tests has dropped by up to 70%. Larger modules paired with standard center clamps tend to exhibit a broader and more inconsistent distribution of breakage pressure, meaning the risk of failure becomes more unpredictable. This is concerning as modules that are near the low end of the breakage spectrum may be close to the required design load, leading to a higher likelihood of failure in the field under normal operating conditions.
In contrast, the modules from 2018, which featured thicker frames and glass, showed more consistent performance, with breakage pressures exceeding required test standards and almost never breaking under normal operating conditions.
Field surveys show an average breakage rate 1-2% of a module population for susceptible modules. While this is a small percentage of the total, a single broken module in a string can trip an inverter, causing significant power disruptions. Some PV plants report approximately a 30% reduction in total power output from a module failure rate of just 2%.
Key Takeaways and Future Research Directions
Data collected shows that as module size increases, mechanical strength decreases, and the risk of failure becomes more pronounced. It was also noted that frame height and glass thickness are key contributors to module strength. The research concluded that, on average, larger modules with 2.0mm glass are approximately 70% weaker compared to 2-meter modules with 40mm frames and 3.2mm tempered glass.
To know if your modules are at risk, GroundWork® recommends our test-to-failure mechanical load test, which determines the maximum pressure a module can withstand and can provide insight into mitigation strategies. For example, if the ratio of the standard deviation to the mean for the test to failure pressure for a sample of modules exceeds 3.5% and the mean is less than 30% of the test load, higher safety factors and more robust clamping systems may be required to prevent module failure in the field.
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