Top 5: Factors Responsible for Glass Breakage in Solar Modules

Glass breakage is a growing concern for the solar power plant operators. With the trend  towards double glass sided modules as seen in Bifacials, or TOPCon with double glass sided construction, the changes in solar PV module design and materials mean breakages are now a bigger risk than ever. These breakages can be due to many reasons and no single factor bears the sole responsibility of operators’ woes.

NREL, a national renewable energy laboratory of the US Department of Energy Office of Energy Efficiency & Renewable Energy, notes that many instances have come forth of PV module glass breaking with no obvious cause – spontaneous breakage. 

Why is Solar Glass Breaking More Often?

Glass on solar panels protects the internal components, keeps out dirt and moisture, and maintains electrical insulation. Earlier, glass breakages were mostly due to clear causes. Impact due to hailstones, wind-blown debris, or even human-caused incidents like vandalism have been one of the common causes.

Further, manufacturing defects like tiny imperfections in the glass or structural weaknesses introduced during production also contributed to the mishaps. Electrical faults like overheating due to faults like series arcs, reverse-bias conditions, or hot spots also were among the major factors.

However, cases of spontaneous glass breakage without a clear cause are now more pronounced too. Unlike traditional breakage patterns that originate from a specific impact point, these fractures appear with no apparent external stress and often follow unusual crack patterns.

Factors Contributing to Glass Breakage

Several interrelated factors increase the risk of glass failure in modern solar panels. These range from technological advancements to designing issues which become genesis of breakages.

#1 Thinner Glass in PV Modules

In a highly competitive solar industry, cost of production, handling, and installation gives the business an edge over competitors. Modern PV modules often use thinner glass to reduce weight and material costs. As per NREL study, while panels commonly used 3.2-mm-thick glass earlier, modern double-glass modules often feature 2-mm glass.

Although 2-mm glass can be fully tempered for increased strength, it is naturally more fragile than thicker glass. The reduced thickness affects how glass distributes stress, making it more prone to cracking due to minor defects. Additionally, thin glass has a shallower compression zone, meaning even small flaws can propagate more easily into full breakage.

Possible Solutions:

Using high-quality tempered glass with surface compression levels that meet or exceed industry standards can be one possible solution. As per NREL, though, 2-mm glass in PV modules does not yet meet the criteria for fully tempered safety glass. 

Other solutions may include increasing the surface compression in thinner glass to improve its fracture resistance. Additionally, heat treatment methods need optimization to ensure that fully tempered thin glass maintains the same compression levels as thicker glass. Further, strengthened edge treatments may help reduce vulnerabilities at stress points.

#2 Edge and Surface Flaws

Glass strength depends on tiny imperfections on its surface and edges. During manufacturing, cutting, handling, and transportation, small defects—often microscopic in size—can form.

When pressure is applied to the glass, these flaws act as stress concentrators, causing cracks to form and spread more easily. Thin glass is particularly susceptible because its compression zone is smaller, making even minor surface defects more impactful.

Possible Solutions:

To keep the glass safe, manufacturers should improve edge treatment techniques. Studies show that heat-strengthened glass typically has moderate surface compression, while fully tempered glass has high compression that helps prevent cracks. 

Using better edge polishing methods could minimize micro-cracks that develop during cutting and handling. Moreover, ensuring quality control during the glass finishing process can help reduce the presence of large flaws that make glass easier to break. Furthermore, Improving handling and packaging methods to prevent damage before installation is always better.

#3 Edge Pinch During Lamination

Double-glass PV modules undergo a lamination process, where two sheets of glass encase the solar cells. During this step, heat and pressure bond the materials together. If the process is not precisely controlled, edge pinch can occur—where the glass edges become compressed unevenly, creating built-in stress. 

This stress weakens the glass structure, making it more likely to break, even under normal operating conditions. Over time, external pressures such as temperature changes or wind forces can trigger sudden and unexpected fractures. Power plants have reported that PV modules with substantial edge pinch experience spontaneous breakage more often than those without.

Possible Solutions:

A key solution to this problem is using spacers during lamination to ensure uniform glass thickness. The thin-film PV industry has used this technique successfully for decades, but many crystalline silicon module manufacturers still struggle with edge pinch. Testing for internal stresses after lamination could also help detect modules that are at higher risk of breakage.

#4 Larger Panel Sizes Without Structural Reinforcement

The solar industry is shifting towards larger PV modules to maximize energy output and reduce costs. Earlier, panels were around 2 sq.m, while modern panels exceed 3 sq.m. These larger modules, while beneficial for maximizing power output, introduce new challenges.

When wind or snow loads apply pressure, larger modules experience greater total stress. The problem worsens when mounting structures remain unchanged, as older mounting designs may not adequately support larger panels. 

There is also a higher likelihood of deflection under pressure. Without proper reinforcement, larger panels can become structurally weak, leading to higher breakage rates. Modules that are mounted incorrectly or have insufficient support points are especially at risk.

Possible Solutions:

One approach to mitigate this risk is redesigning module frames to provide extra rigidity. Some manufacturers have kept the same frame extrusion size despite increasing module dimensions, leading to what experts call “big floppy modules.” 

Increasing mounting points and ensuring frame deflection remains minimal can reduce stress concentrations that contribute to breakage. Additionally, research suggests that glass thickness plays a crucial role in preventing excessive deflection under pressure.

Manufacturers should test frame and mounting designs specifically for XXL-sized panels to ensure they can withstand increased loads. Using high-strength aluminum frames to prevent excessive bending under wind loads can be helpful.

#5 Contact Between Glass and Frames or Trapped Debris

PV module glass should never be in direct contact with metal frames, as even small vibrations and movements can cause cracks over time. Additionally, debris such as sand and dust can become trapped between the frame and glass, leading to abrasion and micro-fractures. 

Studies have found that contact between glass and frames is linked to spontaneous breakage in some PV modules.

Possible Solutions:

A recommended solution is using rubbery silicone spacers which maintain separation between the glass and the frame. Many modules already use silicone gaskets, but some designs leave gaps where the glass directly touches the metal frame. 

Ensuring that the entire perimeter of the glass is properly cushioned can prevent localized stress buildup. Power plant operators should also regularly inspect PV modules for signs of debris accumulation and clean frames to prevent sand-related abrasion.