Solar Modules Under Pressure: What Field Experience Reveals About Glass Breakage

As photovoltaic installations continue to grow in scale and complexity, long-term module reliability is receiving renewed attention. In recent years, field experience across different markets has shown an increasing number of cases where glass breakage occurs without obvious external impact. While such events were once considered isolated, they are now prompting a broader discussion about design choices, materials, and quality control in modern solar modules. 

At BISOL, long-term performance has always been a central design criterion. Observations from the field confirm why this focus is becoming more important than ever. 

The drive for lighter and larger modules 

To meet growing global demand and reduce system costs, the industry has increasingly moved toward larger and more powerful modules. One consequence of this trend has been the reduction of module weight, often achieved by using thinner glass. 

Lower weight can simplify logistics and reduce structural loads. However, glass accounts for a significant portion of a module’s mechanical strength. As glass thickness is reduced, modules become more sensitive to mechanical and thermal stresses encountered throughout their lifecycle, from manufacturing and transport to installation and long-term operation. 

Fragility is often revealed over time 

Independent test programmes and field feedback increasingly show that reduced safety margins can translate into higher fragility. Cracks or breakages sometimes appear shortly after installation, even in the absence of extreme weather or external impact. 

These failures are rarely immediate. Microcracks, often invisible during standard inspections, can propagate gradually due to temperature changes, humidity, or mechanical load. Over time, this can lead to sudden glass breakage, water ingress, insulation failures, reduced availability, or in some cases safety risks for personnel. 

From a project perspective, such failures result in production losses, replacement costs, additional labour, and increased operational risk. 

Limitations of standard testing 

Current certification protocols are designed to ensure basic robustness under defined laboratory conditions. However, modern modules with large formats and thinner materials are exposed to a wider range of combined stresses in real-world environments. 

Field experience suggests that standard tests do not always capture the cumulative effects of transport, handling, installation, temperature cycling, and long-term exposure. This has led to increased discussion within the industry about extending test sequences and quality controls to better reflect real operating conditions. 

Why quality control matters more than ever 

In this environment, relying solely on certifications or warranty statements is no longer sufficient. Developers, installers, and investors increasingly recognise the importance of rigorous quality control throughout the supply chain. 

Effective risk management includes: 

• controlled material sourcing, 

• stable lamination processes, 

• traceable production conditions, 

• sampling and inspection beyond minimum requirements, 

• and careful monitoring of logistics and handling. 

Glass quality in particular requires close attention, as small surface defects or uneven stress distribution can significantly affect long-term durability. 

BISOL’s approach to durability 

At BISOL, durability is not treated as a market trend but as an engineering responsibility. Our module designs prioritise mechanical robustness, conservative material choices, and stable production processes over aggressive weight reduction. 

This approach is supported by: 

• European manufacturing with full process control, 

• extensive mechanical and environmental testing, 

• proven glass-backsheet architectures with long field history, 

• and traceability across materials and production batches. 

The result is predictable long-term behaviour under real operating conditions. 

Proven behaviour in the field 

Long-term reliability is best demonstrated through operation, not assumptions. One of BISOL’s earliest photovoltaic systems, installed at our production site in Slovenia, has been operating continuously for more than 20 years. Periodic measurements confirm degradation levels well below standard industry assumptions, reflecting stable materials and disciplined manufacturing choices. 

Such references provide valuable reassurance for projects where long-term performance and risk management are critical. 

Choosing durability over trends 

Selecting a photovoltaic module is not about following construction trends or chasing marginal cost reductions. It is about understanding how design decisions affect behaviour over decades. 

In a market where project profitability increasingly depends on reliability, durability is not a feature. It is a prerequisite. 

BISOL designs photovoltaic modules to perform reliably in the field, not just on paper.