New coating technology for solar glass

The company Exxosqel, a subsidiary of Exxergy, has developed a new coating technology meant to improve the mechanical strength of solar glass. This technology was created in collaboration with the Fraunhofer Institute for Silicate Research (Fraunhofer ISC), and early tests suggest it could reduce the weight of the glass by up to 40% without compromising its strength.

Weight reduction in solar modules

Currently, glass makes up between 70% and 80% of the total weight of a photovoltaic module, which typically weighs between 11 and 13 kg per square meter. Some heavier designs can reach about 16 kg per square meter. Reducing the glass thickness could lower the use of raw materials, energy consumption, and emissions, while also making transport and installation easier.

Addressing microcracks in glass

This technology targets a major issue in flat glass: microcracks that form during manufacturing and handling. Rather than just covering surface defects, the coating is designed to penetrate these cracks and change their mechanical properties, making the glass more resistant to breaking.

How the coating works

The process uses a multicomponent composite material that forms a three-dimensional network. Once applied, the coating creates covalent bonds inside the microcracks at the molecular level. This slows crack propagation and increases the energy needed to break the glass.

Testing results show strong improvements

Laboratory tests have shown significant improvements in mechanical strength. After adjusting the material and application process, 2 mm thick glass samples showed four times the resistance of a non-tempered reference sample. For 1 mm thick samples, the resistance was seven times higher.

Limitations of conventional methods

Thermal tempering is a common method for strengthening glass, but it becomes less effective as glass gets thinner. A standard thickness of 3.2 mm is typical in photovoltaic modules, but achieving sufficient strength with glass 2 mm or less is difficult using traditional methods.

Alternative strengthening methods

Chemical strengthening through ion exchange is another option, involving replacing sodium ions on the glass surface with potassium ions to create compressive stress. While this method works on thin glass and causes fewer optical distortions than thermal tempering, it is more complex and energy-intensive. Exxergy's technology instead focuses on targeting microscopic defects directly.

Scaling the technology

The main challenge now is scaling the technology for industrial use. So far, the development has focused on small glass samples. The next step is to test larger formats before moving to standard-sized commercial photovoltaic modules.

Collaboration and next steps

Exxergy and the Fraunhofer ISC are working to increase material synthesis capabilities, improve coating application, and automate the process to integrate it into existing production lines. The Fraunhofer ISC brings expertise in material synthesis and coating technologies, with capabilities reaching up to 100 liters in volume.

Current technological maturity

According to Exxergy, the technology has reached technological maturity level 6 (TRL 6). The company has produced standardized prototypes under conditions close to real-world use, and load resistance tests are ongoing. The next goal is to reach TRL 7 by validating the coating in an operational environment.