A new glass coating technology developed by Exxosqel and Fraunhofer CSP could enable thinner, lighter PV modules by improving glass strength and reducing material use.
A newly developed glass-coating approach created by Exxosqel in collaboration with Fraunhofer CSP has the potential to support the production of thinner and lighter photovoltaic modules by increasing the strength of glass while reducing the amount of material required.
Germany’s Fraunhofer Center for Silicon Photovoltaics (Fraunhofer CSP), together with startup Exxosqel GmbH, is working on a thin-glass solar module that relies on a proprietary coating to offset the lower mechanical strength typically associated with thinner glass covers.
“The developed thin-glass module is currently only a showcase demonstrator,” Fraunhofer CSP scientist Ringo Köpge told pv magazine.
The demonstrator module features front and rear glass sheets that are each 1 mm thick, producing an overall glass surface measuring 300 mm × 200 mm. It uses conventional encapsulation materials found in standard PV modules and integrates quarter-cells derived from bifacial M6 9-busbar PERC cells. These quarter-cells are wired in series, with each individual cell generating roughly 1.58 W.
“The module was manufactured using a standard PV laminator, with modifications to process parameters including temperature, pressure, and system setup,” Köpge said.
The coating itself is characterized as a reactive, multi-component surface treatment that is deposited directly onto the glass. It chemically interacts with hydroxyl (Si–OH) groups that are present on damaged glass surfaces and within microcracks, forming covalent bonds with the underlying glass structure.
Exxosqel explained that this chemical interaction partially repairs microcracks, decreases surface brittleness, and enhances the mechanical strength of the glass. The crosslinked composite layer produced by the process is engineered to remain transparent, retain long-term chemical durability, and match the refractive index of glass so that optical losses are kept to a minimum.
“Inspired by the structure of abalone shells, where small amounts of organic material dramatically increase toughness, the coating creates a stronger composite surface while maintaining transparency and durability,” Exxosqel CEO Thomas C. Sauer told pv magazine. “The technology can be integrated into existing glass production or finishing processes and may enable thinner, lighter glass products without compromising mechanical performance.”
The company has not released additional information regarding the chemical formulation of the coating.
According to laboratory testing performed by Exxosqel, the coating substantially increases glass strength. Test results indicate that 2 mm glass samples improved from 79 MPa to 364 MPa, while 1 mm glass samples rose from 184 MPa to more than 1,300 MPa. The company also estimates that using thinner glass substrates could cut material requirements, lower energy use, and reduce carbon emissions by allowing module weight reductions of as much as 40%.
“The special coating process is not limited to the demonstrator module and can also be applied to standard solar modules,” Köpge said.
Fraunhofer CSP stated that applying the coating to ultra-thin glass may offer benefits for applications including building-integrated photovoltaics (BIPV), particularly lightweight module designs and products incorporating printed front glass covers.
The technology may also contribute to lowering photovoltaic module production costs by making it possible to use thinner glass, thereby reducing material consumption, decreasing module weight, and cutting transportation and handling expenses. At the same time, reducing glass thickness introduces questions regarding long-term mechanical durability in real-world operating conditions, especially during severe weather events such as hailstorms.
A recent study conducted in India suggested that PV modules equipped with 3.2 mm-thick front glass may not provide sufficient resistance during storms involving large hailstones. The researchers concluded that front glass should be at least 4 mm thick to prevent substantial damage.
“The common belief is that that reducing glass thickness is inherently incompatible with sufficient hail resistance. This is precisely the conventional limitation that our technology is intended to overcome,” Sauer said. “Our approach uses an entirely different strengthening mechanism and is intended to decouple mechanical performance from the conventional glass-thickness limitation. Testing the hail resistance of full-size modules is one of the next important development steps. Based on the mechanical results obtained so far, we are optimistic, but naturally the large-scale module testing still needs to provide the necessary evidence.”
Originally reported by pv magazine India on Jul 20, 2026.
