EXXOSQEL GmbH and the Fraunhofer Center for Silicon Photovoltaics CSP have developed a glass-glass photovoltaic module. The module's front and rear glass panes are each 1 mm thick. This was reported by Fraunhofer CSP.
To strengthen the thin glass, the developers applied a reactive coating. It compensates for the glass's lower mechanical strength and rigidity. The team sees this design as suitable for lightweight solar modules, including building-integrated photovoltaics (BIPV).
Reducing the glass thickness cuts material use and module weight. It could also reduce transport and installation costs. At the same time, thinner glass has lower mechanical strength and is more prone to deflection.
The front glass must protect the module components during hailstorms and other extreme weather events. The developers therefore need to combine a low glass thickness with sufficient mechanical resistance.
Fraunhofer CSP and EXXOSQEL produced a 300 × 200 mm prototype glass-glass module. The front and rear glass are each 1 mm thick.
The module uses standard encapsulation materials. The team also connected quarter-cut bifacial M6 PERC solar cells with nine busbars in series. Each quarter cell delivers approximately 1.58 W of power.
A key element of the development was EXXOSQEL's multi-component reactive coating. It is applied directly to the glass surface.
The coating reacts with hydroxyl groups on the glass surface. Microcracks form in the glass during cooling and hot forming. The coating forms covalent bonds with the glass matrix and bridges gaps in the microcracks. This increases the surface strength.
The developers matched the optical properties of the coating to those of the glass. In this way, they aimed to minimise losses in light transmission and the coating's impact on module efficiency.
To produce the prototype, the team adapted the manufacturing process to the ultra-thin glass. The module was produced using a standard photovoltaic module laminator. The specialists adjusted the temperature, pressure and equipment configuration, explained Fraunhofer CSP project manager Ringo Köpge.
The prototype is approximately the size of an A4 sheet of paper. Further tests are intended to determine whether the design will retain the required mechanical resistance in full-size modules when subjected to hail impacts.
According to EXXOSQEL CEO Thomas C. Sauer, using thinner glass could reduce module weight by up to 40%. Manufacturers could also potentially reduce energy consumption and CO₂ emissions associated with material use.
According to Sauer, manufacturers could integrate the coating application into existing glass manufacturing or processing operations.
In the next phase, the team plans to transfer the technology to full-size modules and conduct hail resistance tests. The developers cite lightweight modules, printed front glass and building-integrated photovoltaics among the potential applications.
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