Glass-foil modules with TOPCon cells

Glass-foil modules done right. A well-thought-out combination of encapsulation materials in a solar module prevents premature performance losses. Reports of problems with glass-foil modules and TOPCon cells have given this module type a bad reputation. The problems with this module configuration usually lie in an incorrect selection of encapsulation materials that do not take the specific characteristics of TOPCon into account.

Strong and sensitive TOPCon cells

Compared to PERC solar cells, TOPCon cells have a more complex structure. While this leads to higher efficiencies, it also makes the solar cell more vulnerable in some areas. Since 2022, there have been increasing reports of rapid performance loss in TOPCon glass-film modules.

Numerous scientific studies have shown that the metallization and contact surfaces on the front of TOPCon solar cells are particularly susceptible to moisture. This can lead to corrosion and a loss of electrical conductivity, which reduces the performance of the solar module.

Stability through modular design

By choosing the right material, the disadvantage of the sensitive TOPCon cells can be more than compensated for, even with glass foils. The front side of TOPCon cells is susceptible to corrosion, making it particularly important to select the optimal embedding material.

SOLYCO uses polyolefin elastomer (POE) on the front of the R-WF glass-foil module. Potting materials made of POE have a different chemical structure than the more commonly used ethylene-vinyl acetate (EVA). POE blocks moisture transport better, and its low polarity makes it more resistant to PID. For embedding on the back, optimized EVA, with its better adhesion to the backsheet, is the right choice. This layer structure combines the advantages of the various materials.

Abbildung 1: Langzeitstabilität von SOLYCO TOPCon Glas-Folien-Module

Abbildung 2: Aufbau von SOLYCO TOPCon Glas-Folien-Modulen

SOLYCO glass film TOPCon on the test bench

SOLYCO has tested materials and material combinations and offers TOPCon glass-foil modules that have outstanding properties in every respect.

Long-term durability - The Damp Heat Test (DH) is a standardized test for evaluating the long-term reliability and resistance of solar modules to external weather influences.

The standard permits a power loss of 5% after 1,000 hours of testing. In tests conducted by an independent testing laboratory, our TOPCon glass-foil modules exhibited only a 0.4% power loss after 1,000 hours, and only a 4.4% power loss after three times the test duration (3,000 hours). This means that SOLYCO TOPCon glass-foil modules exhibit comparable long-term stability to glass-glass modules.

Hail resistance - All SOLYCO modules are tested for hail impact resistance. The R-WF offers extra-high mechanical stability and, thanks to its 3.2 mm thick front glass, achieves hail resistance class 4. This means the module can withstand hailstones up to 40 mm in size and traveling at speeds of 27.5 m/s without damage. Glass-on-glass modules with thinner front glass typically only achieve class 3 or lower.

Efficiency - The combination of highly efficient TOPCon solar cells and a white backsheet enables a module output of 450 Wp. With a module area of less than 2 m², this corresponds to an efficiency of 22.5%.

Weight - As a glass-on-glass module, the R-WF is lighter than glass-on-glass modules with 2.0 mm front glass, despite its 3.2 mm front glass. The lower weight (21 kg) facilitates transport, handling, and installation, especially on roofs with low load-bearing capacity.

For those who place particular value on hail resistance, glass-foil modules offer an attractive option. Those who also appreciate the higher efficiency of TOPCon solar cells compared to PERC cells will find the SOLYCO TOPCon glass-foil module R-WF 108n.4/450 the optimal solution.