In lightweight and flexible solar modules, traditional glass front covers are being substituted with polymer-based frontsheets
High-reflective black backsheets and non-metallic reflective gap films boost module performance by enhancing infrared and light reflectance
Companies like Fumotech are introducing composite polymer frames that offer greater durability and cost savings over traditional aluminum
As solar technology evolves to meet the demands of specialized applications, manufacturers are exploring new materials to enhance module design. One such emerging requirement is for lightweight and flexible modules, where traditional glass front covers pose limitations. In this context, backsheets are being repurposed under a new name – frontsheets. While glass has largely replaced backsheets in standard module configurations, a reverse trend is emerging in niche segments, with backsheet materials now substituting glass on the front side. Several suppliers are introducing polymer-based frontsheets, offering advantages such as reduced weight, improved flexibility, and enhanced durability, making them well suited for next-generation solar applications. Ethylene Tetrafluoroethylene (ETFE) reinforced with glass fiber, which offers durability, is one of the options. Additionally, KPC and TPC structures are used either alone or in laminated form with glass fiber to enhance impact resistance, although the laminated variants tend to be more expensive.
High-reflective black backsheets are also an interesting topic in the backsheets segment. Bo Jin, Overseas Sales Manager at HANGZHOU FIRST, presented one such solution for BC modules at the TaiyangNews High Efficiency Solar Technologies Conference 2024 (watch here). These backsheets combine black cell-side coatings with white or black airside coatings of PET, achieving over 60% infrared reflectance. Field applications in China have demonstrated power generation improvements of 2.25%-2.62% compared to standard black backsheets. The company also offers PI cover strips designed to conceal interconnection wires in BC modules, available in black or white to match module aesthetics. Other leading backsheet suppliers, such as Cybrid, HANGZHOU FIRST, and Coveme, are also offering such reflective black backsheets (see Hangzhou First Offers F806WH With High Infrared Light Reflectivity).
Reflective gap films: To eliminate energy losses caused by light passing through transparent cell gaps of bifacial modules, the industry has developed a so-called grid or patterned rear cover. Backsheet and glass manufacturers offer tailored products that remain transparent where cells are placed, while the inter-cell spacing is printed with a white reflector. However, during his presentation, Jacob Harris, Overseas Account Manager at Cybrid, emphasized that the screen printing process used for these films leads to uneven heat distribution during glass processing, which has been identified as one of the root causes of module cracking in the field.
To overcome this issue, companies like Cybrid are offering reflective gap films that eliminate the need for pre-printed patterns on glass. These films can be directly applied to glass or backsheets during module fabrication. Traditionally, metallic gap films have been widely used. Cybrid, however, now provides non-metallic gap films in both white and black. While metallic gap films remain a viable option, they are more expensive, whereas non-metallic alternatives are more cost-effective while maintaining comparable performance benefits. Harris outlines the structure of Cybrid’s white nonmetallic gap film, which includes a high-reflectivity top coating, a PET base layer, an additional coating, and an EVA layer for easy lamination. This film achieves 82% reflectivity in the 400 to 1,000 nm wavelength range. The black nonmetallic gap film follows a similar structure but offers 62% reflectivity. These films can be applied to the glass through a fully automated process.
Overall, backsheet companies are leaving no stone unturned. They are leveraging years of polymer know-how developed for solar-related applications to create innovative solutions. One such application is the composite frame. Fumotech, once a leading PVDF supplier, has expanded its portfolio beyond polymer frontsheets to also develop composite frames. The company claims that its products are, of course, more cost-effective, and offer better durability than aluminum frames on top. Fumotech has established a gigawatt-scale production capacity for these composite frames.
The text is an excerpt from the latest TaiyangNews Market Survey on Backsheets & Encapsulation Materials 2024/25, which can be downloaded for free here.