DuPont silicon PV single-layer laminate promises better adhesion and yellowing resistance

DuPont Photovoltaic Fluoromaterials developed a single protective layer solar backsheet technology, TPNext, that improves adhesion for crystalline silicon solar module encapsulants, resistance to UV light, and backsheet production throughput. John Trout, global technical manager at Dupont Photovoltaic Fluoromaterials, discusses the technology.

September 14, 2011 — DuPont Photovoltaic Fluoromaterials (NYSE:DD) developed a single protective layer solar backsheet technology, TPNext, that improves adhesion for crystalline silicon (c-Si) solar module encapsulants, resistance to UV light, and backsheet production throughput. The new laminate consists of Tedlar film, polyester, and an extrusion-coated tie-layer that reduces the use of organic solvent-based adhesives.

Photovoltaics World spoke with John Trout, global technical manager at Dupont Photovoltaic Fluoromaterials, about the technology (listen below). 

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DuPont faced technical challenges to improve adhesion to encapsulants, developing a tie layer that ensures adhesion between the backsheet materials and the EVA. This kind of adhesion is needed for both Tedlar-PET-Tedlar (TPT) backsheets with a Tedlar interlayer, as well as those with a TPE-type backsheet with a tie layer, explained Trout. (TPNext is a TPE-type backsheet.) ?The adhesion has to survive initial adhesion measures such as humidity-free cycling, damp heat, and thermal cycling, etc.,? explained Trout. The company performed the testing in its labs in China and Geneva to ensure a 25-year lifetime of the structure and adhesion.

Another challenge when developing backsheet laminates is that they have to have long-term stability when exposed to UV light. The company has done thousands of hours of accelerated aging tests (UV exposure) with no yellowing, said Trout.

Figure 1. The structure of a crystalline silicon solar cell.
Figure 2. The layered structure of the TPNext backsheet.

An extrusion-coated process is used to put down the tie layer. ?There are no solvents used, so it can typically be done at much greater line speed than traditional means to put down solvent-based adhesives,? said Trout. ?This results in enhanced productivity for the backsheet maker, and it?s a greener process.?

DuPont also signed a licensing agreement with Taiflex Scientific, which plans to use the new laminate in its Solmate backsheet. Trout ends the podcast interview with a discussion of the company?s relationship with Taiflex Scientific.

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