TPE: Tedlar– PET– EVA film: what is it?
TPE (Tedlar– PET– EVA) is the abbreviation of Tedlar Polyester EVA film which is a composite layer film that is used as a back sheet material in solar modules.
The backsheet consists of multiple layers of barrier films and adhesives. The construction of the backsheet is instrumental in protecting the solar cells from different environmental conditions like moisture, UV exposure and other performance threats while also improving solar module efficiency by aiding the reduction of partial discharge. To accomplish this, the solar panel material should be of a robust construction, typically a three layer laminate, and possess high dielectric properties. Most backsheets consist of combinations of films chosen for their different properties. Examples of standard films include: PET or EVA, Tedlar and Kynar. Combinations can be TPT (Tedlar/PET/Tedlar), KPK (Kynar/PET/Kynar) or PPE (PET/PET/EVA) among other combinations
What is Tedlar?
Tedlar is the brand name of DuPont (American chemical company) and it refers to Polyvinyl fluoride (PVF), which is a thermoplastic fluoropolymer material that features high resistance to weather conditions and inherent strength, low permeability of moisture, vapor, oil and a wide temperature operation range (-70°C to +110°C).
Also Tedlar allows for a high degree of light spectrum permeability when transparent.
TPE (Tedlar– PET– EVA) use in solar panels
The Tedlar Polyester Eva material combination highly improves the material qualities of Tedlar and this is the reason it is used as backsheet for solar panels, as it enhances the panels longevity and adhesion and also lower cost.
TPE ( Tedlar– PET– EVA) is one of the most common polymer multi-laminates for solar panels as there are only very few materials which have comparable material qualities.
In the design of traditional solar cells, TPE along with the glass layer on the front side are the key barriers against damaging all external exposure elements, most importantly water, vapor and dirt.
Alternatives to TPE (Tedlar– PET– EVA)
Tedlar is a comparably expensive material and cost is one of the main factors all manufacturers try to reduce by using alternative materials or even new panel types which require no TPE at all. Common alternatives to TPE are TPT (Tedlar/Polyester/Tedlar) among other combinations.
Other companies like Arkema offers a Kynar – a fluoropolymer – that offers equal performance to the Tedlar (becoming harder to obtain). Kynar provides surface protection with impressive longevity and it quickly proved a popular alternative in both single- and double-layer constructions and it is used to produce combinations like KPK (Kynar/PET/Kynar)