TAT is the abbreviation of Tedlar- AI Foil -Tedlar film which is a composite layer film that is used as a backsheet 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.
TAT (Tedlar- AI Foil -Tedlar) use in solar panels
The Tedlar- AI Foil -Tedlar 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.
TAT backsheet provides a range of properties as it has good mechanical strength compared to other common backsheet materials, lower cost and simpler in manufacturing. Also the Tedlar- AI Foil -Tedlar combination has really low Water Vapor Transmission Rates (WVTR) which makes it withstand different exposure conditions in outdoor environments. Yet TAT has a higher cost than some backsheet alternatives due to the high cost of Tedlar.
Alternatives to TAT (Tedlar- AI Foil -Tedlar)
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 TAT (Tedlar- AI Foil -Tedlar) are the commonly used TPT (Tedlar/Polyester/Tedlar) and TPE (Tedlar/Polyester/Eva Film) backsheets 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).