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TPOT: Tedlar-PET-Oxide-Tedlar: what is it?

  TPOT is the abbreviation of Tedlar-PET-Oxide-Tedlar film which is a composite layer film that is used as a backsheet material in solar modules.

Backsheet material

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.  

Tedlar-PET-Oxide-Tedlar use in solar panels

The main factors affecting the aging of PV modules include corrosion of metal materials, delamination of encapsulant polymers and physical damage from external environmental weather conditions like wind, rain and snow. TPOT provides good mechanical properties against that as it has good mechanical strength, good adhesion and electrical isolation from the metal frame. These properties guarantee better performance and longevity of the solar panel which can make the performance decrease due to ageing much lower. Yet, as with all other polymer backsheets, TPOT has a higher cost than other backsheet alternatives due to the high cost of Tedlar and the more complex manufacturing process.   Alternatives to TPOT (Tedlar-PET-Oxide-Tedlar) backsheet For the backsheets, a variety of materials and substructures can be used, including the whole range of Tedlar based polymers, PET  (polyethylene terephthalate) or  PEN (polyethylene naphthalate) based polymers. The Tedlar based backsheets include: TPT, TPE, TAT and TPAT PEN/Al foil/PET (PAP). PET or PEN based backsheets provide less expensive alternatives to Tedlar. Glass is also sometimes used to replace polymer backsheets to provide a much cheaper option with lower properties.  
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