FEVE : Fluoroethylene Vinyl Ether Copolymer: what is it?
FEVE is the abbreviation of Fluoroethylene vinyl ether resin which is a copolymer 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 FEVE (Fluoroethylene vinyl ether)?
They developed Ether (FEVE) resins in the late 1970s in Japan and started being commercially available in the market in 1982. FEVE (Fluoroethylene vinyl ether) resins are amorphous A-B copolymers with repeating fluoroethylene units and substituted vinyl ether. FEVE resins possess both characteristics of hydrocarbons and fluoropolymers. The fluoroethylene groups are the main strength of the FEVE (Fluoroethylene vinyl ether) resin as they make it resistant to UV degradation.
FEVE (Fluoroethylene vinyl ether) use in solar panels
The Fluoroethylene vinyl ether resin provides different qualities that makes it a good backsheet material for solar panels, as it provides good qualities and decreases cost of manufacturing.
Moreover, FEVE backsheet has good mechanical strength, low cost and simple in manufacturing. FEVE resins are also environmentally friendly, is resistant to water absorption and has long-term weather resistance properties in outdoor exposure and makes FEVE backsheet resistant to UV degradation.
However, it has shown some quality issues for high temperature areas like inner layer cracking. As a result, this can lead to areas of corrosion.
Alternatives to FEVE
Clearly, Tedlar is a comparably expensive material and the high cost of Tedlar is one of the main factors all manufacturers try to reduce by using alternative materials or even introduce new panel types which require no Tedlar at all.
And common alternatives to FEVE are TPE (Tedlar/Polyester/Eva Film) and TPT (Tedlar/Polyester/Tedlar) backsheets among other combinations.
Furthermore, other companies like Arkema offers a Kynar – a fluoropolymer which provides surface protection with impressive longevity. That offers equal performance to the Tedlar (becoming harder to obtain).