PEN is the abbreviation of Polyethylene naphthalate film which is a material used in production of composite layer film which 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 PEN?
PEN is the Polyethylene naphthalate. PEN (Polyethylene naphthalate )resin became popular in many industries after U.S. company Amoco Chemicals started commercial producing of NDC (naphthalenedicarboxylic acid) , a raw material of the PEN resin, in 1995. PEN is manufactured in a similar process to that of PET (polyethylene terephthalate), another typical polyester used commonly as a backsheet in solar panels. PEN is used in solar panels as backsheet material, besides that it is used in other products as bottles, plateware, containers and medical product containers. PEN is commonly used in products that require transparency, chemical and heat resistance
PEN based backsheets use in solar panels
PEN based backsheets are used more and more commonly as back sheet material. PET or PEN-based material are used by manufacturers to replace the more expensive Tedlar-based material. PEN based backsheets have many properties that makes suitable to use as backsheet materials, mainly high transparency, higher thermal resistance compared to PET-based products, long lifetime and high chemical resistance. It also has good mechanical strength and low permeability.
Among newer outer layer backsheet materials, those based on polyesters such as PEN and PET are among the most prominent. Collectively, non-fluoropolymer backsheets constituted nearly 60% of the global backsheet PV market by area in 2014 (Global Market Insights, 2017).
Backsheets approximately cost $2 to $7/m2, which makes around 3% to 5% of the total module cost. The more expensive fluoropolymer-based like PVF, PVDF, ETFE, THV while the less expensive non-fluoropolymer-based backsheets are PET, PEN, PP, PA.
On the other hand, Fluoropolymer backsheets (PVF, PVDF, ETFE, THV) can withstand weather conditions quite well, even after years. Non-fluoropolymer backsheets (PET, PEN, PA, PP) tend to be more susceptible to environmental degradation.