Polyolefin: composition and application
Polyolefin is a film which is used as a back sheet material in solar modules.
The backsheet of a solar module consists of multiple layers of barrier films and adhesives. The backsheet construction 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, usually a three-layer laminate, and it should 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 Polyolefin?
It is a type of polymer which is produced from a simple olefin as monomer. Polyethylene for example is a polyolefin produced by the polymerization the ethylene olefin. Most polyolefins produced are made via polymerization with the use of catalysts.
It is mainly used in products like blow or rotationally moulded components, for heat shrink tubing used to protect cables in electronics, seat cushions, tennis racket strings and for rash guards along with use in solar panel backsheets.
Polyolefin use in solar panels
Polyolefin use in the solar module backsheets became popular in manufacturing of thin film solar PV modules. It has excellent chemical resistance. Also, it is extremely inert chemically but exhibit decreased strength at lower and higher temperatures
This ability to withstand UV loads, and contact with chemicals makes the use of polyolefin thermoplastic as a core layer help in providing an excellent moisture barrier to the module, as well as producing high reflectivity and good hydrolic stability.
Furthermore, according to recent studies, this backsheet is used in nearly 10% of the produced modules. As a result, this percentage corresponds to a backsheet market share of around 17%.
Alternatives to Polyolefin
Different types of backsheet are commercially available and types are being researched and produced.
New backsheet made up of glass/ glass layer package designs are used primarily to decrease packaging costs. These new designs benefit from the simplification of the package and manufacturing process while they suffer in the different quality aspects which are provided by the more expensive backsheet material TPT and TPAT among other combinations. Moreover, other famous alternatives are Tedlar and Kynar based backsheets.