1. PVB and EVA
EVA requires two layers; it is pressurized at high temperature by a laminator and becomes one after cooling, which plays a role in fixing and bonding.
PVB is a building material with much better weather resistance, but the price is more than three times that of EVA. EVA is the mainstream of single crystal silicon packaging. For amorphous silicon, we choose PVB for packaging.
2. The difference between TPT, PET and DNP.
In order to maintain the best working condition of solar cells and maintain a service life of 25 years, the backsheet material used must have properties such as UV resistance, water vapor barrier, and weather resistance. TPT, PET, and DNP are just synonyms for solar cell back films, which play a very good role in protecting solar cells.
Solar cell back films are mainly divided into two categories: fluorine-containing back films and fluorine-free back films. Among them, the fluorine-containing back film is divided into two types: double-sided fluorine-containing (such as TPT) and single-sided fluorine-containing (such as TPE); while fluorine-free back film is mostly made of multiple layers of PET glued together with adhesive.
TPT refers to using DuPont’s TEDLAR (trade name) PVF film as both sides of the solar back film, and adding a layer of transparent PET in the middle for lamination, that is, TEDLAR PET TEDLAR, hence the name TPT.
The fluorine-free back film composed of multiple layers of PET glued together with adhesive cannot meet the 25-year environmental test of humid heat, dry heat, ultraviolet and other environmental tests of commercial crystalline silicon solar cell modules due to the characteristics of the material itself. With the use requirements, it is difficult to be suitable for the packaging of crystalline silicon solar cell modules.
The outermost layer of the DNP backsheet is made of PET with excellent water resistance, followed by DNP's unique highly durable adhesive layer, which ultimately achieves the product's excellent durability.
Generally, companies use EVA PET.