Polyolefin Elastomer (POE) film is a crucial component in solar photovoltaic (PV) modules. It acts as a protective layer between the solar cells and the environment, providing electrical insulation, weather resistance, and impact resistance. The production method of POE film is a complex process that involves several stages. In this article, we will explore the production method of POE film for solar PV modules, along with its applications.
The production of POE film involves the following stages:
Polymerization: POE film is made by polymerizing ethylene and an alpha-olefin, such as propylene, butene, or hexene, using a metallocene catalyst. The catalyst is used to control the polymerization process, resulting in a specific molecular weight and composition. The polymerization is carried out in a reactor at high temperature and pressure.
Extrusion: The polymerized POE is then extruded into a thin film using a blown film process or a cast film process. In the blown film process, the extruded material is inflated like a balloon to form a tube, which is then flattened and wound onto a roll. In the cast film process, the extruded material is cooled on a chilled roller to form a flat sheet, which is then wound onto a roll.
Coating: The POE film is then coated with a layer of adhesive to improve its adhesion to the solar cells. The adhesive layer can be made of EVA (ethylene vinyl acetate), which is the most common material used in solar PV modules, or other materials such as TPU (thermoplastic polyurethane) or silicone.
Lamination: The POE film is then laminated onto the solar cells using a hot press. The lamination process involves heating the solar cells and the POE film under pressure, which activates the adhesive layer and bonds the two together. The lamination process also helps to remove any air pockets or wrinkles that may have formed during the assembly process.
POE film is used in solar PV modules as a backsheet, which is the outermost layer of the module that faces the environment. The backsheet protects the solar cells from moisture, UV radiation, and mechanical damage, and also provides electrical insulation. POE film is an ideal material for backsheet applications due to its excellent weather resistance, impact resistance, and electrical properties.
POE film is also used as an encapsulant in some types of solar PV modules. Encapsulants are materials that surround and protect the solar cells, providing both electrical insulation and mechanical support. EVA is the most common material used as an encapsulant, but POE film has some advantages over EVA, such as better weather resistance and lower water vapor transmission rate.