What are the components of a photovoltaic module?
Photovoltaic modules are classified based on the materials used, including inorganic backplanes such as glass and polymer organic backplanes. If the backplane is also made of glass, it is called a bifacial module; otherwise, it is a monofacial module. The glass on one side of the module faces the sun, while the backplane is located on the back of the module.
In recent years, with the development of battery technology, bifacial cells, which can generate electricity from both sides, have significantly improved power generation efficiency, leading to the emergence of bifacial modules. The backplane is the outermost layer on the back of the photovoltaic module, which is in direct contact with the external environment. To be suitable for a variety of climatic conditions, the backplane must meet multiple performance requirements. It is difficult for a single material to meet these demands, so backplanes are typically made from composite structures. In these structures, PET film is used as the base material, with fluorine films or other plastic films adhered to both sides of the base film using adhesives.
PET film has excellent insulation and mechanical properties but poor weather resistance. Fluoropolymer films, including polyvinyl fluoride (PVF) film and polyvinylidene fluoride (PVDF) film, offer excellent insulation, weather resistance, and barrier properties. The primary role of the adhesive is to bond the PET base film with the fluorine film or polyethylene films.
Based on the manufacturing process, backplanes are divided into composite and coating types. In composite backplanes, fluorine films are bonded (usually pressed) onto the PET base film with adhesive, and the fluorine film remains intact. This provides superior overall performance, but at a higher cost. In coating-type backplanes, fluorine resin is directly coated onto the PET base film using a special process, with the adhesive mixed into the fluorine resin. Coating backplanes offer slightly inferior performance compared to composite backplanes, but they are more cost-effective.
Solar module backplanes can be classified based on their fluorine content: bifacial fluorine film backplanes, monofacial fluorine film backplanes, and non-fluorine backplanes. These variations are designed for different environmental conditions based on their weather resistance and other characteristics.