Encapsulation films and backsheets play a critical role in ensuring the performance, durability, and protection of a solar module. Encapsulation films protect the solar cells within a module by acting as a cushion against mechanical stress and vibrations, preventing damage to the delicate cells and interconnections. Encapsulation materials also act as the first level of electrical insulation for the cell matrix. Effective electrical insulation is critical because solar cells are connected in series, generating high operational voltages. Furthermore, they create an airtight seal, effectively blocking moisture ingress that could lead to corrosion of the metal-based interconnectors and cell surfaces when exposed to water vapor. Encapsulation solutions are the first line of defense to safeguard modules from the most common module degradation phenomena such as LID and PID. Beyond protection, the encapsulant also contributes to the structural integrity of a solar module by bonding the cells to the front glass and rear backsheet, preventing delamination. Traditionally, encapsulants are transparent, allowing light transmission. Now, some monofacial modules use reflective (white) encapsulants on the rear to enhance optical absorption and boost module efficiency. While the encapsulation segment does not offer as many options as backsheets, it still features a good variety of choices in polymer chemistry. Coextrusion is increasingly gaining acceptance for producing multilayer film stacks, offering a balance mainly between performance and costs (see Advanced Solar Technologies Drive Changes In Module Materials).
On the other hand, used on the rear side of a module, backsheets are its first line of defense against environmental factors. Like the encapsulant, the backsheet also acts as a barrier against moisture, preventing corrosion of the module's metallic components and blocking moisture ingress. They also offer UV protection to the modules on the rear side. Since modules operate under dynamic environmental conditions, backsheets must be able to withstand a wide range of environmental conditions, and the choice of materials and construction often depends on the specific climate and location of the installation. Traditionally composed of a 3-layer polymer structure, backsheets also come in twin and monolayer configurations, offering varying performance characteristics. Lamination remains the primary manufacturing method, but coatings and coextrusion are gaining traction as alternative technologies. With the rise of bifacial modules, transparent backsheets have become increasingly important to allow light to reach the rear side of the cells (see Solar Encapsulation & Backsheets Adapting To A Shifting Market).
In summary, encapsulation films and backsheets today are available in a wide variety of configurations, polymer chemistries, and manufacturing processes. These offerings are tailored to meet the specific needs of module manufacturers and end customers, balancing longevity, performance and cost considerations.
Survey Participants: This 5th edition of the combined market survey on backsheets and encapsulation materials received responses from 17 companies in total (see table below) , 3 more than last year. The survey features data for 184 products, an increase of 52 compared to the 4th edition). While our surveys typically include most of the market leaders in these segments, the current overview features 4 new companies: Betterial from China, 2 Indian companies, namely Alishan and Sunlink, and Satinal from Italy. Lucky Film from China did not respond to our inquiry and has, thus, been excluded from the survey.
