Backsheets protect modules against moisture, UV radiation, and environmental stresses
Commercial products use laminated, coated, and coextruded structures with diverse material combinations
Backsheet selection depends on module design, application, climate, and cost requirements
Backsheets, while also polymeric at their core, serve a distinct role within the module BOM. Positioned on the exterior rear side of glass-backsheet modules, they act as the outermost line of defense against weathering. Similar to the encapsulant, a backsheet must also block moisture ingress to prevent corrosion of internal metallic components, while also providing heavy-duty UV protection for the internal layers from rear-side solar radiation. Because PV modules are deployed in highly dynamic climates, backsheets must withstand extreme environmental variations. In principle, material selection can be optimized based on the specific climate and geographic location of the installation, supported by a wide variety of commercial chemistries and material combinations.
Structurally, backsheets have traditionally relied on a 3-layer laminate design. However, the market has evolved to include twin-layer and even single-layer configurations featuring highly customizable performance characteristics. The rise of bifacial PV modules has led to the development of transparent backsheets. While standard roll-to-roll lamination remains a dominant manufacturing method, coating-based backsheets, in which protective functional layers are liquid-coated onto a core PET film, have become increasingly popular due to cost efficiencies. Interestingly, the coextrusion process – now used extensively to manufacture multi-layer encapsulation films like EPE – was originally introduced for backsheet designs, though such products never achieved mainstream status.
Previous editions of this survey have extensively detailed the structural evolution of backsheets and the wide variety of configurations that have emerged in the commercial market, along with their respective graphical representations (see the previous edition for complete reference). To summarize, the major backsheet configurations highlighted in our previous edition of the survey include a complex matrix of laminated, coated, and coextruded designs such as TPT, TPE, TPC, TPO, KPK, KPE, KPf, KPO, PPE, CPC, all-PP, PPO, and PPU. The accompanying infographic outlines these prominent backsheet structures, along with their standard industry abbreviations, for quick reference.
All in all, today’s encapsulation films and backsheets are offered in numerous configurations, chemistries, and manufacturing processes. These options are adapted to meet the specific needs of module manufacturers and end users, balancing durability, performance, and cost.
The text is an edited excerpt from TaiyangNews Market survey on Encapsulation Materials & Backsheets 2026, which can be downloaded for free here.
