As they say, change is the only thing that is constant in the solar industry. We started covering the topic of polymer wraps used in solar module manufacturing in 2017, and the first 2 editions were exclusive to backsheets. The encapsulation market segment was mature, robust, and thus not a major subject of discussion, while backsheets, with their multilayer configuration, have been a constant subject of optimization. Subsequently, encapsulation materials also started getting traction with new degradation and reliability issues that have been surfacing with improving cell and module technology, and these polymers were able to address such issues. Thus, encapsulation materials were also included in our market survey starting in 2019, and this is our 5th combined edition since then.
As reflected in this report, encapsulation materials are gradually becoming the focus of this survey, while backsheets have lost their prominence. The reflection of this can also be seen in the current market. The solar industry is undergoing a period of transformation, driven by the rapid adoption of advanced cell technologies and the increasing emphasis on cost reduction and higher reliability. All these aspects favor glass as the rear cover as opposed to polymer-based backsheets. As a result, backsheets are facing severe competition from glass and constantly losing ground in manufacturing. On the other hand, encapsulation materials are becoming increasingly attractive. For now, there is no alternative to encapsulation materials altogether. Some traditional backsheet-only suppliers have also ventured into encapsulation supply, like Jolywood and Endurans. Betting on new production capacities outside of China, the segment is also attracting new players to set up plants in India and the US. At present, mainstream encapsulation solutions are based on 2 core polymer chemistries – EVA and POE. In an effort to meet the demands of both cost and reliability, the segment has developed a coextruded structure consisting of EVA and POE called EPE.
While all of this is not new, the most important developments in the encapsulation segment revolve around compatibility with the changing requirements of cell and module technologies. The segment is increasingly becoming customization-centric. Encapsulation solutions are tweaked according to cell and module technologies. TOPCon attracts the most attention among cell technologies, as do the encapsulation solutions for it. An industry-wide accepted notion about choosing an encapsulant for TOPCon is that POE demonstrates the highest reliability, followed by EPE, with EVA performing the least effectively. Since encapsulation is present on both sides, it provides scope to choose different combinations of these materials for the front and rear sides to attain the desired cost-performance ratio. EPE seems to strike the right balance here, while companies are also trying to improve EVA with respect to limiting its acid-forming attributes (see Transparent Backsheets For TOPCon).
That’s one part of the story. The encapsulation solutions story closely follows cell technology dynamics. Even taking TOPCon as an example, it is not uniform across all manufacturers. In fact, a new variant of TOPCon has emerged that takes the help of lasers (LECO) for metallization. Not only does the LECO-based module behave differently compared to standard TOPCon, but the behavior of such modules differs even based on the manufacturer. This calls for customized encapsulation solutions for different large-scale manufacturers.
These solutions are also different for BC, requiring thin layers on the front and rather thicker films on the rear, which is yet another example of how these polymers are increasingly becoming customized. Again, there is no single solution for all BCs; the combination depends on the base cell architecture – HPBC, TBC, and HBC. At the same time, encapsulation innovations designed for one technology may also benefit other streams. For example, the use of light conversion films, which transform UV light into blue-band radiation, has not only mitigated UVID but also improved overall module performance. Initially designed for HJT, these films are now being explored for TOPCon modules as well (see Designing Solar Modules With Polymers And Composites).
Looking further beyond, following the analogy of encapsulations following cell-level developments, the next possible big thing in cell technology is thetandem architecture based on perovskites. In this context, encapsulation solutions should support low-temperature processing, less than that of HJT. In fact, the industry is ready with solutions based on thermoplastic non-crosslinking type polymer chemistry that can support processing temperatures in the range of 120°C.
Coming to backsheets, the story is not so enticing. The total market size of backsheets is shrinking at a high pace, while solar manufacturing is on an uptrend. That means, on a relative basis, backsheets are losing ground at an even faster pace. Still, a few companies are focusing on innovative transparent variants that can enhance the power yield, like Endurans and Coveme. Several backsheet makers are offering reflective black backsheets that ensure performance with improved aesthetics. A few companies are also offering reflective films that avoid using pre-applied grids on the rear substrate. However, solar is also getting diversified into application-specific solutions. One such application that is growing in popularity is flexible and lightweight modules. Here, backsheet makers can utilize their know-how to replace the front glass with polymers. Although fluorine-based coating on both sides of the backsheet has become mainstream, sustainability and recyclability will also likely gain ground in the backsheet product development. However, none of these seem to be game-changers and would not be sufficient to bring backsheets back to the mainstream so that in the long-run, polymer covers would likely mostly cater only cater to niche and specialty applications.
The text is the conclusion part of the Solar Backsheets & Encapsulants Market Survey 2024/25, which can be downloaded for free here.
