Beyond these mainstream cell technologies, there are also a couple of important developments in the encapsulation materials segment, as outlined below.
IBC: Starting with another advanced cell technology, IBC is also one that has gained some interest of late. While it was SunPower / Maxion in the west and SPIC in China in the past, LONGi's introduction of the HPBC technology has definitely helped turn the attention towards IBC. As to the encapsulation solution for such an IBC structure, while it remains an unknown, HIUV's Senior Marketing Manager Peter Peng expects it may have some special requisites. Since the cell has no fingers or busbars, a thin encapsulant may suffice on the front side, but the rear side could demand a whole different solution altogether (see: Peter Peng's presentation: Reliable Encapsulation Of TOPcon & HJT Modules).
Thermoplastic Polyolefins: The thermoplastic variants of polyolefins are also an interesting variety of encapsulants. The difference with regard to POE type discussed above, which are elastomers, is that the thermoplastic products are of the noncrosslinking type. The key advantage of this material is a low processing temperature of 120 °C. The thermoplastic nature of the material allows module manufacturers to rework on the laminate in case of any defects such as bubble formation. We went into some depth on this topic in our previous edition while discussing Borealis' Quentys product. However, the company has now changed its business model, where it has stopped supplying the encapsulation materials to module makers, but instead selling the Quentys BPO resin. The company has also found a partner in China, which has already launched products into the market. According to Borealis renewable energy program manager Geir Kristian Johnsen, the Quentys BPO resin is also available in Europe and other geographies. He emphasizes that thermoplastic encapsulant films based on the Quentys BPO resin have proven popular for encapsulation of perovskite cells due to the broad processing window.
Silicones: This is also an interesting and well-known material used for encapsulation applications. Several variants of silicones have been introduced in the past with very little success. Dow is now offering a room temperature cured silicone called DOWSIL 9955 that is expected to last for 50 years. The details of this product were discussed in detail in our previous survey TaiyangNews Backsheets & Encapsulation 2021. In summary, the product is offered in a liquid form. Adding a dispensing setup and with a few tweaks, the existing module production line can also be used to implement the solution. Dow is mainly promoting its solution for BIPV applications, where its product matches the reliability of the building materials – typically 50 years. As to the latest updates associated with the product, Guy Beaucarne, R&D Fellow, Building & Infrastructure in Dow Silicones, presented a technical paper in cooperation with BIPV producer Via Solis from Lithuania at the 8th WCPEC conference at Milan. Via Solis is convinced that silicone is the right material for BIPV, due to the long lifetime, better heat resistance and fire resistance, according to Beaucarne. The technical paper discussed the details of encapsulant technology that is based on a two-part condensation cure chemistry and its implementation. Bubble-free laminates have been fabricated both in a laboratory laminator and in a large area plate laminator. A workaround was also successfully investigated for realizing a transparent edge sealant with water vapor barrier properties.
The article is an excerpt from the TaiyangNews Market Survey on Backsheets and Encapsulation 2022-23, which can be accessed free of charge here.