From a technology point of view, the most important trend in the backsheets segment are developments in transparent backsheets. While products are available in all structures, CPC is the main contender with glass on price. There is also good news for these backsheet suppliers. There is an increasing preference in the US market for transparent backsheet based bifacial modules in comparison to glass, and they are exempted from AD duties in India

It is clear that bifacial is the technology of choice as it is exempted from Section 201 tariffs. But why backsheets? Below is a summary of the answers we received from various industry experts. On the supply side, a major chunk of modules imported into the US come from Southeast Asia, and the production efficiency and yield of double-glass modules in these countries are low. Thus, they prefer to produce bifacial modules with single glass, and using transparent backsheet is the only option.

A double-glass bifacial module produced in Southeast Asia is built on glass imported from China, and then shipped to the US, which is complex and involves higher logistics costs compared to using a transparent backsheet in a single-glass module. Also, processing a double-glass module is relatively more complicated than a transparent backsheet based one, the latter essentially being the same as the standard practice. This ease of processibility with transparent backsheet is one of the main reasons why it is gaining popularity, particularly among the Indian module makers exporting to the US.

On the demand side, the current practice with the glass-glass module is that a 2 mm glass is used on both sides. More and more studies indicate that the US is more prone to natural calamities such as hailstorms and hurricanes. In such conditions, the 2 mm top glass cannot provide effective protection, which is why the EPCs are preferring a 3.2 mm glass on the front side and a transparent backsheet on the rear.

Another related topic is insurance coverage. As many areas in the US have a higher risk of hail, insurance companies insist that 3.2 mm glass be used on the front. Adding a 2 mm glass on the rear in addition to a 3.2 mm on the front would increase the module weight considerably. This necessitates the use of transparent backsheet as an effective alternative.Transparent backsheets with a black grid that mimics the appearance of an all-black module are increasingly being preferred in a growing US residential market. In addition, handling costs during installation for the single glass modules are also low, which makes sense in a high labor cost market such as the US.

Not just the US, installers in India are also preferring the transparent backsheet route, especially since their prices are comparable to glass, according to RenewSys’ GCEO Avinash Hiranandani. He emphasizes that they are preferred more due to the practical reasons of avoiding placing a thin fragile material like glass on the rear side, on top of no change required in module production (see Backsheets Manufacturers Update).

Also, in Europe where rooftop is a major segment, transparent backsheets with black grid are very popular, according to Jolywood. The emerging backcontact module technology can also benefit greatly, particularly from black grid white / transparent backsheet, according to Jolywood’s marketing director Chad Yuan. He further emphasizes that transparent backsheets are also used in China; he quotes the examples of China Southern Power Grid and Yudean Group, which use these clear rear covers for their centralized power stations in China. Cybrid’s senior product manager Stephen Gong, at the TaiayngNews Reliability 2022 conference (see recording here)., provided recommendations for using transparent backsheets. Since WVTR varies a lot according to the encapsulation, using POE film is a safe bet when using transparent backsheet, he said. He also highly recommends sequential testing for transparent backsheet before using it in module production (see Latest Trends In Backsheets).

As to the development projects in the transparent backsheets segment, Jolywood shares the most interesting news. According to Jolywood’s CTO Fute Zhang, the company is now entering mass production with its transparent mesh backsheet based on next-generation technology, which has higher UV resistance that justifies its 30-year warranty, similar to double glass. Indeed, this is one aspect the transparent backsheets have been lagging behind on glass. DuPont was the first to overcome this limitation to develop such backsheets in cooperation with its partners. It also played a major role in the commercialization of modules based on transparent backsheets that were warrantied for 30 years by JinkoSolar. In fact, Jolywood was also one of the partners, and according to Zhang, the 30-year warranty with its backsheet is backed by Munich Re.

Jolywood also shared the 3-year outdoor test results of its cooperation with National Solar Photovoltaic Product Quality Inspection and Testing Center (CPVT). Modules using Jolywood’s transparent backsheet were certified to have generated 1.29% more power than double-glass modules of the same type, according to Zhang. The other advantages such as the self-cleaning ability to repel dust particles and strong heat dissipation have also helped in attaining the above boost in power yield.

Féron, while offering PET based backsheets, is working on a transparent variant using polyolefin as the core. Féron, while offering PET based backsheets, is working on a transparent variant using polyolefin as the core. Endurans believes it is working on something disruptive for transparent backsheets that will put the polymers behind cells back into the game, according to Chaturvedi.

As to the share of the transparent backsheet, Fumotech says 10% of its PVDF sales are from the transparent variants while it is 15% for Cybrid. Jolywood seems to be the leader here again too. Yuan says Jolywood’s total shipments of transparent and transparent grid backsheets exceeded 6 GW in 2022, and the total for the industry exceeded 9 GW, showing an annual growth rate of 20%.

The price of the transparent backsheet is naturally not the same as the opaque variants as it requires special materials. Not only should all the films used in the stack be transparent, even the adhesives need to be transparent. All this makes for a complex backsheet making process, and an expensive final product. As with the opaque backsheet, whose prices are very much dependent on the polymer chemistry used for building different layers, it is also the case with the transparent backsheet. According to Crown, its price premium over the opaque variants is about 8 RMB/m2, or 50 to 80% depending on the polymer chemistry according to Lucky Film. For a CPC backsheet, the price is about 16 to 18 RMB/m2; it is the only transparent backsheet that comes with a price advantage of 20 to 30% over glass.

The article is an excerpt from the TaiyangNews Market Survey on Backsheets and Encapsulation 2022-23, which can be accessed for here.