The genesis of the DSM Endurance backsheet begins with the Dutch material company’s 2016 partnership and subsequent acquisition of Chinese backsheet developer Sunshine. DSM was able to build on the proprietary technology platform developed by Sunshine, and combine this with its own expertise in polyolefin-based materials.
“If you look at the strategy of DSM in solar, what we are looking to do is we want to bring new materials and new technologies to the market, and basically lower the cost of energy,” says Jan Grimberg, Business Director Advanced Solar at DSM. “Sunshine developed a coextrusion technology to produce backsheet materials, and we figured that this material was unique compared to all the other backsheets that are currently in the market.”
Currently, most PV backsheets are produced using lamination processes, with multiple layers formed through the use of an adhesive between the layers. In some of these backsheets, exposure to moisture, heat, UV and other environmental conditions has led the layers to become delaminated, which can negatively affect module performance. With coextrusion, however, multiple layers are together pressed into a single piece, eliminating the potential for this problem.
“Coextrusion does it all in one step so you don’t need those adhesives anymore, and with that you are also able to take different materials that are currently being used,” continues Grimberg. “We combined polyolefin materials with a polyamide PA12 layer, both of which are extremely durable. That’s basically what the market is looking for from a technology point of view, and you can provide it at a very efficient cost.”
Previous use of polyamides by backsheet manufacturers revealed a few design flaws in the way these materials were used. As a result, the group of materials is still approached with caution by some PV module makers.
The polyamide PA12 used in Endurance backsheets, however, is a completely different material to those tried previously, and one which already has proven durability from its use in other industries including oil piping and inside dishwashers.
DSM is confident that coextrusion will represent a step change for backsheet manufacturers, with the potential for further innovation and lower cost production than would ever be possible using lamination. “Now, they [backsheet manufacturers] have started to reduce the thickness. But I think that in order to really save cost, innovations are needed. You need to look at different concepts,” says Grimberg. “You see it now, more players stepping into coextrusions and saying that lamination is not an effective process.”
In tests conducted in collaboration with leading research institutes, DSM notes that endurance backsheets have shown optical reflection of more than 90%, superior durability and UV performance, strong resistance to sandblasting, and provide an effective barrier against moisture ingress. Though still a new material to introduce to module makers, market uptake is only in its relatively early stages.
“You see the market is growing, but it takes time for customers to get used to the new materials, they need to think about how to apply them,” comments Grimberg. “We are helping our customers in doing that, and that’s where the competitive edge of DSM lies, that we are able to provide that sort of support, with our global presence and more than 100-year track record in materials sciences.