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On the road to better backsheets

How innovation has driven the next performance/cost breakthrough

How can the solar industry continue on its cost-down roadmap of lowering the LCOE of solar energy, without sacrificing quality and performance? It’s a challenge that applies to many aspects of solar technology, not least to backsheets. Over the past few years, DSM has developed a new generation of Endurance backsheets that help tackle this challenge. Now the global science-based company has raised the bar yet again with the launch of its Endurance Backsheet D15. PES sat down with the DSM Advanced Solar Technology Manager, Sunny Zhao, to discuss how and why this latest innovation came to the market.

PES: It’s great to have this opportunity to talk with you. You work in research & development for DSM. Can you tell us more about your role?

Sunny Zhao: I am the Solar Technology Manager for DSM, based in China at our Research & Technology Development Center. My background is in materials science and I have specific responsibility for developing our backsheet technology.

PES: Before we get onto the new D15 backsheet, can you just give us some background on the philosophy behind the R&D work that you’ve been conducting in recent years?

SZ: It’s now common knowledge that quite some backsheets are failing in the field. In fact, DuPont recently published a report which claims that 16% of the inspected modules in the field showed backsheet defects1. This adds up to an estimated $4.5 billion module investment being at stake in 2020 – and we expect this number to rise even higher in the future.

The numbers tell a story but so does the market. I often get the opportunity to visit solar plants and look at how traditional PET-based backsheets are performing in the field. I see a product with a ‘powdery’ feel at the surface and a ‘snail trail’ phenomena due to backsheet degradation and poor moisture barrier. PET has poor hydrolysis resistance.

In fact, in the lab, I’ve observed traditional PET backsheets cracking and falling apart completely when twisted after undergoing the severe PCT or longer damp/heat test. Furthermore, the moisture barrier of PET-based backsheets is not good. If more moisture gets into the module, the EVA encapsulant will generate more acetic acid, which in turn corrodes the conductive metal of the solar cell – thus causing more power degradation. So, in summary: PET is not a good material for use in solar module backsheets.

At DSM we have invested lots of time and resources in rethinking how to support the solar industry in delivering long-term reliable backsheet performance – in all climates and at a competitive price. There is no doubt that great science and innovation holds the key to success in ultra-cost competitive markets like solar – and much of our work has focused on finding creative ways to apply proven technologies and better materials to solar modules. Which is how we came to create our Endurance backsheet family.

PES: How is the Endurance backsheet portfolio differentiated from traditional backsheets products in terms of technology and materials?

DuPont Global PV Reliability – 2020 Field Analysis Report (2020)

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