First Solar, Intermolecular Pushing Thin-film Solar PV Materials R&D

Speeding up R&D of solar PV materials and processes keeps up the pace for module efficiency gains.

First Solar is arguably the leader in thin-film solar photovoltaics (PV). It's relentlessly inched up conversion efficiencies of its cadmium-telluride (CdTe) technology, while chipping away at manufacturing costs (now at $0.67, reported in November).

The current NREL-confirmed record holder for CdTe at 14.4% total area efficiency and 17.3% cell efficiency, First Solar's module efficiency in production in November 2012 was 12.7% (average), and its roadmap (last updated Dec. 2011) projects a goal of 14.5%-15.0% average efficiency for production modules by the end of 2015. In the company's 3Q12 earnings presentation, CEO Jim Hughes noted the company has begun "seeing significant progress" in heavy investments in R&D to improve its technology and meet — or beat — its existing roadmap. That includes a new laser scribing process to improve module active area loss (rollout completed by mid-2013); modifications to deposition of semiconductor absorber material (full-volume production beginning in mid-2013); a module design change to reduce active area losses and improve uniformity (rolled out in 2H13); and improvements to the back-contact of the module (high-volume rollout in 2H14).

In the same presentation, CFO Mark Widmar pointed out that the 12.7% module efficiency in 3Q12 was one quarter ahead of schedule, with "best" line module efficiency reaching 13.2%. That efficiency, once moved into FSLR's lowest-cost plant, will push module costs down to $0.59/W.

Note that conventional crystalline silicon (c-Si) solar PV modules generally achieve efficiencies in the high-teens or even low-20% range. Thin-film counters its significantly lower efficiency with better performance in high-insolation environments. Anything thin-film PV manufacturers can do to close that efficiency gap with c-Si would be an immense advantage. And in fact, "there's a lot of headroom" to improve thin-film PV performance, which is "really in its infancy" compared to c-Si, explained Sandeep Nijhawan, VP/GM of Intermolecular's clean energy group.

Improving the technology isn't easy, though. Historically the learning curve for module efficiency improvements has been a tenth of a percent or two per quarter, including at First Solar. To keep on a scale of reducing costs (especially in this pricing-pressured market), the name of the game is to accelerate that learning curve. For First Solar that comes down to improving its manufacturing processes.

"The life of glass is what it is; the incoming CdTe material is what it is; formfactors are what they are; and they already have capacity," explained Sandeep Nijhawan, VP/GM of Intermolecular's clean energy group. "The only answer left is to do materials innovation, and make a better solar cell."

That's where Intermolecular comes in with a promise of much faster R&D evaluation of materials, structures, and processes. Its "High Productivity Combinatorial" (HPC) platform divides a substrate into "coupons" each a few cm square — it says it can process 220 unique solar cells per coupon — to enable "massively parallel experimentation on the same substrate," Nijhawan explained. Multiple sets of solar cells thus can be canvassed and evaluated anywhere from 10× to 100× faster than in conventional R&D.

Without going into the specifics of what it's doing with First Solar, Nijhawan explained that essentially thin-film PV is a diode, a complex marriage of materials and interfaces; Intermolecular and its platform "optimize certain processes within that stack." He also wouldn't specify the acceleration number it's achieved for First Solar, except to say that a 10× faster workflow wouldn't have been worth it. In a PR statement, First Solar CTO Raffi Garabedian said the Intermolecular program "targets disruptive advances in our module performance, which will be additive to our current roadmap," which he said "will bear fruit in the coming years."

First Solar and Intermolecular formally tied up in June 2012. By year's end, just six months into the partnership, they had generated novel IP which First Solar licensed, according to Nijhawan, and have now extended their partnership into a two-year collaboration and licensing agreement.

Aside from CdTe thin-film PV, Intermolecular also is working with the King Abdullah University of Science and Technology (KAUST) to help enhance its copper-indium-gallium-diselenide (CIGS) thin-film PV technology. The company also quietly does some work on crystalline silicon, but most of its efforts are focused on thin-film PV, Nijhawan said. Also within its Clean Energy applications, it is working with Guardian Industries, the largest North American glass company and the world’s largest producer of coated glass products, on improved glass-coating applications to help reduce energy consumed in heating and cooling of residential and commercial buildings. Some other areas of focus it's pursuing are in light-emitting diodes (LEDs) and flat-panel display (FPD) manufacturing, to similarly test out and find key improvements in materials and processes.

Source: First Solar/http://investor.firstsolar.com