First Solar raises bar for CdTe with 21.5% efficiency record

U.S. thin-film giant First Solar has achieved record-breaking efficiencies in cadmium-telleride (CdTe) cell efficiencies that have propelled the company ahead of its own research roadmap timeline.

The Arizona-based solar firm has verified the 21.5% efficiency for its latest CdTe PV cell – an achievement that the company claims validates CdTe’s continuing "competitive advantage" over crystalline silicon technology more traditionally used in solar cell production.

The record-breaking cell was developed at the company’s Perrysburg, Ohio fab and R&D center, and has since been independently verified at the Newport Corporation’s Technology and Applications Center (TAC) PV lab.

The U.S. Department of Energy’s National Renewable Energy Laboratory (NREL) has also documented the achievement in its Best Research Cell Efficiencies reference chart.

For First Solar, this latest record-breaking achievement is the eighth substantial CdTe efficiency update since 2011 – which suggests a firmly established trend of rapid performance improvements, the company said.

"Our latest research efficiency record is a result of continued learning in the material science and device physics of CdTe solar cells," said First Solar CTO Raffi Garabedian. "Our work is not done in isolation, but is in part a result of the many fruitful collaborations we have with academia, national labs, and our industrial partners, most notably GE Global Research."

Garabedian added that this collaborative approach to learning had enabled First Solar to optimize conditions in its Ohio fab that in turn have led to greater practical developments in the field. Improved cell efficiency is useless, he said, if it cannot be easily translated from the lab into a commercially viable product that offers something new to the market.

"By virtue of our adaptable thin-film manufacturing process and our dedication to science-based design-for-reliability," Garabedian continued, "First Solar is unique in its ability to rapidly scale such new developments into cost-effective and reliable products."

This latest record has enabled First Solar to exceed its technology roadmap for CdTe technology, which in turn translates to faster commercialization rates. Last March, the company earmarked 2015 as the year in which 22% CdTe efficiency would be hit, making this latest announcement a tantalizing step closer to that goal.

"Given the slope of our research cell improvements and the fact that it’s still February, we remain confident that we’ll meet or exceed our roadmap expectations," Garabedian concluded.

From efficiency to reliability

In addition to improved development curves and cell efficiencies, First Solar was also bullish this week on the strides it has made on module reliability, revealed that its production PV modules recently achieved Atlas 25+ certification status following a rigorous round of testing.

Long-term combined-stress environmental exposure tests were applied to First Solar’s latest modules as part of the Atlas 25+ certification process. The test measures durability and degradation in accelerated environmental conditions designed to mimic long-term service in the real world.

First Solar’s modules passed all parameters of the Atlas 25+ stress tests, which included power output, insulation resistance and visual damage in the hot/arid, subtropical, temperate and “global composite” climate simulations.

"The modules were tested against the most stringent standards available," revealed First Solar SVP for quality and reliability Azmat Siddiqi, adding that formal certification documentation confirming the modules’ performance will be issued by SGS – a leading testing and verification organization.