The U.S. National Renewable Energy Laboratory has verified that production-level copper indium gallium (di)selenide solar cells from Global Solar Energy have achieved 15.45% total area conversion efficiencies. The thin-film CIGS photovoltaics manufacturer says that it has also reached record peak efficiencies of 11.7% on flexible stainless-steel cell strings manufactured on its roll-to-roll lines at its full-scale production facilities in Arizona and Germany.
“The material came directly off our production line,” explained company CTO Jeff Britt during an interview with PV-Tech. “With the experiments at NREL, we compared various stages of our process with their standard process. These are results that popped out during the course of the tests. There were many devices over 15% that were measured, but the 15.45% was the highest efficiency of the group.”
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Noting that the results were for full-area devices, Britt said that if one were to compare this result to the ‘active area efficiency’ calculation that some CIGS companies “back out” of similar testing, Global’s efficiencies “would be somewhere around 16.6%.”
“It’s been a long time since we’ve sent [NREL] anything [to evaluate],” the company CTO told PV-Tech. “This does not represent anything special on our part. We actually took part of the same web [of material] and turned it into production cells, and they were a little less than what we averaged, so we don’t think that this represents an extreme outlier—this is typical of what we make.”
When asked about the median efficiencies of the CIGS cell strings produced at Global’s factories, Britt said they averaged “between 10 and 11%,” noting that they just hit the new record efficiency of 11.7%. “We’ve tracked quite a bit of progress since the beginning of the year, and we’re still moving upwards.”
Harin Ullal of the National Center for Photovoltaics at NREL called the efficiency results “a significant achievement for such rapid deposition on a metal foil substrate in a manufacturing environment.”
“We see high efficiencies in the lab, but for a manufacturing line, that is an impressive number,” he told PV-Tech. Ullal, who has worked with Global for several years, also said that some large glass modules strung with the company’s flex CIGS cells have been sent to NREL and will soon be deployed for outdoor testing.
“In less than two years, Global Solar increased production capacity from 4.2MW to 75MW worldwide and continues to increase the efficiency of our highly flexible and adaptive PV material,” stated Michael Gering, CEO of Global Solar. “These achievements not only help advance the solar solutions developed by our existing customers and partners, but also open the door of opportunity for new usages and BIPV [building-integrated photovoltaics] applications in the market.”
