UD-led team sets solar cell record, joins DuPont on $100 million project

Using a novel technology that adds multiple innovations to a very high-performance crystalline silicon solar cell platform, a consortium led by the University of Delaware has achieved a record-breaking combined solar cell efficiency of 42.8 percent from sunlight at standard terrestrial conditions.

That number is a significant advance from the current record of 40.7 percent announced in December and demonstrates an important milestone on the path to the 50 percent efficiency goal set by the Defense Advanced Research Projects Agency (DARPA). In November 2005, the UD-led consortium received approximately $13 million in funding for the initial phases of the DARPA Very High Efficiency Solar Cell (VHESC) program to develop affordable portable solar cell battery chargers.

Combined with the demonstrated efficiency performance of the very high efficiency solar cells' spectral splitting optics, which is more than 93 percent, these recent results put the pieces in place for a solar cell module with a net efficiency 30 percent greater than any previous module efficiency and twice the efficiency of state-of-the-art silicon solar cell modules.

As a result of the consortium's technical performance, DARPA is initiating the next phase of the program by funding the newly formed DuPont-University of Delaware VHESC Consortium to transition the lab-scale work to an engineering and manufacturing prototype model. This three-year effort could be worth as much as $100 million, including industry cost-share.

The ground-breaking research was led by Allen Barnett, principal investigator and UD professor of electrical and computer engineering, and Christiana Honsberg, co-principal investigator and associate professor of electrical and computer engineering. The two direct the University's High Performance Solar Power Program and will continue working to achieve 50 percent efficiency, a benchmark that when reached would mean a doubling of the efficiency of terrestrial solar cells based around a silicon platform within a 50-month span.

The consortium's goal is to create solar cells that operate at 50 percent in production, Barnett said. With the fresh funding and cooperative efforts of the DuPont-UD consortium, he said it is expected new high efficiency solar cells could be in production by 2010.

The highly efficient VHESC solar cell uses a novel lateral optical concentrating system that splits solar light into three different energy bins of high, medium and low, and directs them onto cells of various light sensitive materials to cover the solar spectrum. The system delivers variable concentrations to the different solar cell elements. The concentrator is stationary with a wide acceptance angle optical system that captures large amounts of light and eliminates the need for complicated tracking devices.

Barnett credits the early success of the program to the team approach taken to solving the problem. Partners in the initial phase included BP Solar, Blue Square Energy, Energy Focus, Emcore and SAIC. Key research contributors included the University of Delaware, National Renewable Energy Laboratory, Georgia Institute of Technology, Purdue University, University of Rochester, Massachusetts Institute of Technology, University of California Santa Barbara, Optical Research Associates and the Australian National University. “What we've done,” he said, “is create a virtual lab by having all of these companies, universities and national laboratories in the consortium. This has given us access to a broad range of capabilities in terms of expertise and equipment.”

The newly formed DuPont-University of Delaware VHESC consortium will be made up of industrial partners, national laboratories and universities.

UD offers one of the nation's broadest research programs in photovoltaics. It is home to the High Performance Solar Power Program in the Department of Electrical and Computer Engineering and the Institute of Energy Conversion, a multidisciplinary laboratory devoted to the research and development of thin film photovoltaic solar cells. Honsberg is developing one of the nation's most complete courses of study for solar power systems, which is partially sponsored by the National Science Foundation's Integrative Graduate Education and Research Training (IGERT) program.

Barnett earned a doctorate in electrical engineering from Carnegie-Mellon University, is a Fellow of the Institute of Electrical and Electronic Engineers (IEEE), was awarded the IEEE's William R. Cherry Award for outstanding contributions to the advancement of photovoltaic science and technology and won UD's Karl W. B_er Solar Energy Medal of Merit in 2001 for “pioneering high-performance, thin-crystalline silicon solar cells, founding and leading a world-class enterprise for the commercialization of solar electric products, and outstanding continuing service to the solar electric power community.”

Honsberg earned a bachelor's degree in electrical engineering in 1986, a master's degree in 1989 and a doctorate in electrical and computer engineering in 1992, all from UD. She was an associate professor in the Centre for Photovoltaic Engineering at the University of New South Wales from 1993-2000 and an associate professor of electrical and computer engineering at Georgia Tech before joining the UD faculty in 2004.

Media contact: Neil Thomas, (302) 831-6408, [nfttwo@udel.edu]
July 24, 2007