|The lateral solar cell architecture with a specially designed concentrator contributes to the enhanced performance. Click to enlarge.|
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% from sunlight at standard terrestrial conditions.
That number is a significant advance from the current record of 40.7% announced in December and demonstrates an important milestone on the path to the 50% 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%, these recent results put the pieces in place for a solar cell module with a net efficiency 30% 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.
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 led the research. The two direct the University’s High Performance Solar Power Program and will continue working to achieve 50% 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 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.
Modern solar cell systems rely on the concentration of sunlight. The previous best of 40.7% efficiency was achieved with a high concentration device that requires sophisticated tracking optics and features a concentrating lens the size of a table and more than 30 centimeters, or about 1 foot, thick. The UD consortium’s devices are potentially far thinner at less than 1 centimeter.
This is a major step toward our goal of 50% efficiency. The percentage is a record under any circumstance, but it’s particularly noteworthy because it’s at low concentration, approximately 20 times magnification. The low profile and lack of moving parts translates into portability, which means these devices easily could go on a laptop computer or a rooftop.—Allen Barnett
Honsberg said the advance of 2 percentage points is noteworthy in a field where gains of 0.2 percent are the norm and gains of 1 percent are seen as significant breakthroughs.
Many of us have been working with programs to take us to a real photovoltaic energy future. This project is already working in that future. DARPA has leapfrogged the ‘conventional,’ demonstrating that creativity and focus can significantly accelerate revolutionary research-bench concepts toward reality, demonstrating this does not have to take decades. This is a first step—but a significant one in making sure our energy future is what we know it should look like.—Lawrence L. Kazmerski, director of the US Department of Energy’s National Center for Photovoltaics at the National Renewable Energy Laboratory
Barnett and Honsberg said that reaching the 42.8% mark is a significant advance in solar cell efficiency, particularly given the unique small and portable architecture being used by the consortium and the short time—21 months—in which it was developed.
During the first 21 months of the VHESC program, a diverse team of academia, government lab and industrial partners, led by UD, was focused on developing the technology basis for a new extremely high efficiency solar cell. The rapid success of that effort has enabled the present transition to a focus on prototype product development.
The team’s approach provides for affordability and also flexibility in the choice of materials and the integration of new technologies as they are developed.
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.
The newly formed DuPont-University of Delaware VHESC consortium will be made up of industrial partners, national laboratories and universities.
(A hat-tip to Marty!)
A. Barnett, C. Honsberg, D. Kirkpatrick, S. Kurtz, D. Moore, D. Salzman, R. Schwartz, J. Gray, S. Bowden, K. Goossen, M. Haney, D. Aiken, M. Wanlass and K. Emery, “50% Efficient Solar Cell Architectures and Designs”, 4th World Conference on Photovoltaic Energy Conversion, Hawaii, May 7 - 12, 2006
C.B. Honsberg, A.M. Barnett, D. Kirkpatrick, “Nanostructured Solar Cells for High Efficiency Photovoltaics”, 4th World Conference on Photovoltaic Energy Conversion, Hawaii, May 7 - 12, 2006.