Photovoltaic development deals targets 22.4 percent cell efficiencies
The units will be based on n-type monocrystalline wafers, which have a higher efficiency potential than traditional p-type solar cells and do not display the same kind of light-induced degradation.
Although n-type cells are more complex to manufacture and have previously needed costly silver contacts on both sides, Fraunhofer ISE has developed a structure that avoids the use of a silver contact grid and makes use of a combination of dielectric layers and localised contacts. REC will assist Fraunhofer ISE in translating the technology from lab scale to a full production-ready concept.
"The PassDop layer delivers excellent results on the conductivity of n-type solar cells. Through it, we can now achieve confirmed cell efficiency of 22.4 percent," said Dr. Stefan Glunz, division director "Solar Cells – Development and Characterization" at Fraunhofer ISE.
Last week REC also revealed the organization is joining forces with the Unversity of New South Wales (UNSW) in the development of an improved hydrogen passivation process that was first discovered at UNSW.
Standard multi-crystalline silicon cells currently have a maximum efficiency of around 17.5% – 18%. According to Professor Stuart Wenham the new technique, patented by his UNSW team, is expected to produce efficiencies of between 19% and 20% once fully developed.
“We are excited by the opportunity to collaborate with UNSW,” said Øyvind Hasaas, President and CEO, REC. “REC has a long history in silicon wafer and cell manufacturing. By combining UNSW’s breakthrough technology with our strong background knowledge of multicrystalline silicon wafers and solar cells, we expect to be able to speed up the development of this new technology.”
As a world record holder in silicon solar cell efficiency, UNSW is a strong partner for REC. Professor Wenham says his team has worked out how to control the charge state of hydrogen atoms in silicon, thereby increasing the ability to generate electricity, something other research teams have previously not been able to do.
“We have seen a 10,000 times improvement in the mobility of the hydrogen and we can control the hydrogen so it chemically bonds to defects and contaminants, making these inactive,” explained Wenham. This improves the quality of the silicon, which in turn translates into higher cell efficiency.
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