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Sharp has made a significant breakthrough by announcing that it has raised the conversion efficiency of its crystalline silicon solar cells to 25.1%. This achievement places it just behind Panasonic, which previously set a record of 25.6% in April 2014.
For many years, the highest recorded efficiency for crystalline silicon solar cells was 25.0%, achieved by the University of New South Wales (UNSW) in March 1999. Now, both Sharp and Panasonic have surpassed this milestone, marking a major step forward in solar technology.
Both companies employ a combination of a "heterojunction" structure—where an amorphous silicon layer is formed on top of a crystalline silicon substrate—and a "back contact" design, which places electrodes only on the rear side of the cell. This design reduces surface recombination and allows more light to reach the active area of the cell, thereby improving efficiency. However, neither company has yet announced when these high-efficiency units will be commercially available.
Sharp has already integrated back contact structures into some of its products. The development of using heterojunctions in back contact designs was first revealed at a Japanese exhibition in December 2012, with an efficiency of 21.7%. Since then, the efficiency steadily increased: 22.3% in February 2013, 24.2% in July 2013, 24.7% in October 2013, 24.9% in February 2014, and finally reaching 25.1% in April 2014.
At 25.1% efficiency, the short-circuit current density reached 41.7 mA/cm², the open-circuit voltage was 736 mV, and the fill factor was 81.9%. The measurement was conducted on a 3.72 cm² test area by the Japan Electrical Safety & Environment Technology Laboratories (JET).
These results are part of a larger research initiative led by the New Energy and Industrial Technology Development Organization (NEDO), titled “Research and Development of Ultimate Silicon Crystal Solar Cells,†and carried out in collaboration with Toyota Technological Institute. This ongoing effort highlights the growing focus on improving solar cell performance through advanced materials and innovative designs. As the industry continues to push the boundaries of efficiency, such breakthroughs could lead to more affordable and sustainable energy solutions in the future.
Huixian Xinwei Refractories Co. , http://www.xinweirefractory.com