DEK Solar and the Institute for Solar Energy Research Hamelin (ISFH) have worked in partnership to increase industrial silicon solar cells' (in this case, Passivated Emitter and Rear Cell, or PERC) conversion efficiency to a record 21.2% using screen-printed metal contacts on the cell rear side and a screen/stencil dual print process on the cell front side. Typically, screen-printed solar cell efficiency ranges from 17.5% to 19.5%, but this latest development sets a new world record for PERC cell conversion efficiency using a screen and stencil printing metallization technique.
Several DEK Solar technologies including the high-accuracy Eclipse metallization platform, Fine Line Stencils™ and precision screens contributed to achieving the record-breaking 21.2% efficiency. The cells' front side was metallized with a Heraeus optimized silver paste using a dual print process that leveraged DEK Solar's precision screens to metallize a five busbar design and the company's Fine Line Stencils to print the 46 µm fingers. DEK Solar Fine Line Stencils enable superb uniformity and high aspect ratios for exceptionally flat and uniform lines, and are capable of printing extremely thin, sub-40 µm lines. Precise control over the relative print height of the busbars and the fine lines not only reduces shadowing loss and silver cost, but also allows non-contacting busbar paste to increase open circuit voltage (Voc) and raise efficiency. The rear metal contacts were printed with DuPont aluminum rear contact paste.
"The significance of this achievement should not be underestimated," explains Tom Falcon, DEK Solar Principal Engineer. "ISFH's and DEK Solar's work have effectively delivered what the solar market is after: high-efficiency, industrial-type, silicon PERC cells produced using the most cost-effective, metallization process via screen and stencil printing. This is, indeed, a breakthrough for the global solar industry."
Dr. Thorsten Dullweber, head of the ISFH research group Solar Cell Production Processes, also notes the importance of this efficiency increase and DEK Solar's contributions: "Improving the efficiency by such a significant amount is no small feat – particularly when one considers that this was carried out using screen and stencil printing methods with an exceptionally small silver paste consumption below 80 mg per wafer. DEK Solar has been and continues to be a very important partner for ISFH, providing not only advanced platforms, stencils and screens, but immense process knowledge as well."
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Acknowledgement: As part of ISFH's HighScreen research project, the 21.2% world-record efficiency work was funded by the German Federal Ministry of the Environment and in collaboration with ISFH project partners SolarWorld AG, Heraeus Precious Metals GmbH & Co. KG, RENA GmbH and SINGULUS TECHNOLOGIES AG. DEK Solar and DuPont Ltd. were key contributors.
About DEK Solar
DEK Solar is a global provider of next-generation technologies and process support to solar cell manufacturers with solutions that include modular metallization platforms, precision screens and materials applications used in backside field coating, current-collector pattern and termination deposition for photovoltaic substrate production. For more information, visit DEK Solar at www.dek.com.
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