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Development of industrial high-efficiency back-contact czochralski-silicon solar cells



Back-contact silicon solar cells feature high efficiencies, simpler module assembly, and improved aesthetics. The emitter wrap through (EWT) cell structure is particularly attractive for use with industrial processing (e.g., screen-printed metallization) and common solar-grade p-type Si materials. We report development of a high-efficiency EWT back-contact cell using p-type Cz silicon and only industrial processing techniques such as screen-printed metallizations, diffusions, and PECVD. An efficiency of 19.0% has been achieved with large area (156-mm pseudo-square) cells. Detailed characterization and modeling have been performed to understand the optical and electrical losses, and these results were used to generate a roadmap to improve the efficiency to over 20%. Copyright © 2011 John Wiley & Sons, Ltd.