Metallization and interconnection for high-efficiency bifacial silicon heterojunction solar cells and modules


By Antonin Faes; Agata Lachowicz; Armand Bettinelli; Pierre-Jean Ribeyron; Jonas Geissbühler

Silicon heterojunction (SHJ) solar cells demonstrate a high conversion efficiency, reaching up to 25.1% using a simple and lean process flow for both-sides-contacted devices, and achieving a record silicon solar cell efficiency of 26.7% in back-contacted configuration. In addition, the field advantages of SHJ cell technology are a native bifaciality and low thermal coefficient providing impressive energy yield. Finally, the technology demonstrates potential cost reduction as it is perfectly suited for thin wafers integration. The SHJ technology is therefore today triggering strong interest in the PV industry, appearing on the roadmap of different cell manufacturers, with several production lines and pilot lines being installed worldwide. One limiting factor of the technology is related to the metallization: due to temperature restrictions on heterocontacts, the standard firing through silver paste needs to be replaced by low curing temperature paste. This type of pastes yield fingers with higher bulk resistivity (two to three times the one obtained with high temperature cured silver pastes) and lower adhesion after soldering. In this paper, materials, processes and costs figures will be reviewed for the metallization and module integration of SHJ solar cells, with a focus on copper plating benchmarked to silver screen-printing, for varying module interconnection technologies.

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Welcome to Photovoltaics International 41. An emerging theme in the industry further downstream is the growing variety of bankable PV modules. It’s a topic we’ll be picking up on 23-24 October at our PV ModuleTech conference in Penang, Malaysia. This issue of PVI captures the ongoing work to drive improvements across the full range of those technologies. From the exploration of next generation CIGs cells to the commercial improvements of PERC by Trina Solar, this edition neatly captures that variety. Fraunhofer ISE reviews the latest results from efforts to improve the texturing of diamond wire sawn wafers. Trina Solar presents a roadmap for PERC improvements that it claims could halve costs while pushing efficiencies to 24% in around seven years. ECN and imec explore the latest developments in integrated cell to module manufacturing approaches from the more familiar multi-busbar and multi-wire to shingling and woven fabric and foil-based module technologies for back contacted cells. Elsewhere, CSEM INES zooms in on a major limiting factor for silicon heterojunction cells, metallization. All the regular features including our news reviews and R&D spending report make a return, plus lots more. Following on from this bumper edition, PVI42 will be published in Spring 2019.

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