By F. Clement, Fraunhofer ISE; M. Neidert, Heraeus Precious Metal; A. Henning, Heraeus Precious Metal; C. Mohr, Heraeus Precious Metal; W. Zhang, Heraeus Precious Metal; B. Thaidigsmann, Fraunhofer ISE; R. Hoenig, Fraunhofer ISE; T. Fellmeth, Fraunhofer ISE; A. Spribille, Fraunhofer ISE; E. Lohmueller, Fraunhofer ISE; A. Krieg, Fraunhofer ISE; M. Glatthaar, Fraunhofer ISE, Freiburg,; H. Wirth, Fraunhofer ISE; D. Biro, Fraunhofer ISE; R. Preu, Fraunhofer ISE; M. Menkoe, Bosch Solar Energy AG; K. Meyer, Bosch Solar Energy AG; D. Lahmer, Bosch Solar Energy AG; H.J. Krokoszinski, Bosch Solar Energy AG
This paper focuses on the latest developments from research on MWT (metal wrap-through) solar cells at Fraunhofer ISE. An overview of the current cell results for mc-Si and Cz-Si material with both Al-BSF and passivated rear side is presented. Recent progress in cell technology and challenges to reaching efficiencies of 20% for industrially processed large-area MWT solar cells are also discussed. Up to recently, MWT cell efficiencies of up to 19% for Cz-Si and up to 17.5% for mc-Si have been reached with industrially feasible processing. Improvements to the design of the MWT cell to increase cell efficiency and to allow an easy module assembly are also presented in this paper, as are first calibrated IV measurements of MWT solar cells.