Stable reverse bias or integrated bypass diode in HIP‑MWT+ solar cells
Fraunhofer Institute for Solar Energy Systems ISE, 79110 Freiburg, Germany
2 Department for Sustainable Systems Engineering, University Freiburg, 79098 Freiburg, Germany
* e-mail: firstname.lastname@example.org
Received in final form: 22 November 2021
Accepted: 24 December 2021
Published online: 31 January 2022
The Metal Wrap Through+ (HIP-MWT+) solar cell is based on the PERC concept but features two additional electrical contacts, namely the Schottky contact between p-type Si bulk and Ag n-contact and the metal-insulator-semiconductor (MIS) contact on the rear side of the cell below the n-contact pads. To prevent thermal hotspots under reverse bias, both contacts shall either restrict current flow or allow a homogenous current flow at low voltage. In this work we present both options. First the stable reverse bias characteristics up to −15 V with a MIS contact using industrially manufactured SiON passivation and second, an integrated by-pass diode using AlOX as insulator in the passivation stack allowing current flows at approximately Vrev = –3.5 V depending on the chosen screen-print paste. The examined Schottky contacts break down at around Vrev = –2.5 V. Reverse bias testing of the cells reveals a solid performance of the cells under reverse bias and an average conversion efficiency of η = 21.2% (AlOX) and η = 20.7% (SiON), respectively.
Key words: MWT solar cells / integrated by-pass diode / silicon / passivation / PERC / back contact
© T. Schweigstill et al., Published by EDP Sciences, 2022
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