‘Solar Module Super League’ (SMSL) member, Trina Solar has set a conversion efficiency record of 24.58% for an i-TOPCon (Industrial Tunnel Oxide Passivated Contact) bifacial solar cell using a super-sized 244.62 cm2 wafer.
Today’s industry standard B-doped monocrystalline silicon still suffers from light-induced degradation of the carrier lifetime. Illumination at elevated temperature leads to a so-called regeneration, i.e. a recovery of the carrier lifetime as well as the solar cell efficiency. However, even though the carrier lifetime on test wafers increases from about 1 ms after processing to 3 ms after regeneration, the corresponding PERC+ cell efficiencies in both states are identical. We discuss possible reasons for this discrepancy. Additionally, we evaluate B-doped Czochralski silicon wafers with an ultra-low oxygen content of 2.6 ppma as well as industrial Ga-doped wafers. Both wafer materials are completely LID-free in lifetime measurements and PERC+ cell efficiencies and enable up to 0.4%abs higher efficiencies than present industry-typical boron-doped wafers.
The Institute for Solar Energy Research Hamelin (ISFH) and the Leibniz Universität Hannover have produced lab cells using polysilicon on oxide – POLO – junctions, in an interdigitated pattern on the rear side and a specially treated p-type monocrystalline wafer to record a cell conversion efficiency of 26.1%.
Finlay Colville talks to Linda Koschier and Stuart Wenham about University of New South Wales (UNSW) alumni having prominent solar cell industry positions and technology issues such as advanced hydrogenation,