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Vertical junction Si cells for concentrating photovoltaics
Author(s) -
Pozner Roni,
Segev Gideon,
Sarfaty Rona,
Kribus Abraham,
Rosenwaks Yossi
Publication year - 2012
Publication title -
progress in photovoltaics: research and applications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.286
H-Index - 131
eISSN - 1099-159X
pISSN - 1062-7995
DOI - 10.1002/pip.1118
Subject(s) - equivalent series resistance , stacking , wafer , optoelectronics , fabrication , photovoltaics , materials science , energy conversion efficiency , voltage , engineering physics , nanotechnology , chemistry , electrical engineering , photovoltaic system , engineering , medicine , alternative medicine , organic chemistry , pathology
ABSTRACT Vertical junction Si cell has shown a potential to operate at high concentrations, mainly the result of reduced series resistance losses due to its low‐current/high‐voltage design, but tests and analyses have so far only shown a modest efficiency of about 20%. We perform a comprehensive optimization study and show that the conversion efficiency of vertical multi‐junction (VMJ) cells can be significantly higher, close to 30% at concentrations of 1000 and higher. Reaching this efficiency requires junction dimensions that are significantly smaller than previous VMJ cells. This may require a different approach in the fabrication process, possibly by using a monolithic method rather than the wafer stacking approach. We also show that increased photoconductivity, which is usually negligible in conventional cells, produces a significant reduction in series resistance at high concentrations making it a significant contributor to the outstanding performance of the VMJ cell at high concentration. Copyright © 2011 John Wiley & Sons, Ltd.