TY - GEN
T1 - Numerical analysis of bifacial silicon-based tandem devices
T2 - 7th IEEE World Conference on Photovoltaic Energy Conversion, WCPEC 2018
AU - Onno, Arthur
AU - Holman, Zachary
N1 - Funding Information:
The information, data, or work presented herein is funded in part by the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, under Award Number DE-EE0007552 and Award Number DE-EE0006709.
Publisher Copyright:
© 2018 IEEE.
PY - 2018/11/26
Y1 - 2018/11/26
N2 - According to detailed-balance analysis, Si-based tandem devices require a top-cell bandgap of 1.70-1.75 eV to be current-matched and deliver high efficiencies in a two-terminal configuration. However, no such top cell - able to deliver the required J sc of approximately 20 mA.cm -2 along with a V oc >1.2 V - has been demonstrated so far. In this work, we present an alternative pathway, using a bifacial c-Si device as the bottom cell. Thanks to the current boost from absorption through the bifacial c-Si cell's rear surface, a lower bandgap is necessary for the top cell. In particular, we show that, with an albedo in the 20-45 % range, the optimal top-cell bandgap lies in the 1.4-1.55 eV range, corresponding to common high-efficiency absorber materials, including GaAs, CdTe, and perovskites. However, when considering more realistic systems where shading of the area under the modules occurs, the optimal top-cell bandgap shifts back to higher values. Moreover, this optimum varies throughout the day, as the ratio between direct and diffuse light as well as their respective spectral components evolve.
AB - According to detailed-balance analysis, Si-based tandem devices require a top-cell bandgap of 1.70-1.75 eV to be current-matched and deliver high efficiencies in a two-terminal configuration. However, no such top cell - able to deliver the required J sc of approximately 20 mA.cm -2 along with a V oc >1.2 V - has been demonstrated so far. In this work, we present an alternative pathway, using a bifacial c-Si device as the bottom cell. Thanks to the current boost from absorption through the bifacial c-Si cell's rear surface, a lower bandgap is necessary for the top cell. In particular, we show that, with an albedo in the 20-45 % range, the optimal top-cell bandgap lies in the 1.4-1.55 eV range, corresponding to common high-efficiency absorber materials, including GaAs, CdTe, and perovskites. However, when considering more realistic systems where shading of the area under the modules occurs, the optimal top-cell bandgap shifts back to higher values. Moreover, this optimum varies throughout the day, as the ratio between direct and diffuse light as well as their respective spectral components evolve.
KW - albedo
KW - bifacial solar cell
KW - current-matching
KW - silicon
KW - simulation
KW - tandem
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U2 - 10.1109/PVSC.2018.8547679
DO - 10.1109/PVSC.2018.8547679
M3 - Conference contribution
AN - SCOPUS:85059909070
T3 - 2018 IEEE 7th World Conference on Photovoltaic Energy Conversion, WCPEC 2018 - A Joint Conference of 45th IEEE PVSC, 28th PVSEC and 34th EU PVSEC
SP - 229
EP - 232
BT - 2018 IEEE 7th World Conference on Photovoltaic Energy Conversion, WCPEC 2018 - A Joint Conference of 45th IEEE PVSC, 28th PVSEC and 34th EU PVSEC
PB - Institute of Electrical and Electronics Engineers Inc.
Y2 - 10 June 2018 through 15 June 2018
ER -