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Title: Energy production advantage of independent subcell connection for multijunction photovoltaics

Authors:
 [1];  [2]
  1. California Institute of Technology, 1200 E California Blvd Pasadena California 91125-0002
  2. Kavli Nanosciences Institute, California Institute of Technology, Pasadena California
Publication Date:
Research Org.:
Energy Frontier Research Centers (EFRC) (United States). Light-Material Interactions in Energy Conversion (LMI)
Sponsoring Org.:
USDOE Advanced Research Projects Agency - Energy (ARPA-E)
OSTI Identifier:
1388844
DOE Contract Number:
SC0001293
Resource Type:
Journal Article
Resource Relation:
Journal Name: Energy Science & Engineering; Journal Volume: 4; Journal Issue: 4; Related Information: LMI partners with California Institute of Technology (lead); Harvard University; University of Illinois, Urbana-Champaign; Lawrence Berkeley National Laboratory
Country of Publication:
United States
Language:
English
Subject:
solar (photovoltaic), solid state lighting, phonons, thermal conductivity, electrodes - solar, materials and chemistry by design, optics, synthesis (novel materials), synthesis (self-assembly)

Citation Formats

Warmann, Emily C., and Atwater, Harry A.. Energy production advantage of independent subcell connection for multijunction photovoltaics. United States: N. p., 2016. Web. doi:10.1002/ese3.125.
Warmann, Emily C., & Atwater, Harry A.. Energy production advantage of independent subcell connection for multijunction photovoltaics. United States. doi:10.1002/ese3.125.
Warmann, Emily C., and Atwater, Harry A.. Fri . "Energy production advantage of independent subcell connection for multijunction photovoltaics". United States. doi:10.1002/ese3.125.
@article{osti_1388844,
title = {Energy production advantage of independent subcell connection for multijunction photovoltaics},
author = {Warmann, Emily C. and Atwater, Harry A.},
abstractNote = {},
doi = {10.1002/ese3.125},
journal = {Energy Science & Engineering},
number = 4,
volume = 4,
place = {United States},
year = {Fri Jul 01 00:00:00 EDT 2016},
month = {Fri Jul 01 00:00:00 EDT 2016}
}
  • Increasing the number of subcells in a multijunction or "spectrum splitting" photovoltaic improves efficiency under the standard AM1.5D design spectrum, but it can lower efficiency under spectra that differ from the standard if the subcells are connected electrically in series. Using atmospheric data and the SMARTS multiple scattering and absorption model, we simulated sunny day spectra over 1 year for five locations in the United States and determined the annual energy production of spectrum splitting ensembles with 2-20 subcells connected electrically in series or independently. While electrically independent subcells have a small efficiency advantage over series-connected ensembles under the AM1.5Dmore » design spectrum, they have a pronounced energy production advantage under realistic spectra over 1 year. Simulated energy production increased with subcell number for the electrically independent ensembles, but it peaked at 8-10 subcells for those connected in series. As a result, electrically independent ensembles with 20 subcells produce up to 27% more energy annually than the series-connected 20-subcell ensemble. This energy production advantage persists when clouds are accounted for.« less
  • Increasing the number of subcells in a multijunction or "spectrum splitting" photovoltaic improves efficiency under the standard AM1.5D design spectrum, but it can lower efficiency under spectra that differ from the standard if the subcells are connected electrically in series. Using atmospheric data and the SMARTS multiple scattering and absorption model, we simulated sunny day spectra over 1 year for five locations in the United States and determined the annual energy production of spectrum splitting ensembles with 2-20 subcells connected electrically in series or independently. While electrically independent subcells have a small efficiency advantage over series-connected ensembles under the AM1.5Dmore » design spectrum, they have a pronounced energy production advantage under realistic spectra over 1 year. Simulated energy production increased with subcell number for the electrically independent ensembles, but it peaked at 8-10 subcells for those connected in series. As a result, electrically independent ensembles with 20 subcells produce up to 27% more energy annually than the series-connected 20-subcell ensemble. This energy production advantage persists when clouds are accounted for.« less
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  • The measurement of the external quantum efficiency (EQE) of low bandgap subcells in a multijunction solar cell can be sometimes problematic. In particular, this paper describes a set of cases where the EQE of a Ge subcell in a conventional GaInP/GaInAs/Ge triple-junction solar cell cannot be fully measured. We describe the way to identify each case by tracing the I-V curve under the same light-bias conditions applied for the EQE measurement, together with the strategies that could be implemented to attain the best possible measurement of the EQE of the Ge subcell.