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

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 AM1.5D 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.
Authors:
 [1] ;  [1]
  1. California Inst. of Technology (CalTech), Pasadena, CA (United States)
Publication Date:
Grant/Contract Number:
AR0000333; SC0001293
Type:
Published Article
Journal Name:
Energy Science & Engineering
Additional Journal Information:
Journal Volume: 4; Journal Issue: 4; Journal ID: ISSN 2050-0505
Publisher:
Society of Chemical Industry, Wiley
Research Org:
California Inst. of Technology (CalTech), Pasadena, CA (United States)
Sponsoring Org:
USDOE Advanced Research Projects Agency - Energy (ARPA-E)
Country of Publication:
United States
Language:
English
Subject:
14 SOLAR ENERGY; energy production; multijunction solar cells; spectral variation; spectrum splitting
OSTI Identifier:
1260849
Alternate Identifier(s):
OSTI ID: 1263703; OSTI ID: 1362113