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Title: Daily Fill Factor Variation as a Diagnostic Probe of Multijunction Concentrator Systems During Outdoor Operation

Abstract

The work presented here is for GaInP2/GaAs tandem cells, but the conclusions are equally valid for GaInP2/GaAs/Ge triple-junction cells. Optimizing a concentrator system which uses multijunction solar cells is challenging because: (a) the conditions are variable, so the solar cells rarely operate under optimal conditions and (b) the conditions are not controlled, so any design problems are difficult to characterize. Any change in the spectral content of direct-beam sunlight as it passes through the concentrator optics is of particular interest, as it can reduce the performance of multijunction cells and is difficult to characterize.

Authors:
; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
National Renewable Energy Lab. (NREL), Golden, CO (United States)
Sponsoring Org.:
USDOE Office of Energy Efficiency and Renewable Energy Solar Energy Program
OSTI Identifier:
1120998
DOE Contract Number:
AC36-08GO28308
Resource Type:
Conference
Resource Relation:
Conference: High and Low Concentration for Solar Electric Applications II: Proceedings of the SPIE Optics and Photonics Conference, 26-30 August 2007, San Diego, California; Proceedings of SPIE Vol. 6649
Country of Publication:
United States
Language:
English
Subject:
14 SOLAR ENERGY; 42 ENGINEERING; PV; MULTI-JUNCTION SOLAR CELL; CONCENTRATOR MODULE; CURRENT-MATCHING; FILL FACTOR; Solar Energy - Photovoltaics

Citation Formats

McMahon, W. E., Emery, K. E., Friedman, D. J., Ottoson, L., Young, M. S., Ward, J. S., Kramer, C. M., Duda, A., and Kurtz, S. Daily Fill Factor Variation as a Diagnostic Probe of Multijunction Concentrator Systems During Outdoor Operation. United States: N. p., 2007. Web.
McMahon, W. E., Emery, K. E., Friedman, D. J., Ottoson, L., Young, M. S., Ward, J. S., Kramer, C. M., Duda, A., & Kurtz, S. Daily Fill Factor Variation as a Diagnostic Probe of Multijunction Concentrator Systems During Outdoor Operation. United States.
McMahon, W. E., Emery, K. E., Friedman, D. J., Ottoson, L., Young, M. S., Ward, J. S., Kramer, C. M., Duda, A., and Kurtz, S. Mon . "Daily Fill Factor Variation as a Diagnostic Probe of Multijunction Concentrator Systems During Outdoor Operation". United States. doi:.
@article{osti_1120998,
title = {Daily Fill Factor Variation as a Diagnostic Probe of Multijunction Concentrator Systems During Outdoor Operation},
author = {McMahon, W. E. and Emery, K. E. and Friedman, D. J. and Ottoson, L. and Young, M. S. and Ward, J. S. and Kramer, C. M. and Duda, A. and Kurtz, S.},
abstractNote = {The work presented here is for GaInP2/GaAs tandem cells, but the conclusions are equally valid for GaInP2/GaAs/Ge triple-junction cells. Optimizing a concentrator system which uses multijunction solar cells is challenging because: (a) the conditions are variable, so the solar cells rarely operate under optimal conditions and (b) the conditions are not controlled, so any design problems are difficult to characterize. Any change in the spectral content of direct-beam sunlight as it passes through the concentrator optics is of particular interest, as it can reduce the performance of multijunction cells and is difficult to characterize.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
}

Conference:
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  • Designing a tandem solar cell for use in a concentrator system is challenging because: (a) the conditions are variable, so solar cells rarely operate under optimal conditions, and (b) the conditions are not controlled, so any design problems are difficult to characterize. Here, we show how the fill factor can be used as a diagnostic tool to either verify correct system design and operation or to help identify a problem. We give particular attention to the detection of spectral skewing by the concentrator optics, as this can reduce the performance of GaInP{sub 2}/GaAs tandem cells and is difficult to characterize.more » The conclusions are equally valid for GaInP{sub 2}/GaAs/Ge triple-junction cells.« less
  • The National Renewable Energy Laboratory (NREL) has been testing amorphous silicon (a-Si) Photovoltaic (PV) modules for more than a decade. NREL has been conducting controlled light-soak testing of multifunction a-Si modules to characterize their performance for stability evaluation as well as to benchmark the technology status. Some of the test modules, after controlled light-soak testing, have been installed outdoors. The authors have observed that under outdoor exposure, the modules further degrade in performance, possibly due to lower outdoor temperatures and varying spectra. The paper presents data on the light-induced degradation for the third controlled light-soak test on multijunction a-Si modulesmore » as well as outdoor performance data on single and multijunction modules under prevailing conditions.« less
  • The National Renewable Energy Laboratory (NREL) has been testing amorphous silicon (a-Si) Photovoltaic (PV) modules for more than a decade. NREL has been conducting controlled light-soak testing of multijunction a-Si modules to characterize their performance for stability evaluation as well as to benchmark the technology status. Some of the test modules, after controlled light-soak testing, have been installed outdoors. The authors have observed that under outdoor exposure, the modules further degrade in performance, possibly due to lower outdoor temperatures and varying spectra. The paper presents data on the light-induced degradation for the third controlled light-soak test on multijunction a-Si modulesmore » as well as outdoor performance data on single- and multijunction modules under prevailing conditions.« less
  • Solar cells fabricated from various III-V compounds have recently produced very high laboratory conversion efficiencies approaching 29% for single junction and 35% for multijunction structures under concentrated illumination. However, due to their relatively limited availability, few of these devices have been incorporated into actual concentrator module structures. Details are presented from two development efforts which have incorporated III-V cells into high efficiency prototype concentrator modules: (1) Varian's GaAs module operating at 1000 suns with flat fresnel lenses; and (2) Boeing's tandem GaAs/GaSb module operating at 50 suns with Entech's domed fresnel lenses.