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Algorithm for Building a Spectrum for NREL's One-Sun Multi-Source Simulator: Preprint

Description: Historically, the tools used at NREL to compensate for the difference between a reference spectrum and a simulator spectrum have been well-matched reference cells and the application of a calculated spectral mismatch correction factor, M. This paper describes the algorithm for adjusting the spectrum of a 9-channel fiber-optic-based solar simulator with a uniform beam size of 9 cm square at 1-sun. The combination of this algorithm and the One-Sun Multi-Source Simulator (OSMSS) hardware reduces N… more
Date: June 1, 2012
Creator: Moriarty, T.; Emery, K. & Jablonski, J.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Crystalline Silicon Short-Circuit Current Degradation Study: Initial Results

Description: Following our observation of slow degradation of short-circuit current (Isc) in crystalline silicon (x-Si) modules that was correlated with ultraviolet (UV) exposure dose, we initiated a new study of individual x-Si cells designed to determine the degradation cause. In this paper, we report the initial results of this study, which has accumulated 1056 MJ/m2 of UV dose from 1-sun metal-halide irradiance, equivalent to 3.8 years at our test site. At this time, the control samples are unchanged, t… more
Date: February 1, 2005
Creator: Osterwald, C. R.; Pruett, J. & Moriarty, T.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Cu(In,Ga)Se2 Thin-Film Concentrator Solar Cells: Preprint

Description: Presented at the 2001 NCPV Program Review Meeting: CIGS cells were designed for operation under concentrated sunlight. This is first report of polycrystalline thin-film cell with efficiency>20%.
Date: October 1, 2001
Creator: Ward, J.; Ramanathan, K.; Hasoon, F.; Coutts, T.; Keane, J.; Moriarty, T et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Evolution of CdS/CdTe Device Performance During Cu Diffusion

Description: Cu diffusion from a ZnTe:Cu/Ti back contact onto CdS/CdTe thin-film solar cells is studied. We find if Cu diffusion is insufficient, the entire CdTe layer is depleted. However, if Cu diffusion is excessive, the depletion width can become too narrow to provide optimum current collection. This analysis suggests that most contact processes used for CdS/CdTe devices are optimized (often unknowingly) to result in a depletion width that extends just far enough into the CdTe to yield the highest possi… more
Date: February 1, 2005
Creator: Gessert, T. A.; Smith, S.; Moriarty, T.; Young, M.; Asher, S.; Johnston, S. et al.
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Partner: UNT Libraries Government Documents Department

Formation of ZnTe:Cu/Ti Contacts at High Temperature for CdS/CdTe Devices

Description: The conclusions of this report are that Cu diffusion from a ZnTe:Cu contact causes good and bad things. The good (Cu in CdS < low 10{sup 18} cm{sup -3})--increase in CdTe N{sub A}-N{sub D} that leads to V{sub oc} and FF improvement. The bad (Cu in CdS > low 10{sup 18} cm{sup -3})--(1) possibly decreased of shunt resistance (?); (2) depletion width in CdTe can become too narrow for optimum current collection at J{sub MPP}; (3) donor reduction in CdS (significant FF loss in LIV); and (4) ex… more
Date: May 1, 2006
Creator: Gessert, T. A.; Asher, S.; Johnston, S.; Duda, A.; Young, M. R. & Moriarty, T.
Item Type: Refine your search to only Presentation
Partner: UNT Libraries Government Documents Department
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Formation of ZnTe:Cu/Ti Contacts at High Temperature for CdS/CdTe Devices: Preprint

Description: We study the performance of CdS/CdTe thin-film devices contacted with ZnTe:Cu/Ti of various thickness at a higher-than-optimum temperature of {approx}360 C. At this temperature, optimum device performance requires the same thickness of ZnTe:Cu as for similar contacts formed at a lower temperature of 320 C. C-V analysis indicates that a ZnTe:Cu layer thickness of {approx}< 0.5 mu m does not yield the degree of CdTe net acceptor concentration necessary to reduce space charge width to its optim… more
Date: May 1, 2006
Creator: Gessert, T. A.; Asher, S.; Johnston, S.; Duda, A.; Young, M. R. & Moriarty, T.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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GaInP/GaAs/GaInAs Monolithic Tandem Cells for High-Performance Solar Concentrators

Description: We present a new approach for ultra-high-performance tandem solar cells that involves inverted epitaxial growth and ultra-thin device processing. The additional degree of freedom afforded by the inverted design allows the monolithic integration of high-, and medium-bandgap, lattice-matched (LM) subcell materials with lower-bandgap, lattice-mismatched (LMM) materials in a tandem structure through the use of transparent compositionally graded layers. The current work concerns an inverted, series-… more
Date: August 1, 2005
Creator: Wanlass, M. W.; Ahrenkiel, S. P.; Albin, D. S.; Carapella, J. J.; Duda, A.; Emery, K. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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High-Efficiency CTO/ZTO/CdS/CdTe Polycrystalline Thin-Film Solar Cells: Preprint

Description: Presented at the 2001 NCPV Program Review Meeting: The device performance and reproducibility of CdTe cells can be improved by using a modified CTO/ZTO/CdS/CdTe device structure developed at NREL.
Date: October 1, 2001
Creator: Wu, X.; Dhere, R. G.; Albin, D. S.; Gessert, T. A.; DeHart, C.; Keane, J. C. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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High-Performance, 0.6-eV, GA0.32In0.68As/In0.32P0.68 Thermophotovoltaic Converters and Monolithically Interconnected Modules

Description: Recent progress in the development of high-performance, 0.6-eV Ga0.32In0.68As/InAs0.32P0.68 thermophotovoltaic (TPV) converters and monolithically interconnected modules (MIMs) is described. The converter structure design is based on using a lattice-matched InAs0.32P0.68/Ga0.32In0.68As/InAs0.32P0.68 double-heterostructure (DH) device, which is grown lattice-mismatched on an InP substrate, with an intervening compositionally step-graded region of InAsyP1-y. The Ga0.32In0.68As alloy has a room-te… more
Date: December 15, 1998
Creator: Wanlass, M. W.; Carapella, J. J.; Duda, A.; Emery, K.; Gedvilas, L.; Moriarty, T. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Highly Efficient 32.3% Monolithic GaInP/GaAs/Ge Triple Junction Concentrator Solar Cells

Description: Based on recent cell improvements for space applications, multijunction cells apear to be ideal candidates for high efficiency, cost effective, PV concentrator systems.
Date: January 1, 2000
Creator: Cotal, H. L.; Lillington, D. R.; Ermer, J. H.; King, R. R.; Karam, N. H.; Kurtz, S. R. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Inverted GaInP/(In)GaAs/InGaAs Triple-Junction Solar Cells with Low-Stress Metamorphic Bottom Junctions: Preprint

Description: We demonstrate high efficiency performance in two ultra-thin, Ge-free III-V semiconductor triple-junction solar cell device designs grown in an inverted configuration. Low-stress metamorphic junctions were engineered to achieve excellent photovoltaic performance with less than 3 x 106 cm-2 threading dislocations. The first design with band gaps of 1.83/1.40/1.00 eV, containing a single metamorphic junction, achieved 33.8% and 39.2% efficiencies under the standard one-sun global spectrum and con… more
Date: May 1, 2008
Creator: Geisz, J. F.; Kurtz, S. R.; Wanlass, M. W.; Ward, J. S.; Duda, A.; Friedman, D. J. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Lattice-Mismatched Approaches for High-Performance, III-V Photovoltaic Energy Converters

Description: We discuss lattice-mismatched (LMM) approaches using compositionally step-graded layers and buffer layers that yield III-V photovoltaic devices with performance parameters equaling those of similar lattice-matched (LM) devices. Our progress in developing high-performance, LMM, InP-based GaInAs/InAsP materials and devices for thermophotovoltaic (TPV) energy conversion is highlighted. A novel, monolithic, multi-bandgap, tandem device for solar PV (SPV) conversion involving LMM materials is also p… more
Date: February 1, 2005
Creator: Wanlass, M. W.; Ahrenkiel, S. P.; Ahrenkiel, R. K.; Albin, D. S.; Carapella, J. J.; Duda, A. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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New GaInP/GaAs/GaInAs, Triple-Bandgap, Tandem Solar Cell for High-Efficiency Terrestrial Concentrator Systems

Description: GaInP/GaAs/GaInAs three-junction cells are grown in an inverted configuration on GaAs, allowing high quality growth of the lattice matched GaInP and GaAs layers before a grade is used for the 1-eV GaInAs layer. Using this approach an efficiency of 37.9% was demonstrated.
Date: November 1, 2005
Creator: Kurtz, S.; Wanlass, M.; Kramer, C.; Young, M.; Geisz, J.; Ward, S. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Procedures at NREL for Evaluating Multijunction Concentrator Cells

Description: The procedures for evaluating the performance of multijunctiion-concentrator cells at the National Renewable Energy Laboratory are described. The accurate measurement of the performance of multijunction cells requires accurate relative-quantum-efficiency-measurements, "matched" reference cells, and a spectrally adjustable solar simulator.
Date: January 1, 2000
Creator: Moriarty, T. & Emery, K.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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PV Cell and Module Calibration Activities at NREL

Description: The performance of PV cells and modules with respect to standard reference conditions is a key indicator of progress of a given technology. This task provides the U.S. terrestrial PV community with the most accurate measurements that are technically possible in a timely fashion. The international module certification and accreditation program PVGap requires certification laboratories to maintain their calibration traceability path to groups like this one. The politics of a "world record" effici… more
Date: November 1, 2005
Creator: Emery, K.; Anderberg, A.; Kiehl, J.; Mack, C.; Moriarty, T.; Ottoson, L. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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PV cell and module performance measurement capabilities at NREL

Description: The Photovoltaic (PV) Cell and Module Performance Characterization team at NREL supports the entire photovoltaic community by providing: secondary calibrations of photovoltaic cells and modules; efficiency measurements with respect to a given set of standard reporting conditions; verification of contract efficiency milestones; and current versus voltage (I-V) measurements under various conditions of temperature, spectral irradiance, and total irradiance. Support is also provided to in-house pro… more
Date: September 1, 1998
Creator: Rummel, S.; Emery, K.; Field, H.; Moriarty, T.; Anderberg, A.; Dunlavy, D. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Thermophotovoltaic Cell Temperature Measurement Issues

Description: The power produced by photovoltaic devices changes with temperature, ranging from 0.1% to nearly 1% per degrees Celsius depending on the structure. The temperature across the surface of TPV cells will vary depending on the amount of absorbed power. Thus the temperature over a region of a wafer where there is no cell will be different from a region of the wafer containing a cell with an antireflection coating and back surface reflector. Vacuum hold-downs or back surface probes may result in loca… more
Date: November 13, 1998
Creator: Emery, K. & Moriarty, T.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Trust But Verify: Procedures to Achieve Accurate Efficiency Measurements for All Photovoltaic Technologies

Description: The measurement of the photovoltaic (PV) performance with respect to reference conditions requires measuring the performance with respect to a given tabular reference spectrum, junction temperature, and total irradiance. This paper discusses the procedures implemented by NREL's PV Cell and Module Performance Characterization Group to achieve the lowest practical uncertainty. This paper describes the process of trusting and verifying software, hardware, calibrations, procedures, and results. As … more
Date: February 1, 2005
Creator: Emery, K.; Anderberg, A.; Kiehl, J.; Mack, C.; Moriarty, T.; Rummel, S. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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