NASA Scientific and Technical Aerospace Reports

ilayer structure, the DLC films not only serve as antireflection coating and protective encapsulant, but also improve the cell
efficiencies.
NTIS
Carbon; Diamonds; Encapsulating; Photovoltaic Cells; Solar Cells
20060002357 National Renewable Energy Lab., Golden, CO USA
Properties of High-Efficiency CIGS Thin-Film Solar Cells
Ramanathna, K.; Keane, J.; Noufi, R.; Feb. 2005; 12 pp.; In English
Report No.(s): DE2005-15016459; NREL/CP-520-37404; No Copyright; Avail.: Department of Energy Information Bridge
We present experimental results in three areas. Solar cells with an efficiency of 19% have been fabricated with an absorber
bandgap in the range of 1.1-1.2 eV. Properties of solar cells fabricated with and without an undoped ZnO layer were compared.
The data show that high efficiency cells can be fabricated without using the high-resistivity or undoped ZnO layer. Properties
of CIGS solar cells were fabricated from thin absorbers (1 (micro)m) deposited by the three-stage process and simultaneous
co-deposition of all the elements. In both cases, solar cells with efficiencies of 16%-17% are obtained.
NTIS
Solar Cells; Thin Films
20060002358 National Renewable Energy Lab., Golden, CO USA
On-Sun Comparison of GaInP2/GaAs Tandem Cells with Top Cell Thickness Varied
McMahon, W. E.; Emergy, K. E.; Friedman, D. J.; Ottoson, L.; Young, M. S.; Feb. 2005; 12 pp.; In English
Report No.(s): DE2005-15016451; NREL/CP-520-37376; No Copyright; Avail.: Department of Energy Information Bridge
This study compares the on-sun performance of a set of GaInP2/GaAs tandem cells with different GaInP2 top-cell
thicknesses. Because high-efficiency III-V cells are best suited to concentrating photovoltaic (CPV) applications, the cells
were mounted on a two-axis tracker with the incident sunlight collimated to exclude all except the direct beam.
Current-voltage (I-V) curves were taken throughout the course of several days, along with measurements of the direct solar
spectrum. Our two major conclusions are: (1) GaInP2/GaAs tandem cells designed for an ‘air mass 1.5 global’ (AM 1.5G)
or a ‘low aerosol optical depth’ (Low AOD) spectrum perform the best, and (2) cells can be characterized indoors and modeled
using outdoor spectra to predict the correct result. These results are equally valid for GaInP2/GaAs/Ge triple-junction cells.
NTIS
Evaluation; Gallium Arsenides; Performance Tests; Solar Cells; Sun; Thickness
20060002369 National Renewable Energy Lab., Golden, CO USA
Hathaway ‘Solar Patriot’ House: A Case Study in Efficiency and Renewable Energy
Norton, P.; Hancock, E.; Barker, G.; Reeves, P.; May 2005; 64 pp.; In English
Report No.(s): DE2005-15016267; NREL/TP-550-37731; No Copyright; Avail.: National Technical Information Service
(NTIS)
This report details the monitored and modeled performance of a solar home outside of Washington, D.C. We modeled the
home energy performance using DOE2.2, performed numerous short-terms tests on the home and monitored its occupied
performance for 29 months. The home uses modular construction, solar water heating, a ground-coupled heat pump, efficient
appliances and compact fluorescent lighting to reduce its energy consumption by 35% compared to the Building America
research benchmark home. The addition of 6kW of photovoltaics increases the savings to 67% compared to the Building
America research benchmark. A more efficient shell to reduce space conditioning loads would have brought the home closer
to its zero energy goals. However, even with efficient lighting and appliances, the lights, appliance and plug loads are a
significant energy consumer. About 4 kW of PV are required to meet the needs of these loads alone. To achieve the zero energy
goal with no further efficiency increases, the Hathaway house would need about 2.6 kW of PV in addition to the 6.0 kW it
now has.
NTIS
Energy Conservation; Evaluation; Performance Tests; Renewable Energy; Solar Houses
20060002391 National Renewable Energy Lab., Golden, CO USA
Crystalline Silicon Short-Circuit Current Degradation Study: Initial Results
Osterwald, C. R.; Pruett, J.; Moriarty, T.; Feb. 2005; 1 pp.; In English
Report No.(s): DE2005-15016390; NREL-CP-520-37357; No Copyright; Avail.: Department of Energy Information Bridge
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