Issue 10 Volume 41 May 16, 2003

Only one solution appeared to meet the goals: the PV-modules have to be connected in parallel to keep the dc-voltage as low
as possible. The low dc-voltage also allows omitting many of the safety components used in series connected PV-system. To
minimize the number of components even more two new PV-wirefree components are designed in which different functions
are integrated. The most innovative new component is the PV-wirefree mounting bus, a current carrying mounting frame. So,
a PV-wirefree system does not include expensive dc-wiring anymore, whereas the number of connectors is reduced
considerably. In this paper the new PV-wirefree components are presented and safety issues related to paralleling PV-modules
are discussed, as well as the additional advantages of PV-wirefree regarding reliability and efficiency.
NTIS
Design Analysis; Power Supplies; Electric Potential
20030036999 National Renewable Energy Lab., Golden, CO
What is the Appropriate Reference Spectrum for Characterizing Concentrator Cells
Emery, K.; Myers, D.; Kurtz, S.; May 2002; 12 pp.; In English
Report No.(s): DE2002-15000983; No Copyright; Avail: Department of Energy Information Bridge
This conference paper describes Consensus standards for determining the efficiency of a concentrator cell or module that
have not been developed. NREL, Sandia National Laboratory, the Fraunhofer Institute for Solar Energy in Germany, and the
Progress in Photovoltaics Efficiency Table authors have informally agreed upon concentrator-cell reference conditions. These
conditions are 25 deg C cell temperature, 1-sun =1000 W/m2 total irradiance, and the ASTM E891-87 direct-normal reference
spectrum. Deficiencies in the direct reference spectrum are discussed, and a more representative reference spectrum for
evaluating concentrator cells is proposed. The spectrum was generated by the SMARTS model, and the atmospheric
parameters are as close as possible to the existing direct spectrum, with the exception that the aerosol optical depth at 500 nm
is reduced from 0.27 to 0.085.
NTIS
Concentrators; Solar Cells; Energy Technology; Spectrum Analysis
20030037000 National Renewable Energy Lab., Golden, CO
Proposed Reference Spectral Irradiance Standards to Improve Concentrating Photovoltaic System Design and
Performance Evaluation
Myers, D. R.; Emery, K. E.; May 2002; In English
Report No.(s): DE2002-15000984; No Copyright; Avail: National Technical Information Service (NTIS)
This conference paper describes the American Society for Testing and Materials (ASTM), the International
Electrotechnical Commission (IEC), and the International Standards Organization (ISO) standard solar terrestrial spectra
(ASTM G-159, IEC-904-3, ISO 9845-1) provide standard spectra for photovoltaic performance applications. Modern
terrestrial spectral radiation models and knowledge of atmospheric physics are applied to develop suggested revisions to
update the reference spectra. We use a moderately complex radiative transfer model (SMARTS2) to produce the revised
spectra. SMARTS2 has been validated against the complex MODTRAN radiative transfer code and spectral measurements.
The model is proposed as an adjunct standard to reproduce the reference spectra. The proposed spectra represent typical clear
sky spectral conditions associated with sites representing reasonable photovoltaic energy production and weathering and
durability climates. The proposed spectra are under consideration by ASTM.
NTIS
Energy Conversion Effıciency; Photovoltaic Conversion; Solar Spectra; Atmospheric Physics; Solar Energy; Irradiance
20030037001 National Renewable Energy Lab., Golden, CO
Terrestrial Solar Spectral Modeling Tools and Applications for Photovoltaic Devices
Myers, D. R.; Emergy, K. E.; May 2002; In English
Report No.(s): DE2002-15000985; No Copyright; Avail: National Technical Information Service (NTIS)
This conference paper describes the variations in terrestrial spectral irradiance on photovoltaic devices can be an
important consideration in photovoltaic device design and performance. This paper describes three available atmospheric
transmission models, MODTRAN, SMARTS2, and SPCTRAL2. We describe the basics of their operation and performance,
and applications in the photovoltaic community. Examples of model input and output data and comparisons between the model
results for each under similar conditions are presented. The SMARTS2 model is shown to be much easier to use, as accurate
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