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Chicago Ridge, IL, United States

Habte A.,National Renewable Energy Laboratory | Andreas A.,National Renewable Energy Laboratory | Ottoson L.,National Renewable Energy Laboratory | Gueymard C.A.,Solar Consulting Services | And 7 more authors.
43rd ASES National Solar Conference 2014, SOLAR 2014, Including the 39th National Passive Solar Conference and the 2nd Meeting of Young and Emerging Professionals in Renewable Energy | Year: 2014

Indoor and outdoor testing of photovoltaic (PV) device performance requires the use of solar simulators and natural solar radiation, respectively. This performance characterization requires accurate knowledge of spectral irradiance distribution that is incident on the devices. Spectroradiometers are used to measure the spectral distribution of solar simulators and solar radiation. On September 17, 2013, a global spectral irradiance intercomparison using spectroradiometers was organized by the Solar Radiation Research Laboratory (SRRL) at the National Renewable Energy Laboratory (NREL). 10 spectroradiometers from different laboratories participated in the intercomparison. The intercomparison was aimed to understand the performance of the different spectroradiometers and to achieve internal performance-based measurement and calibration qualitycontrol checks undertaken by the laboratories. The Simple Model of the Atmospheric Radiative Transfer of Sunshine (SMARTS) model outputs were used in the outdoor intercomparison as an explanatory tool. The intent was to better understand how well the SMARTS-modeled spectra compare to various types of spectroradiometers considering that the model has a finer resolution than the instruments under scrutiny. Aside from spectral regions corresponding to sharp absorption bands and fast-changing sky conditions, the overall results of the comparison demonstrated less than 10% difference among the participating spectroradiometers and between the measured and SMARTS outputs. The results of this first intercomparison will help to decrease systematic inter-laboratory differences in the measurements of the outputs or efficiencies of PV devices and harmonize laboratory experimental procedures. Source

Zielnik A.,Atlas Material Testing Technology LLC
PPCJ Polymers Paint Colour Journal | Year: 2012

The need for faster weather testing of wood coatings has put demands on results being provided through a laboratory rather than the more time consuming outdoor methods. A common method is to coat a single wood board, with different formulations or film thicknesses. This provides a common platform to minimize substrate variables. A variety of wood types is used such as various species, heartwood and sapwood versions, and different ring and grain patterns, especially for woods with high extractables and staining potential. The most common technique is the fluorescent condensation'-based tester defined in ISO 4892-3. This technique alternates either UV-A or UV-B exposure at elevated temperature and humidity with a slight cool-down to promote moisture condensation on to the specimens. Xenon arc lamp-based weathering testers have the advantage that when properly set up they are the closest to reproducing full-spectrum solar radiation and its effects on materials. Source

Zielnik A.,Atlas Material Testing Technology LLC
PPCJ Polymers Paint Colour Journal | Year: 2012

Fresnel sunlight concentrators and xenon arc weathering devices have been developed by Atlas Material Testing Technology, to provide faster results over real time. Fresnel sunlight concentrators track the sun during the day and focus 10 images of the sun on to the test target. The test specimens are then cooled so that their temperatures are near to what they would be on a static test fence. Periodic water sprays can be programmed to provide wetting or thermal shock during the day and/or night time dew wetting typical of south Florida or operated dry. As only the direct beam sunlight is focused, the actual concentration factor is about 8X over a natural exposure. This acceleration is seasonally dependent upon the sun and the test acceleration is, therefore, highest in summer. Xenon arc technique is relatively inexpensive and very useful in screening large numbers of binder formulations for UV and moisture resistance. Source

Nichols M.,Ford Motor Company | Boisseau J.,BASF | Pattison L.,BASF | Campbell D.,BASF | And 8 more authors.
Journal of Coatings Technology Research | Year: 2013

A new accelerated weathering protocol has been developed which closely replicates the performance of automotive and aerospace coating systems exposed in South Florida. IR spectroscopy was used to verify that the chemical composition changes that occurred during accelerated weathering in devices with a glass filter that produced a high fidelity reproduction of sunlight's UV spectrum matched those that occurred during natural weathering. Gravimetric water absorption measurements were used to tune the volume of water absorption during accelerated weathering to match that which occurred during natural weathering in South Florida. The frequency of water exposure was then scaled to the appropriate UV dose. A variety of coating systems were used to verify the correlation between the physical failures observed in the accelerated weathering protocol and natural weathering in South Florida. The new accelerated weathering protocol correctly reproduced gloss loss, delamination, cracking, blistering, and good performance in a variety of diverse coating systems. For automotive basecoat/clearcoat paint systems, the new weathering protocol shows significant acceleration over both Florida and previous accelerated weathering tests. For monocoat aerospace systems, the new weathering protocol showed less acceleration than for automotive coatings, but was still an improvement over previous accelerated tests and was faster than Florida exposure. © 2013 American Coatings Association & Oil and Colour Chemists' Association. Source

Dumbleton D.,Atlas Material Testing Technology LLC | Slomko R.,Atlas Material Testing Technology LLC
Conference Record of the IEEE Photovoltaic Specialists Conference | Year: 2013

We begin from the basic premise that the primary enemies of PV modules are heat, light and moisture, plus numerous other possible stressors which may or may not be participants, depending upon the specific location of the module. We have adopted a Coffin-Manson model to estimate what the effects of thermal cycling might be upon the PV module in support of empirical observations. It describes part of the environmental durability to be anticipated from subject modules (1). Although this model ignores the effects of humidity, solar irradiance, voltage variation and other mechanical and chemical stresses, it does offer us an estimate of the equivalence of a test methodology to a part of the real world environment. A realistic example of its use is described and calculated. © 2013 IEEE. Source

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