In-situ comparison of thermal measurement technologies for interpretation of PV module temperature de-rating effects
PV array temperature
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PublisherSPIE-INT SOC OPTICAL ENGINEERING
CitationTeri Elwood ; Whit Bennett ; Teh Lai and Kelly Simmons-Potter " In-situ comparison of thermal measurement technologies for interpretation of PV module temperature de-rating effects ", Proc. SPIE 9938, Reliability of Photovoltaic Cells, Modules, Components, and Systems IX, 99380Q (September 26, 2016); doi:10.1117/12.2237934; http://dx.doi.org/10.1117/12.2237934
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AbstractIt is well known that the efficiency of a photovoltaic (PV) module is strongly impacted by its temperature such that higher temperatures lead to lower energy conversion efficiencies. An accurate measurement of the temperature de-rating effect, therefore, is vital to the correct interpretation of PV module performance under varied environmental conditions. The current work investigates and compares methods for performing measurements of module temperature both in the lab and in field-test environments. A comparison of several temperature measurement devices was made in order to establish the ideal sensor configuration for quantifying module operating temperature. Sensors were also placed in various locations along a string of up to eight photovoltaic modules to examine the variance in operating temperature with position in the string and within a larger array of strings.
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Laboratory germination responses of 3 love-grasses to temperature in relation to seedbed temperatureRoundy, B. A.; Young, J. A.; Sumrall, L. B.; Livingston, M. (Society for Range Management, 1992-05-01)Laboratory tests are often conducted to determine seed germination responses to temperatures for seedbed ecology interpretations and revegetation seeding rate calculations. To determine the utility of laboratory germination tests for indicating seedbank germinability of lovegrasses we measured seedbed temperatures and soil water on 2 semidesert grassland sites in the Southwest. We also tested germination of Lehmann lovegrass (Eragrostis lehmanniana Nees), 'Cochise' lovegrass (E. lehmanniana Nees X E. trichophora Coss & Dur.), and plains lovegrass (E. intermedia Hitch.) seed collections associated with natural or artificial revegetation studies on these 2 sites in relation to an array of constant and alternating temperatures. Germination responses to different temperatures varied with the year and source of collection and seed age and differed compared to those reported in the literature. Lehmann and Cochise lovegrass had high germination at temperature alternations similar to wet seedbed temperature extremes in December (0,2/15 degrees C) and these species and plains lovegrass were germinable at moderate temperature alternations representative of wet seedbeds in April (10/30 degrees C). Ability to germinate in laboratory tests at these temperatures is not necessarily indicative of germinability in the field for Lehmann lovegrass, which has been observed to germinate in April, not December, in wet seedbeds. All species had maximum or near maximum germination at a temperature alternation of 20/40 degrees C, which is similar to wet seedbed temperature extremes during the summer rainy period when these species usually emerge. Because of the variability in germinability of different seed collections of lovegrass over time, specific collections should be tested at specific ages relevant to seedbed ecology and revegetation studies or projects. Laboratory germination tests which mimic actual wet seedbed temperature curves might be more predictive of seedbed germinability than the usual tests which expose the seeds to abrupt temperature alternations.