Objective Method for Selecting Outdoor Reporting Conditions for Photovoltaic Performance

    Research output: Contribution to conferencePaper


    Outdoor performance of photovoltaic modules and systems depends on prevailing conditions at the time of measurement. Outdoor test conditions must be relevant to device performance and readily attainable. Flat-plate, nonconcentrator PV device performance is reported with respect to fixed conditions referred to as Standard Reporting Conditions (SRC) of 1 kW/m? plane of array total irradiance, 25? Cdevice temperature, and a reference spectral distribution at air mass 1.5 under certain atmospheric conditions. We report a method of analyzing historical meteorological and irradiance data to determine the range of outdoor environmental parameters and solar irradiance components that affect solar collector performance when the SRC 1 kW/m? total irradiance value occurs outdoors. We used datafrom the 30 year U.S. National Solar Radiation Data Base (NSRDB) , restricting irradiance conditions to within +/- 25 W/m? of 1 kW/m? on a solar tracking flat-plate collector. The distributions of environmental parameter values under these conditions are non-Gaussian and site dependent. Therefore the median, as opposed to the mean, of the observed distributions is chosen to represent appropriateoutdoor reporting conditions. We found the average medians for the direct beam component (834 W/m?), ambient temperature (24.4? C), total column water vapor (1.4 cm), and air mass (1.43) are near commonly used SRC values. Average median wind speed (4.4 m/s) and broadband aerosol optical depth (0.08) were significantly different from commonly used values.
    Original languageAmerican English
    Number of pages8
    StatePublished - 1999
    EventAmerican Solar Energy Society Solar 99 Conference - Portland, Maine
    Duration: 12 Jun 199915 Jun 1999


    ConferenceAmerican Solar Energy Society Solar 99 Conference
    CityPortland, Maine

    NREL Publication Number

    • NREL/CP-520-26229


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