Rapid changes in insolation in southern England due to variation in cloud cover: influence on operation and testing of solar modules

Stephen Reynolds, Erin Goldstraw

    Research output: Chapter in Book/Report/Conference proceedingConference contribution

    Abstract

    Analysis of insolation data recorded in southern England during June 2009 reveals that on an active day, changes in irradiance (ramp rate) exceeding 1 % per second may occur up to 5 % of the time. This leads to uncertainties in outdoor PV performance figures, since current-voltage scans are taking place under non-constant light levels. We investigate the relationship between fill factor and ramp rate by an equivalent-circuit simulation, which provides an indication of the underlying noise levels to be expected from this source when compiling fill factor trends from raw outdoor test data. We have also computed the insolation amplitude spectrum and sought to assign the spectral features to diurnal, meteorological and stochastic effects. Comparison with experimental measurements suggests that ramps make a minor contribution to the noise level under typical measurement conditions. However the pronounced non-gaussian nature of the statistical frequency distribution of ramp rates suggests this may be responsible for ‘outlier’ data points.
    Original languageEnglish
    Title of host publicationSEEP 2013 - 6th International Conference on Sustainable Energy and Environmental Protection
    Subtitle of host publicationProceedings
    EditorsJurij Krope, Abdul Ghani Olabi, Darko Goričanec
    Place of PublicationMaribor
    PublisherUniversity of Maribor, Faculty of Chemistry and Chemical Engineering
    Pages270-275
    Number of pages6
    ISBN (Print)9789612483791
    Publication statusPublished - 2013
    Event6th International Conference on Sustainable Energy & Environmental Protection - Maribor, Slovenia
    Duration: 20 Aug 201323 Aug 2013
    http://www.seepconference.co.uk/SEEP2013.pdf

    Conference

    Conference6th International Conference on Sustainable Energy & Environmental Protection
    Abbreviated titleSEEP
    CountrySlovenia
    CityMaribor
    Period20/08/1323/08/13
    Internet address

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    Keywords

    • Photovoltaics
    • Ramp rate
    • Fill factor

    Cite this

    Reynolds, S., & Goldstraw, E. (2013). Rapid changes in insolation in southern England due to variation in cloud cover: influence on operation and testing of solar modules. In J. Krope, A. G. Olabi, & D. Goričanec (Eds.), SEEP 2013 - 6th International Conference on Sustainable Energy and Environmental Protection: Proceedings (pp. 270-275). University of Maribor, Faculty of Chemistry and Chemical Engineering. http://www.seepconference.co.uk/Venue.html