Lohmann, Gerald M. and Monahan, Adam H. and Heinemann, Detlev (2016) Local short-term variability in solar irradiance. Atmospheric chemistry and physics, 16 (10). pp. 6365-6379. ISSN 1680-7324

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Characterizing spatiotemporal irradiance variability is important for the successful grid integration of increasing numbers of photovoltaic (PV) power systems. Using 1 Hz data recorded by as many as 99 pyranometers during the HD(CP)2 Observational Prototype Experiment (HOPE), we analyze field variability of clear-sky index k* (i.e., irradiance normalized to clear-sky conditions) and sub-minute k* increments (i.e., changes over specified intervals of time) for distances between tens of meters and about 10 km. By means of a simple classification scheme based on k* statistics, we identify overcast, clear, and mixed sky conditions, and demonstrate that the last of these is the most potentially problematic in terms of short-term PV power fluctuations. Under mixed conditions, the probability of relatively strong k* increments of ±0.5 is approximately twice as high compared to increment statistics computed without conditioning by sky type. Additionally, spatial autocorrelation structures of k* increment fields differ considerably between sky types. While the profiles for overcast and clear skies mostly resemble the predictions of a simple model published by Hoff and Perez (2012), this is not the case for mixed conditions. As a proxy for the smoothing effects of distributed PV, we finally show that spatial averaging mitigates variability in k* less effectively than variability in k* increments, for a spatial sensor density of 2 km<sup>-2</sup>.

Item Type: Article
Additional Information: Publiziert mit Hilfe des DFG-geförderten Open Access-Publikationsfonds der Carl von Ossietzky Universität Oldenburg.
Subjects: Science and mathematics > Physics
Science and mathematics > Earth sciences and geology
Divisions: Faculty of Mathematics and Science > Institute of Physics (IfP)
Date Deposited: 19 Sep 2017 10:24
Last Modified: 20 Dec 2017 11:25
URI: https://oops.uni-oldenburg.de/id/eprint/3247
URN: urn:nbn:de:gbv:715-oops-33288
DOI: 10.5194/acp-2016-2

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