Lohmann, Gerald M. and Monahan, Adam H.
(2018)
Effects of temporal averaging on short-term irradiance variability under mixed sky conditions.
Atmospheric measurement techniques, 11 (5).
pp. 3131-3144.
ISSN 1867-8548
Abstract
Characterizations of short-term variability in solar
radiation are required to successfully integrate large numbers
of photovoltaic power systems into the electrical grid.
Previous studies have used ground-based irradiance observations
with a range of different temporal resolutions and
a systematic analysis of the effects of temporal averaging
on the representation of variability is lacking. Using highresolution
surface irradiance data with original temporal resolutions
between 0.01 and 1 s from six different locations
in the Northern Hemisphere, we characterize the changes in
representation of temporal variability resulting from time averaging.
In this analysis, we condition all data to states of
mixed skies, which are the most potentially problematic in
terms of local PV power volatility. Statistics of clear-sky index k* and its increments [...] (i.e., normalized surface irradiance
and changes therein over specified intervals of time)
are considered separately. Our results indicate that a temporal
averaging time scale of around 1 s marks a transition in representing
single-point irradiance variability, such that longer
averages result in substantial underestimates of variability.
Higher-resolution data increase the complexity of data management
and quality control without appreciably improving
the representation of variability. The results do not show any
substantial discrepancies between locations or seasons.
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