Time Series Analysis of Hourly Global Horizontal Solar Radiation
Solar Energy, 41 (5):
423--429 (1988)Abstract
Accurate design and optimization of short response time solar energy
systems with storage are sensitive to the stationary and sequential
characteristics of hourly solar radiation. We perform monthly time
series analyses of hourly global horizontal solar radiation for a
wide range of climatic stations that span temperate and tropical
conditions. The stationary statistics for individual hours are found
to be very similar to the corresponding results for daily total global
horizontal radiation, in keeping with a related fundamental observation
of Liu & Jordan. Investigation of sequential properties shows that
autocorrelation coefficients are, to a good approximation, independent
of time of day and that persistence times are nearly as long as the
entire daylight period, mainly due to the effect of very strong correlations
at one-hour lag times. The isolated effect of two-hour and longer
lag times, via the partial autocorrelation coefficients, is found
to be negligible in most, but by no means all, instances. Finally,
we find no universal correlation between hourly autocorrelation coefficients
and monthly average radiation figures