The U.S. Department of Energy's National Renewable Energy Laboratory (NREL) has produced and made available a data set showing what happens, second by second, when clouds pass over a solar power installation.
Seventeen measurement stations near Hawaii's Honolulu International Airport on the island of Oahu collected data at one-second intervals over the course of a year. NREL says the data will be of interest to utilities, developers of large-scale photovoltaic systems, forecasters, system operators, laboratories and universities.
‘The time-synch data are unique,’ says NREL Senior Scientist David Renne. ‘All 17 stations make a one-second measurement at exactly the same time. This allows the array to 'see' clouds moving through and simulates how a PV system might behave.’
‘If [developers] have good statistical information about cloud patterns, they can design systems and wire them together along certain orientations to minimize the impact of cloud passage, and dampen those fluctuations,’ Renne added.
NREL found that in the case of very large arrays of solar panels, a smoothing of fluctuation occurs, compared to the sharp spikes and plunges that can happen when a cloud passes by a single panel or small rooftop array.
One year's worth of the data from the study can be found on NREL's Measurement and Instrumentation Data Center website.