Abstract

We characterize the irradiance enhancement events that occur when coastal stratocumulus clouds dissipate, caused by the breakup of the cloud layer into smaller cloud elements. The analysis includes 91 days in 2016 and 2017 that presented transitions from stratocumulus to clear skies in Southern California, using solar irradiance measurements and a clear sky model to describe the enhancement events. We find that a breakup process that starts later in the day lasts longer and is linked to stronger enhancement, as well as stronger down-ramps. Strong enhancement events are also linked to higher wind speeds during the breakup and lower solar zenith angle. The potential benefit of an irradiance enhancement forecast is assessed by evaluating a battery ramp-rate control system. Compared to a forecast that does not capture the solar variability, a good forecast would allow to use a smaller battery and to cycle it less, extending its lifetime.