Utility Scale Solar and Wind Power Variability in the Southwest United States

We present an analysis of the variability of two years of utility scale solar and wind power among the utilities of the Southwest Variable Energy Resource Initiative, primarily in Arizona and New Mexico. We find that SVERI solar variability that arises from changes in cloud cover tends to be greatest when looking at small (under five minute) times scales, while changes over 1 hour time scales are mostly attributable to solar position rather than clouds. SVERI solar variability also exhibits distinct seasonal trends. SVERI wind variability increases as the time scale increases from 1 minute to 60 minutes and exhibits less pronounced seasonal trends. Geographic diversity of solar and wind power plants within and among utilities reduces the aggregate solar and wind variability. We also present the variability data in the context of the electrical load. Near real time data from the SVERI utilities is available at https://sveri.energy.arizona.edu/