Correlations Between Large-Scale Solar and Wind Power in a Future Scenario for Sweden

Future power systems are likely to include large amounts of variable power generation such as solar and wind power. As a variable output has to be balanced by the power system's reserves, it is important to study the time variability, coincidence, and correlations between power sources. The effect of output smoothing from dispersion of wind power plants is well established, but there is a need to study more renewables in combination. This study analyses large-scale solar and wind power in a future scenario for Sweden, using climatic data covering eight years with an hourly resolution. It is shown that solar and wind power are negatively correlated on all time scales, from hourly to annual, but that the correlation is strongest for monthly totals. Combining solar and wind power reduces total variations in terms of standard deviation, but hour-to-hour variability is always higher with a larger share of solar power.