Large-Scale Variability of Weather Dependent Renewable Energy Sources

The fluctuation of photovoltaic and wind power generation is directly related to the weather variability. In this study, 8 years of data from a weather model were used to simulate the spatial and temporal characteristics of photovoltaic and wind power generation in Europe. Imbalances in the power system between photovoltaic (PV) plus wind power generation and consumption are investigated in a full (energy) supply scenario. Two different approaches in spatial aggregation are analyzed (i) unlimited crossborder power flows to simulate one European control zone and (ii) no crossborder power flows, i.e. deviations between generation and consumption are balanced on a regional level. On all investigated time scales the fluctuation of imbalances can be reduced by 50% in a common European control zone, i.e. power flows smooth out spatial differences in PV and wind power generation on a European wide grid very effectively. Consequently, less energy from storage facilities is required to meet imbalances, e.g. storage losses are reduced by about 50%. The optimal mix between PV and wind energy in the power system depends on the time scale. While on the monthly time scale roughly 40% of PV is favourable to minimize the variance of imbalances, the optimal share of PV is only 20% on the hourly time scale, because of the strong impact of the diurnal cycle on PV generation.