Can Reanalysis Products Reliably Represent Solar and Wind Energy Resources and Their Complementarity over China

Global reanalysis products are indispensable for reconstructing historical meteorological conditions and are crucial particularly for estimation of solar and wind energy resources. Although previous studies have evaluated reanalysis performance for individual resources or regional biases, systematic assessments of their capacity to simultaneously simulate solar and wind energy as well as their complementarity remain limited. This study evaluates the performance of ERA5, MERRA-2, and JRA-55 in estimating solar and wind energy resources across China during 1980–2022, with the help of ground-based observations as a reference. Results show that ERA5 displays superior overall performance in reproducing spatiotemporal patterns of solar and wind energy. Reanalysis products generally reproduce interannual variations and declining trends in solar energy, none fully capture the observed “decline-then-recovery” pattern in wind energy. ERA5 also demonstrates a strong spatial consistency with observations in representing solar-wind complementarity at daily to monthly scales. At the annual scale, ERA5 performs best in representing solar-wind complementarity in southern China, while MERRA-2 overperforms in northern China. This study calls for caution in interpreting solar–wind complementarity in existing studies that rely solely on reanalysis products and provides guidance for their applications in supporting solar and wind energy planning and management.