Increasing the resolution of solar and wind time series for energy system modeling: A review

Bottom-up energy system models are often based on hourly time steps due to limited computational tractability or data availability. However, in order to properly assess the rentability and reliability of energy systems by accounting for the intermittent nature of renewable energy sources, a higher level of detail is necessary. This study reviews different methods for increasing the temporal resolutions of time series data for global horizontal and direct normal irradiance for solar energy, and wind speed for wind energy. The review shows that stochastic methods utilizing random sampling and non-dimensional approaches are the most frequently employed for solar irradiance data downscaling. The non-dimensional approach is particularly simple, with global applicability and a robust methodology with good validation scores. The temporal increment of wind speed, however, is challenging due to its spatiotemporal complexity and variance, especially for accurate wind distribution profiles. Recently, researchers have mostly considered methods that draw on the combination of meteorological reanalysis and stochastic fluctuations, which are more accurate than the simple and conventional interpolation methods. This review provides a road map of how to approach solar and wind speed temporal downscaling methods and quantify their effectiveness. Furthermore, potential future research areas in solar and wind data downscaling are also highlighted.