Hydropower dataset for creating operational constraints in aggregated energy system models covering European bidding zones

The dataset was developed to address potential over- and underestimation of hydropower flexibility in highly aggregated, large-scale energy system models. Researchers and modellers can utilise the created generation and ramping constraints to increase the accuracy of their models with regard to hydropower. The raw data were taken from ENTSO-E's transparency platform: historical generation data aggregated by hydropower type and bidding zone for 2020-2024. Included types of hydropower are "pumped hydro storage plant, "run-of-river hydropower with pondage”, and "reservoir hydropower". Subset 1 (HydropowerConstraints_NominalValues.xlsx & HydropowerConstraints_RelativeValues.xlsx) provides data series for creating maximum and minimum generation constraints and defining maximum ramping rates. The resulting constraints reflect historically observed operating ranges. The set includes absolute values derived directly from the transparency platform data, as well as relative values (% of installed capacity) that enable the application of the proposed constraints to any other data source. Subset 2 (PondageVolume.xlsx) consists of estimated storage volumes for run-of-river hydropower plants, aggregated by bidding zone. The volumes are given in hours of full-capacity output, allowing them to be utilised independently from the chosen data source. The main files for both subsets are in xlsx-format, but each set is also available as machine-readable csv- and json-files. The utilisation of the dataset has been demonstrated in a case study developed for the North European Energy System Model (available via GitHub). The related scientific publication by Kiehle et al. (2026) has been published in Applied Energy. Furthermore, the data and the creation of the dataset have been described in detail in a companion Data in Brief submission (currently under review). Version 1.2.0: Layout updates to all Excel files. Separation of HydropowerConstraints.xlsx into HydropowerConstraints_NominalValues.xlsx & HydropowerConstraints_RelativeValues.xlsx. Narrowing down the provided number of pondage volume estimates. Addition of data files in machine-readable alternative formats (csv & json). Version 1.1.0: Updates to HydropowerConstraints.xlsx - cleaned layout and adjusted ramping constraints.