Hi everyone,
ok, perhaps this is not exactly open data, but this is probably the right section.
Finally, ENTSO-E has also published the hydropower data for their ERAA 2023 assessment (ERAA Downloads | ENTSO-E – ERAA 2023 (entsoe.eu)).
Given that the data is - as usual - stored in Excel and CSV files, some of them quite big (220 MB per file), I have spent a few hours to re-structure the data in a more efficient format (Parquet, cross-platform and used by Pandas, R/Arrow, Power Bi) and a more user-friendly structure for modellers (long tables).
The data is here: ENTSO-E ERAA 2023 files in Parquet format (zenodo.org).
The methodology behind the data is described in the PDF in the ERA 2023 Downloads page.
Enjoy the data!