Dronninglund water pit thermal energy storage dataset

Water pit heat storage has been proven a cheap and efficient storage solution for solar district heating systems. The 60,000 m3 pit storage in Dronninglund represents in many ways the state-of-the-art large-scale heat storage, demonstrating a storage efficiency higher than 90% during its operation. The storage is used for seasonal and short-term heat storage of solar heat generated by a 37,573 m2 solar collector field and supplies heat directly to the district heating grid or is used during winter as an alternative heat source to a heat pump. This study aims to provide an overview of the available information on the Dronninglund water pit heat storage, including a detailed description of the design, ground conditions, and operating strategy. The used dataset (2014-2020) has been the foundation for most investigations and simulations of pit thermal energy storages. However, due to a lack of public documentation, various studies have used different post-processing methods and assumptions, leading to inconsistent results. Therefore, the dataset has been manually quality-controlled, and erroneous data have been removed with the aim of establishing a high-quality reference dataset. Moreover, an overview of the available parameters and metadata is provided, along with example plots. To promote the usage of the quality -controlled dataset, all the developed quality-control routines and Python scripts are made available on GitHub.