Monitoring data from a large-scale ultra-high-vacuum flat-plate collector solar plant for district heating in Racconigi, Italy

Highlights Operational measurement data from a solar district heating plant using high-vacuum flat plate (HVFP) collectors, feeding into the district heating network of Racconigi, Italy. The dataset covers the full year 2025 at 1-minute sampling resolution, including all seasons. The collector array consists of 525 TVP Solar MT-Power v4 high-vacuum flat plate collectors with a total gross collector area of 1,029 m², installed at a fixed tilt of 35°. The solar field is part of a complex energy hub that includes a high-efficiency cogeneration (CHP) unit, a heat pump, a 350 m³ thermal storage tank, and backup gas boilers, making this a representative case of hybrid solar district heating integration. The dataset originates from a real commercial-scale district heating application, operated by Engie Italia (Engie Servizi S.p.A.), serving approximately 5,600 equivalent inhabitants. Plant and collector array description The data is from a high-vacuum flat plate collector array located at the district heating centre of Racconigi, Italy. The solar field was designed by TVP Solar SA and TRESOL Srl, and is operated by Engie Italia as part of the local district heating network. The solar thermal system was integrated into the existing district heating infrastructure in 2025. The district heating network has been operational since 2012, extends over 12 km, and delivers approximately 9.4 GWh of thermal energy annually to 114 connected users (residential, public, and commercial buildings). The collector array has a total gross area of 1,029 m² and consists of 525 TVP Solar MT-Power v4 collectors, high-vacuum flat plate collectors with a gross area of 1.96 m² per unit, certified with a Solar Keymark datasheet (license 011-7S1890F, issued 2017-05-24). Key collector performance parameters and incidence angle modifiers are provided in the JSON metadata file. The collectors are installed at a fixed tilt of 35° with an azimuth of 190°, arranged in 11 rows with a row spacing of 5.0 m. The heat transfer fluid is water. The solar field is directly connected to a 350 m³ thermal storage tank, supplying hot water at 75 °C.   Data files DIGISOLAR_data_2025_filtered.csv  Time-series measurement data at 1-minute resolution, covering the full year 2025 (January to December). Data channels include global tilted irradiance (GTI), solar field inlet and outlet temperatures, ambient air temperature, volumetric flow rate, and instantaneous thermal power output. All data channels are described in the JSON metadata file. Racconigi__parameters.json  Domain-specific metadata file in both human- and machine-readable format. Contains information about data owner, plant designer and operator, as well as plant location, collector field configuration, thermal and optical collector performance parameters, and data channel descriptions with physical units. Unit strings are parsable by the Python pint package. This file provides all information required to interpret and analyse the time-series data. Photos (2× JPG)  Photographs of the installation and collector field. Acknowledgment This dataset is published as part of DIGISOLAR Deliverable D1.4 ("Long-term monitoring data for performance verification and FDD data preparation"). DIGISOLAR has received funding from the European Union's Horizon Research and Innovation programme under Grant Agreement number 101235027 — DIGISOLAR — HORIZON-CL5-2024-D3-02. Data owner TVP Solar SA