At the core of the INDHEAP technical work was the creation of digital tools and models to support system sizing and control. The PERSEE and MODELICA platforms were adapted to simulate hybrid solar systems, enabling the development of digital twins for the demo site in Spain and replication sites in Cyprus and Portugal. These models facilitated the design of optimal control strategies that respond dynamically to weather conditions and energy prices, aiming to maximize solar resource utilization and minimize energy costs.
A flexible electro-thermal energy storage (e-TES) system was developed, incorporating electric heaters and thermocline technology. Bio-based oils were tested for thermal stability, with promising results for refined sunflower oil below 210°C. Although not suitable for the demo site, these findings support future sustainable storage solutions. The e-TES system was integrated into the digital twin and control framework, allowing for real-time adaptation to fluctuating energy supply and demand.
Innovations in photovoltaic integration included the HeliosBox structures, which were optimized for industrial rooftops with reduced weight, installation time, and cost. A web-based tool was launched to assess available surfaces and guide PV deployment. Field tests and mechanical validations confirmed the robustness of the system under industrial conditions.
In parallel, the development of the T200 solar thermal collector introduced several mechanical and optical enhancements. Improvements to the tracking system and collector geometry increased precision and efficiency, while three receiver designs were explored—most notably a vacuum tube variant that significantly reduced heat losses and achieved high stagnation temperatures. These prototypes are undergoing testing to validate performance under real-world conditions.
The integration of hybrid systems into industrial processes was addressed through detailed modeling and simulation. For the demo site, a three-loop configuration was proposed, separating solar field, storage, and supply systems. Integration concepts for replication sites were also drafted, considering site-specific constraints and energy profiles. Pinch analysis and energy flexibility assessments revealed that process adaptation—particularly flexible operation of thermal loops—can substantially reduce fossil fuel dependency and support full decarbonization by 2050.
Demonstration planning advanced with finalized process diagrams, risk assessments, and component selections. The demo unit’s integration strategy was validated, including the choice of heat transfer fluid and storage volume. Preparations for site implementation and procurement are underway.
Overall, the INDHEAP project has successfully laid the technical foundation for deploying hybrid ST+PV systems in industrial settings. The combination of advanced modeling, innovative components, and tailored integration strategies positions the project to deliver significant energy efficiency gains and carbon reductions in the next phase.
