Thermal energy storage (TES) plays a key role in concentrating solar power (CSP) plants by enhancing dispatchability and improving overall system efficiency. This study presents a comparative techno-economic analysis of three TES configurations integrated into CSP plants: (i) the conventional two-tank molten salt system, (ii) a phase change material (PCM)-based system with a cascade arrangement, and (iii) a concrete-based system. While technical performance simulations indicate similar annual energy production across all cases, significant differences emerge in economic viability. The PCM TES system demonstrates the lowest levelized cost of electricity (LCoE) at $14.35/kWh, leveraging its high energy density and reduced material requirements, despite lower efficiency (93 % compared to 99 % in molten salt). Conversely, the concrete TES system, while capable of extended discharge at partial loads, incurs higher parasitic losses and investment costs, resulting in a higher LCoE ($16.16/kWh). The cost analysis further highlights the cost-performance quotient (CPQ) as a valuable metric for assessing TES competitiveness, with PCM exhibiting the most favorable CPQ of $1.04/kWh. These findings underscore the necessity of integrating economic assessments into TES selection for CSP plants. Moreover, the study identifies opportunities for cost reduction in concrete TES through optimized modular designs and improved material formulations. This work provides valuable insights for policymakers, engineers, and industry stakeholders aiming to enhance the financial feasibility of next-generation CSP storage solutions.

This study receives funding from the Ministerio de Ciencia e Innovación – Agencia Estatal de Investigación (MCIN/AEI/10.13039/501100011033) through the PCI2020-120695-2 project and the European Union “NextGenerationEU”/PRTR“. CSP-ERA.NET is supported by the European Commission within the EU Framework Programme for Research and Innovation Horizon 2020 (Cofund ERA-NET Action, N° 838311). This work was partially funded by the Ministerio de Ciencia e Innovación de España TED2021-132216A-I00 funded by MCIN/AEI/10.13039/501100011033 and the European Union by NextGenerationEU/PRTR. This work was partially funded by the Ministerio de Ciencia e Innovación – Agencia Estatal de Investigación (AEI) (PID2021-123511OB-C31 – MCIN/AEI/10.13039/501100011033/FEDER, UE) and (RED2022-134219-T). This work is partially supported by ICREA under the ICREA Academia programme. The authors from University of Lleida would like to thank the Departament de Recerca i Universitats of the Catalan Government for the quality accreditation given to their research group (2021 SGR 01615). GREiA is certified agent TECNIO in the category of technology developers from the Government of Catalonia.