## 6 Conclusions  
Based on the comparative analysis conducted in this study, the following key conclusions can be drawn:  
* Superior Performance of Solid Particles: Solar tower power plants utilizing solid particles as the thermal energy storage (Scenario III) exhibit significantly enhanced technical performance compared to traditional molten salt systems (Scenario I). This includes a 7.4% increase in annual electricity generation, higher sun-to-electricity efficiency (16.7% vs. 15.5%), an improved CF (61.1% vs. 56.9%), and greater thermal storage energy density (160 Wh/kg vs. 115 Wh/kg).
* Economic Advantage of Solid Particles: The improved technical performance translates into better economics, with the solid particle configuration showing a 9% lower LCOE (192 USD/MWh) compared to the molten salt baseline (211 USD/MWh), despite potentially higher costs for some next-generation components.
* Potential of Carnot Battery Integration: Incorporating a Carnot battery system to store surplus grid electricity (curtailment) successfully increases the overall annual electricity output and boosts the plant's CF and efficiency in both molten salt (Scenario II) and solid particle (Scenario IV) configurations. The improvements are more pronounced when coupled with the more efficient solid particle system.
* Economic Challenges of Curtailment Storage: Despite increasing energy output, the integration of the analyzed Carnot battery system leads to a higher overall LCOE and a high LCOS. This is primarily attributed to the current costs of the additional equipment (electric heater, heat exchangers, compressor) and the cost of the curtailed electricity absorbed, combined with a system operation strategy optimized for solar energy rather than curtailment storage (resulting in round-trip efficiencies of ~25-27%).
* Reduced Parasitic Consumption Potential: Solid particle systems show potential for lower parasitic energy consumption associated with storage maintenance compared to molten salts, indicated by a higher average annual SOC in the thermal storage.
* Need for Further Optimization: To realize the full potential of integrating curtailment storage in CSP plants via Carnot batteries, further research and development are necessary. This should focus on reducing the capital costs of the required components and developing advanced control and operational strategies that co-optimize the use of direct solar energy and stored grid curtailment to improve round-trip efficiency and overall economic viability. Looking ahead, the role of solid particle systems is expected to strengthen as technological maturation and economies of scale reduce capital costs, enhancing their competitiveness. Similarly, Carnot batteries could play a strategic role in future electricity systems with high renewable penetration, where increasing curtailment levels demand flexible, long-duration storage solutions.  
**Author Contributions:** Conceptualization, methodology, software, S.G.-B.; validation, S.G.-B. and M.A.R.-B.; formal analysis, investigation, data curation, writing--original draft preparation, S.G.-B.; writing--review and editing, S.G.-B. and M.A.R.-B.; visualization, S.G.-B.; supervision, M.A.R.-B. All authors have read and agreed to the published version of the manuscript.  
**Funding:** This research received no external funding.  
**Institutional Review Board Statement:** Not applicable.  
**Informed Consent Statement:** Not applicable.  
**Data Availability Statement:** The original contributions presented in the study are included in the article, further inquiries can be directed to the corresponding author.  
**Conflicts of Interest:** The authors declare no conflicts of interest.