Small-scale concentrated solar power system with thermal energy storage: System-level modelling and techno-economic optimisation

A dynamic, techno-economic model of a small-scale, 31.5 kW_e concentrated solar power (CSP) plant with a dish collector, two-tank molten salt storage, and a sCO₂ power block is analysed in this study. Plant solar multiple and storage hours are optimised using a multi-objective genetic algorithm to minimise the levelised cost of electricity (LCOE) and maximise the capacity factor (CF). The optimal LCOE is found to be ranging from 122.7 USD/MWh_e to 217.8 USD/MWh_e when using optimistic and pessimistic power block cost assumptions. In contrast, the literature reports an LCOE of 193.9 USD/MWh_e for a similar 31.5 kW_e CSP system without storage. The addition of thermal energy storage in the system configuration dramatically improves the CF from 30.4%—reported in the literature—to 87.2% obtained from the present model. The sensitivity analysis suggests that upscaling the system to 400 kW_e reduces the LCOE to 121.9–172.2 USD/MWh_e as a result of lower unit power block costs at larger scales. The comparison of CSP and PV-battery systems in three distinct locations—characterised by varying direct and global solar resources—indicates that the CSP system is promising in locations with abundant direct normal irradiance (DNI). For locations with medium DNI resource, the LCOE of PV-battery system is within the margin of uncertainty of CSP system. In low-DNI locations, PV-battery systems proved to be preferable.