The integration of concentrated solar power (CSP) system and photovoltaic (PV) can extend the dispatchability of solar energy while contributing to carbon neutrality goals. This paper investigates a real case of zero-carbon integrated energy system energized entirely by solar energy, incorporating CSP, PV, thermal energy storage (TES), and batteries. The system utilizes an extraction condensing steam turbine with flexible heat-to-power ratio as CSP power block, complemented by a segregated steam generation system (S-SGS) enabling direct thermal production from TES, to reduce coupling between electrical and thermal outputs. Based on the case, comprehensive techno-economic analysis through annual hourly production simulation demonstrates that the hybrid system achieves continuous 24-hour operation and meets a 91.17% annual production rate with a levelized cost of energy (LCOE) of 0.121 USD/kWh, representing 2.4% and 4 % reduction compared to the system operating without S-SGS and in separate heat and power production modes, respectively. For reliability enhancement, our analysis reveals that a thermal storage duration to solar multiple ratio of 5.5–5.8 enables the most economically efficient reliability improvements. This optimization allows the system to achieve a 99% annual production rate at an LCOE of 0.172 USD/kWh. However, attaining reliability levels comparable to conventional urban power grids would necessitate prohibitively expensive investments despite significant technological advances.