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• Alkali metal thermoelectric converter was combined with solar tower system. • For continuous power generation, thermal energy storage was utilized. • The impact of various solar tower parameters on the hybrid system was analyzed. • and the highest efficiency of 18% is obtained when the total heliostats area is 14,500 m 2. Solar tower plants (STPs) can foster reduce toxic emissions and a cleaner environment. Here, to step forward in this advance, this system is employed as a heat source for an alkali metal thermoelectric converter (AMTEC). Thermal energy storage (TES) is applied to stabilize the performance of the hybrid system along with solar irradiation fluctuations. The considered system is investigated on three different days for the humid subtropical climate of Bandar Abbas, Iran. This study's primary outcome and contribution is a novel simulation framework via TRNSYS to predict the performance of the system under fluctuations of solar irradiation at this site. Both TES and STP systems are defined in TRNSYS software as a new component type via utilizing the Fortran program. The effects of various parameters, including the total energy absorbed by the central receiver, the thermal capacity of TES, and the heliostats field area, are investigated on crucial output parameters of the AMTEC. The mass flow rate of the heat transfer fluid at several areas is then studied in different operating conditions. The optimum area for the heliostats (14,500 m 2), leading to the highest AMTEC efficiency (18%) is determined, which requests a TES tank volume of 28.13 m 3. This system is noticed to have its most remarkable performance in June and July. [ABSTRACT FROM AUTHOR]

• Annual dynamic simulations of solar water heating system with and without phase change materials were conducted. • A thorough parametric study was carried out in different climate zones. • Optimization of phase change temperature and design parameters usage amount was performed. • The highest power saving rate using phase change material is 31% in Lhasa. • The highest heat loss saving rate using phase change material is 9.9% in Guangzhou. Recently there have been many reports on the application of phase change materials (PCM) in solar water heating system (SWHS). However, there are some doubts and different views in this field, since the sensitivity of the system to the PCM design parameters and external conditions. In this study, a typical SWHS with a PCM storage tank is proposed to overcome the existing problems. The mathematical model is established and validated against experimental data. Annual simulations have been done under a typical user load and different PCM design parameters (phase change temperature, PCM usage amount) among six cities which have different meteorological conditions. The results indicate that the application of PCM in SWHS can reduce the power consumption of electric auxiliary heater (EAH) and the heat loss, but the benefits vary widely by regions and PCM design parameters. The highest power saving rate is up to 31% in Lhasa which has extremely abundant solar energy, while for the heat loss saving rate the highest value is 9.9% in Guangzhou which is located in the hot summer and warm winter zone. Besides, a parametric study has been conducted to explore the power saving potentials with different PCM design parameters in different regions, as well as to discuss the optimal phase change temperature and the PCM usage amount. This study aims to provide theoretical references and suggestions for the design of the PCM storage tank in SWHS. [ABSTRACT FROM AUTHOR]