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The performance of the tower based concentrated solar thermal (CST-tower) plant is very sensitive to the operation strategy of the plant and the incident heat flux on the receiver. To date, most studies have been examined only the design mode characteristics of the cavity receivers, but this paper significantly expands the literature by considering non-design operating conditions of this important sub-component of the CST-tower plants. A feasible non-design operating conditions of the cavity receivers that was considered in this study is the storage mode of operation. Two practical dynamic control strategies were examined then to find the most efficient approach: fixed solar field mass flowrate (Approach “A”) and fixed outlet temperature at receiver (Approach “B”). To evaluate the performance of the cavity receiver, a thermal model is developed to be used for design and non-design analysis. The thermal model has been then validated against available data from the Gemasolar operating solar Tower plant. In non-design conditions, the effects of heat transfer fluid (solar salt) temperature and flowrate are mainly evaluated in terms of the non-dimensional receiver thermal output, non-dimensional power output, receiver energetic efficiency, receiver surface temperature, receiver outlet temperature, and the fraction of solar field usage. The results of this study (e.g. off design receiver efficiency correlations) assist researchers to evaluate cavity receivers without performing detail simulations. They also help investigators to choose an appropriate control strategy and to analyze the viability of other CST-tower subcomponents that have thermal interactions with the receiver (e.g. dynamic control of the phase change storage unit or its boundary conditions).