In this paper, the effect of solar resource variability has been assessed on the start-up time and different heat transfer phenomena associated with a high temperature particle receiver. The receiver analyzed in this study has a cylindrical cavity made of three different layers in order to have good absorption, higher durability and lower thermal heat losses. A detailed transient mathematical model is developed, considering the input solar energy to the receiver aperture and all heat losses from the receiver cavity. The developed transient model is employed to study the time required to achieve a receiver start-up temperature from room temperature to 1000°C, under steady-state and transient operation, for the climatic conditions of Pinjarra, Australia. Furthermore, the total energy gain by the receiver and associated heat losses including re-radiation, convection, and conduction have been accounted for, with and without considering the solar resource variability. The results revealed that an uncertainty of about 40% exists in the prediction of the receiver start-up time and associated heat losses during the start-up period under steady state operation, with a constant input heat flux. This uncertainty in the prediction of the receiver start-up time and losses will directly affect the overall performance and design of the receiver, which will result in unscheduled disruption of the industrial process. This indicates a need to analyse the performance of high temperature particle receivers under transient conditions, considering the solar resource variability for practical implementation of this technology to different processes. This will help to investigate better control strategies for the inflow of particles, based on the real-time climatic conditions, to achieve better thermal performance.