This paper deals with the hourly simulation of an ejector cooling cycle assisted by solar energy. The system is simulated using the TRNSYS program and the typical meteorological year (TMY) file that contains the weather data from Florianópolis, Brazil. The ejector cycle uses R141b as the working fluid and a one-dimensional ejector is modelled in EES (Engineering Equation Solver). A cooling capacity of 10.5kW is considered and a parametric optimization is carried out to select the optimum size of the system. Simulation results show the auxiliary energy usage and the useful heat gain for different types and areas of solar collector. Additionally, the effect on energy usage of storage tank, collector slope angle and hot water flow rate is studied. The optimized system consists of 80m 2 of flat plate collector tilted 22° from the horizontal, a 4m 3 hot water storage tank and a mass ratio equal to 8.