The aim of this work is to study, through computational fluid dynamics (CFD) models, the charge transient of a thermocline sensible thermal storage for concentrated solar power plants (CSP). A thermocline storage is characterized by the stratification of the temperature inside the tank, in which the upper part is at a higher temperature than the lower part. This solution allows to avoid the classic double tank configuration used for CSP applications, in which the two tanks contain the fluid at two different constant temperatures. The thermocline storage allows, therefore, to supply the cold fluid to the solar field and the hot fluid to the power plant using a single tank.