A solar thermal power plant comprises a solar radiation receiver mounted on a tower surrounded by a heliostat field to receive solar radiation reflected by heliostats. A power generation circuit includes a steam turbine for driving an electrical generator to produce electrical power, and water in the power generation circuit is heated directly by solar radiation reflected onto the solar radiation receiver by the heliostat field to generate steam to drive the steam turbine. An energy storage circuit includes a thermal energy storage fluid, such as molten salt, which is capable of being heated directly by solar radiation reflected by the heliostat field. A heat exchanger is also provided for recovering thermal energy from the thermal energy storage fluid. The recovered thermal energy may then be used to generate steam to drive the steam turbine.