Abstract: A method for setpoint value adjustment of a setpoint value, particularly for automatic power and/or frequency or primary and/or secondary frequency regulation, in a solar thermal steam power plant having a primary heat source that is not freely adjustable and an additional heat source and also to a solar thermal steam power plant is provided. A present power range for this solar thermal steam power plant is ascertained for at least one prescribed time during operation of the solar thermal steam power plant. This present power range is limited by an upper and a lower control range limit. For the setpoint value adjustment, a currently prescribed setpoint value for the solar thermal steam power plant is set in the present power range if the currently prescribed setpoint value is outside the present power range.