A solar thermal installation and method for operating a solar thermal installation includes a solar collector arrangement which defines a solar collector fluid passage so that a first heat quantity can be supplied to a fluid, and which has a first fluid infeed connection and a first fluid output connection. A heat exchanger fluid passage permits a second heat quantity to be supplied to a fluid. A heating fluid receiving device is fluidically connected with a first fluid output connection and fluidically connects a second fluid output connection to the first fluid output connection by bypassing the solar collector fluid passage. A consumer device is connected to the heating fluid receiving device. At least a portion of the first heat quantity and second heat quantity can be supplied to the consumer device. A control device controls an operation of the gas turbine depending on the first heat quantity.