A method for generating steam for a turbine electric power plant uses solar radiation. Solar radiation is directed onto a solar receiver. The solar receiver includes a first section, which receives feedwater input and is arranged to heat the feedwater input to generate steam using the directed solar radiation. Feedwater flows through a feedwater vessel to serve as feedwater input to an inlet of the first section of the receiver. Water is separated from the steam in steam separation vessel, which is in fluid communication with an outlet of the first section of the receiver. The feedwater input may be selectively preheated by a source of preheat other than solar energy in response to system operating conditions, predicted insolation schedule, or an electrical energy tariff schedule.