Abstract: A concentrating solar power plant utilizes two heat transfer fluids. A first heat transfer fluid is heated in a field of concentrating solar collectors. A second heat transfer fluid is heated through a heat exchanger using heat imparted from the first heat transfer fluid. The second heat transfer fluid is then further heated, for example in a second field of concentrating solar collectors, and power is generated utilizing thermal energy extracted from the second heat transfer fluid. The second heat transfer fluid may be a solar salt, and may thus have a higher working temperature than the first heat transfer fluid. The power plant may realize the power generation efficiency improvements offered by utilizing a high temperature working fluid, while at least some of the plant does not require backup heating to protect against freezing events.