High-temperature solar thermal systems and methods are described. In one aspect, a system is described that includes a heat engine power conversion system, or a “heat engine,” with a fluid working medium. The heat engine includes a first input, a second input, and a heat exchanger. The first input receives heated high temperature tolerant particles, or “heated particles,” from a solar energy collection and distribution component that is coupled to the heat engine. The heat engine's second input receives the working fluid medium used to drive the power cycle in the heat engine. The heat exchanger transfers heat from the received heated particles to the working fluid medium, and thereby, energized the heat engine's power cycle.