A system is provided for producing mechanical energy. The system may include a solar collector configured to receive solar energy and an external heater configured to provide secondary thermal energy. Furthermore, the system may include an engine disposed in communication with the solar collector and the external heater. To this end, the engine may be operable to receive the solar energy from the solar collector, receive the secondary thermal energy from the external heater, and convert the solar energy and the secondary thermal energy to mechanical energy. Additionally, the system may include a controller in communication with the solar collector, the engine, and the external heater. The controller may be configured to control an amount of solar energy and an amount of secondary thermal energy received by the engine.