A solar power conversion system using a plurality of engines to convert solar energy to electrical energy. The plurality of engines are supported adjacent to a housing having a single thermal cavity. The cavity is provided with solar energy from a solar collector. Each of the engines can be turned off or regulated to maintain an optimum operating temperature for a common heater head in communication with each of the engines. Therefore, the power conversion system can be regulated for variations in insolation to maintain an optimum temperature in the heater head. Therefore, increased life cycle energy efficiency of the power conversion system can be obtained.