The focus of this work is on exploring the design of an aircraft hybrid propulsion system by integrating a gas turbine engine with an electric motor assisted by solar power. We discuss how the two systems can work in tandem while optimizing the efficiency. The Pilatus PC-12, a single engine, mid-sized turboprop aircraft, was chosen as the platform for this study. The hybrid system is optimized for maximum efficiency, and further significant fuel savings were found to be possible by including thermoelectric generators.