Due to the need for alternative means that can be used to generate power with high efficiency and less harm to the environment, the free piston Stirling engine has emerged and research has been carried out to prove its relevance. This study is carried out in the thermal energy conversion unit, using solar energy to generate power. This form of renewable energy can be employed for power production using the free piston Stirling engines which converts thermal energy into mechanical energy. The application is considered for micro-CHP applications in small-scale businesses and units. In this study the regenerator being the heart of the Stirling engine and its heat storage and recovery ability is analysed. The quasi-steady flow of the thermodynamic model of the free piston Stirling engine is developed, the thermal losses and effectiveness of the regenerator are considered and the effect on the output results generated during its operation is analysed and presented.