Stirling machines have been always extensively studied. NASA has suggested Stirling machines for applications is spacecraft [1].Ford considered the Stirling machines for common passenger cars in early 1970s [2]. Stirling machines have been considered a possibility for moving submarines [3]. Many studies considered Stirling machines in connection with solar power [4]. However, with the reduction of the price of solar panels along the last decade,  photovoltaic solar energy became very cheap. At the present time, the cheaper options of energy are onshore wind and photovoltaic solar [5]. 

Another interesting option is given by Stirling machines: As they work on basis of difference of temperature, by preserving the cold of the night and the heat of day, Stirling machines can be activated, thus producing electricity. This enables the application of Stirling machines in homes. For example, small Stirling machines can be used for charging rechargeable batteries (and cell phones), among other applications.