The Thermo-Mechanical Generator was invented in 1967 and is an ingeniously simple and elegant heat engine operating on a Stirling thermodynamic cycle that can yield cogenerated electrical and thermal energy from moderately hot heat sources (200-500°C). A new version of this heat engine has been invented that is capable of operating off concentrated solar energy provided by inexpensive, acrylic Fresnel lenses. A key innovation in the technology is the use of a digital thermodynamic Smoleniec/Stirling cycle to optimize the performance of the heat engine in real time. A state space analysis of the engine has been completed that demonstrates that the invention can operate successfully. So far, the analysis has predicted an output electrical power of 1.9 kW when operating between hot and cold temperature limits of 500 C and 20 C respectively. Under these conditions the engine operates at a frequency of 87 Hz.