A thermal engine would be far more efficient on a spacecraft than Solar cells.
It has drawbacks as well, especially as it gives vibrations to the spacecraft . Also, it relies on a fluid, which introduces failure modes.
As for Stirling engines, they have essentially drawbacks. A
turbine is far better in any aspect.
Here a description of such a Solar electricity generator for spacecraft , including the Sunlight concentrator, the spillway, and other uses of a similar hardware to produce cold and store cryogenic propellants indefinitely:
http://saposjoint.net/Forum/viewtopic.php?f=66&t=2051
but you'll have to be logged into see the drawings, alas. Not my website, and the owner changed that recently.
Also, Nasa-sponsored projects want to use Stirling engines to convert heat from radioisotopes into electricity on spacecraft . Called an RTG, it uses thermocouples up to now; a thermal engine would be more efficient and save scarce Pu-238, but here again, a turbine is better.
Marc Schaefer, aka Enthalpy
