Energy Generation in Space

There are two MAJOR problems that attend the use of
turbines in hard vacuum and orbit.
1) They are machines with moving parts that must be
lubricated and replaced on a regular basis. The
failure rate of mechanical devices, regardless of
environment, is easily 10,000 times more likely than
the failure rate of solid state devices.
2)For a turbine to function, it must have a heat sink
somewhere, which necessitates the building of a LARGE
radiative surface to dump the residual heat of
operation. No such requirement for the solor cells
themselves, though the conversion to micro waves would
have some residual waste heat, I doubt it would be as
significant as that from a heat engine such as
turbines.