Electricity generation on the Moon

Does anyone know much about solar thermal generators? Presumably the
collectors would be easier for a robot to make than PV cells, but I have
no idea what kind of tolerances are needed for the generator and heat
exchangers. I was thinking of something like a Sterling engine, but
isn't there also a way to generate electricity using a high temperature
difference across a pair of metals? Can any in-situ resources be used as
the working fluid?
Even if we can't robotically build the generators, we could ship one
or more and build the rest in place.