There was an article in (Homebrew I think) about someone building a homemade fuel cell generating electricity from their homemade hydrogen electrolyzer. The cost was kind of expensive for the membranes and tolerances.
Now why can't we homebuild the same for this with solar concentrators using the HEAT?:
Inventor Develops 60% Efficient Solid-Sate Heat Engine -
That's 6 0, 60 percent efficient.. the highest I have ever heard of a solid state by many times over.. that uses a membrane like a fuel cell with no moving parts.
http://peswiki.com/index.php/Directory:Johnson_Electro_Mechanical_Systems
Just a link. DanB's stated hydrogen policy is "only if you built it"