I keep reading about how great the energy density is for hypothetical fuel cells, but as far as I can tell these objects do not exist in any practical form outside of laboratory prototypes and "educational" kits. I keep reading statements like "our company is developing... blah blah". When I do a search on Amazon for fuel cells the only thing that comes up is "kits", books on "how to build your own cells" (LOL), and racing fuel cells (which are just special gas tanks, not hydrogen fuel cells).
So, practical fuel cells actually exist or it is just a bunch of hype and wishful thinking? By "practical" I mean a fuel cell of 500-2000 watts for a home solar system and includes cost as a factor.
After further searching around I did find some practical fuel cells and found out why they are not readily available: because a 500 W cell that would be enough to power, say, a computer, costs \$10,000. For \$10,000 I can buy enough electricity to power the computer for hundreds of years. So, the practicality of these devices appears to be limited to the International Space Station and things like that.