the idea of solar pv panels on a car , making electricity and then electrolysing hydrogen for a fuel cell sounds nice,
but then one has to consider the efficiency.. (Solar is already low density power so its not going to generate enough power to run a car but considering that most commercially available solar pv - may be 12-14% efficient and then electrolysis which is around 45-50% efficient - you are getting about 6% of the solar energy youll be lucky to run a radio much less moving a car..

instead of electrolysis you would still be better off charging batteries or a compressor ..