This is really just a footnote to my previous post but it’s too good not to share: a Dutch team has built a family-sized, street-legal car which runs completely on solar power and (even in Holland!) can be expected to produce twice as much energy as it needs for normal use and then (bonus!) feed the excess back into the grid when parked at home.
Here is a short BBC report – http://www.bbc.co.uk/news/world-europe-23339794. Clean Technica has run two reports on it as well – this one with a follow-up video here.
October update: This car is competing in the World Solar Challenge from Darwin to Adelaide – see pre-race interviews and footage on ABC at http://www.abc.net.au/news/2013-10-04/mainstream-solar-cars-race-to-reality/5000390