Can you think of a device with a better name than the Sun Cracker? Better yet, the Solar Water Cracker!
The CHP cracker would use a parabolic solar dish to concentrate sunlight on a thermal reactor where water would be dissociated. The resulting hydrogen and oxygen would be filtered out, with the hydrogen sent off to a fuel cell to allow it to combine with oxygen in the air and make electricity. The temperature in the Solar Water Cracker furnace can reach 2200 C (3990 F) with a solar energy to electricity conversion rate (via the fuel cell) of 44 percent.
Wait a sec... that's not bad at all! Current solar technology gets about 10% conversion efficiency(if I recall correctly). Think about that in terms of transportation: you could have solar panels all over your roof for solar energy or a parabolic dish less than a quarter of the size. Either one could provide the energy to power your car (or home or whatever).
If your having trouble with the concept, imagine a satellite dish (like a dish network dish). The dish directs incoming signals (very weak, dispersed signals) towards the little arm that is centered in the middle. It's all geometry and trigonometry (fairly simple... relatively). You're basically concentrating a bunch of weak signals (or, in this case, weak energy). For sunlight, you simply need to reflect the light towards a common collector. On a BIG scale, it looks like this collector (which uses the heat to melt salt):