Here's a link I've posted before displaying the current amount of energy produced by the various sources. The amount of land that we'd have to devote to solar to make a meaningful contribution would be unsustainable.
https://flowcharts.llnl.gov/content/energy/energy_archive/en...
Re:Germany sets new solar-power record
by MikeCapone on Friday June 01, 2012 @05:36PM
(#4055940)
I'm not sure, I've often seen maps with areas required to power the world with solar* and while they are big, they aren't impossible, especially if done smartly (big solar farms in deserts connected via HCDC transmission lines, but also solar PV and solar water heaters on rooftops close to users).
* http://www.landartgenerator.org/blagi/wp-content/uploads/200...
http://www.ted.com/talks/donald_sadoway_the_missing_link_to_...