There's incredible potential for solar power, and prices are falling quickly. The cost of a photovoltaic system dropped by 40 percent over the last two years.
So how quickly will we be able to shift over to a solar energy economy? Here's another chart from Greenpeace's Solar Generation 2010 executive summary.
The unimpressive "reference scenario" assumes a reduction in political support for a transition to solar. But the yellow and red lines show were we could get by 2050 with a continuation or an increase in the political and economic support for solar. We can hit 20 percent if we shift the paradigm.
Photo (cc) from Flickr user Wayne National Forest