From page 19 of the brilliant report, Tracking the Sun III: The Installed Cost of Photovoltaics in the U.S. from 1998-2009 (large pdf).
It’s worth noting that this has nothing to do with the state’s solar resources. This is the upfront cost to install the modules. The difference in cost of solar electricity is likely even more severe since many of the least expensive states also have better sun.
