The National Renewable Energy Laboratory and Lawrence Berkeley National Laboratory collaborated to provide the most comprehensive, accurate data on solar pricing in the USA.
http://www.nrel.gov/docs/fy13osti/56776.pdf. The data are stunning!
A highlight includes that, for systems quoted to consumers in the fourth quarter of 2011 and installed in 2012, residential systems cost $4.39/watt, commercial rooftop systems $3.43/watt, and utility scale systems $2.79 per watt. Those are amazing prices and are the single, biggest reason why the USA will install 3,200 megawatts of solar during 2012.
Only a few years ago, the panel costs alone would have been $4 per watt. Now full systems are installed for less.
Moreover, prices continue to fall, making this critically important report out-of-date as soon as it was published. That's how quickly the solar revolution is moving.