For most home programs, a 1 kilowatt system costs around 10,000 dollars to install. On sunny days it can receive 1,600 kilowatt hours a year, but on cloudy days it receives less than half that amount, only around 750 kilowatt hours per year.

http://ezinearticles.com/?Solar-Energy-Advantages-Disadvantages&id=50178

How many cloudy days in Washington and Oregon each year? On average for Seattle - 201.
http://lwf.ncdc.noaa.gov/oa/climate/online/ccd/cldy.html
http://www.wrcc.dri.edu/htmlfiles/westcomp.ovc.html

>>>Personally, I think any new building in America should be required to have solar panels. But outside of a radical policy like that, all sectors of America are developing alternative forms of energy.
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>>Some areas don't get enough sun to benefit from solar panels (cost versus return).
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>Like where?