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Solar modules now selling for less than €0.06/W in Europe
(www.pv-magazine.com)
This is a most excellent place for technology news and articles.
The underground suggestion was only to counter the argument of space usage.
There's a million other ways to go. Solar on every parking lot, over every irrigation canal, and along every highway. Some farming can be done under solar panels, as well; some commercial crops prefer shade, such as strawberries.
The US uses about 30% of its land for cows. One simple plan is that we all eat one less burger a week. Which would be a good idea, anyway.
Land usage is so not a problem as soon as you open up the dual use possibilities.
For dual use, I'm particularly partial to the solar fence