[jonrick46]

The lens used to magnify the sun would have to be light weight. A Fresno method comes to mind. The collector would need to be cleaned periodically. A large application would put people to work cleaning solar collectors.

[aruanan]

A Fresno method comes to mind.

Is that something they use in California? Or do you mean fresnel?

[JerseyHighlander]

Another company is developing mylar balloons to use as magnifiers over PV cells. Cheap, easy to handle, replaceable. But they would might melt if put over a 85C surface day in day out?

Youtube video of their demo project:
http://www.youtube.com/watch?v=kROgE4Jdm-k

homepage:
http://coolearthsolar.com/