I saw a very interesting programme on Discovery the other week about these lenses. They improved the sunlight reaching a photovoltaic panel by a factor of 8. This caused a heat problem which they solved. The lenses appear to be a mass of tiny prisims in plastic. I can find out very little about them other than their inventor Mark O'Neill works here at Entec Solar:
http://www.entechsolar.com/press-releases-details.php?id=126
Are they costly to manufacture? Are they widely available?
Could they be put over a vacuum tube solar collector to improve performance during the winter here in Ireland or would it get too hot for the tubes?
It would be fantastic if it was so simple but somehow I doubt it. Does anyone have any knowledge about this type of lens?