Stellaris uses a Concentrating Photovoltaic Glazing (CPG) that they claim can reduce manufacturing costs of PV modules by up to 40%. The technique can also increase efficiency by over 20%. As a point of measurement most PV systems have efficiency of 13 - 15%, while some advanced techniques have garnered 20%.
http://whereisnick.typepad.com/cleantechspotlight/2006/06/stellaris.html