We came across this spectacular application of concentrated solar power via designboom. André Broessel is the inventor/designer behind Rawlemon, a social design company in Barcelona that has patented the dual axis tracking ball lens technology that they have dubbed "B.torics" and which has incredible potential for building integrated photovoltaics.
The design is somewhat similar to a Fresnel lens CPV with a very wide focus, but instead of compacting the lens into the flat Fresnel shape, Rawlemon has left the spherical lens' beautiful form unadulterated in its perfect geometry. The visual effect is obviously stunning. And while the fabrication may be somewhat more complicated than flattening the lens, leaving the sphere whole has two benefits that seem to offset this.
First, every section cut that is made in the face of a lens to flatten it into its Fresnel shape creates inefficiencies in the optics when compared to the original lens. Rawlemon's sphere maintains 100% optic purity which leads to greater efficiency and more KW capacity per unit of surface area. Second, by leaving the lens as a complete orb, the tracking can take place behind the lens. The benefit of this is that instead of a system where an large wall of CPV modules has to be moved to track the sun, each multijunction cell can rotate like a little satellite behind its spherical lens. This design leaves the "wall" of modules free to stay in its static position, either as a vertical building facade or at any angle.