Thin film solar cells, old-fashioned standby silicon solar cells, CIGS, CadTel (see First Solar), multi-junction cells....the list goes on as solar cell materials get more exotic. There was the circle of solar cells known to the world as Solyndra. Prism Solar divided light up into different wave lengths and Solaria uses advanced optics with strips of Silicon such that less Silicon is necessary while throwing sun trackers in the mix. Many technologies going after the same goals of reduced cost and increased efficiency.
What if someone used a mix and match of pieces of these other strategies together, whipped it up in a pan and made a layer cake? A North Carolina startup called Semprius says it can produce efficiencies as high as fifty percent by stacking various semiconductors together with each one collecting a different frequency of light. According to the MIT Technology Review, this technology could produce electricity as cheaply as burning natural gas-but without the emissions and high carbon footprint.
The technology is said to relate to how the semi conductor layers are applied on top of each other. Semprius has just a few granted patents so far on its solar cell technology. The most recent patent appears to be related to printing layers of semiconductor materials-along with using form factors, lenses and metal mesh to promote light collection on the appropriate semi conductor layers. This patent has cited much research that has come before — even more than would be expected in a long researched field like solar energy. In most patents, a half-page or even full-page of previous patents or other references is not uncommon, but in this case there were 14 pages of cited references. This could mean that the inventors had done more than their share of research prior to working on the problem solved and documented in these patents...or that they tried to bury the Patent Office in a mountain of paper.
As with most new technologies, the problem lies in cost and the value proposition — in this case the cost of producing the layers of semi conductors required for the more efficient solar cells. Given the freefall in solar cell prices over the last several years, Sempius will need to achieve the efficiencies they claim or the cells may not be cost effective and they may very well go the way of Solyndra and others.
Research in solar technologies has been on the rise the last several years and recently patents resulting from such research have surpassed those of long time leader fuel cells according to the Clean Energy Patent Growth Index. Solar technologies topped all others in 2013 and in the first quarter of this year. The top solar patentees for 2013 are depicted below.
As can be seen, big solar players from the various corners of the solar world dominate the patent rankings, but not by as much as in some of the other fields where absolute numbers of patents are higher. For example, GM was the leader in fuel cell patets with over 120 and Ford dominated the hybrid/electric vehicle rankings with over 40. Also, there were over 600 different solar patent grantees in 2013 while there were about half that for fuel cells and wind technologies, and even less for Hybrid/ Electric vehicles in 2013 according to the CEPGI. The large number of solar players may mean there is much more to do and that no one approach will be the winner.
So there may be hope for a technology like that pursued by Semprius given that research continues in the solar industry by many more players pursuing new innovations in different ways than in some of the other cleantech arenas. Maybe Semprius' layering of semiconductors idea will be the one that takes the cake.
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