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Holographic Solar Collectors
An anonymous reader writes "The MIT Technology Review is reporting that Prism Solar Technologies has developed a technique to use holograms to concentrate light onto photovoltaic (PV) cells. While the implementation is only about a 10x increase over PV cells without collectors such as mirrors/lenses (mirror/lens approaches can do 100-1000x), it is a great deal simpler, more compact, and cheaper. Also because of the concentration, there is less need for physical PV cell real estate compared to crystalline PV silicon cells of similar output."
Products like this decrease the amount solar panels needed. Many of the wonderful improvements are available, but at a very high cost. This development specifically reduces the cost needed to attain the same amount of power.
Funnypics
From the article it is clear that this technology is specifically designed to address two of your concerns. Admittedly it helps to have a background in physics in order to understand some of the concepts (particularly the optics.) Firstly, the holographic lens and waveguide have been designed to direct certain ranges of wavelengths to the silicon and the other wavelengths away from it. This helps to prevent overheating of the silicon cells. Secondly, the lens system is there in order to collect more light per area of silicon used. This causes the $/Watt to increase, while the efficiency (Watts converted per Watt theoretically availlable) remains the same (well, in a perfect world, it sounds like this will work significantly better in their second generation.)
My first thought reading the headline was that this was just called a "hologram" to get some buzz, over what is a very generic, straightforward way of increasing the power delivered to the expensive part, the solar cell. But (for those too lazy to RTFA) this is different for three reasons:
1) It is almost omnidirectional - a Fresnel lens is a flat subsititue for a regular lens, with limited off-axis focusing ability. This seems to use the glass as a lightguide instead, with a broader angular reach (in exchange for limited scalibility - bigger the glass width to thickness ratio, the more light lost because of increased internal reflections & distance from entrance to cell)
2) It uses a hologram to selectively reject useless frequencies like infrared, which is 80% (IIRC) of the energy of sunlight, but generates no electricity from the cell. In fact, infrared is harmful to the cell, because it increases its temperature, which reduces its effeciency!
3) Because of the above features, it does not need a turning mechanism to follow the sun, the solar cell (which is the most expensive part) lasts much longer because it is not heated as much even though it is capturing much more useful light and converting that into electricity, it is flat and relatively easy to handle, unlike traditional solar cells with large, bulky, moving "capture" mechanisms placed in front of them....
In summary, it is cheaper per kilowatt-hr, AND more effecient, AND more practical for installation (no moving parts or seperated pieces). This is pretty neat.