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Politics : Formerly About Advanced Micro Devices -- Ignore unavailable to you. Want to Upgrade?

To: tejek who wrote (355456)	10/20/2007 11:08:33 AM
From: d[-_-]b	Read Replies (1) \| Respond to of 1576956

Don't you think we will continue to see improvements of this magnitude? Perhaps - but it could take another couple decades to go from 40% to 60% and that would probably be the upper limit, to attempt 100% just hits the law of diminishing returns, it'll be so expensive to get that last bit of efficiency it would be cheaper to simply buy another panel - someday. With all available silicon fabs used for cell phones and all the other gadgets - little room exists for solar production. Fabs cost billions to build now days and anyone doing so would be investing in a commodity product with a limited future. Four generations of development First The first generation photovoltaic, consists of a large-area, single layer p-n junction diode, which is capable of generating usable electrical energy from light sources with the wavelengths of sunlight. These cells are typically made using a silicon wafer. First generation photovoltaic cells (also known as silicon wafer-based solar cells) are the dominant technology in the commercial production of solar cells, accounting for more than 86% of the solar cell market. Second The second generation of photovoltaic materials is based on the use of thin-film deposits of semiconductors. These devices were initially designed to be high-efficiency, multiple junction photovoltaic cells. Later, the advantage of using a thin-film of material was noted, reducing the mass of material required for cell design. This contributed to a prediction of greatly reduced costs for thin film solar cells. There are currently (2007) a number of technologies/semiconductor materials under investigation or in mass production. Examples include Amorphous silicon, Polycrystalline silicon, micro-crystalline silicon, Cadmium telluride, copper indium selenide/sulfide. Typically, the efficiencies of thin-film solar cells are lower compared with silicon (wafer-based) solar cells, but manufacturing costs are also lower, so that a lower cost per watt can be achieved. Another advantage of the reduced mass is that less support is needed when placing panels on rooftops and it allows fitting panels on light or flexible materials, even textiles. Third Third generation photovoltaics are very different from the previous semiconductor devices as they do not rely on a traditional p-n junction to separate photogenerated charge carriers. These new devices include photoelectrochemical cells, polymer solar cells, and nanocrystal solar cells. Dye-sensitized solar cells are now in production. Fourth Fourth generation Composite photovoltaic technology with the use of polymers with nano particles can be mixed together to make a single multispectrum layer. Then the thin multi spectrum layers can be stacked to make multispectrum solar cells more efficient and cheaper based on polymer solar cell and multi junction technology used by NASA on Mars missions. The layer that converts different types of light is first, then another layer for the light that passes and last is an infra-red spectrum layer for the cell - thus converting some of the heat for an overall solar cell composite. Companies working on fourth generation photovoltaics include Xsunx, Konarka Technologies, Inc., Nanosolar, Dyesol and Nanosys. Research is also being done in this area by the USA's National Renewable Energy Laboratory ( nrel.gov ).