November 1, 2007

POWER GLASS-light and electricity


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The ideas of sustainability, self-sufficiency and energy saving are nowadays in the basic vocabulary of current architectural production world-wide. However, one of the greatest problems architects face when using photovoltaic panels is the formation of building facades, as the specific form of these extremely useful elements affects radically the design process. The launching of new materials gives way to the better integration of sustainability and energy saving in everyday architecture. One good example is Power Glass, produced by XsunX, which makes it possible to manufacture windows that generate electricity and still allow 70 percent of light to pass through.

Power Glass is made using amorphous silicon, the non-crystalline form of silicon that can be deposited in a very thin film and remains flexible. If we are going to compare the non-crystalline silicon and the crystalline silicon we see that the crystalline silicon used in conventional solar cells is a thousand times thicker, requiring more silicon. And crystalline silicon must be deposited on a rigid substrate that can withstand high manufacturing temperatures. The applications of amorphous silicon thus far have been primarily in liquid-crystal displays and thin-film transistors; its photovoltaic applications have been limited by its relatively low power-producing efficiency compared to crystalline silicon.

XsunX company is using a cassette system that allows high-volume production of thin films with low risk of contamination. Solar cells are applied in a thin layer - about 0.2 microns thick - onto large rolls of supporting material. The process happens at 150 °C, low enough to use plastic or polyester substrate. Multiple cassettes or film are processed simultaneously and the result is rolls of photovoltaic film. The flexible film is then applied, like low-e coating, to the surface of a multi-plane window. The film allows edge-to-edge coverage. This system makes the entire window an active energy conversation area.

Of course there are other materials that are aiming to perform the same function, like Scheuten Solar’s product. This product is consisting of opaque solar cells in glazing, separated by clear spaces, but it is resulted in visible mosaic or stripes, actually changing the way light enters the building. Power Glass- on the other hand- looks more like tinted solar glass, without a pattern. It blocks 30 percent of the incoming light, uniformly across the window opening.

What encourages Power Glass to fly economically is that it doesn’t only look like a tinted glass, but it works like one and at the same time produces electricity. The primary electrical energy cost of a large building is air-conditioning (A/C) and lighting. Using Power Glass to transform 4-5 % of the solar energy into electricity instead of using conventional tinted glass, the lighting and the A/C load decreases. So the annual energy consumption in a building that would normally be huge is much smaller having Power Glass performing both functions.

Links:

http://www.xsunx.com/advanced-celldesign.htm

http://www.hollandtrade.com/vko/zoeken/showbouwsteen.asp?bstnum=1464

http://www.scheutensolarsystems.nl/

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