What Are Solar Film Cells?

This new emerging technology might just change the world. Solarenergy and ‘going green’ are getting a lot of attention these days.Many people are talking about thin film solar cells, also called solarfilm.

Solar film cells are getting a lot of attention because they addressthe biggest issue with solar energy: cost. The development of thistechnology has take great strides in recent years because they arecheaper to manufacture than traditional solar panels. Thin film solar panelsare what you would find in a solar calculator, and this technology isbeing expanded into panels for large residential and commercial use. Global Solar Energy, for example, recently installed a 750 kilowatt array that provides 25% of factory’s power needs.

There several technologies that exist that fall under the solar film heading:

1. Amorphous or Thin Film Silicon. This technology uses thesame science that is found in the rectangular solar panels we areseeing more and more of in the world. Instead of using hard crystallinesilicon that must be encased in tempered glass and aluminum frames likenormal solar panels, the silicon is deposited on a flexible piece ofmetal or plastic and then coated. This technology is generally lessefficient, but much cheaper to make. To produce the same amount ofenergy as a traditional solar panel, you would need 30-50% more surfacearea of thin film silicon solar.

2. Cadmium Telluride. This technology is less popular thanthin film silicon for several reasons. While it is more cost-effectiveto manufacture, it is less efficient than silicon. Additionally, thematerials in these cells tend to be toxic, leading to concerns aboutthe manufacturing process and the long term environmental effects ofthe cells. Studies are being done as we speak to investigate the longterm toxicity of cadmium telluride since the economics of thetechnology are very attractive. Typical efficiencies for these cellsare around 15%. This means that 15% of the total energy that fell onthe cell was converted to electricity.

3. CIGS. CIGS is an acronym for’copper indium gallium(di)selenide’ (see why we call it CIGS?). CIGS cells have the mostpromise for bringing down the cost of solar since the economics ANDefficiencies are very promising. In 2005, the National REnewable EnergyLab achieved a world record 19.9% efficiency for a CIGS cell. Thismeans that 19.9% of the total energy that fell on the cell wasconverted to electricity. This is approaching the world record for acommon solar panel of 24.7%. This very exciting because manufacturersanticipate the cost of mass-produced thin film cells to be around$1.00/watt. Common silicon solar panels we are used to seeing are closeto $5.00/watt. Companies such as Shell, Nanosolar, and Honda areinvesting heavily in this technology. Nanosolar is particularlyinteresting in that is has the backing of Silicon Valley venturecapital and the Google founders. They are in the process of building amassive manufacturing facility and claim that they will produce solarcells at 1/10th the cost of current cells. Very exciting.


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