Advances in solar cell technology
July 1, 2008
New technologies in solar are moving so fast it’s hard to keep on top of it.
It’s becoming abundantly clear that solar cell production is not moving fast enough, and companies are scrabbling for alternatives to silicon that are more affordable, can be produced more rapidly and with less toxic waste associated with some of the production methods.
Production of silicon solar cells used up to 33% of the world’s electronic grade silicon production in 2006. In addition, the production of silicon is expensive and some production methods entail hazardous chemical solvents that can find their way into the environment.
Video of solar panel production.
Toxic waste
One byproduct of polysilicon production is silicon tetrachloride, a colorless, toxic liquid that causes irritation to the respiratory tract, sneezing, coughing, burning throat, a constricting sensation of the larynx and difficulty in breathing. When it combines with water it becomes highly corrosive to metals.
A recent article in the Washington post exposed how solar cell production in China is leaving behind toxic waste, dumping it openly and polluting the land and aquifers.
There is interest in producing silicon from other materials, such as rice hulls, but even this requires leaching the silicon from the hulls with hydrochloric acid. http://www.osti.gov/energycitations/product.biblio.jsp?osti_id=6204723
With all this in mind, many are turning from silicon to find less expensive options. A recent testing of dye-sensitized, silicon-free solar cells in China holds promise.
The technology entails printing a thin film of nano-sized particles of titanium dioxide which is then sprayed with dye which is in contact with an electrolyte solution. When solar radiation hits the dye it injects a negative charge in the pigment nano-particle and a positive charge into the electrolyte solution, which converts sunlight into electrical energy.
So far, the thin film panels
are less efficient than silicon, but there are hopes that productivity can increase significantly soon and compete with silicon in a real way, thereby reducing the cost of solar energy to our environment.
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