The trick is to mold the acrylic such that it bends the light in a certain direction when it enters the first optic. It must assure that the light maintains that angle to prevent it from escaping and guide it to the glass optic at the center. Precision is crucial–not just in the design of the optics, but also in creating the molds to mass-produce them.
The company expects that its first commercial versions of the system will be composed of acrylic wafers about eight square inches in size containing a secondary glass optic that’s about twice the diameter of a nickel.
Ray LaPierre, a professor of engineering physics at McMaster University, in Ontario, Canada, and an expert in high-efficiency solar cells, first saw Morgan Solar’s LSO prototype in December at a Canadian solar conference and walked away impressed. “Their design is certainly novel, is physically sound, can be cheaply manufactured, and has a good chance to revolutionize concentrator [technology] ” says LaPierre.
But like other PV concentrators, Morgan Solar’s technology still requires a tracking system to keep it facing the sun. Researchers at MIT have eliminated the need for trackers by developing special dye coatings that can absorb diffuse light, but Morgan Solar’s technology is closer to market. Nicolas Morgan adds that trackers today are precise, reliable, and add “marginal” cost for 44 percent more power. Some business and engineering decisions must still be made, but he expects that the company will be able to build its system for less than $1 per watt by 2011–“and with some vertical integration, considerably less.” This would lead to a product close to 30 percent efficient at costs competitive with thin film.
“I think the concept should be pursued,” says engineering professor Roland Winston, an expert in nonimaging optics at the University of California, Merced. He does, however, question the use of acrylic as a concentrator material: “Acrylic has not been proven for long-term use, especially under concentrated sunlight.”
John Paul Morgan says that’s the main reason why the company is using both acrylic and glass in its system. The company has intentionally limited concentrations within the acrylic portion to 50 suns and has the smaller glass optic doing the heavy lifting. “We want this system to last for 25 years, so we’re trying to really understress the material,” he says. “Once we’ve proven we can push the acrylic further, we’re going to shrink the glass optic.”
A number of pilot projects planned for 2009 will test the concentrator in the field. The company expects commercial production to begin sometime in 2010.
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