Solar Researchers Concentrating Their Efforts

As any child who’s played with mirrors and magnifying lenses outdoors knows, such simple devices, when paired with sunlight, can generate significant energy. Researchers currently are looking at new ways to adapt similar principles to improving solar-energy production. Resulting products are showing promise in both improving photovoltaics’ performance and reducing overall system costs.

A new system from Pasadena, Calif.-based Soliant Energy brings solar-concentrator designs common in large-scale solar-collector farms to small-scale roof-top installations. Instead of flat panels, Soliant’s approach uses trough-like aluminum modules—each about the size of a standard gutter—mounted into a rectangular frame. A strip of photovoltaic material runs along the bottom of each trough and a lens-like acrylic lid caps off each unit. Some light is reflected off the gutter’s reflective interiors onto the photovoltaic material, while more is focused onto this strip by the acrylic lens. The troughs are designed to tilt from side to side, to track the sun’s progress through the sky.

The Soliant units produce as much power as conventional flat panels, according to U.S. Dept. of Energy (DOE) officials quoted in a recent Technology Review article on the technology, but are less expensive because they use 88% less silicon. The company expects to start shipping its new system in late 2007, and it will be receiving up to $4 million in DOE funding to research second-generation improvements to its designs.

Improving the performance of the photovoltaic material used in concentrator designs could make these systems even more efficient. Sylmar, Calif.-based Spectrolab, a Boeing subsidiary, has developed a solar cell more than twice as efficient as those used in typical rooftop panels. The new cells are made from “metamorphic” materials, a class of materials previously unexplored for such applications, which can, among other advantages, capture infrared light previous cells have not been able to use.

Using Spectrolab’s research along with other product-development efforts, Boeing is promising to cut the delivered price of electricity using concentrated systems to 15 cents per kilowatt hour by 2010—today’s solar power systems come in at an estimated 32 cents per kilowatt hour—and cut that price in half, again, by 2015. The company is participating in a $29.8 million concentrated-photovoltaic development partnership with the DOE to achieve that goal.

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