Prof's research may chop price of better solar cells

[Bob Of Burleson]

Exotic, Highly-Efficient
Solar Cells May Soon
Get Cheaper

Kevin Bullis
TechnologyReview.com

The world’s most efficient solar cells are twice as efficient as the ones people put on their roofs, but hardly anyone uses them because the semiconductor materials they’re made of are so expensive. That could be about to change.

Ali Javey, professor of electrical engineering and computer sciences at the University of California at Berkeley, has found a far cheaper way to manufacture these better-performing semiconductors. This advance could lower the cost of high-efficiency solar cells, potentially making them as cheap as conventional ones. Javey says the new process could be a “game changer” for solar cells.

Improving the efficiency of affordable solar cells will be essential for making solar power competitive with fossil fuels. Fewer cells would be needed, reducing costs for materials and installation, a large share of the total cost of solar power.

Early tests suggest solar cells made from the materials would have an efficiency of about 25 percent, which is far better than conventional silicon solar cells, which are less than 18 percent efficient. And a preliminary analysis by the National Renewable Energy Laboratory suggests Javey’s cells could be made as cheaply as conventional ones.

The most efficient solar cells available today are made from materials called III-V semiconductors, a group that includes gallium arsenide and indium phosphide. Making solar cells from these materials normally means starting with expensive crystals of the semiconductor material, then exposing the crystals to vapors that produce the thin films need for a solar cell.

Javey’s process instead grows thin films for solar cells on top of a cheap material—glass or a sheet of metal. The vapors used in the process are cheaper than those normally used, and they’re used far more efficiently, reducing waste.

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