A Moore’s Law for Solar

“Think thin,” says Applied’s Charlie Gay. He’s one of the several big guests at Intersolar next week.

Michael Kanellos July 10, 2009

Michael Kanellos

SANTA CLARA, Calif. -- Several people (myself included) have posited that alternative energy won't likely have its own Moore's Law, the phenomenon in the chip market that lets things get cheaper, smaller and better over time.

It looks like the critics might be wrong.

Charlie Gay, the president of Applied Solar, the solar arm of semiconductor-equipment-maker Applied Materials, says solar panel makers are experiencing steady cost reductions by making solar panels steadily thinner. Manufacturers can't reduce the X and Y dimensions of the solar cell easily – that would reduce the surface area exposed to the sun, which in turn would reduce the power that a given panel could produce.

But by producing thinner wafers, the amount of raw material gets reduced without reducing performance.

"The Moore's Law for solar is that as time goes by, things get thinner and still absorb light," he said during a tour of Building 21 at Applied, where the company conducts testing and research on its equipment. (Gay will be speaking at Intersolar U.S. taking place in San Francisco next week. Our video interview with him will appear on Intersolar TV and on the Greentech Media site next week.)

The latest amorphous silicon solar modules made on Applied's SunFab line, for instance, contain some layers measuring 100 angstroms thick, or about 30 atoms. These sheets of motherglass are 61 square feet in size.

"That is 30 atoms uniformly deposited from one side to the other," he said.

The difference between chips and solar panels, however, comes in how these improvements are implemented. In the semiconductor world, companies shift from one manufacturing node to a more advanced one approximately every two years. "Solar in a sense is more analog. It continues to improve over time," he said.

Gay also defended amorphous silicon. Applied primarily makes equipment for makers of silicon crystalline and amorphous crystalline solar panels, and it is particularly interested in promoting amorphous silicon. Several analysts assert that the future for thin film will be dominated by cadmium telluride and copper indium gallium selenide (CIGS) panels, both of which potentially will provide higher efficiencies than amorphous silicon.

Amorphous, however, is gaining in efficiency, he noted. Some amorphous manufacturers employing Applied's machines can achieve module efficiencies of 8 percent.

Just as important, the manufacturing tools are more standardized, he noted. Makers of other types of thin film panels often have to customize their equipment.

"The question is: What is the technology that can scale?" he said.