NREL tests Global Solar's CIGS at 15.45% efficiency
German and U.S. firm also reaches new record of 11.7 percent efficiency for solar cell strings in production at its two facilities
Berlin- and Tuscon, Ariz.-based Global Solar Energy announced today that tests from the U.S. Department of Energy's National Renewable Energy Lab confirmed 15.45 percent energy-conversion efficiency of the company's copper indium gallium diselenide (CIGS) material.
Vice President of Sales and Marketing Tim Teich told the Cleantech Group that the accomplishment helps strengthen the company's position as it targets the building-integrated photovoltaic market with its lightweight, flexible thin-film solar products.
Teich said NREL took a Post-it Note sized sample of the CIGS material from Global Solar's production roll, adding NREL's own topcoat and grid lines.
"What they're trying to validate is the purity and quality of the CIGS layer," Teich said.
Global Solar also said today it reached a new record for peak efficiency of solar cell strings from its production lines. The company's 35-megawatt German and 40-MW U.S. factories produce the strings with efficiencies averaging more than 10 percent and with an upper range of 11.7 percent—a new high for the company, Teich said. Global Solar said in January 2008 that it reached an average of 10 percent efficiency at production (see Global Solar claims 10 percent efficiency for thin-film).
The difference in efficiencies of the material and the solar strings is due to losses and materials that keep the cost of the products down, Teich said.
"The toughest thing for CIGS is to get into production with high efficiencies," he said.
Global Solar's new efficiency milestones are in line with competitors. Ascent Solar Technologies said in July that NREL verified 10.4 percent efficiency of its CIGS solar modules (see NREL confirms Ascent's flexible solar at 10.4 percent), while HelioVolt said last year that independent testing at Colorado State University confirmed it reached 12.2 percent conversion efficiency of its CIGS solar cells (see HelioVolt says it boosts thin film efficiency).
But instead of cut-throat competition, Teich applauded the successes.
"The efficiency of CIGS at these companies is going up, which is fantastic because for CIGS to be accepted the marketplace has to have more than one company showing these efficiencies," he said. "They key distinction is: Who is really in production?"
Global Solar started production of its CIGS thin-film solar cells on a flexible substrate in 2004. In the past two years, the company expanded from 4.2 MW to 75 MW of peak production capacity between its two factories. The German factory is located within a commercial building owned by Solon, which purchased Global Solar in 2007 from UniSource Energy for $16 million (see Germany's Solon establishes U.S. operations in Tucson).
Global Solar expects to produce about 20 MW this year, split evenly between the two facilities, Teich said.
"With the market downturn, we haven't turned them on full throttle," he said. "We are turning them on to the tune of our customer orders, and as the market returns we will be able to ramp up the lines as opposed to installing new lines."
Teich said that reaching volume production is the main roadblock for CIGS producers to match the $1 per watt price point of thin-film leader First Solar, which uses cadmium telluride technology (see Is 5N Plus losing traction with First Solar?).
"CIGS at scale can meet those kind of costs out there today. The trouble is CIGS is behind in scale," Teich said. "Can we get $1 per watt? Yes, as long as we have a market that is drawing the volume production."
However, Global Solar doesn't aim to compete directly with First Solar or crystalline PV module maker Suntech. Instead, Global Solar wants to puts its CIGS on flexible foils in order to incorporate the technology into building integrated photovoltaics (see Global Solar introduces a thin film alternative).
"[Solar is] headed into a mature industry where giants rule," Teich said. "Plus, it's sort of a shame to put a flexible solar cell into rigid glass."
Teich said Global Solar is working on several BIPV projects but that he was only allowed to talk about one: Dow Chemical is working to incorporate the company's CIGS technology into roof shingles.