Suntech Power said Wednesday it now holds the world record in producing the most efficiency multicrystalline silicon panels, beating a record previously held by Sandia National Laboratories.

A panel sporting the company's newly developed Pluto cells was able to convert 15.6 percent of the sunlight that strike it into electricity, Suntech said.

The Fraunhofer Institute of Solar Energy Systems in Germany, one of the few labs in the world whose test results are recognized by the industry, verified the efficiency of the panel. The panel rolled off a new factory line China-based Suntech set up to start shipping Pluto panels earlier this year.

The new record will be included by the science journal Progress in Photovoltaics (PIP) that periodically publishes a list of record-holding efficiency for different types of solar cells and panels.

"Improving the conversion efficiency of multicrystalline silicon modules has proven particularly challenging and this is a very impressive achievement for such a large module from a commercial supplier," said Martin Green, research director of the ARC Photovoltaics Centre of Excellence at the University of New South Wales in Australia, in a statement.

"I can confirm that the 15.6% multicrystalline module result is the highest known conversion efficiency measured by a PIP-recognized test center," added Green, who is on the journal's committee.

Suntech's efficiency number isn't much higher than the 15.5 percent record previously held by Sandia. But Suntech contends its panel could have surpassed 16 percent if it were tested without its frame, as was the case with Sandia's panel.

The new record is a boost to Suntech's plan to market panels assembled with Pluto cells, which it developed with technology licensed from the University of New South Wales. Suntech's founder and CEO Zhengrong Shi taught at the university for years. 

The university holds the world record for silicon cells made in a lab, which were tested by Sandia and yielded 25 percent efficiency. Cells made in the labs tend to be able to achieve higher efficiencies than those from commercial production lines.

The Pluto technology focuses on improving the cell's ability to trap light to boost electricity production. Pluto cells also use copper instead of silver for its collector and bus lines, which act as highways for transporting the electricity produced by the cells.

Silver is the common material from these lines, but it can be pricey. Copper has similar conductivity but is cheaper. Suntech also uses less copper to further reduce cost, said Steve Chan, Suntech's chief strategy officer, in an interview. Chan who declined to disclose Pluto's manufacturing costs.

Pluto can be used to make either monocrystalline or multicrystalline cells. The technology has produced monocrystalline cells with close to 19 percent efficiency and multicrystalline cells over 17 percent, Suntech said.

In general, monocrystalline cells are more expensive to make partly because growing single-crystal silicon is more time consuming and energy intensive, but they yield higher efficiencies. Most of the silicon panels on the market today are of the multicrystalline variety. 

SunPower, in San Jose, Calif., is known for producing the most efficient monocrystalline silicon cells for the market today. It is making cells with 22.5 percent efficiency. Its panels could achieve a little over 19 percent efficiency.

Suntech started shipping Pluto panels earlier this year, but the volume has been small. Suntech is producing them at about 1 megawatt to 2 megawatts per month, Chan said.

The company expects to ship 10 megawatts to 15 megawatts of Pluto panels by the end of 2009. Pluto panels have been installed in China and Australia. Suntech is waiting for IEC and UL certification to sell them in Europe and the United States.

Suntech is ramping up its production to mass produce them in 2010, when Suntech is set to have the manufacturing capacity to produce 300 megawatts of Pluto cells and panels per year, Chan said.

Suntech already has a 1-gigawatt capacity to produce silicon cells with an older technology, making it one of the few in the world with that much production capability.

The company plans to convert its existing lines to make Pluto products, a process that would take about three years, Chan said. Suntech has historically produced mostly multicrystalline silicon cells. Chan declined to say whether the company would shift that strategy with its Pluto lines.

Suntech is scheduled to announce its second-quarter earnings on Thursday.