The polysilicon shortage might be over soon, but that isn't stopping Trina Solar from devoting its resources to developing products using a dirtier but cheaper class of silicon.

Trina (NYSE: TSL) said Tuesday it has been developing solar panels using upgraded metallurgical-grade (UMG) silicon, which isn't as pure or efficient at converting sunlight into electricity as the polysilicon that has been commonly used to make solar panels. But UMG silicon is cheaper, making it attractive to solar companies that must stay competitive by offering lower-cost products.

Interest in UMG silicon emerged when solar companies found themselves competing with chip companies for the purer polysilicon in the last several years.

Investors are increasingly betting on the UMG silicon. Sunnyvale, Calif.-based CaliSolar, which uses UMG silicon to produce solar cells, just raised $101.9 million (see CaliSolar Snags $101.9M for UMG-Silicon Cells). Blue Square Energy, meanwhile, is looking to raise $25 million after the North East, Md., startup replaced its CEO and laid-off employees.

UMG silicon producers such as Timminco in Canada are inking more supply deals. The UMG silicon technology received a nod of approval when Timminco announced in March that its subsidiary, Becancour Silicon, would supply UMG silicon to Germany-based Q-Cells, the world's largest solar cell maker.

But skepticism remains strong about the ability of UMG silicon makers and their customers to produce products that can reach similar efficiency as those built with purer silicon.

Besides, many analysts believe the shortage of the purer silicon is likely to be over soon (see New Research Predicts End of Silicon Shortage). In fact, with so many new factories coming on line to produce the purer silicon, the solar industry is bracing for a possible oversupply of the material and a price drop for solar panels (see Analysts Pick Next Year's Solar Winners).

China-based Trina has been an established maker of ingots, wafers, solar cells and panels using the purer polysilicon. It began investigating the use of UMG silicon in mid 2007, said Jifan Gao, Trina's chairman and CEO, in a statement.

The company claims its UMG-silicon products can reach 14 percent efficiency, but didn't specify whether it meant cell or panel efficiency. Blue Square, on the other hand, recently said its solar cells have reached 14.6 percent efficiency.

In comparison, solar cells from purer silicon on the market today can get to 22 percent efficiency.

Trina plans to begin making UMG-silicon panels this quarter at its existing factories and sell them under a different, yet-announced brand. 

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