President Barack Obama wants the United States to develop a solar industry, but it’s tough for new solar companies to compete against established players in China and Europe, which have already invested in manufacturing equipment and found ways to drive down costs. One away to get around this could be to invent new, and far cheaper manufacturing methods. Now one start-up, 1366 Technologies, has demonstrated just such a process to the National Renewable Energy Laboratory, in Golden, CO.
Solar cell manufacturing today is a slow and convoluted process. First you use extremely expensive processing techniques to produce ultra-pure ingots of silicon, then you saw the ingots up into extremely thin wafers. In the process you throw out half of the silicon you took all that trouble to purify as sawdust. 1366 is developing a way to take the ultra pure silicon and make wafers without any sawing. It wastes less of the pricey material, and it’s potentially much faster than other methods. This can increase the amount of solar cells you can make (which reduces overall costs). They’re cagey about the details, but it seems to involve pouring out molten silicon.
About six months ago, NREL gave 1366 Technologies $500,000 to try to demonstrate the process. At the time, all they’d done is show that the technique works with tin. They were given a year to prove it worked with silicon, but they’ve already finished, demonstrating that the process can make small, 1-inch silicon wafers, which were used to fabricate solar cells that are more efficient than many of the solar cells currently on the market (so-called thin-film cells made of CdTe or amorphous silicon). The company is now scaling up the process to make 6-inch wafers, and working to improve the efficiency to about 16 percent, which would be competitive with crystalline solar cells from established manufacturers.
The technology is the invention of Emanuel Sachs, a professor of mechanical engineering at MIT. He previously came up with a technique for making wafers without sawing, but that process was much slower than the new one, and wasn’t compatible with conventional solar cell fabrication equipment. The new process is compatible, and promises to be faster. It could reduce the cost of making wafers by over 70 percent, says Frank van Mierlo, the CEO of 1366.