Solar Energy Start-up Attacks PV Wafer Costs

While the cost and efficiency of solar electric systems have improved steadily over the years, the initial investment is still an expensive, capital intensive proposition. Reducing the cost of photovoltaics (PV) has undeniably been the greatest challenge and most sought-after goal in the industry.

Los Gatos, California – December 3, 2003 [SolarAccess.com] Every now and again researchers, companies, or combinations of the two, announce significant progress towards bringing the cost of PV down. Solaicx is the latest company to announce a new manufacturing technology that it says will supply its customers the material and technology to create solar cells with high conversion and efficiency at very low costs and in large volume. The company, with seven U.S. patents in process, is attacking the cost structure of the expensive single crystalline wafer, the heart of 86 percent of solar cells made today. Wafers typically account for 50 percent of a PV module’s cost, according to the company. Solaicx’s CEO Bob Ford said the company’s solution is to reduce the amount of silicon used, provide higher quality material that enables 21 percent solar cell conversion efficiency, and create the equipment and processes necessary for handling high volumes of material. Part of their approach is to start from scratch with all their technology and hardware so as not to loose any efficiency on equipment that may have been retrofitted from other industrial processes. “Most of the equipment and processes used today have been adopted from the semiconductor industry, designed for the meticulous handling of each wafer,” Ford said. “As the photovoltaic industry has emerged into a substantial business, it is time that the photovoltaic industry utilizes equipment and processes designed for high throughput without compromising the quality of the product. Solaicx has the technologies to build the equipment and processes designed for high volume manufacturing while improving the quality of the product.” Ford said the company manages its silicon use through three primary improvements. The wafers are thinner and there is much less loss in the sawing process. But the most important element is making wafers that will have high minority carrier lifetime, enabling the company’s customers to build these 21 percent efficient solar cells, Ford said. The first two essentially deal with the manufacturing process while the later deals with improving the electrical properties. Bill Yerkes, the company’s Chief Technology Officer explained how improvements in PV minority carrier lifetime is integral to his company’s technology. The “lifetime” measurement is essentially the length of time that electrons would remain excited, or active after a pulse of light hits the PV cell. After a period of time the electrons that were stimulated by the light would damp out and all stop moving around. A solar cell is a like a diode, and so the longer the electrons can keep moving around the better chance they have of crossing the electrical junction. Once the electrons cross the diode junction they cannot come back so they must follow the wires to the electrical load and then back to the cell after performing the electrical work, which could be charging a battery or contributing towards to a home’s electrical demands. “So you might say ‘lifetime’ in a mechanical sense is like ‘how long will a tuning fork keep ringing’ after it is struck,” Yerkes explains in another way. “Really high lifetime single crystal wafers have a lifetime of more than 1 millisecond. Not so good lifetime would only be a wafer with 100 microseconds. So it is easier to make 20 percent efficient cells when you have 1 millisecond or more lifetime wafers, and maybe you can only make 15 percent cells with 100 microsecond wafer lifetime.” So the minority carrier lifetime numbers are high, but if it’s the economics that matter the most to the photovoltaic industry, then what are the numbers here? Ford said the by late 2004, the company’s customers will be able to reduce their module manufacturing cost per watt by $0.45. By the end of 2006, Ford anticipates his company’s customers to be able to reduce the module manufacturing cost by almost $1.00 to less than $1.50 per peak watt. The company is still in development stage and does not anticipate generating their first revenues until the fourth quarter in 2004 from a wafer manufacturing line that will be capable of 8MW annual capacity. Ford said they are about to close their angel financing round and expect to raise venture capital by mid-2004. The company has four patents pending and three additional patent applications in process. The solar PV landscape is now a highly competitive field, loaded with different technologies – amorphous thin-films, multi-crystalline, triple junction, polymers, dyes, concentrating lens PV hybrids and nanotechnology – all with the goal of distinguishing themselves from the rest as the most cost-effective approach to harnessing electrical power from the sun. Whether Solaicx’s approach is the answer remains to be seen, but it’s certainly a new company worth keeping an eye on.
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