3D design improves solar cell efficiency

Santa Barbara, Calif., has a company called Solar3D, which plans to make silicon solar cells more efficient than traditional batteries because it uses the concept of light trapping with fiber optics. . The company claims that its three-dimensional design can concentrate light into silicon to be captured, allowing this material to spend more time converting light into electricity.

Silicon has a theoretical maximum photoelectric conversion efficiency of 29%, but the efficiency of solar panels on the market today is only 15% to 18%. Solar 3D's design has no definitive efficiency figures yet, but CEO Jim Nelson said, “I think it will be close to the theoretical efficiency of silicon. We can't reach 29% and no one can achieve it with silicon. High, but we want to be as close as possible."

Solar 3D's design will overcome two factors that reduce the efficiency of solar cells. First, 30% of the light that hits the solar panel is reflected and lost. Second, many electrons generated when light hits silicon are re-absorbed by this material before reaching the peripheral circuit.

Nielsen said that this new design has some grooves, and the light collecting layer on the top is made of silicon dioxide or other similar materials; these grooves can guide light down and help eliminate reflections. The lower layer is an array of three-dimensional structures, each one a few microns wide, which is trapped by simulating the waveguides used in the fiber. The fiber contains two cylindrical layers with different refractive indices that continuously reflect light back to the core. Nielsen said that this three-dimensional structure will cause light to bounce around until the photons produce as much electrons as possible. "We will also make the contacts very close to where this happens so that the electrons don't have to move very far," he said.

There are many other notions of light trapping. Another method to borrow optical fiber technology is fiber-optic solar cells. Researchers at Georgia Tech have produced and wound dye-sensitized solar cells. However, Nielsen said that solar 3D's batteries use traditional silicon materials, so their preparation can be used in existing production equipment, can also be put into existing modules.

Solar 3D is at a very early stage. It started when it came to a time when venture capitalists were afraid to invest in solar technology because of the high start-up costs. But this company does not seek venture capital. On the contrary, it comes from private investors, including Nelson, who has a financial background, but has a passion for renewable energy. Analysts say that the company’s success will depend on whether its manufacturing costs can compete with conventional crystalline silicon technology. "It is very difficult for emerging technologies to gain a foothold in the market," said Matthew Feinstein, an analyst at Lux Research. "Bank discountability is often a major problem because these technologies do not have a reliable track record."

These technologies like Solar 3D are expected to bring higher efficiencies. They are very good because they will make solar power cheaper. Georgina Benedetti said that he is a Frost & Sweet. Analysts at Frost & Sullivan. However, she said, “The main challenge facing the industry is the competition from China's manufacturing industry.” The cheaper solar panels made in China, coupled with cost control issues, caused Solyndra to collapse. This is a solar panel maker in Fremont, Calif., which recently announced bankruptcy and has previously received support from the U.S. Department of Energy.

But Nelson does not seem to be intimidated. He believes in the design of solar 3D, and this design can be compatible with existing solar energy infrastructure. "Our whole approach is to consider mass production," he said. "Our whole purpose is to make it competitive." The company expects to have a prototype device by the end of 2011.