XConomy reports on a technique for increasing the efficiency of solar panels using "black silicon" - SiOnyx Brings “Black Silicon” into the Light; Material Could Upend Solar, Imaging Industries

Silicon is a wonderfully cooperative element. It takes relatively little energy to promote the electrons in a silicon crystal from their usual, docile orbits around the atomic nuclei into wild, free circulation. That’s what makes silicon a semiconductor—valuable for electronic switching devices such as transistors, sensing devices such as the CCDs in cameras and X-ray machines, and energy-generating devices such as photovoltaic cells.

But silicon would be more wondrous if it were even more responsive—if an incoming photon needed less energy to knock loose an electron, for example, or if a single photon could kick loose many electrons. In pursuit of this vision, chemists, physicists, and engineers have spent decades trying out various ways of modifying silicon crystals—for example, by doping them with atoms of arsenic or other elements that put more free electrons into the mix.

Almost ten years ago, graduate students in the laboratory of physics professor Eric Mazur at Harvard University stumbled across a new way of making silicon more responsive: they found that if they blasted the surface of a silicon wafer with an incredibly brief pulse of laser energy in the presence of gaseous sulfur and other dopants, the resulting material—which they called “black silicon”—was much better at absorbing photons and releasing electrons. And this week, after nearly three years in hyper-stealth mode, a spinoff company with an exclusive license from Harvard to commercialize the process has begun talking with reporters.

Executives for the company, called SiOnyx, believe that its technology will help semiconductor manufacturers build far more sensitive detectors and far more efficient photovoltaic cells, using essentially the same silicon-based processes they currently depend on—thereby revolutionizing areas such as medical imaging, digital photography, and solar energy generation.

Cleantech.com has a report on a massive expansion of silicon production by Hemlock Semiconductor.

In a $1.5 billion expansion, Hemlock says it will produce 46,000 metric tons by 2012. Hemlock, Mich.-based Hemlock Semiconductor today began production at its new polysilicon facility. The polycrystalline silicon producer says it expects to nearly double its output for both semiconductor and solar energy industries this year.

A joint venture of Dow Corning, Shin-Etsu Handotai Co. and Mitsubishi Materials Corporation, Hemlock already has claim as the world’s leading maker of silicon—the raw material of solar cells. By year end, the company says the site is expected to produce 9,000 metric tons of silicon, bringing the company’s annual capacity to approximately 19,000 metric tons, making the production facility the “largest single polysilicon facility in the world.”

An additional expansion with operations and supply will begin in 2010 and by the end of 2011, the Michigan-based company anticipates the facility will produce 36,000 tons annually.

In 2005, global silicon production was 26,000 metric tons and came from a small number of producers including Hemlock and MEMC of the U.S., REC and Elkem of Norway, Wacker of Germany and Tokuyama of Japan. ...

Last year Hemlock entered a 10-year silicon supply agreement with San Jose, Calif.-based SunPower, with deliveries from this deal slated to begin in 2010. According to last year’s deal, the silicon is expected support more than two gigawatts of solar cell production by SunPower.

Technology Review reports that the end of the silicon shortage is in sight, with capacity (and solar panel output) expected to increase sharply and prices expected to drop.

Solar electricity is about to get much cheaper, industry analysts predict, because a shortage of the silicon used in solar panels is almost over. That could lead to a sharp drop in prices over the next couple of years, making solar electricity comparable to power from the grid.

High demand generated by government subsidies worldwide and a shortage of processed silicon have kept prices for solar-generated power much higher than average electricity prices over the past few years. Solar power is more than three times the cost of electricity from conventional sources, according to figures from the industry tracking firm Solarbuzz and the United States' Energy Information Administration. Solar power cost about $4 a watt in the early 2000s, but silicon shortages, which began in 2005, have pushed up prices to more than $4.80 per watt, according to Solarbuzz.

Crystalline silicon has long been the staple of the semiconductor industry. But it's also the active material in the most common type of solar panel, and the increased use of solar power has led to the shortage of the material. Indeed, the growth in silicon production hasn't kept pace with the rise in solar power. "It takes about two or three years to add capacity," says Travis Bradford, an industry analyst for the Prometheus Institute. The shortage has been severe enough to drive up silicon prices to more than 10 times normal levels, to $450 a kilogram, adds Ted Sullivan, an analyst at Lux Research.

The added silicon production capacity is now starting to begin operations. While only 15,000 tons of silicon were available for use in solar cells in 2005, by 2010, this number could grow to 123,000 tons, Sullivan says. And that will allow existing and planned production of solar panels to ramp up, increasing supply. "What that means, practically, is that [solar] module prices are going to come down pretty dramatically in the next two or three years," Bradford says.

A report from Michael Rogol, an analyst at Photon Consulting, says that demand for solar panels will quickly rise in response to even slightly cheaper prices, holding the price drop between 2007 and 2010 to a mere 20 percent. But others think that the demand will have trouble responding quickly to lower prices. That's in part because the market for solar has been generated by government subsidies, especially in countries such as Germany and Spain, and there are limits to how fast these subsidized markets can grow.

Regardless of the growth in demand, Bradford predicts that over the next couple of years, production of solar panels will double each year.

In a recent presentation, Bradford said that prices for solar panels could drop by as much as 50 percent from 2006 to 2010. In areas that get a lot of sun, that will translate to solar electricity costs of about 10 cents per kilowatt hour, matching the average price of electricity in the United States. That will make solar affordable and, eventually, will vastly increase the market, Bradford says. "You can't even begin to imagine the transformation that that's going to create."

Technology Review (my favourite source of energy technology research news) has a look at solar startup Solaria (backed by Q Cell) and their efforts to reduce the amount of silicon used in solar cells - "Slicing Up Silicon for Cheaper Solar".

Solaria, a startup based in Fremont, CA, intends to cut the cost of solar panels by decreasing the amount of expensive material required. It has recently started shipping its first panels to select customers. This spring the company will begin production of solar panels at a factory built to produce 25 megawatts of solar panels per year.

Current high costs for the type of silicon used in photovoltaics have significantly driven up the price of conventional solar panels. Solaria's cells generate about 90% of a conventional solar panel's power, while using half as much silicon, says Kevin Gibson, Solaria's CTO.

Ordinarily, the silicon in a solar panel spans its surface, collecting light from as much area as possible. But Solaria slices the silicon into thin strips and spaces them apart so that they only account for about half the panel's area. A clear molded plastic cover collects light from the entire panel and funnels it to the strips of silicon.

This approach saves money because the total costs of the molded plastic, other extra materials, and added manufacturing steps still are lower than the cost of the additional silicon used in conventional solar panels. Solaria also reduces costs by using manufacturing equipment already developed for the semiconductor industry, thus avoiding expensive customized equipment. Gibson says Solaria's first products will be economical enough to compete with panels produced by much larger companies, and that successive product generations will cost between 10 and 30 percent less than their competitors.

Silicon prices are high now. But the element is abundant, and already new facilities are coming on-line to produce more refined silicon. For Solaria is to be competitive in the long run, it will need to implement other cost-saving measures, especially improving the overall efficiency of its solar panels, says Tonio Buonassisi, a professor of mechanical engineering at MIT.

Such improvements are possible, Gibson says. For example, in conventional solar cells, wires for collecting current are placed on top of the cell, where they block some of the incoming sunlight. Solaria could place its wires between the strips of silicon, where they block no light. Because the wires wouldn't need to be made thin to avoid blocking light, they could be sized to collect electricity more efficiently.
Solaria will be competing with many other companies that have developed ways to use less silicon. Evergreen Solar, based in Marlboro, MA, discovered a lower-waste technique of processing silicon. A group at the Australian National University developed slices of silicon set on edge to collect light and produce electricity. Stellaris, based in Lowell, MA, has created a technology that, like Solaria's, uses low concentrations of light to reduce the amount of silicon needed.