The Solar Cell That Turns 1 Photon into 2 Electrons
Solar cells are picky. If an incoming photon has too little energy, the cell won’t absorb it. If a photon has too much, the excess is wasted as heat. No matter what, a silicon solar cell can never generate more than one electron from a single photon. Such harsh quantum realities severely limit the conversion efficiency of photovoltaic cells, and scientists have spent decades looking for work-arounds.
Now, researchers at the Massachusetts Institute of Technology’s Center for Excitonics have published a compelling case that the key to greater solar efficiency might be an organic dye called pentacene. In today’s issue of Science Daniel Congreve, Jiye Lee, Nicholas Thompson, Marc Baldo and six others show that a photovoltaic cell based on pentacene can generate two electrons from a single photon—more electricity from the same amount of sun. Scientists have suspected for some time that this might work; today’s paper is proof of concept.
The key is a phenomenon called singlet-exciton fission, in which an arriving photon generates two “excitons” (excited states) that can be made to yield two electrons. Previous researchers had accomplished similar tricks using quantum dots (tiny pieces of matter that behave like atoms) and deep-ultraviolet light. “What we showed here,” Baldo says, in addition to using visible light, “is that [this process] works very, very effectively in organic materials.” Full Article:
Peel-And-Stick Solar Power
Peel-and-stick, or water-assisted transfer printing (WTP), technologies were developed by a group at Stanford and have been used before for nanowire based electronics. A new partnership between Stanford University and the U.S. Department of Energy's National Renewable Energy Laboratory (NREL) has conducted the first successful demonstration using actual thin film solar cells, NREL principal scientist Qi Wang said.
The university and NREL showed that thin-film solar cells less than one-micron thick can be removed from a silicon substrate used for fabrication by dipping them in water at room temperature. Then, after exposure to heat of about 90°C for a few seconds, they can attach to almost any surface.
Wang met Stanford's Xiaolin Zheng at a conference last year where Wang gave a talk about solar cells and Zheng talked about her peel-and-stick technology. Zheng realized that NREL had the type of solar cells needed for her peel-and-stick project. Full Article:
Largest Wind Farm In Southern Hemisphere Opens Down Under
The 420 megawatt Macarthur wind farm was opened in the state of Victoria on Friday. It is the largest wind farm in the southern hemisphere and its 3 megawatt Vestas turbines are the largest in Australia. The Mcarthur Wind Farm is actually the first project to use Vestas’ V112-3.0 MW wind turbines. The project’s expected operating capacity is 35% and its cost was almost exactly one billion dollars.
One billion dollars may sound like a lot of money, probably because it is, but that doesn’t mean it’s not a good deal. The wind farm has an operating life of 25 years and if a 5% discount rate is used for the cost of money, it will generate electricity at about 6 cents a kilowatt-hour. While this is slightly higher than the average price of electricity generated from coal in Australia, it does have the very large advantage of being non-fatal on both the personal and planetary scales. It’s also cheaper than electricity from new coal plants and is a major reason why Australia is extremely unlikely to ever build any new coal capacity.
Why First Solar is buying a silicon solar cell startup no one's heard of
First Solar is buying an under-the-radar startup called TetraSun to add expertise around silicon solar cell manufacturing to its technology portfolio, which until now has focused on using the material cadmium telluride to make solar cells.
The Arizona-based thin film solar giant announced the pending acquisition on Tuesday during its analyst day — its first since 2009 — in which it laid out a persuasive technology and business development plan for the next five years. Investors liked what they heard and pushed the company’s stock up by nearly 50 percent during trading.
So why TetraSun? Apparently Silicon Valley-based TetraSun has some disruptive silicon cell designs that set it apart from the rest of the silicon solar companies. Its designs require fewer manufacturing steps to produce conventional silicon cells, and eliminates the need for silver and transparent conductive oxide. Silver is used to transport electricity produced by the cells, while the oxide is a coating that protects the cells and helps the semiconductor material (such as silicon or cadmium telluride) to grab the light more effectively to produce electricity.
First Solar claims that TetraSun’s cells also can perform better in hot climates than conventional silicon cells. That feature will make solar panels with TetraSun’s cells more desirable in places like the Middle East and India, two markets with a lot of potentials for growth. First Solar says it plans to start making TetraSun’s cells in the second half of 2014.
California sets windpower-generation record, says Cal ISO
The Folsom-based California Independent System Operator, which operates the state's wholesale electricity transmission grid, said today that wind power turbines on the grid set a new record of 4,196 megawatts on Sunday.
The record came at 6:44 p.m. That mark came on the heels of Friday's passing of the 4,000-megawatt threshold.
Previously, the ISO's all-time record peak output for wind energy was 3,944 megawatts on March 3.
"With these impressive wind-production levels, California is well positioned to meet the 33 percent by 2020 green power goal," said ISO President and CEO Steve Berberich. "Our control center operators are tracking a steady increase in renewable energy ... "
Currently, ISO said there is a total of 5,899 megawatts of wind plant capacity installed within the California grid.
California is the nation's second largest producer of wind power, trailing only Texas.
ISO said that Texas, which has a current wind-generation peak capacity of 10,407 megawatts, reached a record peak of 9,481 megawatts on February 9.
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BrightSource shelves second major solar project this year
BrightSource Energy on Wednesday shelved a major solar power project in California for the second time this year.
In a document filed with the California Energy Commission, BrightSource said it "has determined there is a need to suspend" its application to permit the 500 megawatt Hidden Hills solar thermal power project until further notice.
The company did not give a reason for the suspension, and company officials were not immediately available for comment.
BrightSource, based in Oakland, said it will continue to evaluate the project, which was to be located in Inyo County near the Nevada border.
In January, BrightSource suspended its 500 MW Rio Mesa project in Riverside County, California after multiple delays in the permitting process.
Late last year, CEC staff said the Hidden Hills project would have "significant" impact on the environment, adding that the use of photovoltaic solar panels "would be environmentally superior" to BrightSource's solar thermal technology.
BrightSource disputed those claims at recent hearings, and the CEC was expected to issue a final decision on the project later this year.
Solar panel robot doesn't need water to clean
Saudi Arabia wants to spend over $100 billion to build vast solar arrays and reduce its dependency on oil to generate electricity. But desert sandstorms pose a major challenge to keeping solar panels clean and efficient.
Japanese startup Miraikikai is developing a solution to getting rid of this pesky dust and grit: a cleaning robot that doesn't need water.
The firm has produced the Wall Walker wall and ceiling robot, and recently unveiled a prototype solar panel cleaner built with researchers at Kagawa University.
It weighs about 24 pounds -- light enough to be carried by one person -- and measures about 22 inches across.
It cleans with a rotating brush and can operate for up to two hours on a battery charge.
The robot's efficacy has been demonstrated in arid regions, Miraikikai said in a release, and the machine can clean panels as well as human workers.
Making optimal use of the device would result in low-cost cleaning even in areas with relatively cheap labor costs.
Eagle death at Nevada wind farm brings federal scrutiny
A single dead eagle could spell trouble for a White Pine County wind farm that sells power to NV Energy.
The U.S. Fish and Wildlife Service is conducting an investigation after a golden eagle was killed in late February at the Spring Valley Wind Farm, about 300 miles north of Las Vegas.
San Francisco-based Pattern Energy, which owns the 152-megawatt wind energy project, reported the dead bird and turned it over to federal authorities within 36 hours of its discovery.
“They did all the things they were supposed to because of an eagle death,” said Jeannie Stafford, spokeswoman for the Fish and Wildlife Service in Nevada.
Even so, the wind farm could face a fine of up to $200,000 because it does not hold a federal “take” permit that would allow the incidental death of a golden or bald eagle.
Stafford said the matter is under investigation by the service’s Office of Law Enforcement.
This Company Is Kickstarter for Solar Power
Here's how Mosaic works: Investors contribute a minimum of $25 to a project. Over the next 5 to 10 years—depending on the project—the investors will make that money back, plus interest. The return on the investment ranges from 4.5 to 6.4 percent annually, depending on the project. They can support projects in any state, but right now only accredited investors and people in New York and California can invest in the projects, due to regulatory barriers in other states. In order to qualify, projects must be for organizations that are financially stable, have adequate insurance, and benefit the wider community in some way. Recent projects include affordable housing projects, a convention center, several nonprofits, a grocery store, and a Native American reservation.
Mosaic's founders want to do for solar energy what Kickstarter has done for bands and independent films, or what Kiva has done for upstart projects in the developing world. But Mosaic's model goes beyond most other crowdsourcing sites, by not only allowing supporters to invest in the solar project but also make a profit doing so.
Foxconn invests in solar power in China
Foxconn has announced plans to build a solar power network in China encompassing new factories and plants.
According to a statement released by the Chinese Ministry of Commerce, the Taiwanese electronics manufacturer is investing in one research center, five solar-power components factories, and 20 solar-power generating plants in the southern province of Guangxi.
Foxconn since 2012 has been shifting its focus toward solar power, pouring nearly 100 billion yuan (US$16 million) in other provinces in China, where the government has provided solar manufacturers with heavy subsidies.
In the face of competition, increasing labor cost and pressure from business customers, Foxconn's cellphone subsidiary company had failed to meet market expectation and reported an annual loss of US$316 million in its fiscal 2012. Hence, to some, the moves could be seen as part of a strategic plan.
Despite last week bankruptcy filing of SunTech, China's biggest solar panel manufacturer, the outlook for the domestic market remains encouraging, according to Shen Hongwen, an analyst from CIConsulting company. Foxconn should be able to tap the expanding Chinese market by utilizing its financing power and management expertise, Shen said.
Nanowires Break Limit of Solar Cell Efficiency
How much energy can we use from the sun's rays? Apparently, we can utilize far more than previously thought. A new study shows that the energy limit is far higher than first believed.
The new study, described in the journal Nature Photonics , studied how to develop and improve the quality of nanowire crystals. These nanowires possess a cylindrical structure and a diameter that's about 10,000 part of a human hair. They hold enormous potential for the development of solar cells and the future of quantum computers and other electronic products.
So how do these nanowires work? They naturally concentrate the sun's rays into a very small area in the crystal that they possess by up to a factor of 15. Due to the tiny nature of the wire's diameter, the crystal can cause resonances in the intensity of light in and around nanowires. These resonances can concentrate the sunlight and convert it into energy, essentially giving a higher conversion efficiency of the sun's light.
Previously, scientists thought that the efficiency limit of sunlight was far lower. Known as the "Shockley Queisser Limit," it was held as a landmark for solar cell efficiency for many years. Yet with the discovery and development of these nanowires, it seems that the limit is far higher than previously thought.
Stanford's solar cell turbocharger could boost solar power output by 50%
Scientists at Stanford University have improved the efficiency of a revolutionary solar cell by around 100 times. Unlike standard photovoltaic cells, which only capture light energy, Stanford’s new device captures both light and heat, potentially boosting solar cell efficiency towards 60% — way beyond the 30-40% limit of traditional silicon photovoltaic solar cells.
This new device uses a process called photon-enhanced thermionic emission (PETE). In photovoltaic cells, photons strike a semiconductor (usually silicon), creating electricity by knocking electrons loose from their parent atoms. The PETE process is similar, but also very different and altogether rather complex. In essence, think of it as the photovoltaic equivalent of a turbocharger. Full Article.
Chinese solar power firm defaults on debts
Suntech, one of the world's biggest solar panel manufacturers, has defaulted on a $541m (£358m) bond payment in the latest sign of the financial squeeze on the struggling global solar industry.
Suntech Power Holdings' announcement was a severe setback for a company lauded by China's Communist government as a leader of efforts to make the country a centre of the renewable energy industry. Its founder, Shi Zhengrong, became one of the industry's most prominent entrepreneurs and a billionaire, only to see most of his fortune evaporate as the company's share price plummeted.
The company is "exploring strategic alternatives with lenders and potential investors," David King, who replaced Shi as a CEO last year, said in a statement.
Suntech was due to make a $541m bond payment on Friday but ran short of cash following heavy losses over the past year.
U.S. Solar Market Grows 76% in 2012
GTM Research and the Solar Energy Industries Association® (SEIA®) today released U.S. Solar Market Insight: Year-in-Review 2012, the definitive analysis of solar power markets in the U.S.
With another record-breaking year, solar is the fastest growing energy source in the U.S., powering homes, businesses and utility grids across the nation. The Solar Market Insight annual edition shows the U.S. installed 3,313 megawatts (MW) of solar photovoltaics (PV) in 2012, a record for the industry. Perhaps most importantly, clean, reliable, affordable solar is continuing a major growth pattern that has made it a leading source of new electricity for America that's increasingly competitive with conventional electricity across dozens of states today.
Even with the cost of solar falling for consumers, the market size of the U.S. solar industry grew 34 percent from $8.6 billion in 2011 to $11.5 billion in 2012—not counting billions of dollars in other economic benefits across states and communities. As of the end of 2012, there were 7,221 MW of PV and 546 MW of concentrating solar power (CSP) online in the U.S. -- enough to power 1.2 million homes.
At the state level, 2012 was another year for breaking records. California became the first state to install over 1,000 MW in one year, with growth across all market segments. Arizona came in as the second largest market, led by large-scale utility installations, while New Jersey experienced growth in the state's non-residential market.
In addition to record annual installations, the fourth quarter (Q4) of 2012 shattered all-time quarterly records as well, with 1,300 MW of installed PV, besting the previous high by a whopping 64 percent. The residential and utility segments had their best quarters ever, installing 144 MW and 874 MW respectively.
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