Self-assembling and reassembling solar cells

Okay, just yesterday I blogged that a lot of the time the mundane “a ha” moment that puts together well-known materials and processes leads to scientific advancement (the case I was referring to in the post was a simple acid bath technique that made creating solar cells much cheaper). And then again sometimes the big sexy breakthrough gets the headline (as usual) and really deserves it.

If this technique for solar cells that self-assembles the light-harvesting element in the cell, and then breaks it down for re-assembly essentially copying what plants do in their chloroplast, is able to reach acceptable levels of efficiency, it will be an absolute game-changer. Instead of a solar cell that’s (hopefully) constantly bombarded with the full effect of the sun and constantly degrading under the solar assault, these cells will essentially be completely renewed by each reassembly. No degradation over time, just a brand new light-harvesting element with a relatively simple chemical process.

From the second link:

The system Strano’s team produced is made up of seven different compounds, including the carbon nanotubes, the phospholipids, and the proteins that make up the reaction centers, which under the right conditions spontaneously assemble themselves into a light-harvesting structure that produces an electric current. Strano says he believes this sets a record for the complexity of a self-assembling system. When a surfactant — similar in principle to the chemicals that BP has sprayed into the Gulf of Mexico to break apart oil — is added to the mix, the seven components all come apart and form a soupy solution. Then, when the researchers removed the surfactant by pushing the solution through a membrane, the compounds spontaneously assembled once again into a perfectly formed, rejuvenated photocell.

“We’re basically imitating tricks that nature has discovered over millions of years” — in particular, “reversibility, the ability to break apart and reassemble,” Strano says. The team, which included postdoctoral researcher Moon-Ho Ham and graduate student Ardemis Boghossian, came up with the system based on a theoretical analysis, but then decided to build a prototype cell to test it out. They ran the cell through repeated cycles of assembly and disassembly over a 14-hour period, with no loss of efficiency.

Is solar power cheaper than nuclear?

Surprisingly, maybe so.

From the link:

One of the issues associated with shifting from using fossil fuels to alternative energy sources is the cost. While adherents of alternative energy tout its benefits, many are skeptical, pointing out that such alternatives are just too expensive. Advocates of nuclear power point out that it is less polluting (if you don’t count storage of spent fuel) than fossil fuels, and that it costs less than alternatives like solar power.

A new study out of Duke University, though, casts doubt on the idea that nuclear power is cheaper than solar power. Using information from North Carolina, the study shows that solar power may be more cost efficient than nuclear power. With costs dropping on the production of photovoltaic cells, and with solar cells becoming increasingly efficient, it appears that — in North Carolina at least — solar installations offer a viable alternative to nuclear power, which is the source for about 20% of the electricity in the U.S.

Selenium improves solar efficiency

I like the “anti-sunscreen” intro to this news on improving the efficiency of photovoltaic solar cells with selenium.

The release:

Selenium makes more efficient solar cells

This release is also available in Chinese.

		IMAGE: This is a sunset over the Pacific Ocean as seen from Highway 1 south of Monterey, Calif. LBNL’s Marie Mayer, who took the photo, calls sunlight and water “two sustainable… Click here for more information.

College Park, MD (August 3, 2010) — Call it the anti-sunscreen. That’s more or less the description of what many solar energy researchers would like to find — light-catching substances that could be added to photovoltaic materials in order to convert more of the sun’s energy into carbon-free electricity.

Research reported in the journal Applied Physics Letters, published by the American Institute of Physics (AIP), describes how solar power could potentially be harvested by using oxide materials that contain the element selenium. A team at the Lawrence Berkeley National Laboratory in Berkeley, California, embedded selenium in zinc oxide, a relatively inexpensive material that could be promising for solar power conversion if it could make more efficient use of the sun’s energy. The team found that even a relatively small amount of selenium, just 9 percent of the mostly zinc-oxide base, dramatically boosted the material’s efficiency in absorbing light.

“Researchers are exploring ways to make solar cells both less expensive and more efficient; this result potentially addresses both of those needs,” says author Marie Mayer, a fourth-year University of California, Berkeley doctoral student based out of LBNL’s Solar Materials Energy Research Group, which is working on novel materials for sustainable clean-energy sources.

Mayer says that photoelectrochemical water splitting, using energy from the sun to cleave water into hydrogen and oxygen gases, could potentially be the most exciting future application for her work. Harnessing this reaction is key to the eventual production of zero-emission hydrogen powered vehicles, which hypothetically will run only on water and sunlight. Like most researchers, Mayer isn’t predicting hydrogen cars on the roads in any meaningful numbers soon. Still, the great thing about solar power, she says, is that “if you can dream it, someone is trying to research it.”

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The article, “Band structure engineering of ZnO_1-xSe_x alloys” by Marie A. Mayer, Derrick T. Speaks, Kin Man Yu, Samuel S. Mao, Eugene E. Haller, and Wladek Walukiewicz will appear in the journal Applied Physics Letters. See: http://apl.aip.org/applab/v97/i2/p022104_s1

ABOUT APPLIED PHYSICS LETTERS

Applied Physics Letters, published by the American Institute of Physics, features concise, up-to-date reports on significant new findings in applied physics. Emphasizing rapid dissemination of key data and new physical insights, Applied Physics Letters offers prompt publication of new experimental and theoretical papers bearing on applications of physics phenomena to all branches of science, engineering, and modern technology. Content is published online daily, collected into weekly online and printed issues (52 issues per year). See: http://apl.aip.org/

ABOUT AIP

The American Institute of Physics is a federation of 10 physical science societies representing more than 135,000 scientists, engineers, and educators and is one of the world’s largest publishers of scientific information in the physical sciences. Offering partnership solutions for scientific societies and for similar organizations in science and engineering, AIP is a leader in the field of electronic publishing of scholarly journals. AIP publishes 12 journals (some of which are the most highly cited in their respective fields), two magazines, including its flagship publication Physics Today; and the AIP Conference Proceedings series. Its online publishing platform Scitation hosts nearly two million articles from more than 185 scholarly journals and other publications of 28 learned society publishers.

Lower cost solar cells

Yesterday I blogged about a new solar energy process that might supplant photovoltaics, at least in large-scale desert installations because of dramatically increased efficiency. Today it’s a breakthrough with photovoltaic solar cells in regards to production cost. I like seeing all this innovation is the solar space, especially since it’s a bit all over the map. Incremental improvement is always nice, but anytime research is going after all sorts of targets the odds of a major breakthrough go up.

From the second link:

One of the most promising technologies for making inexpensive but reasonably efficient solar photovoltaic cells just got much cheaper. Scientists at the University of Toronto in Canada have shown that inexpensive nickel can work just as well as gold for one of the critical electrical contacts that gather the electrical current produced by their colloidal quantum dot solar cells.

The change to nickel can reduce the cell’s already low material costs by 40 to 80 percent, says Lukasz Brzozowski, the director of the Photovoltaics Research Program in Professor Ted Sargent’s group. They present their research in the July 12, 2010 issue of Applied Physics Letters.

Black silicon bringing down the cost of efficient solar

The latest news in one of the two areas — cost in this case — solar needs to continue to see improvement for widespread use.

From the link:

A simple chemical treatment could replace expensive antireflective solar cell coatings, bringing down the cost of crystalline silicon panels. The treatment, a one-step dip in a chemical bath, creates a highly antireflective layer of black silicon on the surface of silicon wafers, and it would cost just pennies per watt, say researchers at the National Renewable Energy Laboratory (NREL). They’ve used it to create black silicon solar cells that match the efficiency of conventional silicon cells on the market.

Solar goes black: These two solar cells were fabricated on a silicon wafer treated to create an antireflective black silicon surface. The silvery areas around the cells are a different color because the highly absorbent black layer has been etched away.
Credit: Hao-Chih Yuan

Beautiful nanotech image — photovoltaic solar cell

This is a nice gallery of nanotech images from New Scientist. Here’s the description from the series, “Chemist George Whitesides has collaborated with MIT and Harvard photographer-in-residence Felice Frankel to produce No Small Matter, a book of images of the micro and nanoworld.”

From the first image, my favorite:

Sun catchers

This is a close-up of the top side of a photovoltaic solar cell. The cell converts the energy from the sun’s photons into electrical energy by taking advantage of the photo-electric effect. This cell is made of a wafer of crystalline silicon.

Light is absorbed by the wafer and creates charge that is collected by silver conductor lines, shown in the image as the gold-coloured strip. The cell is coated with silicon nitride which acts as an anti-reflective surface, preventing light energy from bouncing away and giving the cell its blue-violet colour.

Rather than attaching solar panels to our roofs, recent research suggests that in the future we could paint solar cells on to our houses, removing the need to rely on expensive silicon wafers.

(Image: Felice Frankel)

Nanoantennas and high-speed optical data networks

Via KurzweilAI.net — Looks like this nanotech has applications in communications, medicine and alternative power, to name three.

Nanoantennas allow for high-speed optical data networks

KurzweilAI.net, Oct. 22, 2009 Gold nanoantennas smaller than 100 nm that transmit and receive light have been developed by Karlsruhe Institute of Technology researchers. The antennas could be used in new optical high-speed data networks and in chip manufacturing and photovoltaic devices, and for the study of individual biomolecules. (LTI) More info

Solar costs are dropping

Interesting news from the Lawrence Berkeley National Laboratory.

The release:

Installed cost of solar photovoltaic systems in the US fell in 2008

Researchers at the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) released a new study on the installed costs of solar photovoltaic (PV) power systems in the U.S., showing that the average cost of these systems declined by more than 30 percent from 1998 to 2008. Within the last year of this period, costs fell by more than 4 percent.

The number of solar PV systems in the U.S. has been growing at a rapid rate in recent years, as governments at the national, state, and local levels have offered various incentives to expand the solar market. With this growth comes a greater need to track and understand trends in the installed cost of PV.

“A goal of government incentive programs is to help drive the cost of PV systems lower. One purpose of this study is to provide reliable information about the costs of installed systems over time,” says report co-author Ryan Wiser.

According to the report, the most recent decline in costs is primarily the result of a decrease in PV module costs. “The reduction in installed costs from 2007 to 2008 marks an important departure from the trend of the preceding three years, during which costs remained flat as rapidly expanding U.S. and global PV markets put upward pressure on both module prices and non-module costs. This dynamic began to shift in 2008, as expanded manufacturing capacity in the solar industry, in combination with the global financial crisis, led to a decline in wholesale module prices,” states the report, which was written by Wiser, Galen Barbose, Carla Peterman, and Naim Darghouth of Berkeley Lab’s Environmental Energy Technologies Division.

In contrast, cost reductions from 1998 through 2007 were largely due to a decline in non-module costs, such as the cost of labor, marketing, overhead, inverters, and the balance of systems.

The study—the second in an ongoing series that tracks the installed cost of PV—examined 52,000 grid-connected PV systems installed between 1998 and 2008 in 16 states. It found that average installed costs, in terms of real 2008 dollars, declined from $10.80 per watt in 1998 to $7.50/W in 2008, equivalent to an average annual reduction of $0.30/W, or 3.6 percent per year in real dollars.

Costs Differ by Region and Type of System

Other information about differences in costs by region and by installation type emerged from the study. The cost reduction over time was largest for smaller PV systems, such as those used to power individual households. Also, installed costs show significant economies of scale—small residential PV systems completed in 2008 that were less than 2 kilowatts (kW) in size averaged $9.20/W, while large commercial systems in the range of 500 to 750 kW averaged $6.50/W.

Installed costs were also found to vary widely across states. Among systems completed in 2008 and less than 10 kW in size, average costs range from a low of $7.30/W in Arizona, followed by California, which had average installed costs of $8.20/W, to a high of $9.90/W in Pennsylvania and Ohio. Based on these data, and on installed cost data from the sizable German and Japanese PV markets, the authors suggest that PV costs can be driven lower through large-scale deployment programs.

The study also found that the new construction market offers cost advantages for residential PV systems. Among small residential PV systems in California completed in 2008, those systems installed in residential new construction cost $0.80/W less than comparably-sized systems installed in rooftop retrofit applications.

Cash Incentives Declined

The study also found that the average size of direct cash incentives provided by state and local PV incentive programs declined over the 1998-2008 study period. Other sources of incentives, however, such as federal investment tax credits (ITCs), have become more significant. For commercial PV systems, the average combined after-tax value of federal and state ITCs, plus direct cash incentives provided by state and local incentive programs, was $4.00/W in 2008, down slightly from its peak in 2006 but still a near-record-high. Total after-tax incentives for residential systems, on the other hand, were at an historic low in 2008, averaging $2.90/W, their lowest level within the 11-year study period.

The drop in total after-tax incentives for both commercial and residential PV from 2007 to 2008 more than offset the cost reduction over this period, leading to a slight rise in the net installed cost, or the installed cost facing a customer after receipt of financial incentives. For residential PV, net installed costs in 2008 averaged $5.40/W, up 1% from the previous year. Net installed costs for commercial PV averaged $4.20/W, a 5% rise from 2007.

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The report “Tracking the Sun II: The Installed Cost of Photovoltaics in the U.S. from 1998�,” by Ryan Wiser, Galen Barbose, Carla Peterman, and Naim Darghouth may be downloaded from http://eetd.lbl.gov/ea/emp/re-pubs.html. The research was supported by funding from the U.S. Department of Energy’s Office of Energy Efficiency and Renewable Energy (Solar Energy Technologies Program) and by the Clean Energy States Alliance.

Berkeley Lab is a U.S. Department of Energy national laboratory located in Berkeley, California. It conducts unclassified scientific research and is managed by the University of California. Visit our website at http://www.lbl.gov.

Sanyo sets solar conversion record

Via KurzweilAI.net — Sanyo broke its own record for solar cell energy conversion efficiency.

SANYO Breaks Solar Cell Record

Azonanotechnology, May 21, 2009 SANYO Electric has broken its own record for the world’s highest energy conversion efficiency in practical size (100 cm2 or more) crystalline silicon-type solar cells, achieving a efficiency of 23.0% (until now 22.3%) at a research level for its proprietary HIT solar photovoltaic cells.   Read Original Article>>

Solyndra offers an interesting solar design

I’m all for innovative solar installations. This design from Solyndra looks fairly promising. I’m very excited about eventually putting some solar collecters on my home and start selling electricity back to the grid.

From the link:

The company’s photovoltaic rods are able to catch rays from any direction, meaning they don’t need to be tilted to point at the sun. Also, since they’re not shaped like a silicon kite, they don’t need the same big, beefy installation brackets. This cuts installation costs in half and has helped to drive $1.2 billion in orders from eager would-be customers of this three-year-old startup. Want to see ’em for yourself? Head on down to the Solar Power International Expo next week in sunny San Diego.

(Hat tip — Wes)

Most efficient solar cells to date

From KurzweilAI.net — This is yet another in a long string of solar breakthroughs. The most efficient photovoltaic cells yet, converting almost 50% of harvested light into electricity. Kudos to the US Department of Energy’s National Renewable Energy Laboratory.

NREL Solar Cell Sets World Efficiency Record at 40.8 Percent

ElectricalEngineer.com, Sep. 29, 2008Scientists at the U.S. Department of Energy‘s National Renewable EnergyLaboratory (NREL) have set a world record in solar cell efficiency with a photovoltaic device that converts 40.8 percent of the light that hits it into electricity. The new design uses compositions of gallium indium phosphide and gallium indium arsenide to split the solar spectrum into three equal parts that are absorbed by each of the cell‘s three junctions for higher potential efficiencies.   Read Original Article>>

Making solar just a little greener …

… by making the plastic components out of cotton and castor beans. From KurzweilAI.net, a link to the story about BioSolar:

 

Making a Solar Cell Component without Using Fossil Fuels

ScientificAmerican.com, Aug. 13, 2008 BioSolar is creating new plastic backing for photovoltaic cells out of renewable cotton and castor beans rather than petroleum products, while costing 25 percent less than conventional backsheets, the company says.   Read Original Article>>

New solar plants in Cali to service almost 250,000

This deal is significant because it involves utility-scale solar photovoltaic plants. Pacific Gas & Electric inked contracts for two solar power plants and those deals brings its contractual commitment to alternative power to around 25%.

From the link:

Pacific Gas & Electric Co.announced two utility-scale solar photovoltaic contracts that will deliver a combined 800 megawatts of solar power to the utility from two massive solar power plants to be built in San Luis Obispo County.

The two plants combined will produce enough electricity to power approximately 239,000 homes a year, according to the utility.

PG&E said Thursday afternoon it entered an agreement with Topaz Solar Farms LLC, a subsidiary of OptiSolar Inc., for 550 megawatts of thin-film solar power. It also entered an agreement with High Plains Ranch II LLC, a subsidiary of SunPower Corp, for 250 megawatts of high-efficiency solar power.

The deals mark a significant commitment to solar PV technology and signal renewed interest in photovoltaic, which has been considered less economical than other types of large-scale solar power.

Up until now, most of the utility-scale solar contracts have been for solar thermal power plants, which utilize fields of mirrors to focus the sun’s rays to boil water and generate steam to power a turbine.

“These landmark agreements signal the arrival of utility-scale photovoltaic solar power that may be cost-competitive with solar thermal and wind energy,” Jack Keenan, chief operating officer and senior vice president for PG&E, said in a statement.

Major solar breakthrough at NREL

This is exciting news for alternative energy.

From the PhysOrg.com link:

Scientists at the U.S. Department of Energy’s National Renewable Energy Laboratory (NREL) have set a world record in solar cell efficiency with a photovoltaic device that converts 40.8 percent of the light that hits it into electricity. This is the highest confirmed efficiency of any photovoltaic device to date.

The inverted metamorphic triple-junction solar cell was designed, fabricated and independently measured at NREL. The 40.8 percent efficiency was measured under concentrated light of 326 suns. One sun is about the amount of light that typically hits Earth on a sunny day. The new cell is a natural candidate for the space satellite market and for terrestrial concentrated photovoltaic arrays, which use lenses or mirrors to focus sunlight onto the solar cells.

Latest breakthroughs — stem cells, solar and hard drives

Here’s a more traditional (for this blog) posting from KurzweilAI.net — a stem cell breakthrough, solar energy harvesting breakthrough, and another breakthrough (see a theme here) in hard drive capacity.

New Technique Harvests Stem Cells at Earlier Stage

HealthDay News, July 9, 2008 Researchers at Vrije Universiteit Brussel have derived human embryonic stem cells (hESC) earlier in the development stage of a blastomere (when it only has four cells), so the whole embryo is not destroyed. Previously, scientists were able to derive hESC lines at the 8-cell stage, but that methodhad variable success rates and required the cells to be cultured with established hESCs. The new method doesn’t require a co-culture. The development could make stem cell researcheasier to conduct by not raising as many ethical concerns. It could also change pre-implantation genetic diagnosis (PGD), by enabling the biopsy of one cell from a 4-cell stage embryo. This would let the remaining three cells grow into a blastocyst (five-day embryo) that could be implanted into the uterus and develop into a healthy baby. Currently GPD is performed at the 8-cell stage. See Also Stem cell breakthrough leaves embryos unharmed   Read Original Article>>

Organic dye lets window panes harvest the Sun

New Scientist news service, July 10, 2008 MIT electrical engineer Marc Baldo had developed a method to turn up to 20% of incident light into electricity at a fraction of the cost of conventional photovoltaic cells. Exotic organic dyes are coated onto an ordinary sheet of glass, trapping light inside the glass and allowing it to be channelled to photovoltaic cells placed along the edges of the sheet. The dyes can absorb light across the visible spectrum and emit it at the longer frequencies needed for optimal conversion.   Read Original Article>>

Seagate’s Latest Desktop HDD Has 1.5TB Capacity

Hot Hardware, July 10, 2008 Seagate announced Thursday three new consumer-level hard drives today, which it claims are the “industry’s first 1.5-terabyte desktop and half-terabyte notebook hard drives.” The company claims that it is able to greatly increase the areal density of its drive substrates by using perpendicular magnetic recording (PMR) technology.   Read Original Article>>