Tag Archives: Photovoltaics

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Tiny Solar Cells Could Pay Big Dividends in Cost, Energy Efficiency

Sandia researcher Greg Nielson with "glitter-sized" solar cells. (Photo by Randy Montoya)

The big news out of Sandia National Laboratories today is micro solar cells — or “glitter-sized” as Sandia is calling them — that could halve the cost of solar panels while nearly doubling their efficiency.

Engineers have been working on Microsystems-Enabled Photovoltaics (MEPV) for some time, but the technology may have reached a tipping point, according to Sandia MEPV team leader, Greg Nielson.

“As the cells have matured and gotten to the point where we’re getting good, consistent performance, we’re ready to jump into making systems,” says Nielson. “We’ve got these cells; now what are we going to do with them?”

The answer: get them out of the lab and put them to work in the real world, thanks to an award by the Federal Laboratory Consortium. The technology transfer award allows Sandia to partner with private companies in five states, the National Renewable Energy Laboratory (NREL) in Golden, Colorado, and researchers at the University of South Florida. The team will adapt microfabrication technologies (already used in the semiconductor industry) to produce a new generation of crystalline silicon solar cells that could be as thin as 2-microns.

Scanning Electron Microscope image of a single MEPV solar cell.

The diminutive cells are suspended in an ink-like solution and then printed onto an ultra-thin and low-cost substrate. The top layer of this “sandwich” is comprised of microlenses to focus the sun’s rays directly onto each solar cell.

Solar power has been taking a beating lately — unfairly, and politically motived, say supporters of renewable energy — because of the failure of the government-supported Solyndra company. But, as one solar-backer said, “for every failure there are dozens of new success stories that never get mentioned.”

Today’s announcement by Sandia is probably just the kind of story he had in mind.

There’s an excellent video illustrating the manufacturing process here. You can learn more about the technical details of MEPV development here and here.

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Solar Power | Coming on Strong

PV America event (Courtesy of PV America)

Even before Japan’s nuclear nightmare began, the solar power market in the U.S. and abroad were set for another year of remarkable growth, according to several analysts and industry leaders.

One such individual suggested recently that the only close analogy to the coming surge in solar photovoltaic panels (PV) is Apple, Inc.’s performance last year after the iPad took off.

Excitement over solar’s continuing growth-spurt served as background music for a PV industry gathering that ended in Philadelphia last night.

“The solar industry is the fastest growing industry in America!” Rhone Resch, president and CEO of the Solar Energy Industries Association (SEIA), told some 3,000 conference-goers. “We are growing faster than wind energy, faster than telecommunications, and, thank goodness, we are even growing faster than the mortgage foreclosure industry!”

Bob Gibson, VP for market intelligence at the Solar Electric Power Association (SEPA), pointed to one large source of growth for the industry: utilities expanding their energy mix to include solar.

“In very real and growing ways,” said Gibson, “electric utilities … across the country are part of the renewable energy industry, and in particular, the business of building and providing solar power.”

The Numbers

Figure 1. Top 10 States for PV installtions, 2010. (The Phoenix Sun)

And there are a lot of data to support such enthusiasm.

While the U.S. GDP grew just 2.8% in 2010, the domestic solar market jumped by 67% last year, according to GTM Research.

The GTM/SEIA U.S. Solar Market Insight, 2010 Year in Review holds a lot more good new for the solar sector. For example, grid-connected PV installations rose to 878 MW (megawatts) last year, a 102% increase over 2009.

While the pattern of growth was widespread, ten states account for over 60% of all new installations (see the breakdown in figure 1).

Notice that California grabbed the lion’s share, at 35% of the total. And that was before the state legislature passed a bill (on March 30) mandating that utilities obtain one-third of their electricity from renewable energy sources, including solar power, by the end of 2020.

(To be fair, former CA Governator, Arnold Schwarzenegger, had issued an executive order calling for the same goal, in 2009. That EO, however, could have been overturned by another governor and so didn’t provide the level of predictability utilities need to make significant investments in solar- a stability they now have.)

Other positive indicators cited in the GTM report:

  • A marked increase in U.S. PV component manufacturing: 97% for wafers, 81% for silicon cells, and 62% for PV modules.
  • The largest Concentrating Solar Power (CSP) plant built in two decades went online. (Martin Next Generation Solar Energy Center, 75-MW, in southeastern Florida.
  • The installation of nearly 29,500 solar pool heating systems and 35,500 hot water systems.

You can read the entire article, complete with more images and at no charge, at Forbes.com.

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New Tech | ‘Dust buster’ cleans up solar’s act - without water

Even clean energy can get dirty

Dust: it’s enemy number one for solar photovoltaic panels (PV) in the sunny, warm areas with the most potential for solar power. That’s because it takes less than a tablespoon of dust per square meter to reduce the electrical output of a typical PV panel by 40 percent.

“In Arizona,” says Professor Malay Mazumder of Boston University, “dust is deposited each month at about four times that amount. Deposition rates are even higher in the Middle East, Australia and India.”

Few home owners in the Southwest want to climb up on their roof several times a month to hose off the light-blocking dust. Utility-sized PV installations are hand-washed or use mechanical sprayers — but either way is costly. In the desert there’s the additional problem of increasing water use in an arid land — one that is likely to grow drier as the climate changes.

The solution to this problem (or at least a solution) comes from the U.S. space program — which is fitting, given that PV panels were pioneered by NASA in the 1960s and ’70s to power satellites and, most recently, rovers on Mars.

At the 240th National Meeting of the American Chemical Society (ACS) last weekend, Dr. Mazumder reported on advances in bringing the same technology used to clean dust from the Mars rovers down to Earth.

The trick to cleaning PV panels without water is to incorporate an Electrodynamic Screen (EDS) like the one on the Mars rovers. An EDS is a thin, electrically sensitive layer on the surface of the panel. When enough dust accumulates on the EDS, a sensor triggers a small electric pulse which repels the dust.

NASA first developed the idea for an “electric curtain” in 1967. In 2003, NASA’s Electrostatics and Surface Physics Laboratory (ESPL) worked with researchers at the University of Arkansas at Little Rock (where Dr. Mazumder then taught) to design and build an EDS for the Mars rovers. (The ESPL website has a short video showing test modules working under space conditions.)

Mazumder reports that the EDS developed by his lab can remove 90 percent of dust particles from a square meter of PV paneling in two minutes using just 10 watts.

Mazunder said the Earth-version of the EDS should be commercially available within a year.

Not all PV panels may require EDS technology, says Alan Bernheimer, a spokesman for First Solar, the world’s largest manufacturer of thin-film PV.

“Theoretically it would be possible to apply this technology to thin film solar modules,” Bernheimer wrote in an Email. “First Solar’s advanced thin film technology, however, is productive in diffuse and lower light conditions, such as those caused by dust.”

While even thin-film panels eventually need to be cleaned, Bernheimer said First Solar has no plans to adopt the EDS technology.

For traditional silicon-based PV manufacturers, however, the development of waterless cleaning technologies is likely to be seen as a milestone on the road to renewable, sustainable, energy.

You can read a 2008 paper about EDS technology co-written by Prof. Mazumder here (PDF).