by Reuters
CHICAGO--U.S. researchers have devised a way to make flexible solar cells with silicon wires that use just 1 percent of the material needed to make conventional solar cells.
The eventual hope is to make thin, light solar cells that could be incorporated into clothing, for instance but the immediate benefit is cheaper and easier-to-install solar panels, the researchers said.
The new material, reported on Sunday in Nature Materials, uses conventional silicon configured into micron-sized wires (a micron is one-millionth of a meter) instead of brittle wafers and encases them in a flexible polymer that can be rolled or bent.
"The idea is it would be lower-cost and easier to work with by being more flexible than conventional silicon solar cells," Michael Kelzenberg of the California Institute of Technology in Pasadena, who worked on the study, said in a telephone interview.
Solar cells, which convert solar energy into electricity, are in high demand because of higher oil prices and concerns over climate change.
Many companies, including Japanese consumer electronics maker Sharp and Germany's Q-Cells SE, are making thin-film solar cells using organic materials such as polymers, but they typically are less efficient at converting solar energy into electricity than conventional cells using silicon.
The study is among the latest to combine the flexibility of the new organic or carbon-containing films with the high efficiency of silicon, which is heavy and stiff.
Kelzenberg said the material uses about 1/100th as much silicon per cell area as a silicon wafer.
"It is potentially a route to bypass many of the costs associated with producing solar cells," he said.
He said a big problem with working with silicon wafers is they are fragile.
More testing is needed but Kelzenberg said the material would be about 15 percent to 20 percent efficient, about the same level as solar cells used on roofs to heat homes.
A similar effort is under way in the lab of John Rogers, a professor of materials science at the University of Illinois-Urbana-Campaign, who is working on ways to make inorganic materials more flexible.
While many companies are investing in organic solar cells--basically materials like plastic that contain carbon--Rogers said these materials have relatively low performance, less long-term reliability and an unproven cost structure.
"We like the inorganics--trying to adapt them and use them in nonstandard ways," Rogers said in a telephone interview.
Last year, his team reported on a new manufacturing process that creates thin arrays of solar cells that are flexible enough to be rolled around a pencil and transparent enough to be used to tint windows on buildings or cars.
"We can make them stretch like a rubber band or bendable like a sheet of plastic," he said.
He is founder of a start-up semiconductor company called Semprius in Durham, N.C., that last month announced a joint effort with Siemens to develop large systems for utility-scale power generation.
"The same technology they are using to make these rigid utility-scale modules could be used for flexible devices as well," he said.
Rogers said that the company has funding from the U.S. Department of Defense and the CIA.
Story Copyright (c) 2010 Reuters Limited. All rights reserved.
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Topics: Solar, Energy efficiencyTags: silicon solar cells,solar cells,Nature MaterialsShare: Digg Del.icio.us Reddit Yahoo! BuzzFacebook Twitter
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One Block Off the Grid: Bulk solar, tell your friends Add a Comment (Log in or register) (22 Comments) prev next by monkeyfun14 February 14, 2010 2:10 PM PST
Now how much cheaper are we talking?
Like this Reply to this comment by codynews February 14, 2010 2:48 PM PST
I have a few apartment buildings with big flat roofs that I'd LOVE to put solar panels on. Each time I've looked at them ("now cheaper", "we'll finance!" "tax rebate available!") the numbers don't work.
It's a simple binary decision for me: If they have a life span of x years, I want to be able to finance them over x years, where my monthly payment is equal to or less than the electric savings they provide (or rather, the electric $ they generate as from what I've been told you don't actually use the power they produce directly, rather it feeds the grid to go against your own consumption).
I can't pay $300k for something that'll produce much less than that in savings :(
I'll keep looking...
Like this Reply to this comment 3 people like this comment
by Bakkster February 15, 2010 6:45 AM PST
You're half right in that you don't use the energy they produce directly. Firstly, solar photovoltaics produce Direct Current power, while the grid uses AC. This DC must be converted to AC (with a loss) before it can be used in your house.
However, if you are using power while your panels are operating, you do use that power directly. Any leftovers go back to the grid and your meter runs backwards, crediting you for the electricity supplied. If you are using more power than the panels supply, though, you will be using both your panel power and grid power.
However, you are correct that it's a binary decision on cost. The biggest factor is where you live: how much available sunlight you have and how direct it is. It is much more likely to be cost-effective at southern latitudes with little cloud cover, and highly unlikely at northern latitudes with little sunlight.
Like this by ColeSlaw82 February 15, 2010 12:05 PM PST
@Bakkster - I believe that codynews may be correct that he isn't directly using the energy his solar cells are producing. Some utility companies use a system with two meters on a structure. One of the electricity being used, and one for the electricity being generated. Both are read and then the generated is subtracted from the used electricty and that is your bill. The energy you generate all goes back onto the grid, and round-a-bouts may come back to you. The kind of metering you are thinking of is a true "net metering" where the meter on your structure can measure electricity in both directions so you are truely using your own power before generating back on to the grid.
Truely, it is semantics. Both systems have advantages and disadvantages but either way you are generating electricity and saving money (or not saving, as in cody's case)
Like this by mike_ekim February 16, 2010 11:57 AM PST
@ Bakkster and ColeSlaw - you both have missed his point - he doesn't care that he may not be directly using the power he produces. He cares that over the life of the investment he will be loosing money.
codynews - you raise good points, but keep in mind that a solar investment is much like other investments. you will be paying a fixed proce to pay off the panels, and the cost of electricity will continue to increase. Much like real estate (which you are obviously educated in) - if you have enough tenants to pay off the morgatge, and only 'break even', then in the end you have an apartment building you own. Likewise, if you take a small loss every month because you went to solar, but in (say) 10 years you own the solar system free and clear, you will begin enjoying 'free' power. And have an improvement to your property, should you look at selling.
But then again, why take on an investment where you loose every month and then profit at the end, when you could invest elsewhere and break even every month or maybe even make a couple of bucks, then profit at the end.
Like this by tech_crazy February 14, 2010 4:08 PM PST
While I am sure that this may be a radical improvement but is too good to believe. I looked at the abstract of the paper (needs paid access for the full paper) and it says, "with a peak external quantum efficiency of 0.89". If pure planar Si (or some other chemistry e.g. SunPower solar cells) is 29% efficient ), this is at most 3 times as efficient. So, the article seems misleading. Reducing the area to 1% would also reduce the corresponding output of the cells.
If Martin has more information, it would help putting it here.
Like this Reply to this comment by richard993 February 14, 2010 6:14 PM PST
What are we saying here exactly? Are we saying that for the same output of a typical solar cell at 20% efficiency, we achieve the same output with only 1% of the material used? or are we saying that the cell has the same efficiency but because it has less surface area, it's output is lower?
If it is the latter, it's too bad, because the research article is very misleading and hardly considered a breakthrough.
Think about it this way... if you achieve the same efficiency and output using 1% of the material, then using the same amount of material of a normal cell, you would increase the amount of electricity generated by a factor of 100. This would be considered to be the breakthrough of the century and would make solar cells an ultimate energy source.
But this is not what the misleading researcher is actually saying... but he has achieved his purpose: to get everybody's attention!
Like this Reply to this comment by drfillgood February 14, 2010 7:44 PM PST
Efficiency of solar cells means the percentage of the sunlight's energy that is converted to electrical energy for any surface area exposed to light, under ideal circumstances. So it's not trying to say how efficient it is per amount of material used. The article doesn't explain how it calculates solar cell efficiency, but this is pretty standard stuff in the solar cell industry.
Like this by USDecliningDollar February 15, 2010 9:27 AM PST
I agree with what you are saying, seems like this is basically a press release to generate interest - basically nothing really new and nothing really ground breaking. Seems like a lot of PR spin.
Like this by zyxxy February 16, 2010 6:31 AM PST
I think the material usage is because they are depending on the polymer for physical support. The silicon is just there to convert the sunlight to electricity. In a standard silicon panel, a large portion of the physical silicon consumed is so you can physically process and handle the cells. The sun only strikes the top surface, the active area is very thin. The remainder of the material is just to provide a reliable structure underneath. They are encapsulating silicon 'wires' inside a polymer sheet. Completely different structure and process.
Like this by drfillgood February 14, 2010 7:38 PM PST
The CIA is funding solar energy now? How does that make any sense?
Like this Reply to this comment by artistjoh February 15, 2010 3:37 AM PST
You think that the CIA doesn't use devices that use energy and that many of those devices are located in remote areas without reliable power supplies? Imagine an operative in a barren waste where foreign secret facilities are often located and he needs to use GPS to accurately pinpoint the location and satellite links for communications and potentially guiding in military strikes.
Such a person relying on conventional batteries can only be there for a very short time, someone with a solar array can easily be spotted but a flexible solar panel that can be draped over rocks etc and worn will be very portable and much easier to disguise.
The CIA and Defence departments would have a significant interest in developing this kind of technology.
Like this by drfillgood February 15, 2010 9:14 AM PST
I'm not arguing that the CIA or DoD have uses for solar cells, but at this point, solar cells already exist, present research is only likely to yield marginal improvements, and it isn't a technology that would give either of those agencies (but specially the CIA) a serious increase in operational ability. I guess they were sold on the flexible, "it could be woven into your clothing" part of the technology, so it could recharge the increasing amounts of electronics worn by soldiers and operatives. Still, it's a stretch.
Like this by zyxxy February 16, 2010 6:33 AM PST
Or you could roll up a huge sheet into a shipping tube for transport. Lots of area in a small container. Plus these are supposed to be more durable, less fragile, in handling. Both good factors for air drops.
Like this by freedomlovr February 15, 2010 7:36 AM PST
I like this. There are many applications I can see. This would be perfect for an aftermarket mod for electric cars. Just think, a solar charged car, never need to buy gas or plug it in...
Like this Reply to this comment by TogetherinParis February 15, 2010 9:27 AM PST
CIA? Forget about it. This company isn't real. CIA is just transferring tax funds to Cuban death squadders again. The same Cubans who stood with George H.W. Bush on Dealy Plaza over the body of JFK have received millions in CIA training, funding, special scholarship opportunities, car dealerships, beer dealerships, port jobs, you name it. It is a national disgrace to reward out of tax-payer funds the very same people who drew Vince Foster out of the White House and murdered him in a public park, the people who drugged up assassins to shoot Ronald Reagan and to shoot at Jerry Ford (because they were in George Bush's way) to murder LBJ, MLK, RFK, Wallace, and JFK.
Like this Reply to this comment by Mr_fleabite February 16, 2010 7:57 AM PST
WHOA, don't spend all your crazy in one place. Sprinkle that around it'll last longer.
Like this by mattie121 February 15, 2010 6:06 PM PST
A lot of you a missing a very important point. Most thin film photovoltaics rely on bulk properties of the materials in their photoconversion. Nanowires have another effect: the geometric constraints of the nanowire geometery mean that the electronics properties are not the same as the bulk properties. So this paper is saying that by using this effect, they can create greater efficiency with lower material content. This is good.
Also, many don't seem to be aware that a lot of the silicon in conventional photovoltaics is not active in the photo conversion process. So a large amount of the Si used in solar cells could be thrown away if there were ways to get the Si crystals to grow properly, sadly, this is not the case. Many have worked on getting Si films to grow on things like glass (much cheaper substrate) but it's not working out too well.
This is very promising indeed.
Matt
Like this Reply to this comment 2 people like this comment
by zyxxy February 16, 2010 6:36 AM PST
Exactly. Save the material for the active layer and use something else for physical support.
Like this by ac5501 February 16, 2010 8:57 AM PST
Vapor ware? Just one more energy "wonder" product we will never see. I'm still waiting for ethanol from switch grass. They said we would have that in 3 years... back in 2005. How about bio diesel from algae. I've been hearing about that one since 04, and back then it was only a couple years away.
How about the high/room temperature super conductors. I'm seeing a pattern here.
Like this Reply to this comment by brewster_13 February 16, 2010 9:30 AM PST
"15 percent to 20 percent efficient, about the same level as solar cells used on roofs to heat homes"
FYI, solar photovoltaic cells are not used to heat homes, they are used to create electricity. They are, generally in the 15 - 20% efficient at converting sunlight into electricity
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