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The new solar cells from the University of California, Berkley use nanopillars to create cheap and efficient cells. An optimized cost could cut solar power costs to a third of current levels.  (Source: Ali Javey, UC Berkeley)
New technology may unlock some massive savings

One of the biggest factors in solar power remaining an expensive power source, despite constantly improving efficiencies, is the inherent cost of materials and processing for solar cells made of polysilicon.  Cutting these costs could make the solar power the preferred energy source for mankind, but thus-far there has been little high-performance designs made with cheaper processes or materials.

Now University of California, Berkeley researchers have created a new type of solar cells that may offer exactly that -- lots of solar energy with low processing and materials costs.  The new type of solar cells are composed of tiny nanopillars in a thin film layer atop aluminum foil.  The foil is enclosed in a protective layer of transparent, rubbery polymer.

The total materials costs are quite low, and the production costs, while not fully determined also look promising.  Ali Jarvey, an electrical-engineering and computer-sciences professor who led the work, cheers, "You won't know the cost until you do this using a roll-to-roll process, but if you can do it, the cost could be 10 times less than what's used to make [crystalline] silicon panels."

The cells use a nanofilm of cadmium telluride with uniform 500-nanometer-high pillars of cadmium sulfide laid on top of it.  Other thin-film solar cells with pillars have been made before, says Professor Jarvey, but they have relied on more expensive deposition techniques.  Further, the new cells have an efficiency of 6 percent in transforming sunlight into electricity, where past designs had efficiencies of less than 2 percent.

Silicon-based photovoltaics still have the cell beat in efficiency with 20 percent or more in commercially available designs; however, they are extremely pure, expensive crystalline silicon.  Impurities can cause electrons to get trapped in the semiconductor, so the expensive process of making this high quality crystal material is unavoidable for that design.  Purity is much less of a cost concern in the new design.

Creating an equivalent amount of power would require three times the area (panels) of photovoltaic cells, given their respective efficiencies.  This means that given the cost estimates, solar power costs could be cut to a third of the current levels.

Another key advantage of the new design over traditional photovoltaic panels is flexibility.  Traditional crystalline panels would break if flexed.  The thin film nanopillar cells, though, can be rolled and unrolled with ease.

The new design essentially divides silicon's responsibilities.  The thin film material absorbs light and generates electrons, while the pillars conduct the electrons to the circuit and help to trap light.  As electrons have a shorter distance to travel to reach the pillars they're less likely to get trapped by defects, and thus crystal quality is less of a concern.

Currently the cells are produced using a relatively cost-effective anodizing design to grow the pillars on a thin aluminum foil film, the bottom electrode.  The thin semiconductor film is then layered over the pillars and a top electrode of copper and gold is layered thinly to complete the circuit. 

Two key areas of improvement are the top film and the production process.  Adopting a roll-to-roll production system could speed up the assembly and make it cheaper.  Also, currently the gold only allows half the sunlight to enter the cell as its semi-opaque.  Replacing the gold with a transparent material like indium oxide could double the efficiency to 12 percent or more, while not significantly impacting the cost of materials.

States Professor Yang, "(The) architecture is most important--materials we can continue working on. The beauty of this paper is the demonstration of how well the architecture works."

The research appears in this month's edition of the journal Nature Materials.



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RE: Can I roll this thing
By randomposter on 7/7/2009 10:43:45 AM , Rating: 2
You actually raise an interesting point from an op-ed piece I read several years ago ... the basic premise was that the American culture of consumption (water, energy, food, etc.), personal space, modern conveniences, meticulous personal hygiene, etc. essentially preclude many Americans from participating in a space diaspora, if one is coming.

Other cultures like China, Japan, India, or even Europe are more predisposed to compromise and forgoing comfort for the greater good. You are much more likely to successfully house 500 people like that in a closed ecology biosphere.

Personal freedom at the expense of communal ideals may be the American way, but for a spacefaring society it's not tenable.


RE: Can I roll this thing
By mdogs444 on 7/7/09, Rating: -1
RE: Can I roll this thing
By randomposter on 7/7/09, Rating: 0
RE: Can I roll this thing
By mdogs444 on 7/7/09, Rating: 0
RE: Can I roll this thing
By randomposter on 7/7/09, Rating: 0
RE: Can I roll this thing
By Schrag4 on 7/7/2009 1:54:35 PM , Rating: 4
No, you're just missing the point of his response. The idea tha Americans wouldn't fare well in space is a huge assumption based on the fact that we are spread out and enjoy plenty of food, water, etc, when people from other parts of the world are packed together and have fewer of those resources (whether it's true or not). His point is that the only reason people in other parts of the world live like that is because they're forced to, and we don't live that way because we are not forced to. We're all human beings, and we all do what we have to to survive, and we all will take whatever comforts we can afford.

Your point is somewhat valid, it would be an adjustment for many Americans, but I think it goes a little far. Obviously if the benefits of living in space outweigh living on Earth where you can sprawl out and eat lots of food and take long showers, then anyone would do it, regardless of where they're from. But I guess I see your point. If living in space really has no benefits and sucks like you describe, I guess Europeans might decide to live there and Americans might not.


RE: Can I roll this thing
By Regs on 7/7/2009 11:00:50 PM , Rating: 2
It's a rather grey point if you ask me. Yes, America is mostly covered in forest, farm, or even uninhabited by man completely. Man however decided not to live in these areas for a reason. The decided to live in crowded metropolises closer to resources and next to the coast lines.


RE: Can I roll this thing
By TSS on 7/8/2009 9:10:28 AM , Rating: 2
quote:
I guess Europeans might decide to live there and Americans might not.


ohhh so that's why every human from earth in all space related context sounds american. they are! :P


RE: Can I roll this thing
By Silver2k7 on 7/7/2009 4:25:47 PM , Rating: 2
So when does the Babylon project begin ;)

http://en.wikipedia.org/wiki/Babylon_5


RE: Can I roll this thing
By djcameron on 7/7/2009 12:15:51 PM , Rating: 5
quote:
Is there some plan I'm not aware of to blast Texas into space?

Hey Beavis, th-th-that would be cool.


RE: Can I roll this thing
By menace on 7/7/2009 5:54:40 PM , Rating: 2
We can put giant domes over our cities and cover them with this stuff.


RE: Can I roll this thing
By FITCamaro on 7/7/2009 4:17:37 PM , Rating: 2
I think American's are perfectly fine giving up living space when there's a reason. But there isn't as we're not short on space in the vast majority of the country.


RE: Can I roll this thing
By Boze on 7/7/2009 7:17:45 PM , Rating: 1
I just want (hopefully, although doubtfully) myself and my descendants to colonize new planets and gain the mineral rights to them so 200 years from now, two of my female descendants can marry someone named Weyland and the other can marry someone named Yutani and my future family can then use their ridiculous wealth to explore and mine other planets while keeping a keen eye out for hostile life forms to be used in urban pacification.


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