Solar cell breakthrough
by NICK ROSEN on MAY 4, 2010 - 10 Comments in ENERGY

Caltech's brightest minds

Nanotechnology has come to the rescue of the solar industry — and not a moment too soon.

Solar cells have long been a favorite of people trying to reduce or eliminate their energy bills. Yet throughout its history, the relatively expensive up-front costs of obtaining photovoltaic cells has deterred many from investing in the technology. Now scientists from the California Institute of Technology (Caltech) have developed a new solar cell that will cost a tiny fraction of current prices. The researchers hope that their breakthrough will change the economics of solar forever.
The new cells consist of tiny silicon wires that measure a mere 1 micron in diameter. These wires are embedded into plastic plates where they convert light into electricity at an exceptional rate of efficiency. Any light that is leftover bounces around inside the wire matrix until it finds another wire that can absorb it. When all is said and done, nearly all the light is captured and converted into electricity.
Less silicon
The beauty of the new cell technology is that only two percent of the cell is composed of semiconductors, which are the most expensive component. The other 98 percent is made from inexpensive (albeit oil-based) plastic, which translates into significantly lower prices for consumers as opposed to existing solar cell technologies.
That low price is in inverse proportion to the rate at which the cells convert sunlight to electrical power.  The tips of the wires on a conventional panel cover only a few per cent of the cell’s sun-facing surface, so much of the light hitting the cell passes through unabsorbed.
In February this year, Harry Atwater and his colleagues (pictured above) at the California Institute of Technology in Pasadena reported a solution to this problem. They used microscale silicon rods slightly thicker than nanowires, and poured a polymer containing light-reflecting nanoparticles into the spaces between them. The polymer scatters unabsorbed light back onto the rods and this, combined with a silver reflecting layer at the bottom of the device, allows the cells to absorb up to 85 per cent of incoming light. Still, losses – chiefly from imperfections in the crystal structure of the microrods – drive the overall efficiency below the 20 per cent achieved by the best crystalline silicon cells (Nature Materials , vol 9, p 239).
So why the fuss, if these devices are no more efficient than what went before? The key is that although these cells are merely as efficient as conventional devices, they use only about a hundredth of the material. What’s more, they are highly flexible: grown on a bed of silicon, Atwater’s microrod arrays can simply be peeled off and stuck pretty much wherever you want. “They could even be integrated into buildings, as components that match the shape of roof tiles,” says Atwater. He has started up a company, Alta Devices, to do just that, and has recently received research funding from the US Department of Energy.
Though roughly the same thickness as conventional solar cells, the new cells contain far less silicon. The team is currently working on expanding the voltage capacity and size of the cells in order to manufacture large, flexible sheets that can be manufactured inexpensively using “roll-to-roll” fabrication equipment.
The team has yet to release any side-by-side comparisons of the new cells versus the old cells, but as the technology is refined, researchers will likely conduct the necessary experiments to gain this data and make it available to the public.

Solar cell breakthrough
Scientists from the California Institute of Technology (CIT) have developed a new solar cell that will cost a tiny fraction of current prices.

Solar cells have long been a favorite of people trying to reduce or eliminate their energy bills. Yet throughout its history, the relatively expensive up-front costs of obtaining photovoltaic cells has deterred many from investing in the technology. The researchers hope that their breakthrough new technology will change that.
The new cells consist of tiny silicon wires that measure a mere 1 micron in diameter. These wires are embedded into plastic plates where they convert light into electricity at an exceptional rate of efficiency. Any light that is leftover bounces around inside the wire matrix until it finds another wire that can absorb it. When all is said and done, nearly all the light is captured and converted into electricity.
The beauty of the new cell technology is that only two percent of the cell is composed of semiconductors, which are the most expensive component. The other 98 percent is made from inexpensive plastic, which translates into significantly lower prices for consumers as opposed to existing solar cell technologies.
That low price is in inverse proportion to the rate at which the cells convert sunlight to electrical power.  The tips of the wires on a conventional panel cover only a few per cent of the cell’s sun-facing surface, so much of the light hitting the cell passes through unabsorbed.
In February this year, Harry Atwater and his colleagues at the California Institute of Technology in Pasadena reported a solution to this problem. They used microscale silicon rods slightly thicker than nanowires, and poured a polymer containing light-reflecting nanoparticles into the spaces between them. The polymer scatters unabsorbed light back onto the rods and this, combined with a silver reflecting layer at the bottom of the device, allows the cells to absorb up to 85 per cent of incoming light. Still, losses – chiefly from imperfections in the crystal structure of the microrods – drive the overall efficiency below the 20 per cent achieved by the best crystalline silicon cells (Nature Materials , vol 9, p 239).
So why the fuss, if these devices are no more efficient than what went before? The key is that although these cells are merely as efficient as conventional devices, they use only about a hundredth of the material. What’s more, they are highly flexible: grown on a bed of silicon, Atwater’s microrod arrays can simply be peeled off and stuck pretty much wherever you want. “They could even be integrated into buildings, as components that match the shape of roof tiles,” says Atwater. He has started up a company, Alta Devices, to do just that, and has recently received research funding from the US Department of Energy.
Though roughly the same thickness as conventional solar cells, the new cells contain far less silicon. The team is currently working on expanding the voltage capacity and size of the cells in order to manufacture large, flexible sheets that can be manufactured inexpensively using “roll-to-roll” fabrication equipment.
The team has yet to release any side-by-side comparisons of the new cells versus the old cells, but as the technology is refined, researchers will likely conduct the necessary experiments to gain this data and make it available to the public.

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10 comments

1 GreenUrban » Blog Archive » Solar cells at a tenth the price…someday.. { 05.05.10 at 12:02 am }

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2 Anthony Geering { 05.06.10 at 11:32 pm }

Dear Sir,
I am very interested in how your product is coming along & what time scales before this type of photovoltaic product will be available to the market, as I am conducting an experiment on the best type of solar panels are available for the British climate.
I have a small project in the UK which I am about to embark on :-
The Arts & Crafts Eco Project. The project is to develop 3 1/2 acres of abandoned light industrial land with an array of hickle de pickley tin shacks, an old disused saw mill, & a 22m x 18m Dutch barn in need of completing. The site is idyllic & right on the edge of the countryside, a stones throw from a beautiful lake, with open fields, & country walks. The site is watched over by a beautifully restored ancient windmill built in 1750 which is directly next to it all. The land is situated in the English countryside adjoining the small old village of Holton next to the old market town of Halesworth in Suffolk. To begin with have started to work on the land & the barn roof span will be doubled in size & the area’s will be covered in solar panels using different models to study them to determine which technology gives the most back to the grid. Stage 2 There is a 200m by 15m sloping wall for more solar panels which we will build designer/modernist Artists & Craftsmen’s workshops in the American A&C bungalow styles, We have high hopes with the development of the site, there are some grants for funding here & added incentives available therefore we are always looking for more sponsorship to finance the project & asking corporate companies to donate materials to the project, & in return they will be mentioned & given advertising space on our website soon to be launched. The project will be filmed & documented for TV through a production company, throughout the whole development from start to finish. It is Grand Experiment in Solar energy with Architecture & Design for a sustainable living & working. This project has no boundaries & we will breathing new life & beauty in form & function into this disused abandoned site, in the true Arts & Crafts tradition to work with the land & to harmonise with the environment & using as much green sustainable materials that are possible, working closely with the planners, & they will be working with us, incorporating modern technology in Solar energy, wind turbine & or hydro-electric power. We have a project engineer HND from Sizewell B Nuclear power station , & with his skills we want to try alternative power sources, invent things or adapting things to show people how we all can get sustainable power for very little outlay. Stage 3 :- There is another 1/2 an acre with a uninhabitable bungalow needing demolishing to be replaced with a futuristic American style bungalow covered in solar panels that look like tiles & are the tile of choice. I look forward to hearing from you. many thanks Anthony Geering MD. Puritan Values Ltd.

3 Mike Waltman { 05.16.10 at 6:43 am }

When will it be available? How much per watt? Can you tell the efficiencies? How much cheaper is it, I can get some good pricing on line? I need about 608 SF for a project in Cedar
City Utah, it could provide for a good test site> Contact me at macronology@aol.com

4 Ralph McEWEN { 05.31.10 at 2:09 am }

I am interested in acquiring solar cells. Please forward information, and let me know what the price/watt is. Thank you,
Ralph

5 Anup S. Jubbal { 08.19.10 at 5:51 am }

We are seeking technology transfer for manufacturing solar pannel in India.
Appreciate hearing your favourable response
Thanks.
Anup S. Jubbal
Ph.(604)582-2563

6 Dr. Pranab Paul { 08.25.10 at 7:23 am }

we are interested in setting up of such unit for commercial production under your guidance and technology, please send your offer

7 Kevin { 01.10.11 at 9:54 am }

I am interested in your solar cells. Please let me know what the price/watt is, and when available

8 joe { 10.20.11 at 1:07 pm }

I’m doing a project and I am interested in acquiring solar cells. Please forward information, and let me know what the price/watt is. Thank you,
Joe

9 cedar finance { 06.14.13 at 3:24 am }

I savour, cause I discovered just what I was looking for. You’ve ended my four day lengthy hunt! God Bless you man. Have a nice day. Bye

10 Tamela { 09.08.13 at 1:50 am }

Have you ever thought about writing an e-book or
guest authoring on other sites? I have a blog centered on the same information you discuss and would love
to have you share some stories/information. I know my subscribers would
enjoy your work. If you are even remotely interested, feel free to send me an e mail.

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