Cal Tech discovery makes flexible solar-cells and solar-cell clothing a reality

[Rybold]

"Caltech researchers may have unlocked the holy grail of gadget-powering clothing, thanks to a recent discovery that could eventually produce cheap, flexible solar cell microfibers. The team, led by Harry Atwater, says the bendy solar cells use just 1% of the silicon needed by a solar cell with the same output. Additionally, the bendy cell does this with only 5% of the size. The base that "grows" the micrometer-wide silicon wires is also reusable, further lessening the future costs of a pair of theoretical Gap Gadget khakis. Better still, the Caltech cells are efficient, reflecting back only about half as much energy as a similar sized "traditional" cell.
So they're small, flexible and cheap. Seemingly perfect, but will they really work in the merciless real world? So few of these promising designs end up passing that test. If they don't work we'll always have those solar powered tobacco leaves to fall back on.
Oh, and these guys, who are working on kind of the same thing, but prettier (that's their image, above). In any event, the future of solar cell clothing appears bright, or leafy, depending on where its coming from. [New Scientist]

Cheap, Flexible Microfiber Solar Cells and the Future's Energy-Producing Clothing - Solar Power - Gizmodo

[chogan2]

Ah, you teaser, where's the details.

Holy moly. It's the Roach Motel of photocells. Photons check in, but they never check out.

http://media.caltech.edu/press_releases/13325

Emphasis mine:

"The silicon wire arrays created by Atwater and his colleagues are able to convert between 90 and 100 percent of the photons they absorb into electrons—in technical terms, the wires have a near-perfect internal quantum efficiency. "High absorption plus good conversion makes for a high-quality solar cell," says Atwater. "It's an important advance."

Now there's a guy who knows how to be understated.

Now I'm sitting here thinking, sure, I bet you can see the sample under a microscope. Nope:

"The structures we've made are square centimeters in size," he explains. "We're now scaling up to make cells that will be hundreds of square centimeters—the size of a normal cell." Atwater says that the team is already "on its way" to showing that large-area cells work just as well as these smaller versions."


I want to buy stock.



Thank you for the posting.

[ceric]

I will believe it when Prof. Atwater abandons his tenure and start up his company with it. If not, it is all hype. This won't be the 1st time "someone claims something"...

[icarus]

Still waiting for "printable Nano solar" to break the $1/watt barrier,, waiting,, waiting,

[fuzzy1]

I'm still waiting for numerous other photovoltaic breakthroughs to bear fruit and reach the market. It would sure be nice if at least one does so in the timeframe I need.

The efficiencies listed here for specific steps, not the whole system.

1st, there will be losses from the surface (e.g. glass cover) that encapsulates and protects these cells.

2nd: "The silicon-wire arrays absorb up to ... 85 percent of total collectible sunlight." No mention of what band limits they consider to be collectible.

3rd, "... convert between 90 and 100 percent of the photons they absorb into electrons". Photons arrive with a wide range of energies, but output electrons will have identical energies. Something must be lost in this transition, though there are multiple ways for it to happen, and no details are supplied.

4th, the energized electrons need to be collected and transported to the output terminals. Some don't make it.

Not being a PV expert, I'm probably missing some more losses. The final system efficiency will not be similar to the single step efficiencies mentioned in these press releases.

[drees]

Originally Posted by icarus

Still waiting for "printable Nano solar" to break the $1/watt barrier,, waiting,, waiting,

At the manufacturing cost level, they (First Solar / Nanosolar) already have. In fact, First Solar claims that they reached that benchmark a whole year ago.

But - there's no reason for them to sell it that cheap as long as demand outstrips their supply and their competition (silicon PV) is not able to match their prices.

As ceric said, though - when these things hit mass production and are price competitive, then I'll cheer. Although if they really are 90-100% efficient, they'll command quite a price premium over convention panels netting 10-20% efficiency at best.

[chogan2]

For my part, sorry to be such a cheerleader, but I've never seen anyone claim anything like that before, in a science journal. Might just show that I haven't seen much.

Ah, here, read the press release if you want to know more. It says the thing absorbs 96% at the peak frequency and 85% of "total collectible sunlight", whatever that might mean. It then says that 90% or better of that is converted to electrons. But it does not give the bottom-line efficiency number.



Caltech Researchers Create Highly Absorbing, Flexible Solar Cells with Silicon Wire Arrays - Caltech


Very prescient comment about believing it when you see Atwater start a company. Turns out he already has, although when I look for it, it is uniformly described as a stealthy startup or words to that effect:

The Brentwood Group, Ltd. - Selected current searches


Still cannot find the overall efficiency number.

[icarus]

Originally Posted by drees

At the manufacturing cost level, they (First Solar / Nanosolar) already have. In fact, First Solar claims that they reached that benchmark a whole year ago.

But - there's no reason for them to sell it that cheap as long as demand outstrips their supply and their competition (silicon PV) is not able to match their prices.

As ceric said, though - when these things hit mass production and are price competitive, then I'll cheer. Although if they really are 90-100% efficient, they'll command quite a price premium over convention panels netting 10-20% efficiency at best.

Dress,

My point is, I don't think that Nano/first solar has a product available in the general market place yet, using this technology. I admit I may have missed any product introduction, as I don't follow all this stuff all the time. Point is, until I can buy it off the shelf at my local solar retailer, it all comes under the category of "vapor ware"

Icarus

PS to Chogan,

I some ways it makes little difference (in a practical way) about how efficient any given hardware is at converting sunlight to useable electricity on a square foot basis. (The exception might be portable or wearable hardware). Whether or not a Pv puts captures 5% of the power per square meter or 15% isn't what matters, but rather what is the cost per unit of power (watt) of that hardware. What is needed is cheaper cost per watt, not really more watts per sq meter. We've got lots of area to put Pv,, if it is cheap enough.

[drees]

Originally Posted by icarus

My point is, I don't think that Nano/first solar has a product available in the general market place yet, using this technology. I admit I may have missed any product introduction, as I don't follow all this stuff all the time. Point is, until I can buy it off the shelf at my local solar retailer, it all comes under the category of "vapor ware"

Your opinion, but I don't consider multiple GW of installed PV to be vapor ware. First solar had 1GW installed early last year and manufactured 1GW of panels last year. They target large business and utility installations (similar to Nanosolar) which is why you can't get them from your local distributor.

Thin film tends with it's substantially lower module efficiencies tends to not be as effective as silicon for residential installs where roof-space is often tight.

[icarus]

Dress,

As I said, I don't follow this very closely. I wasn't aware that they had actually installed 1 gw in 2009. Was this a Beta site? Can you provide some links for those of us that are lazy,,,LOL,

Icarus