Solar Cells Crystallized Out of Molten Silicon

Hot Toddy sends in a link to a story up on Digital World Tokyo about a more efficient process for manufacturing solar cells. It involves dropping molten silicon from a height of 14 m; surface tension causes tiny spheres 1 mm in diameter to form; the silicon crystallizes in the 1.5 seconds of free-fall. The spheres can be mounted on surfaces of any shape. They capture light from many directions, increasing their solar efficiency. Kyosemi is the company behind the Sphelar technology. Some of the pages on this site date to 2003 and the status of most listed Sphelar products is either "under development" or "engineering sample is available."

Nice concept, but reality may be different!

[DamonHD]

For example, the statement about solar panels not having to be flat already applies: there are flexible, stickable (see the UniSolar laminate for example) ones now, with Fresnel lenses etc.

In fact, for many uses, solar is easily laid on an existing flat surface such as a roof. Flat is very often convenient.

The issue about capturing light from any angle is only valid if the individual cells/balls and their connectors (and any surrounding obstacles such as walls and trees) don't get in the way. Multi-layer cells and mechanical trackers and even mirrors mitigate these problems in existing systems: http://www.earth.org.uk/note-on-solar-PV-for-diffuse-light.html [earth.org.uk]

Anyway, interesting, and it would be good to test some in places like the tops of walls, roof ridges, pathways, etc.

Rgds

Damon

Innovalight

[sanman2]

So nobody's been payint attention to Innovalight in the news lately?

They have the cheaper and more efficient technology:

http://www.news.com/Pour-yourself-a-silicon-solar-panel/2100-11392_3-6213132.html?tag=nefd.top [news.com]

www1.eere.energy.gov/solar/solar_america/pdfs/41741.pdf

Multiple Exciton Generation is where it's at. Only nanoparticle quantum dots can achieve that, and it's the means to get the highest solar efficiency, because it 's about generating multiple electrons of current for each photon absorbed by you

Re:

[neophytepwner]

I wonder if we could use the silicon from all the computers in our landfills to make solar cells?

Re:

[Orange Crush]

Sure, but the recycling process is probably less efficient than starting from raw materials (it is one of the most abundant elements on the Earth's surface.) Semiconductor grade silicon must be highly purified and there's really not that much in a typical computer (only the chip dies themselves, which are relatively tiny).

Re:

[iRegister]

Can't see how a mechanical tracker solution could be cheaper to install or to upkeep.

trackers double the cost of a system

[SuperBanana]

Multi-layer cells and mechanical trackers and even mirrors mitigate these problems in existing system

Having recently spoken with someone who worked for a solar energy contractor that did large-scale commercial installations, tracking systems double the cost of the system.

Before you scream "zOMG I googled it and they only cost $x dollars", remember that any time you transition from a static system to a dynamic one, complexity and cost go up. It's not just the cost of the tracker device; it's the cost o

Re:

[DamonHD]

Tracking and receiving diffuse light don't necessarily make a great deal of difference all the time anyway, as I should have said, eg a flat panel at 75* from the horizontal in London (England) will get most of what mid-winter light there is to have anyway, except in really cloudy weather when maybe facing stright-up would be better.

I'm not especially advocating mechanical tracking, I'm just not convinced that the invention described will capture any more than the other solutions I mentioned because of shad

Re:

[Spuntina]

What would really be nice is if someone could capture old discs and transform them into solar panels.

Re:

[WilliamSChips]

Actually the sun produces UV light as well, better known as blacklight.

ATS / Spheral Solar Power

[Mr. Flibble]

Uh, this looks like the same thing that came out from Spheral Solar Power, that was bought (and later divested) by Automation Tooling Systems:

http://environment.newscientist.com/article/dn3380 [newscientist.com]

Re:

[ahfoo]

Yep, the former darling of Slashdot submissions that disappeared off the map last year. I was a real cheerleader for their business plan so I was disappointed when they gave up. My two cents on what happened was that they decided amorphous silicon AKA thin film was going to put them out of business. Those suspicions are based partly on watching all the action around Swiss company Oerlikon. They're a turn-key provider of thin film production plants and they're making a lot of deals in Taiwan and China in the

Re:ATS / Spheral Solar Power

[bombastinator]

This discussion bring back to me an ancient memory of myself reading, I believe a "Popular Science" magazine blurb in the school library when I was a little kid. This memory is really old, like Madonna wearing 10 crucifixes at a time old.

The article was about a system that used little silicon spheres set onto dish shaped depressions pressed into a piece of tinfoil. The individual cells looked like an orange in a shallow cereal bowl. (but, you know, lots and lots smaller.) The dish acted as a solar reflector thereby making the effective efficiency higher for a given amount of pure silica. It produced less electricity per square inch than equivalent conventional cells, but it's total cost was supposed to be lower.

IIRC The material proved be a dud for many reasons. It was overly delicate, they had a serious problem with reliably attaching the spheres to the aluminum, an when they finally got it going the actual efficiency numbers were far lower than they were predicting.

I mark this as one of those ideas that crop up every now and again when it's been long enough for people to forget that it was stupid the last time.

Cannonballs!

[Gibbs-Duhem]

Neat! This is the same method that was used to make cannonballs during the US Civil War.

I can't find any references to cannon ball manufacture on Wikipedia, but my high school had a cannon forming tower (it was originally a civil war arsenal).

Outside of that, the more techniques the merrier! I'm somewhat curious how they create a PN junction out of a homogenous liquid of silicon, but I suppose that can be done afterwards. I'd also be a bit curious if it's single crystalline. I very much doubt it, as there is no seed crystal to nucleate on, so there should be a lot of independent surface nucleation sites (IAAMS).

Re:

[Cutterman]

Small-shot, not cannonballs! Shot-towers were once not that uncommon to see. Given the mass of a cannonball, temperature when molten and a normal environment, you'd need a very tall shot tower to cast cannonballs! Now I suppose some slashdotter will promptly work out just how high a cannonball shot tower would have to be....(I'm too lazy). The Cutter

Re:

[Gibbs-Duhem]

They fell into a pool of water. The drop was just to give it long enough to let surface tension form a sphere from the original blob of molten lead. Not to say you're wrong about it being small shot, I wasn't particularly attentive in high school. But they definitely always called it the cannon tower, and I'm pretty sure I was told it was for cannon balls.

You were misled.

[Kadin2048]

Someone misled you. Shot (for shotguns) is made in freefall using a tower. And it basically does work the way you're thinking: it doesn't necessarily solidify all the way, but the outside does, and that's enough for it to retain its shape when it hits the water at the bottom of the tower.

Cannonballs were generally made out of cast iron. If you look at an authentic one that's in good shape, you can usually see the mold lines and sprue marks where it was poured. They were usually poured into sand molds that were then knocked away after they cooled.

Some very old cannon balls (prior to the 18th century at least) were cast bronze or cut stone rather than iron, but most people switched to iron as soon as they were able to because it's a harder, cheaper material than bronze, and easier to work with and more effective than stone. (Bronze remained as a material for the cannons themselves well into the 19th century, though, since it has greater tensile strength than cast iron and is less likely to shatter.)

Also, if you think about pouring large quantities of viscous liquid, you'd realize that "dropping" a cannonball wouldn't work; rather than forming a sphere, you'd probably form a teardrop or ellipsoidal shape* due to the air resistance. Forming spheres via freefall cooling is only practical (in normal Earth gravity) for rather small parts, where the surface area to mass ratio is low.

* I'm told that if you look at the shot produced in a shot tower closely enough, all of it is really ellipsoidal rather than truly spherical, but it's such a small difference that it's normally ignored.

Re:

[phaunt]

Also, if you think about pouring large quantities of viscous liquid, you'd realize that "dropping" a cannonball wouldn't work; rather than forming a sphere, you'd probably form a teardrop or ellipsoidal shape* due to the air resistance.

Are you sure about the teardrop shape? Contrary to popular belief, rain drops don't have this form; see here [psu.edu].

Re:

[Calinous]

It wasn't more effective than stone - but it was much cheaper.
      Stone had some great advantages: it broke into fragments in case of impact (making it worse for breaking walls, but much better against ships and infantry on hard ground), it didn't rust (an iron ball in sea conditions would rust, and increase its diameter).
      Cutting spheres from stone became much more expensive than making them from molten iron when iron was plentiful.

You were misled too!

[ajs318]

The "teardrop" shape only exists while the droplet is suspended from the liquid mass -- it is caused by surface tension trying in vain to attract the droplet to the mass. Once the droplet has separated from the rest of the liquid, then the surface tension is acting evenly in all directions over the surface of the droplet. And that's the only force acting on it (it's in freefall, so no gravity; and we can discount air resistance, because the molten stuff has so much higher a viscosity than the air through

Re:

[Danny Rathjens]

Thanks, that gave us the correct term to look it up. :) http://en.wikipedia.org/wiki/Shot_tower [wikipedia.org]

Re:Cannonballs!

[mishmash]

Not quite cannonballs, but shot: http://en.wikipedia.org/wiki/Shot_tower [wikipedia.org]

Re:

[maz2331]

Canonballs were usually made from cast iron, not lead. I can't see using this technique for 2500 degree molton iron....

Melbourne Central shot tower

[Nefarious Wheel]

In the city of Melbourne, deep down in the Antipodes, a very tall (50M) 19th century shot tower is enclosed in a dome in the city centre, above the Melbourne Central train station http://en.wikipedia.org/wiki/Coops_(Melbourne_Central)_Shot_Tower [wikipedia.org].

So let me be the first to say it -- ours is bigger than yours!

Re:Melbourne Central shot tower (OT)

[kanweg]

Yeah, but pointing down.

Bert

Re:

[kanweg]

It isn't as bad as you think, as iron melts at just over 1500 degrees.

Bert

Re:

[FasterthanaWatch]

You and your metric system...

Re:

[dbIII]

Polycrystalline cells work fairly well now. The largest expense and energy expenditure in conventional silicon solar cells is taking a lot of care to make sure you only have one big crystal, the same thing that is done for the semiconductors that could be made out of the next wafer. Polycrystalline cells avoid all such hassle and I don't think it would matter if there are a few dozen big crystals starting from points on the surface of the sphere.

There's a few shot towers still around and if you look on wi

Scotchlite(TM)

[Anonymous Coward]

The same process with molten glass produces the tiny beads for Scotchlite(TM) reflective material, [3m.com] which has been around for half a century or so.

Re:

[icepick72]

Neat! This is the same method that was used to make cannonballs during the US Civil War.

In context of dropping silicon from 14m, your statement reminds me of a Looney Toons Road Runner & Wile E. Coyote episode. Cue the anvil.

Accidental discovery

[werdnapk]

Sounds like one of those accidental discoveries...

"Ah crap, I just knocked over the vat of molten silicon we had sitting on the roof ledge!! My boss is gonna be super mad at.... oh hey, look at all these little balls! Weeee, silicon balls!"

Re:

[Anonymous Coward]

Silicone balls - for those less endowed.

Think there's going to be enough time?

[Colin Smith]

http://europe.theoildrum.com/node/3060 [theoildrum.com]

 

Re:

[Colin Smith]

Yes. Clearly I'm new here...
 

Re:

[dbIII]

Yes I do, even though I also believe in peak oil despite there not being enough data to indicate when. The Iranians certainly don't have a clue how much oil is in Iran for one thing, and to melt the silicon you would use a furnace run on coal or gas or electricity from non-oil sources for another.

Re:

[Belacgod]

There's a lot more oil, and it's being exploited a lot less efficiently, than people realize. We'll be underwater from global warming before we run out of oil.

Re:

[Colin Smith]

It's not really a question of running out. It's a case of going from spending 10% of our effort and income on energy to spending 80% of our effort and income on acquiring energy. And the effect that will have on our civilisation.
 

Re:

[Belacgod]

And when we get to 30-40%, assuming we haven't switched to nuclear, solar, and wind, we'll be underwater. My point is that we won't get to the bad consequences of relying on expensive, inaccessible oil until the bad consequences of relying on oil in general have screwed us sideways.

Re:

[mdsolar]

There is little electricity generated from oil and silicon processing mainly uses electricity so this is not a direct concern. Some at that site suggest that the impact of oil scarcity on society could be so large that industry will be disrupted. That would be an indirect effect. However, few there seem interested in potentially large oil fields like the Bakken Formation: http://www.undeerc.org/price/ [undeerc.org] so that there may be a bias in some of the analysis.
--
Rent solar power for your home: http://mdsolar.bl [blogspot.com]

Re:

[fritsd]

Disclaimer: I don't know anything about geology so please correct me if I say stupid things)

A US DOE report (here [doe.gov]) calls this

The resources of the Bakken Formation are defined by the United States Geological Survey (USGS) as unconventional "continuous-type" oil resources. This means the hydrocarbons within the Bakken have not accumulated into discrete reservoirs of limited areal extent. Other examples of "continuous-type" oil or natural gas resources are from low-permeability (tight) formations (e.g. Austi

Re:

[mdsolar]

The curious thing about the link I gave is that the amount of oil might be 400 billion barrels. There seem to be a lot of maybes in oil exploration. Quantifing those, which all seem to push up URRs, is something that I don't see happening all that much. In any case, production from the formation is growing rapidly and that, at least, ought to get notices. That is production of light sweet crude.

Re:

[fritsd]

That's more than a factor 1000 difference! I could imagine an uncertainty between 27 or 40000 barrels, but 270 million or 400 billion, that would be "this would sustain the current consumption in USA for 14 days" vs. ".. for 54 years". But as you say if production has started then we'll see how much is produced. I thought shale needed a wholly different production process from drilling.

Re:

[Shihar]

Peak oil is an environmental problem, not an economic problem. There are lots of fuel alternatives, they are just expensive or environmentally damaging. As oil prices rise, alternative methods of energy storage become viable. As alternative energy sources become profitable, the price of oil drops. The result is that no matter how hard you try, you can't force oil prices up rapidly over a long period of time. The worst that will happen will be a steady long term climb as oil is phased out and new energy

Of course it's an economic problem

[Colin Smith]

Peak oil is an environmental problem, not an economic problem. There are lots of fuel alternatives, they are just expensive or environmentally damaging

The problem all the alternatives have is that they require more input energy to acquire than oil does.

At the moment, we pretty much drill a hole in the ground and start sucking. The energy put in is tiny relative to the energy we get out. As we have to put more energy in to find our energy we have less energy to expend elsewhere. Even nuclear energy has a lower energy return than oil does. When the ratio of energy input to energy output falls to 1:1, the entire economy is employed finding and exploiting ne

Re:

[Shihar]

We won't be abandoning skyscrapers and cars. There are lots of alternatives out there that we don't try for one reason or another. If costs is your concern, then coal is the answer. The rest of the world might be in a bit of a tight spot, but the US and China own a massive portion of the worlds coal supply. If these two nations are willing to rip up their country side and dump some more CO2 into the air, they will easily and happily meet all energy demands. The US in particular owns a mind numbing supp

Space?

[WindBourne]

Is it possible that this will be the new manufacturing that helps push space? It would be interesting to see an automated machine inside of a BA-330, and then have a falcon 9 pick up and drop off.

No need

[Anonymous Coward]

It's trivial to create a zero-G manufacturing environment here on Earth. The only limitation is that it's only zero-G for a couple of seconds (as it falls down a tower). That is apparently enough for many types of processes such as this one. In space there's no limit on the duration, so growing protein crystals etc might be easier, but the costs of doing anything in space are so enormous that those protein crystals had better be worth thousands of dollars a pound to make them worth doing in space.

Re:Space?

[dbIII]

Hot liquid metal inside an aircraft - what fun! Look up "liquid metal embrittlement" to see why this would have to be done very carefully and why you currently cannot take mercury on an aircraft. In short the liquid metal gets into any small flaws, dissolves it into a sharp crack quickly, and then after a short time the crack gets long enough that it goes at the speed of sound in the material - more than 4miles/second (6.6km/s) in steel.

Re:

[rachit]

Enjoy your trip to Cuba, dbIII. :)

Crystallized, huh?

[Anonymous Coward]

You know, a crystal structure sure has a lot of surface area compared to its weight, maybe, just maybe -- no! definitely, it's an idea, I feel it coming, it's, it's -- a-hem:

I HAVE A DREAM.
I have a dream,
That one day,
Crystallized solar cells will be so light
And so cheap
That you could spray them on a helium balloon.
And that you will.
On half of the balloon.

Only the balloon is parabolic.
And the inside is coated -- half of it,
Yes, forming the shape of a dish,
With something that reflects radiowaves.
And I have a

Re:

[Yoozer]

Mod parent up - this was poetic.

Never mind the panels

[upside]

Did you see the USB humping dogs [digitalworldtokyo.com]? Those really blew me away.

Everybody knows...

[dotancohen]

Silicon makes everything better... ...especially (ideally) spherical shaped objects...

Bilbo-speak in TFA

[chudnall]

Ow, my brain:

Standard cell manufacturing results in half as much silicon being wasted as is actually used.

"I know less than half of you half as well as I should like and I like less than half of you half as well as you deserve." ~ Bilbo Baggins

Isn't that how they make ball bearings?

[Associate]

And Quaker State?

Re:

[mangu]

No [madehow.com].

Details needed.

[JavaManJim]

Missing from the story are important and obvious details.

1. Electrical output efficiency compared to a correctly aimed flat solar panel.

2. How are tiny silicon balls connected to produce electricity?

Any other questions, please chip in.

Thanks, Jim

Re:

[AugustZephyr]

How massive (read density) are these spheres compared to a standard solar panel or film? Would it be practical to place these on a structure without any more load bearing support? Although the following may already suggest that this is a non-issue:

"It is also possible to create "power-generating window glass" while maintaining a certain level of transparency."

Re:Details needed.

[ChrisMaple]

Links in the article lead to the details you ask for. Electrical efficiency appears to be about 11% in sunlight, although this is my estimate extrapolating their graph of packing density. Flat, quality silicon cells run 15% to 23%, IIRC.

The balls are p-type silicon doped n-type on the surface. A small, flat slice is removed to expose the p-type interior. Contact to the n-type region is any convenient place on the spherical surface; contact to the p-type region is the center of the flat area.

Finally, some solar tech with balls...

[jpellino]

... hopefully it'll have legs, too.

I can't find anything about the actual technique..

[argent]

I can't find anything on the site about the actual technique for turning silicon microspheres into cells. How are they prepared, mounted, and connected?

silicon sprinkles

[SoyChemist]

And then they cover the whole thing in rich creamery butter.

AGW

[pipingguy]

This is all bullshit, we should be spending trillions on trying to modify the planet's behaviour instead. Now mod me down, thanks.

Re:

[ClownSoup]

Exactly. Ban the cotton gin! Screw Technological Advancement! Tell people to modify their behavior!

NextFest

[Jeremi]

FWIW, they were demonstrating these at the Wired NextFest in Los Angeles last month. I didn't get the details, but they seemed to basically work... at least, they had a curtain of them (several square feet) strung up with several lights pointing at it, and if you blocked the lights with your hands, the toy train that the spheres were powering would stop moving...

Solor Powered Jewelry?

[Presence2]

I wonder if you could alter the composition to add colors, or would it interfere with the light collection properties. That way you could string them together in patterns and perhaps apply them on jewelry, that could provide juice for the myriad of electronic gizmo's we cart around every day.

Re:

[H0D_G]

adding a colouring agent would damage the very semiconductor properties you were after- the silicon currently used is incredibly pure, with only a minor imperfection to cause the "holes". if you wanted another colour, another coating would need to be added

Video and Interview with Kyosemi CEO about Sphelar

[dk3nn3dy]

You can find more info and a video with Kyosemi CEO here [diginfo.tv].
Disclaimer: I work for this company.

Not just Solar Cells, also Sensors

[dk3nn3dy]

the nice thing about this (that i forgot until now) is that they aren't just solar cells. working with AIST, a national research center in japan, the cells are also used as sensors to recieve infra-red data from an array of LEDs. this data is converted into electrical signals inside the receiver then sent to a speaker, so they've basically created a wireless, battery-less remote speaker unit. pretty cool... video here [diginfo.tv] and product info here [kyosemi.co.jp]

Concentrating Solar Power

[clv101]

Nice idea, I'd also check out concentrating solar power though. To me this seems to be a simple, conventional engineering task. Future information here: CSP on The Oil Drum [theoildrum.com]