So long, silicon: Researchers create solar panels from cheap copper oxide | Hacker News Reader

So long, silicon: Researchers create solar panels from cheap copper oxide

extremetech.com

117 pointsmaxko8740 comments

The takeaway from this article is that they came up for a technique to use cheaper materials instead of silicon. This is significant because silicon is very expensive and every increasing demand is also increasing the prices of it at a very fast rate. I took a class on CMOS Digital Design where the professor went over manufacturing overhead for a processor. The cost of the silicon alone was astounding, not even taking into account all the other overhead that comes with the process.

Unfortunately, like a lot of other research in this field, its real world applicability may be relatively limited. One of the reasons for this is that so much time, money, and infrastructure has been put into modern silicon semiconductor manufacturing that no one really wants to touch anything else. It could mean starting from scratch and requiring massive amounts of R&D and process planning to break even.

The real breakthroughs come when someone keeps the existing silicon process in mind and makes discoveries that use the existing infrastructure. That's the kind of research that really "changes" things.

If someone could come up with a manufacturing system that was cheap and easy to swap out or modify the process, they could literally change technology as we know it. If you could have the capability to scale processes easily, a lot of the really cool and cutting-edge research could get implemented on a large scale.

EDIT: I graduated as an electrical engineer and have taken several clean room processing classes, in case you were wondering.

From what I've learned, silicon is abundant in the earth crust. The problem is that you need a very very high purity to make useful wafers. So technically, its not a problem of scarcity, just a lack of miners producing it in a very pure form, which could be solved by having more of them.

Are there some other difficulties that I'm overlooking?

It's expensive to manufacture silicon at semiconductor quality, even when talking about polycrystalline wafers. (Monocrystalline wafers, used for "chips", is even more expensive and prone to defect." People are increasing production of polycrystalline silicon wafers but the demand is much greater than the supply, even with this increase. The cycle basically goes like this: polycrystalline gets more expensive because of demand -> supply increases -> prices go down (in theory) -> demand increases -> polycrystalline gets expensive again.

This is an endless loop right now, as the total amount of possible demand is >> than the growth of polycrystalline foundries. Furthermore, LCD displays also use this form of polycrystalline silicon, which doesn't help with the demand problem. Decently-graded silicon is inherently expensive to manufacture because of the process involved.

The takeaway is that if these metal-oxides are cheaper to produce, even if they are more expensive for the raw material, the cost savings would carry over to the products. Equally relevant when talking about solar cells is how much energy is needed to produce the cells themselves. Right now, an enormous amount of energy is required for silicon solar cells. Helping the energy crisis doesn't help if something takes that much energy to produce. (I do not know the ratio of lifetime energy output versus energy to manufacture but I am sure it's not very good.)

Again, you have this 180 degrees backwards. There was a huge rush to build out polysilicon module fabs in China that has caused a huge oversupply. Now module manufacturers are going out of business daily, leaving an oversupply of polysilicon capacity.

Here, from a few days ago:

http://www.pv-tech.org/news/polysilicon_headwinds_unchanged_...

That's really interesting. The industry is in a different place compared to when I was familiar with it.

The price of polysilicon, the stuff that a large portion of commercially available solar panels use, is NOT increasing. In fact, just the opposite has happened. If you want to know why Solyndra really failed so dramatically, you need to understand what this chart means to the solar industry:

http://etfdailynews.com/2012/03/27/solar-energy-industry-bey...

Prices of polysilicon are forecasted to drop over the long term. That means any technology that wants to compete in solar cells had better be really, really cheap. First Solar can produce modules at around $.70/Watt. Many Si module manufacturers are producing at sub $.90/Watt. Given that Si modules that have been in place for decades and still function, any other materials are a risk for a 25+ year investment.

(I also graduated as an EE, but I also work in PV test and measurement, so I work with this stuff everyday, and my paycheck depends on it.)

Source article (not so breathless and a more reasonable title): http://arstechnica.com/science/2012/08/discovery-opens-door-...

And no OnSwipe, either, thanks.

Disclaimer: I am not a physicist, and most of this is from memory relating to DIY experiments ~2 years ago.

* Copper oxide panels are not new.

* They are much less efficient than silicon panels.

* Cu2O is much more expensive than silicon.

My guess is that the copper oxide would be much cheaper to work into much thinner sheets than silicon, which is also expensive to purify, so although the raw material may be more expensive, the processing costs and volume used might be where the savings are made.

Also, the abstract on the referenced paper seems to indicate that the efficiency of this design is reasonable. I didn't go beyond the paywall to find out more though.

Photovoltaics (PV) are a promising source of clean renewable energy, but current technologies face a cost-to-efficiency trade-off that has slowed widespread implementation.(1, 2) We have developed a PV architecture—screening-engineered field-effect photovoltaics (SFPV)—that in principle enables fabrication of low-cost, high efficiency PV from virtually any semiconductor, including the promising but hard-to-dope metal oxides, sulfides, and phosphides.(3) Prototype SFPV devices have been constructed and are found to operate successfully in accord with model predictions.

http://pubs.acs.org/doi/pdf/10.1021/nl3020022

You can deposit thin films of silicon on to, say, ordinary glass. Usually, this is done with CVD, although I think epitaxial growth is also a popular technique.

The problem is that this tends to produce amorphous silicon, which is not especially efficient. There is a good deal of work to get to the point where monocrystalline silicon thin film cells are viable outside of the lab, though.

Actually, there's a way to make thinner silicon sheets; A particle accelerator bombards these wafers with hydrogen ions: http://www.extremetech.com/extreme/122231-solar-panels-made-...

That's what I thought as well. Silicon is basically.... well, sand, isn't it?

In the same way that aluminum and iron are basically sand, yes.

Going from sand to pure polysilicon is extremely energy-intensive and expensive.

Cu2o is still about 2-3x as expensive, though.

Silicon wafers (cheap ones) cost about $150/kg. Polysilicon (good luck making a wafer out of it) costs about $30/kg (market has crashed). Copper costs about $7.50/kg.

It's not terribly energy intensive. You want to see energy intensive, pick up a beer can. Aluminum is electricity in solid form.

Silicon is capital equipment intensive. It is processed in batches. While each batch is being processed, it ties up an expensive processing station for a long time.

1 pound of metallurgical grade silicon takes about 1 pound of coal and 1 pound of wood chips.

1 pound of polysilicon takes about 2 pounds of metallurgical grade and even more energy.

1 pound of wafer takes about 2 pounds of polysilicon and even more energy.

Aluminum probably doesn't take as much energy but the difference is Silicon's energy is cheap (coal and wood chips for the first step).

Isn't the reason that silicon is cheap to process is because there are high-silicon sands at Silicon Valley and other places?

By the way, would a solar furnace be feasible to replace your first step, eliminating CO2 result?

I'm sure you didn't mean it as such, but that's actually kinda funny; no, Silicon Valley did not get its name from the manufacture of Silicon from sand. Most of the sand that is sourced to make your microchips and solar cells comes from quartz mines and sand pits in Appalachia; Alabama, SE Ohio, and West Virginia are probably the top producers. Silicon Valley imports wafers and has historically had very little to do with how those wafers got made.

In fact, according to the foreman at one of said plants I talked to, they use pieces of quartzite that are more like pebbles than sand; no point in crushing it further I guess.

The function of the carbon is not just to create the heat but also to give the oxygen some way to remove itself. In fact, I believe the oxygen would still rather bond to silicon than carbon but the carbon is able to pull enough physically away as gas to make the reaction work. The resultant gas is mostly CO, carbon monoxide, which somehow becomes CO2 after the plant's done with it.

http://agmetalminer.com/2009/02/26/power-costs-the-productio...:

"Although the newest smelters can be closer to 12,500 kWh per ton let’s say most smelters are consuming electricity at 14,500-15,000 kWh/ton of ingot produced."

So, that is 12 to 15 kWH per kilogram.

Compare that with http://www.rsi-silicon.com/media/SolarGradeSilicon_050611.pd...:

"In making MG-Si, approximately 12 kilowatt-hours of electrical energy are consumed per kilogram of silicon produced."

That already is in the same ballpark, for MG = metallurgical grade silicon. Getting from there at the purity needed for chip production is energy intensive. From the same text: "Energy consumption for the Siemens process is ~200 kilowatt hours/kilogram of silicon produced"

Even correcting for a potential bias of the author (who has his own patented process that he claims to be more efficient and, I guess, that he wants to sell), I conclude that, per kg, production of silicon-grade silicon is way more energy expensive than production of aluminum.

On the other hand, http://www.rsi-silicon.com/media/SolarGradeSilicon_050611.pd... seems to indicate that chip-quality silicon is overkill for solar cells. A dedicated factory for solar cell silicon would be more energy efficient than what exists now.

Not really. Sand is (among other things) silicon but silicon(crystalline) is not sand.

It's not just sand. It's sand with the oxygen removed. The oxygen (especially every last atom) doesn't want to leave.

Silicon has to be purified to 99.9999% at the very least to make a crappy solar cell. Add four more 9's to get to making decent microprocessors. Getting certain impurities out (that behave exactly like silicon in a chemical sense) is really difficult.

You're using some interesting numbers. Citation?

http://www.techradar.com/us/news/computing-components/proces...

http://www.cam.ac.uk/research/features/solar-grade-silicon-a...

That's 30 seconds of Googling. I can't vouch for how accurate they are.

And aluminium is basically clay.

But 75% of the price of aluminium is electricity.

Yes, silicon panels are not the only solution. Although not as efficient as silicon other techniques have other qualities that make it commercially viable (price, scaling, maintainability) as explained in this video by nano solar http://www.nanosolar.com/nanosolar-technology-overview

This article is really very wrong about conventional solar cell manufacture - especially the "Almost every solar panel..." paragraph. Here's a decent resource on standard manufacturing technology: http://pveducation.org/pvcdrom

How about we mine mars to make solar panels from Iron Oxide? Or bring machines to mars that will build solar panels?

Then we could have an entire electrical power source for human habitation or machine experiments.

Getting to the point where the amount of energy it will require to get the panels out of Mars' gravity will be less than the energy delivered will take a long time. And what are you going to do when something breaks down?

You're 32 years late on that idea: http://www.islandone.org/MMSG/aasm/

As it stands, we have not yet built a factory using exclusively robots. I'm sure that this would have very useful applications on Earth, as well as on Mars, if you were interested in tackling it :).

If you want to start somewhere: http://phys.org/news/2010-12-sahara-aims-power-world.html

I found the picture humorous, reminded me of so many post holocaust games, unfortunately it also reminded me of some cities I passed through that border the Ohio river.

Post-apocalypse, not post-Holocaust

Post-holocaust is perfectly correct. The event of nuclear war is often refereed to as a nuclear holocaust. Note the lack of capitalization on the 'h' making it not signify the proper name for the event, the Holocaust. http://en.wikipedia.org/wiki/Nuclear_holocaust

"a great or complete devastation or destruction, especially by fire" - sgtm

I'm glad I'm not the only one who has to do something when someone corrects a person, but is wrong themselves. One of my BIGGEST pet peeves!

I would still bet the OP actually meant apocalypse, even if their mistake turned out sorta correct. "Post-holocaust" is a rare usage.

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