# Solar cell could be cheaper than fossil fuel



## rochesterricer (Jan 5, 2011)

http://www.tgdaily.com/sustainability-features/60289-solar-cell-could-be-cheaper-than-fossil-fuel


By harvesting waste heat, researchers from the US Department of Energy’s National Renewable Energy Laboratory (NREL) have for the first time built a solar cell with an external quantum efficiency over 100 percent.

A cell's external quantum efficiency is the number of electrons flowing per second in its external circuit, divided by the number of photons per second entering it, and is different at different wavelengths.

The best result for the NREL solar cell was 114 percent. it means, says the team, that solar energy has a competitive future, making it possibly cheaper than energy from fossil or nuclear fuels.

The team used a process called Multiple Exciton Generation (MEG), whereby a single absorbed photon of appropriately high energy can produce more than one electron-hole pair per absorbed photon.

Ten years ago, NREL scientist Arthur J Nozik predicted that MEG would be more efficient in semiconductor quantum dots - tiny crystals of semiconductor - than in bulk semiconductors.

Quantum dots, by confining charge carriers within their tiny volumes, can harvest excess energy that otherwise would be lost as heat – and therefore greatly increase the efficiency of converting photons into usable free energy.

The researchers hit the 114 percent external quantum efficiency with a layered cell consisting of antireflection-coated glass with a thin layer of a transparent conductor, a nanostructured zinc oxide layer, a quantum dot layer of lead selenide treated with ethanedithol and hydrazine, and a thin layer of gold for the top electrode.

They claim the fabrication of quantum dot solar cells lends itself to inexpensive, high-throughput roll-to-roll manufacturing.


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## bjfreeman (Dec 7, 2011)

Current price Retail is $1.25 per watt
we have had one such solar company go tits up with new tech.
I wish the best and wait to see what the dollar per watt ends up.


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## ElectriCar (Jun 15, 2008)

rochesterricer said:


> http://www.tgdaily.com/sustainability-features/60289-solar-cell-could-be-cheaper-than-fossil-fuel
> 
> 
> By harvesting waste heat, researchers from the US Department of Energy’s National Renewable Energy Laboratory (NREL) have for the first time built a solar cell with an external quantum efficiency over 100 percent.
> ...


All that and cheap too? Now that's the cats meow right there!


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## PhantomPholly (Aug 20, 2008)

Yep. Solar is still in its technological infancy, just now moving towards the phase where the rate of improvement accelerates rapidly. In a couple of years it will be cheaper to install new solar cells than it will be to repair or replace the steam turbines in a coal plant. When replacement is as cheap as, or cheaper than, basic maintenance then replacement becomes a certainty.


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## Sunking (Aug 10, 2009)

PhantomPholly said:


> Yep. Solar is still in its technological infancy, just now moving towards the phase where the rate of improvement accelerates rapidly.


Not quite sure that is true as it is a very mature technology of about 100 years with no major advance in 50 years when Bell Labs developed the monocrystaline PV cells. Sure there has been some technical changes like multicrystaline and thin film developed but they are not improvements over monocrystaline. Quite the opposite as they are not as efficient and much shorter life cycles, they are just less energy intensive to manufacture. It is a lot like Cathode Ray Tubes and Vacuum Tubes as there is not much more you can get out of them.


Today's prices are selling below manufacturing cost and companies trying to liquidate inventories before going bankrupt as the market collapses. The two largest manufactures Suntech (STP) peaked on 12-17-2007 @ $85.16, today @ 2.15 or -97.47%, and First Solar (FSLR) peaked on 5-12-2008 @ $311.14, today @ $34.24 or -88.9%. Some other large companies like Evergreen Solar do not even exist anymore.


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## PhantomPholly (Aug 20, 2008)

Sunking said:


> Not quite sure that is true as it is a very mature technology of about 100 years with no major advance in 50 years when Bell Labs developed the monocrystaline PV cells. Sure there has been some technical changes like multicrystaline and thin film developed but they are not improvements over monocrystaline. Quite the opposite as they are not as efficient and much shorter life cycles, they are just less energy intensive to manufacture. It is a lot like Cathode Ray Tubes and Vacuum Tubes as there is not much more you can get out of them.
> 
> 
> Today's prices are selling below manufacturing cost and companies trying to liquidate inventories before going bankrupt as the market collapses. The two largest manufactures Suntech (STP) peaked on 12-17-2007 @ $85.16, today @ 2.15 or -97.47%, and First Solar (FSLR) peaked on 5-12-2008 @ $311.14, today @ $34.24 or -88.9%. Some other large companies like Evergreen Solar do not even exist anymore.


From a manufacturing point of view, the technology is in its infancy. Even if advances in materials and coatings do not improve efficiency significantly, price will undoubtedly come down - and price is the main driver.


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## Sunking (Aug 10, 2009)

PhantomPholly said:


> From a manufacturing point of view, the technology is in its infancy. Even if advances in materials and coatings do not improve efficiency significantly, price will undoubtedly come down - and price is the main driver.


Well Monocrystaline dominates the market at 80%. Mono panels are extremely energy intensive products. Basically it is glass, and the price will always be a multiple of the source fuel.

Two Jewish tailors have shops next to each other named Abram and Sheth. One day Abram and Sheth are outside talking talking shop in front of their stores. Abram has noticed Sheth is very busy and Abram asked Sheth; "_what do you do to have such good business"?_. 

Sheth replies: _"I sell suits at half the cost you charge."

_Abram then asked; "_how much profit do you make"?_ 

Sheth replies; "_I sell below cost_". 

Abram then asked; "_how do you stay in business_"?

Sheth replies: "*I make up for it in volume*".


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## JRP3 (Mar 7, 2008)

Solar manufacturing technique reduces costs and increases panel efficiency:
http://www.nrel.gov/news/features/feature_detail.cfm/feature_id=1629


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## PhantomPholly (Aug 20, 2008)

JRP3 said:


> Solar manufacturing technique reduces costs and increases panel efficiency:
> http://www.nrel.gov/news/features/feature_detail.cfm/feature_id=1629


That is the sort of thing I am talking about.

Certainly, sometimes the big boys cut cost to below profit - presumably to drive their competitors out of cash and business. That is a short-term tactic that only works if you have more cash than your competitors. Long term cuts come from new techniques and materials.


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## efan (Aug 27, 2009)

Sunking said:


> Well Monocrystaline dominates the market at 80%. Mono panels are extremely energy intensive products.


you seem to be very knowledgeable on the topic!!! could you help me understand how polycrystalline compares to monocrystalline? any major disadvantages?


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## Sunking (Aug 10, 2009)

efan said:


> you seem to be very knowledgeable on the topic!!! could you help me understand how polycrystalline compares to monocrystalline? any major disadvantages?


I will try to help out as best as I can, but from a laymen and consumer POV the difference really boils down to efficiency, product life span, and initial cost.

Monocrystaline are the original crystals developed by Bell Labs in 1955 for NASA which are large crystal structure of unbroken crystals with no grain boundaries. It is a very highly refined product, requiring very energy intensive process with very large amounts of energy inputs. So much so it is very difficult for them to ever produce an EROI. Their main advantages are:



Highest efficiency compared to other technologies on the market. Efficiency is not all that important if space is not an issue, but becomes an issue with labor, materials and limited space.
Highest product life span of 80% rated power output after 25 years of service life.
On the down side they are the most expensive of the current technologies, but very mature and most reliable.


Poly or multicrytaline technologies are not as pure, heavily doped with P&N substrate material, man made synthesized crystals using chemical vaporization process sprayed on glass substrate with grain and small boundaries. 

Think of it like granulated sugar partially melted and mixed with flavor to make cotton candy blown on a stick, vs a fully melted liquid sugar to the CRACK Stage, poured, and made into a thin layer of glass. It is a waste product of integrated circuit manufacturing. It is somewhat less expensive to manufacture, but less efficient, and does not have the life span of mono products. They are very easy to recognize as they have a jewel like blue color, and highly metallic reflective quality pleasing to the eye.


Hope that helps.


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## PhantomPholly (Aug 20, 2008)

efan said:


> you seem to be very knowledgeable on the topic!!! could you help me understand how polycrystalline compares to monocrystalline? any major disadvantages?


My answer is a bit different than Sunking's in that I am only referring to articles and have no personal experience in the industry. Multicrystalline and Monocrystalline here refer to diferent types of substrate - both being made from silicone, although those terms could apply to crystals of other types of materials. Multicrystalline is slightly less efficient than monocrystalline, but has tended to be slightly cheaper to manufacture and so is favored by Chinese manufacturers. Here's an article that discusses both.

Monocrystalline is more efficient today with slightly higher cost, but there have been recent advances that may make it cheaper per watt in the near future.

Gallium Arsenide is more efficient than either silicone crystal type in converting sunlight; the drawback has been that it is more costly, but processes using only thin layers may overcome that disadvantage. I believe that solar cells for spacecraft use Gallium Arsenide because the additional material cost is offset by the lower weight / fewer square feet of panels required. From this link, a bit more than half way down the article:

"Other promising early-stage energy startups are based on efforts to circumvent well-known manufacturing limitations. For example, Alta Devices, a company in Santa Clara, California, whose founders include leading researchers from Caltech and the University of California, Berkeley, is developing a way to make photovoltaic cells using films of gallium arsenide that are only a micrometer thick. Gallium arsenide, which is widely used as an ingredient in lasers and other photonic devices, has great optical properties but is too expensive for most solar cells. The new technology, however, uses so little of the material that its price is no longer prohibitive. Alta Devices has spent the last several years perfecting the production process; it has begun a pilot line to make the photovoltaic materials next year and hopes to start commercial production in 2013."

I believe that as we continue our march into the nano realms we will discover a lot more tricks to keep making solar panels more efficient while continuing to reduce their costs.


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## efan (Aug 27, 2009)

thank you both, that was very informative!
the reason I am interested is that I have the opportunity to take advantage of 'preferential feed in tariffs' offered here, and the contracts signed between the solar power producer and the energy company are 20 years long...I know that both poly and monocrystalline will last at least that long, just wanted to see if one had any major advantage over the other. 
PS. I have already build an array using monocrystalline, and am now thinking of doing another one perhaps using polycrystalline.


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## PhantomPholly (Aug 20, 2008)

Here's an article with a cool chart showing record efficiencies by material type and assembly technologies. You can click on the chart for an expanded view.


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## Sunking (Aug 10, 2009)

efan said:


> the reason I am interested is that I have the opportunity to take advantage of 'preferential feed in tariffs'


I hope you are not talking about SREC's in the USA. That pyramid scheme collapsed here already and is worthless.


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## efan (Aug 27, 2009)

Sunking said:


> I hope you are not talking about SREC's in the USA. That pyramid scheme collapsed here already and is worthless.


Not in the USA. EU.


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