Self-Assembling Photovoltaic Cells

dhj writes "MIT scientists have developed a self-assembling photovoltaic cell in a petri dish. Phospholipids (think cell membranes) form disks which act as the structural support for light responsive molecules. Carbon nanotubes help to align the disks and conduct electricity generated by the system with 40% efficiency. The assembly process is reversible using surfactants to break up the phospholipids. When filters are used to remove the surfactants the system reassembles with no loss of efficiency even over multiple assembly/disassembly cycles. The results were published September 5th in Nature Chemistry."

Comments

Like this story from before?

[PCPackrat]

http://science.slashdot.org/story/10/09/07/0424217/Self-Assembling-Photovoltaic-Tech-From-MIT

Re:Like this story from before?

[Required Snark]

Yes. The story was disassembled into it's component letters and then reassembled to harvest more Slashdot trolls. Recycling at it's most efficient.

Re:Like this story from before?

[beakerMeep]

To be fair, the article on MIT's site is dated "September 7, 2010."

Naturally the only logical conclusion for the dupe is that MIT News hired some Slashdot editors.

Re:Like this story from before?

[snookerhog]

it starts with self assembling Slashdot entries. Before you know it, the self assembling photovoltaic overlords are installing themselves on your roof.

Re:Like this story from before?

[Genda]

Go ahead, mock Slashdot!!! Do you have any idea just how much it costs to bring a story from 09/19/2010 through a wormhole to 09/07/2010??? You should be getting down on your knees and thanking your robotic overlords that Slashdot spares no expense (not even space and time) to get you the latest news!

Re:Like this story from before?

[el3mentary]

Dude...you need to get out more.

Re:Like this story from before?

[Anonymous Coward]

It seems to have added extraneous apostrophes in the process. Check your code. It's means "it is".

Re:Like this story from before?

[Anonymous Coward]

The exce'ss apostrophe's are their on porpoise. They have been found to attract troll's more affectively.

Re:Like this story from before?

[Jeremi]

Dude...you need to get out more.

Don't bother... I've been there. Way overrated IMO.

Re:Like this story from before?

[Ihmhi]

Has NOBODY seen Stargate SG-1? This is how the replicators started, dammit!

Re:Like this story from before?

[causality]

To be fair, the article on MIT's site is dated "September 7, 2010." Naturally the only logical conclusion for the dupe is that MIT News hired some Slashdot editors.

That's not possible. The grammar of MIT's articles is far too good. It doesn't contain spelling errors that a basic spellchecker would have fixed. It doesn't have links to stories that are behind a paywall when freely accessible ones are also available. It doesn't needlessly link to someone's blog when articles a bit closer to the primary source are readily available. If it has the occasional blatant factual error that the slightest and most basic fact-checking would have corrected, this remains to be demonstrated.

To reiterate, there's no possibility that MIT News has hired some Slashdot editors. They probably list "ability and willingness to run a quick automated spellchecker" and "familiarity with English grammar" as requirements for their editors. They have little incentive to engage in the other practices I listed.

Incidentally, it's not an instance of a "grammar nazi" when you expect paid professionals who call themselves "editors" to either correctly and consistently use basic spelling and grammar or, failing that, call themselves something other than "editors." Maybe "reposters" would be a good title. The standard and the expectations are higher for "editors" who draw a wage. It's not the same situation as the Slashdot users who post for leisure and are nit-picked over issues of grammar.

Re:Like this story from before?

[derGoldstein]

Last time Slashdot recycled a story was on the 10th.
If this is what's going to happen from now on, then I'lll start recycling my posts:

"Slashdot has become so big that the left hand doesn't know what the right hand is doing, and neither hand actually READS Slashdot..."
(originally posted on Friday September 10, @04:20AM)

Re:Like this story from before?

[catmistake]

Dude...you need to get out more.

Don't bother... I've been there. Way overrated IMO.

uh... no argument here, but how do I get back in?

Re:Like this story from before?

[c0lo]

Yes. The story was disassembled into it's component letters and then reassembled to harvest more Slashdot trolls. Recycling at it's most efficient.

Did you mean self-assembled?

Re:Like this story from before?

[thynk]

AND self assembling does not necessarily mean self manufacturing or self replicating.

Now, if they were some how able to splice these photo voltaic cells into a plant or algae so you could grown a film of solar panels, now that would be cool.

Oh joy. *Another* photovoltaic breakthrough

[gestalt_n_pepper]

To be tossed in the same boxes as "may lead to a cure for obesity" or "may lead to breakthrough in cancer treatment."

Wake me when I can buy it at Wal-Mart, and if there's a penny stock or investment opportunity, I'm not interested.

Re:Oh joy. *Another* photovoltaic breakthrough

[physburn]

Yes fraid so, but i'm sure your know the reason why photovoltaic technologies very important, oil running out and global warming aren't exactly new news either.

---

Solar Power Feed @ Feed Distiller

Re:Oh joy. *Another* photovoltaic breakthrough

[JWSmythe]

Ditto.

    Anyone can make any sort of wild "forward looking statement". I may have designed a zero emissions perpetual motion power generator. If I can get enough hits to my site, and persuade enough investors, I'll make a fortune!

    Come visit my site today! We'll all be rich!

    I'm still waiting for flying cars, obediant robots to clean the house, distant places to live or visit, green energy, world peace, and a few other things. World of tomorrow my ass. When I was a kid, they kept telling us about how by the year 2000 everything would be so different. Ya. I have gray hair, no flying car, and moon weekend home. Tell your grandchildren that all the lies of things coming in the year 2100 are lies! Lies! The cake is a lie!

    ({snicker})

Re:Oh joy. *Another* photovoltaic breakthrough

[got2liv4him]

That's what they tell us...

Re:Oh joy. *Another* photovoltaic breakthrough

[sirrunsalot]

Anyone can make any sort of wild "forward looking statement". I may have designed a zero emissions perpetual motion power generator. If I can get enough hits to my site, and persuade enough investors, I'll make a fortune!

It's been done. But I get the sense they're more desperate than filthy rich.

Ya. I have gray hair... The cake is a lie!

I love that you have gray hair and said, "The cake is a lie!" In fact, I'd say this shows we've already entered a brave new world even if flying cars haven't really panned out. Fact is, it's 2000 and things are different. Even in my lifetime (no gray hair yet) computers and communication have become completely pervasive in every aspect of our lives. Things will be different in 2100 in ways you can't imagine—and won't really need to worry about—but it's just that the reporters get carried away and want to know every potential application of things like this. And the scientists who spend all day in those cramped labs start daydreaming about sex-bots and life goes on.

Re:Oh joy. *Another* photovoltaic breakthrough

[Idiomatick]

We do have car-planes ... have for a really long time. They just aren't that great. What you really want is a CHEAP economical car plane that can take off like a harrier jet from your driveway.

We do have obedient house cleaning robots. The roomba vacuums for us and there are robots to clean the eaves, wash floors/windows and clean pools. The jetsons was 2062, so we still have some time before you can complain about the quality of those products anyways. I'm not sure what you are complaining about here... Go order some house cleaning robots online?

While we are no where where we could be for space travel/exploration that is because funding collapsed, during the Apollo missions we WERE on a trajectory to visit mars by now. And no one really thought the other things would happen by now.

Tech has a better track record than people on /. seem to give it. But really it does quite well. We just wish it were better. Good thing too, thats why we keep advancing.

Re:Oh joy. *Another* photovoltaic breakthrough

[Lennie]

I prefer climate change, instead of global warming. Climate change doesn't add to the confusion. But it was "colder in winter this year", etc.

Re:Oh joy. *Another* photovoltaic breakthrough

[daveime]

Of course the overriding theme of "Global Warming" is that extra CO2 is causing extra warming. If you make the theme "Climate Change", and then point out that this winter was colder than last winter, some people might start asking awkward questions like "what the fuck is making it colder ?".

Perhaps CO2 also flies south for the winter ?

Re:Oh joy. *Another* photovoltaic breakthrough

[mr_mischief]

For goodness sake, we can't have honesty for the fear of awkward questions now? Are you over there welcoming our new anti-sex-ed overlords?

Solar power has the same problem right now as Linux. Stop snickering in the back, I'm serious and I'm going somewhere with this. People keep trying to convince others to use Linux because of the problems with Windows. There are flaws in that, though. For one, there are improvements to Windows from time to time. A big one was going from Vista to 7 so quickly, with its better UAC and better performance. Another has been Microsoft's better security over recent years, even though there are still issues. When you sell Linux (or OS X or any other OS) on Microsoft's weaknesses, then counter-arguments are easy to make based on improvements to Windows. People are used to it, and most don't care that it's proprietary and closed-source because they themselves aren't going to mess with the code anyway. There's plenty of infrastructure around it. They just don't see the weaknesses as that big a deal for now, and won't switch for ideology. They'll switch when you can show them that for their situation Linux (or, again, OS X or QNX or Solaris or BSD...) is actually just as easy an just as cheap and offers some additional advantages, too.

Do you know the problems with marketing solar right now? It's being compared to oil. People are used to oil. There's lots of infrastructure around it. Advances are being made to make burning oil more efficient. The price tends to come back down after any big spike. The cars have better driving range and lower initial purchase cost running on oil. Sure, it'd be better for society as a whole in the long run if we could use solar (or wind, or hydrogen fuel cells, or geothermal, or some combination). Yet people are going with the easy, convenient devil they know until something solves their particular problems better.

A supplementary technology that wants to take over a small part of the market can be almost as good and in theory better. Some people will make an investment in their future. Some will even spend more than they would otherwise just to advance the technology and the agenda to get it out there and raise awareness. That's fine if you're okay with having a supplementary position for a technology. This is where OS X and Linux are on desktops, and it's where solar is for energy.

A replacement technology has to be better for the masses right now. People as a whole are too self-interested to throw away existing infrastructure and existing investments to pay a higher price for solutions almost as good or even as good as what they've got. They either want very nearly as good for a lot less investment of both time and money, as good for somewhat less, or will pay very slightly more for a huge return over what they have. This is where OS X is for workstation-class machines at many media production houses and where Linux is for server farms. It's where solar is for small niches like satellites, weather stations, handheld calculators, and electric livestock fences.

For any OS to replace Windows on a large share of mainstream desktops, it has to offer the kind of third-party support Windows does for less, or be not just somewhat easier to use and more secure but far easier and impenetrable for the same cost. You have to sell people on its strengths, not on the weaknesses of the incumbent. The incumbent might be bumbling and have its share of false starts, but it's getting better itself and still has a lot of support. Yes, I'm tempted to bring Congressional politics in after that...

Photovoltaic solar, solar thermal, wind, geothermal, fuel cells, and other technologies for energy suffer the same position. They are great technologies, and they are getting better. Oil, coal, and natural gas are the big boys in the market, though. There's infrastructure around them. Hydroelectric has made inroads at the expense of farmland and forests. Solar has its niches. Geothermal with pumps powered by the grid is becoming more popular for home hea

Re:Oh joy. *Another* photovoltaic breakthrough

[Eclipse-now]

Wake me up when battery technologies are 1000 times cheaper. Then I might actually be interested in solar PV again. Otherwise, we need reliable baseload power and no matter what the renewablists say, wind & solar can't do that yet. Not 24/7/365.

Another recycled story?

[WSOGMM]

Ok, it's our job to recycle the conversation. I'll start with the first comment from the last article (but recycled into a new comment): Call me when I can pick it up at Lowe's.

Re:Another recycled story?

[suomynonAyletamitlU]

OiouooeeeoeaioIaieioeoeaaieueeioaeoe ktsrjbtrcclthcnvrstnllstrtwththfrstcmmntfrmthlstrtclbtrccldntnwcmmnt yy ,'.'():

aeeIaiiuale CllmwhncnpcktptLws '.

Would it kill you to organize your recycling? You don't even have to alphabetize it, just separate the vowels and consonants from the garbage, to make our lives easier. And we don't recycle y's, either, you can just throw those away.

Re:Another recycled story?

[catmistake]

And we don't recycle y's, either, you can just throw those away.

I'd hang on to them, they're collectable as hell to those that collect them. You never know when you'll run into a phiosopher or some y's guys, and then you can pick up a few bucks.

Over simplification

[Scotty L]

They are talking about flourescent fat and detergent, right?

40%!

[ebonum]

One of the problems with solar that no one seems to talk about is the system is limited by the size of the southern facing roof on a house. In the case of desert power generation, a large amount of land is required. If solar cells can make the leap from 12% efficiency to 40%, this will change everything. Your roof installation will be able to produce a much more meaningful amount of power especially in the context of trying to run air conditioning during day light hours. More importantly, the same applies for many malls, warehouses, factories, etc. At 12% efficiency, the roof of a mall is simply too small to generate enough power to be off the grid during the day. The amount of land required per MegaWatt will drop considerably. At 40% efficiency solar starts to become a much more viable option.

Re:40%!

[DFJA]

One thing that is worth remembering is that plants have an energy conversion efficiency of about 1%, if I remember correctly. So although 12% may seem low it is still a lot better than nature achieves. This is worth bearing in mind when you see fields of oil seed rape or other energy crops being grown - it would be far more efficient to cover the land area with photovoltaics. You could even grow sheep in the gaps between the panels.

Re:40%!

[sunspot42]

Nobody needs to go "off the grid" for solar to become viable. It all comes down to $ per kw/h. Even if solar can only meet 10-20% of your needs, if you can recoup your investment in a reasonable timeframe, solar is viable.

If you live in Phoenix and have a $200 a month light bill, a hypothetical $2,500 solar array that saves you just $40 a month but which lasts for 20 years looks like a pretty good deal - it'll pay for itself 3 times over. Unlike, say, a $2,500 3D television. And of course there's the network effect - if everybody installs one of the things, demand for electricity declines by 10-20% - as does the price - meaning you could all be saving a lot more than just $40 a month. That'll also spill over into the cost you pay for locally-produced goods and services.

Re:40%!

[MarkvW]

That's true, but plants turn carbon from the air into a solid. If my solar panels could manufacture carbon fiber bicycles, I'd be really happy.

Re:40%!

[cheater512]

Actually photosynthesis tops out at 25% efficiency.
11% using the sun's spectrum.

It all depends on where you want to measure the efficiency.

Re:40%!

[physburn]

Don't know where you get the 12% number from. Sun Power solar cells are already 22% efficient, while the average commercial solar cells are 17 or 18% efficient.

---

Solar Power Feed @ Feed Distiller

Re:40%!

[Peach Rings]

demand for electricity declines by 10-20% - as does the price - meaning you could all be saving a lot more than just $40 a month

I wonder though if it's possible for energy costs to go down. It might be like bandwidth, where once the ISP has invested in the architecture to support a certain throughput it doesn't really cost them much to run it at full capacity and they don't save any money by turning things off and letting fiber go dark.

Hydroelectric and nuclear power aren't ever going to be turned down, and it makes no sense to do so because it saves no money. Oil is sort of the same thing: x barrels of oil gush out of the seafloor monthly, and it's a constant flow. All the infrastructure and support for a certain amount of power going to the grid is almost completely paid for.. if people don't use it, it's not saving the energy companies any money and prices won't budge.

Re:40%!

[Black Gold Alchemist]

FYI, at 20 percent efficiency in California, here's the math. One watt-peak = 2 kWh/year. One house = 11040 kWh /year, thus = 5520 watts peak.
At 1 kW/m^2 (100 percent), you get 5.5 m^2, which means 2.3 meters (7.7 feet) on a side.
At 40 percent, you get 13.7 m^2 = 3.7 meters (12 feet) on a side.
At 20 percent you get 27.6 m^2 = 5.5 meters (17.23 feet) on a side.
At 10 percent you get 55.2 m^2 = 7.4 (24.3 feet) meters on a side.

Re:40%!

[JWSmythe]

    Actually, you hit on something that must be adjusted for solar to work. Modern structures are rarely insulated enough. That insulation can be natural (semi-subterranean homes), or artificial (like XPS, EPS, and fiberglass). On a few occasions, I've had opportunities to look inside residential walls. Rarely are the walls insulated well. They're insulated well enough to pass inspection, and meet the bare minimum of the building codes. For example, I was replacing the wall around a tub/shower. On the outside wall, there was only about 3/4" encapsulated fiberglass behind the concrete block wall. I guess that was enough to pass inspection at the time. The person who owns the house noted that in the summer, the A/C couldn't keep up. All you had to do was touch any of the interior walls. You could feel the outside heat on the exterior facing walls (from inside) and even the interior walls (not facing outside). The heat from the attic was heating the interior walls too.

    As long as it is acceptable to build houses as cheaply as possible, we will continue using more power than is required. So yes, solar can be way too expensive to supply even the power to just cool the house.

    There are some very interesting projects that people have done for alternative methods of cooling homes. While you may be able to hack something together from your local big-box hardware store, you'll never see a full kit nor instructions on doing it there. The building codes in your are may expressly forbid some. I know plenty of people who live in planned communities, where they are not allowed by deed restrictions, to put up solar panels, windmills, or even change the construction of their roof (a white roof reflects more solar energy than a black shingle roof).

Re:40%!

[elashish14]

Where are you getting this 12% efficiency factor from? That may be a decent figure for thin-film solar cells, but single-crystal silicon solar cells (the highest manufacturable efficiency) are well past 20% right now. And I don't believe the article at all when it says 40% power efficiency. Even the most advanced multijunction cells barely eek past 40% efficiency (and I think that's only due to the light being highly concentrated - >100x).

What they probably meant is that the quantum efficiency is 40%, especially since it's impossible for any solar cell to exceed 86% within the detailed balance limit. 40% is nothing special compared to existing technology, though it's surprisingly high for a novel technology like this.

Re:40%!

[strack]

thats a unfair comparison of the tangible monetary benefit of a solar array vs the intangible entertainment value of a 3d tv.

Re:40%!

[Black Gold Alchemist]

There are some very interesting projects that people have done for alternative methods of cooling homes.

Do you have any good links on this regard? I'm quite interested in this. I've been looking at (though not building yet) distillation refrigerators using solar heat as fuel.

Re:40%!

[Black Gold Alchemist]

I disagree. Let's assume I can sell you a very very cheap solar cell that runs at 2% efficiency.

We already have that. It's called biofuel.

Re:40%!

[Anonymous Coward]

Negative. You're assuming that if power use decreases by 10-20%, the cost of power will decrease. It will not. The power company will charge more for less.

Also, $200/mo light bill?! Maybe for AC in Phoenix... but that's a lot of lights. :)

Re:40%!

[Black Gold Alchemist]

Congrats on getting the sig joke.

Re:40%!

[celle]

"At 20 percent you get 27.6 m^2 = 5.5 meters (17.23 feet) on a side.
At 10 percent you get 55.2 m^2 = 7.4 (24.3 feet) meters on a side."

Ok, who owns/rents/whatever a house that's less than 25 feet per side in this day and age?

Re:40%!

[sunspot42]

Hydroelectric and nuclear power aren't ever going to be turned down,

Not entirely true, as someone has already noted. Hydro especially can be turned "up and down" as demand dictates. We burn very little oil for electricity - it's too expensive for that. We do burn a lot of coal though, and if solar were capable of supplying just 10-20% of our energy needs, it would certainly put a dent in the cost of coal-generated power.

Re:40%!

[sunspot42]

Who cares? Use solar where it's economical. Use something else in Lansing.

Re:40%!

[sunspot42]

Let's assume I can sell you a very very cheap solar cell that runs at 2% efficiency. In this case, you will quickly recoup your investment, but you aren't producing much power. Do you plan to make your roof 5 to 10 times as large?

No, but if they're cheap enough at just 2% efficiency to pay for themselves quickly, it might make sense to cover the sides of buildings with them, as well as parking garages, covered parking spaces, the sides of freeways, etc. So in aggregate you could end up generating just as much power as you might with more expensive, more efficient cells, just by carpeting every exposed surface with them.

However, most cells these days are in the 10% and up efficiency range, and growing more efficient (and cheaper) with each passing year. So your hypothetical seems kinda unlikely.

Re:40%!

[sunspot42]

Negative. You're assuming that if power use decreases by 10-20%, the cost of power will decrease. It will not. The power company will charge more for less.

That's not true. The cost of power in many places in the US (and elsewhere, I'd imagine) varies during the course of the day depending on demand. So when demand is low power is cheap, but when demand is high (in the sunbelt, on hot sunny days), the price of power skyrockets, sometimes to ten times or more what it costs when demand is low.

Solar cells have the unique property of generating maximum power just at the time when utility rates peak in the sunbelt. So looking at the average cost of power and comparing that to the cost of power generated by a solar cell doesn't begin to tell the whole story. Look at the peak cost of power and see how much of that a solar installation will shave off of your electric bill. And of course, thanks to the network effect, if everyone starts installing these things, the peak cost of electricity across the sunbelt will implode. Either way, consumers win. The power companies could try to jack up the cost a little, but they aren't going to be able to jack it up tenfold.

Also, $200/mo light bill?! Maybe for AC in Phoenix... but that's a lot of lights. :)

We were paying $200 a month in Phoenix to cool a 4 bedroom home 25 years ago. I'd imagine it's substantially more expensive today, especially when you factor in all the electronic, power sucking gizmos in the average home of 2010, from massive HD sets to power-guzzling desktop computers. My Core 2 box and its two LCD monitors consumes about 5 times as much electricity as my old Atari 800XL, 1050 disk drive and Amdek Color I monitor did back when I lived in Phoenix 25 years ago.

Re:40%!

[Ol Biscuitbarrel]

I wonder about the costs of scaling up here, since this process uses electrodes of platinum and silver.

Re:40%!

[camperdave]

It's all well and good to talk about Phoenix. What sort of power do you reckon you could wring out of those four hours of sunlight that brighten our northern winter days?

Re:40%!

[I(rispee_I(reme]

Amen:

3DTV with no broadcast programming yet: $2000-3000

Watching your wall-eyed toddler walk into plainly visible obstacles: Priceless.

Re:40%!

[Black Gold Alchemist]

Pretty much no one. If one did own such a house, unless they are doing aluminium smelting, their electricity consumption would probably be lower. Less lights and all. The goal with solar is to get it so that the electricity generation of a solar panel per unit area is larger than the electricity consumption per area of the house.

Re:40%!

[zrbyte]

40% is just the efficiency of the individual molecules in converting photons to electric charge. The overall efficiency of the device must be abysmal. The real breakthrough here lies in the fact that these guys can disassemble and reassemble the component light harvesting molecules of the device. This is important since photovoltaic devices using organic molecules are prone to degradation during irradiation by sunlight (see: http://en.wikipedia.org/wiki/Polymer_solar_cell).

Re:40%!

[DFJA]

Actually photosynthesis tops out at 25% efficiency. 11% using the sun's spectrum.

It all depends on where you want to measure the efficiency.

Can you provide a link for that 25% figure? If my 1% figure is too simplistic or just plain wrong I'd like to know about it - it was years ago I read it.

Re:40%!

[baegucb]

Speaking from experience, when demand for a utility goes down 10-20%, the utility company will try to raise rates 10-20% based on the fact that they have had a drop in revenue, but still have the same costs.

Re:40%!

[Anonymous Coward]

As long as it is acceptable to build houses as cheaply as possible, we will continue using more power than is required. So yes, solar can be way too expensive to supply even the power to just cool the house.

The sad thing is that building poorly insulated houses does not, by any mean, means that the house is built "as cheaply as possible". In fact, once you account for the projected energy spending, anyone will easily understand that cheapening out on the thermal aspects of any house ends up constituting an extra source of maintenance expenses. Any competent civil engineer who is employed designing the thermal behavior of any project is forced to design details such as the insulation as a function of the energy which is needed to preserve the interior with a comfortable environment. That means that the project must be based on a cost/benefit analysis, which is performed with a certain time frame in mind to be able to the investment in insulation/HVAC to break even.

Re:40%!

[strack]

well in that case it would be the cost difference between a tv with the high refresh capabilities needed for 3d, and a equivalent size tv without those capabilities. which is only probably 100 - 200 dollars difference.

Re:40%!

[cheater512]

Oh sorry I forgot to include it.
http://en.wikipedia.org/wiki/Photosynthetic_efficiency
That article goes in to quite a bit of detail.

Re:40%!

[Nikker]

If you check out TFA a comment submitted by H2Wizard

There is a serious problem with the paragraph comparing the solar conversion efficiency of this system with photovoltaics. The 40% given by the authors is a quantum yield for a single wavelength of light (785nm). The best solar cells have a quantum yield of better than 95% at all wavelengths across the entire visible and near IR spectra, more than twice as efficient as what is reported here. The 20% efficiency given for solar cells is the efficiency for converting the entire solar spectra into electricity. The solar conversion efficiency of this system is several orders of magnitude lower than that.

That paragraph needs to be deleted.

Editor’s note: The article has been corrected to remove the comparison with the efficiencies of conventional PV devices (“or about double the efficiency of today’s best solar cells.”). The paper does not make this comparison.

So essentially the numbers mentioned in the article have no mention of actual efficiency other than at the quantum level (the energy still has to be stored which is where most solar cells achieve the 10-20%(of the entire spectrum), so if we assume the losses are identical we are much lower than 1% efficiency. The interesting thing about this research is the ability to reconstruct the molecules involved in the harvesting, finding a more efficient method (TFA states it can possibly reach 100%) but again in this implementation is only recovering electrons at the 785nm wavelength.

As for your argument that we should only consider individual deployments at this time isn't completely accurate. By first deploying in areas such as the Nevada desert and other sparsely populated areas we get companies involved which employ their own scientists. It would be similar to how the electronics industry would reform its self if each customer had a background in computer science, overnight most of the products would disappear since a great deal preys on the ignorance of the individual consumer. If and when photo voltaic energy becomes a commodity item we all know that the industry will be infiltrated (as it is now) with inferior and incomplete products with big hype and short term gains. Someone who is investing a magnitude of magnitudes more will cut most of the cruft from the available technologies to select the one with the highest ROI. Once this becomes the established course the consumer industry will compete with each other producing that technology rather than shots in the dark. Making individually deployable cells will be more refined from this process rather than starting with the end consumer since they are unable to really discriminate the available technologies and many will choose improperly supporting poor companies and scaring other adopters via bad press.

Re:40%!

[Maury Markowitz]

> If solar cells can make the leap from 12% efficiency to 40%

Umm, you need to read the statement again. The statement is that the _wiring_ is 40% efficient. The silver wires used on the panels on my roof is about 90%.

*yawn*

> run air conditioning during day light hours

False dichotomy. Every watt you generate on your roof is 55% of a watt that doesn't come from coal. That is a worth doing.

Going "off grid" for a mall is pointless. The grid is excellent for delivering power 24/7. Forget about replacing the grid, think about replacing coal.

Maury

Maury

Re:40%!

[Abstrackt]

Do you have any good links on this regard? I'm quite interested in this. I've been looking at (though not building yet) distillation refrigerators using solar heat as fuel.

I'm not sure if this is exactly what you're looking for, but I've done a lot of research on building a passive house in a climate with extreme temperature variations and the following links made good starting points:

http://en.wikipedia.org/wiki/Passive_solar_building_design
http://en.wikipedia.org/wiki/Superinsulation
http://en.wikipedia.org/wiki/Ground-coupled_heat_exchanger
GreenBuildingTalk forums

Other options include designing the overhang of your house to be long enough to block most of the sun during the summer when it's higher but short enough to allow most of all of the sun through in the winter when it's lower, planting leafy trees with a lot of little branches near windows (the leaves block light during the summer and the small branches allow it through during the winter), and one that I cannot stress enough: the better your insulation is the more comfortable you'll be.

In my current house the biggest change came from putting in triple-pane argon-filled windows. We could only afford to do half the house at a time and the half of the house with new windows was much more pleasant to be in both during the summer and the winter.

Re:40%!

[Maury Markowitz]

> but single-crystal silicon solar cells (the highest manufacturable efficiency) are well past 20% right now

Commercial cells available in quantity are lower, about 15 to 17%.

That's only the cell itself. If you consider the losses due to resistance on the front surface, reflection off the wiring on the front face, wiring losses, and the area of the panel that is not covered by cells (look at an image of any mono-Si panel) you'll get PANEL efficiency around 14% for just about every panel in the world.

Maury

Re:40%!

[Mindcontrolled]

If you want to be real efficient, I guess you gotta take some clues from the usual "Passive House" concepts. Now, passive house in it's original form is more geared towards temperate to cold climates, but the key element should be the same in a hot climate, namely controlling the ventilation in the house tightly and insulating as good as possible. Exchange humidity and heat between incoming and outgoing air using ERV, cool the incoming air in a second stage with an air-to-ground heat exchanger and in a third stage with a solar driven absorption heat pump. Combine that with passive measures like painting the roof white or planting stuff on it, and providing ample shade for the sun side, and you should be set.

Re:40%!

[More Trouble]

Speaking from experience, when demand for a utility goes down 10-20%, the utility company will try to raise rates 10-20% based on the fact that they have had a drop in revenue, but still have the same costs.

That's what I've seen in Central Virginia, as usage dropped. Which makes solar (or whatever) 10-20% more competitive. Of course, these are requests by the utility to raise rates, since the utilities here remain regulated.

This effect is not limited to electricity, either. Same thing happened with our water utility -- all that effort to get people to conserve water really paid off! If you reduced your usage, your bill stayed about the same. If you didn't reduce, then you got to pay more.

Re:40%!

[baegucb]

Thank you. I did state they'd "try to raise rates". But I hadn't thought through all the implications. But in my case, solar isn't a good match for my circumstances, since I live way north. And until I am sure it's financially and physically viable for me to do so, I won't be doing that. Think of the problems involved with hail during the summer and heavy snow with little daylight during the winters, But I do appreciate your comment since it got me thinking about alternatives again :)

Re:40%!

[Black Gold Alchemist]

All that's good. Thanks. The only problem is I don't know if my parents would like my green energy obsession to involve nearly a full rebuild of their house.

Re:40%!

[Black Gold Alchemist]

Like I said in replay to the other post, the only problem is I don't know if my parents would like my green energy obsession to involve nearly a full rebuild of their house. Thanks for the links. That adsorption heat pump, especially.

Re:40%!

[anyGould]

I disagree. Let's assume I can sell you a very very cheap solar cell that runs at 2% efficiency. The price is so low that the $ per kw/h is very low. However, this is not a viable option. In this case, you will quickly recoup your investment, but you aren't producing much power. Do you plan to make your roof 5 to 10 times as large?

$ per kw/h is important, but it is not the only important metric.

I do agree that there is no absolute need to be off the grid. However, it seems to me that a logical goal for the technology should be: a typical house should be able to cover its southern facing roof with solar panels and produce enough power to run lights, refrigerator, and A/C on a summer day at noon.

I'd say a more realistic goal is to be saving money.

Let's take another look at that 2% grid - if that solar power is cheaper than buying from the grid (after taking the infrastructure into account), then why wouldn't you use it? It's cheaper than the grid.

Re:40%!

[anyGould]

Actually, check out Net Zero Energy Home (our local building's site is here). The idea was to balance out over the course of the year - you'd be drawing power during the winter, but supplying during the summer (when we get those nice sixteen hour days).

The cost of building was coming down nicely as well - if/when I build a home, I'll be seriously looking at one done this way.

Re:40%!

[uninformedLuddite]

Do you have any good links on this regard? I'm quite interested in this. I've been looking at (though not building yet) distillation refrigerators using solar heat as fuel.

This is a good start. Earth tubing is easy to understand, easy to explain to luddites and is a fairly easy addon to an existing structure. And before anyone points it out I like the word easy.

Re:40%!

[Black Gold Alchemist]

Wow. Good link.

The thing I am interested in about ground source heat pumps is that I have read that temperatures in the ground go down to 55 F at 4 feet and hold relatively constant. Below that, they get hotter. What I am interested in is how this relates to the metal gadolinium (and some other compounds). Gadolinium is magnetic at below 65 F, and non-magnetic above. If you have a gadolinium (or gadolinium plated) wheel immersed in a 70 F bath of water, and cooled by a 55 F air/water source, part of the wheel will be magnetic and part not. If a magnet is placed against the wheel, it will spin with great torque, thus generating electricity.

Re:Obligatory ISR

[Sulphur]

In Soviet Russia, self-assembling photovoltaic cells develop you.

Yeah Yeah. Now how do I get out of this cell?

Not really.

[S-100]

First, California is far from a typical location when it comes to solar radiation. The same setup up north would be multiples of that size, plus all you are doing is matching 100% of the load, but over a 24 hour period, you only get 30-40% of the rated output. So don't forget those batteries and the expensive inverters.

Re:Not really.

[Maury Markowitz]

> The same setup up north would be multiples of that size

We use 1150 kWh per kWp in Toronto. The Bay Area gets about 25% more. So "multiples" in that case is a little less than "2".

Here's some numbers to consider. The local power company pays 80 cents per kWh for rooftop solar (yes, you read that right). At that price, a system normally pays off in 10 years or less. That means if all you want to do is break even, it would be at about 40 cents a kWh.

Now that's a lot more than you pay now (in most places). But that's _retail_cost_. The cost of installation is perhaps half that if you consider very large installations, 10 MWp and up. So in those cases, the breakeven price is likely closer to 25 cents.

That's in Toronto. In Mohave and the Great Sandy Desert, it's better by about 50 to 100%. So we're looking at maybe 12.5 to 20 cents a kWh. Which is quite reasonable, and on the same order as wind power.

Now that is a lot more expensive than coal, which is somewhere around 4 to 6 cents per kWh. However, it's unlimited and clean. How much is that worth?

Maury

Re:Not really.

[S-100]

What's it worth? Depends upon who you are referring to. Some solar users are the recipients of cash gifts from other people in the form of government subsidies. So everyone else is participating in paying a small group of other people. When assessing solar's economic viability, one should make a distinction between the actual costs vs. the subsidized costs borne by the public via government subsidies. As for multiples, there's an EPA solar calculator form that will predict the solar output in a given location. My location in the northeast has a solar multiplier of less than 3, while much of the southwest has a multiplier over 7. To me, that's a "multiple".

Wrong approach

[S-100]

For decades I've been hearing about these miracle solar cells that will be available "real soon now", but they are all based on this precious technology to make them smaller and more efficient. Why the overwhelming focus on efficiency? Better to focus on manufacturability. The current cells are incredibly fragile and fussy, so they get put on the roof, which makes everything more complicated - efficiency is then inordinately important, maintenance and installation are more complicated, and nobody will be admiring that NASA hardware cluttering up the neighborhood. So let's come up with a solar cell that is 1% efficient, but that can be laid by the truckload like asphalt or cement. Imagine if we could tap solar power from our driveways, patios, and streets? Get it off the roof. Maybe make a net that can overlay a grass lawn and handle typical lawn use? Overcome the precious nature of current solar cells with a simple system that can make up for those disadvantages by being ubiquitous.

Not For Sale Yet

[Plekto]

Title pretty much says it all. I'm not interested in "cheap" and "easy" and "free" energy or anything else if it's not going to ever make it to market. As it is, despite several years of "breakthroughs" in solar power, if you went out today to get solar installed for your home, you would be using 1980s era technology at thousands of dollars per KW.

Wake me up when I can actually buy any of this.

$20?! awww, I wanted a peanut!

[Thud457]

I'd prefer some magic beans that grow a space elevator.