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Hairy Solar Cells Could Mean Higher Efficiency

ScuttleMonkey posted more than 5 years ago | from the warm-fuzzy dept.

Power 203

kitzilla writes "Two research groups working independently have come up with what they say are cheap processes for growing nanowires to be used with solar cells. The 'hairy' cells provide a direct path for electrons collected at the panel face to reach an electrode, something which has the potential to dramatically improve system efficiency."

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203 comments

Not first (1, Funny)

jack2000 (1178961) | more than 5 years ago | (#23467766)

Any one who writes first deserves to be banned! Also who sees this to be the hair of cyborgs...

Re:Not first (-1, Offtopic)

Columcille (88542) | more than 5 years ago | (#23469174)

Hairy solar cells... Does this mean we are one step closer to slightly greasy solar atoms that will help people grow skin?

Anonymous Coward (2, Informative)

Anonymous Coward | more than 5 years ago | (#23467804)

solar cells are pn junctions and DO NOT Collect electrons. i am to lazy to get into solid state theory right now. so go figure how exactly pv cells work.

Re:Anonymous Coward (5, Informative)

QuasiEvil (74356) | more than 5 years ago | (#23467922)

AC's got it right. For those who are TLTRTFM (Too Lazy To ...), what the poster should have said is that they help channel charge carriers away from the junction so that they don't immediately recombine. *That* is one of the holy grails of PV design, and one of the reasons that current production cells are incredibly inefficient.

Let me guess... (5, Funny)

kiick (102190) | more than 5 years ago | (#23467806)

They expect to have something ready in 3 to 5 years.

If every solar cell advance that was announced actually led to improvements of solar cells you could actually buy, then they would be 99.9999999% efficient and cost less than crackers.

But I'm not bitter, nooooooo.

Re:Let me guess... (4, Informative)

frying_fish (804277) | more than 5 years ago | (#23467894)

Slight problem at the moment is band gap, and tuning a semiconductor to have the appropriate bandgap that will cover the visible spectrum. Currently there is no single device that is sensitive to the whole visible spectrum, but there is research into this. This is one of the major reasons for the low efficiency in solar cells.

Re:Let me guess... (4, Insightful)

tepples (727027) | more than 5 years ago | (#23467934)

Currently there is no single device that is sensitive to the whole visible spectrum
Then why not have some sort of dichroic reflector [wikipedia.org] pass specific wavelengths to specific PV cell banks?

Re:Let me guess... (3, Interesting)

WhiteDragon (4556) | more than 5 years ago | (#23468296)

Currently there is no single device that is sensitive to the whole visible spectrum
Then why not have some sort of dichroic reflector pass specific wavelengths to specific PV cell banks?
Good idea, but someone beat you to it [uspto.gov]

Re:Let me guess... (2, Insightful)

arotenbe (1203922) | more than 5 years ago | (#23469888)

Thus proving something everyone on Slashdot already knew: when it comes to rapidly advancing technology, patents do nothing but move the state of the art back 10 or 20 years.

Re:Let me guess... (1)

H0D_G (894033) | more than 5 years ago | (#23469350)

Because reflectors can cause energy loss. better way to tune a semiconductor is using controlled dimensionality- use Quantum Dots.

Re:Let me guess... (1)

g0dsp33d (849253) | more than 5 years ago | (#23470038)

Wouldn't micro (nano?) bands of prisms and repeating strips of particular frequency sensitive solar panels work as well?

Re:Let me guess... (0)

Anonymous Coward | more than 5 years ago | (#23469988)

As described, the filters would not help. Filters, by nature, only pass a portion of the spectrum fed to them. The light reflected (in the case of dichroic filters) cannot be put to use by the photovoltaic device. Now, absorption and re-emission in a usable frequency range, as mentioned in a post below, would be beneficial.

Re:Let me guess... (3, Informative)

chuckymonkey (1059244) | more than 5 years ago | (#23467900)

Personally I love solar voltaic panels with a little of that canned cheese on them. On a more serious note, why do people not focus on the tech that we have now? For instance if you want solar the solar thermal systems are pretty cheap to build and have decent efficiency. I just don't get why everyone is so stuck on solar voltaic which is as someone else said in a perpetual early adoption stage when a good chunk of baseline power could be provided by solar thermal.

Re:Let me guess... (1)

timmarhy (659436) | more than 5 years ago | (#23468006)

because solar thermal is even more of a joke than PV is....

Wow, are u clueless or what (4, Informative)

Anonymous Coward | more than 5 years ago | (#23468358)

Thermal solar is the lowest costs of all AE except for hydro. At this time, it is the same costs as a recent coal plant i.e. a plant that is cleaner than average. Of course, the solar thermal is clean all the way around.
In addition, it is fairly easy to store the heat in salts and generate during the night. Spain, Arizona, New Mexico, Northern Africa, etc. are all headed in GW size of solar thermal. Spain expects to sell power back to its northern neighbors at a tidy profits. Arizona has a 1/4 GW install going in. In addition, another group is close to building a 1/2-3/4 GW in NM or southern CO (possible to take advantage of 3 different power companies and 5 states incentives).

All in all, the only joke is a fool like you.

Re:Wow, are u clueless or what (1)

kesuki (321456) | more than 5 years ago | (#23468516)

solar thermal has a number of problems, though, not the least of which is that pipes that are gotten very hot by the sun tend to burst or at least fracture much more frequently than in other applications...

in systems large enough to generate megawatts of electricity there are solutions to this problem, but systems meant to be installed on top of a residential roof are notoriously bad for needing to be repaired every season, for some unlucky souls...

Re:Wow, are u clueless or what (1, Interesting)

Anonymous Coward | more than 5 years ago | (#23469012)

but systems meant to be installed on top of a residential roof are notoriously bad for needing to be repaired every season, for some unlucky souls...
Your anecdote is stale. It was also retired two decades ago. Modern systems are reliable to the degree of other residential systems. This is due to engineering and manufacturing improvements

Re:Wow, are u clueless or what (1, Interesting)

Anonymous Coward | more than 5 years ago | (#23470632)

This weekend i am giving a tour of a residential roof top solar thermal system that has been in operation for 20+ years. It only went through one upgrade during that time.

There may have been problems with systems installed back in the 70s but few problems with modern systems.

In China and Europe there thousands of these systems installed and they have proven very reliable.

Not sure why these myths are so persistent.

Re:Wow, are u clueless or what (2, Interesting)

caffeineboy (44704) | more than 5 years ago | (#23468632)

..and I'll believe it when I see it.

Planned installations chasing incentives are a far cry from power plants installed to meet grid needs.

24h power (storage and retrieval of energy) is unnecessary system complexity when you are not looking to replace the current grid, and at their current level of deployment (nil, pretty much) this is not a concern. You might want to co-fire with natural gas to avoid thermal cycling of your plant like they do at Kramer Junction in CA, but that's beside the point.

Furthermore, there is a strong disincentive to producing 24h, and that is the overnight bulk rate for electricity - maybe $.06/kwh vs more than $.20 at peak when you have the solar resource.

Re:Wow, are u clueless or what (1, Informative)

timmarhy (659436) | more than 5 years ago | (#23469454)

nonsense. the largest thermo solar power plant is just 64 mega watt - enough for 15,000 homes. compared to coal fired stations that can supply 700,000 homes, yes it's a JOKE.

Re:Let me guess... (1)

ShieldW0lf (601553) | more than 5 years ago | (#23468424)

This new technology has a liability in that it breaks down when exposed to air, but if they could be manufactured and deployed in space, they might prove very effective. I find that a lot more interesting than the liquid salt solutions, personally. Cool shit.

Re:Let me guess... (4, Insightful)

Tweenk (1274968) | more than 5 years ago | (#23468716)

a good chunk of baseline power could be provided by solar thermal.
Baseline power is the minimal power required during the day, so it has to be supplied constantly. Solar thermal plant output drops to 0 watts at night unless you use some means of energy storage, and is severely reduced during the winter or when there are thick clouds, so they're not suited to supplying baseline power unless a reliable means of storing huge amounts of energy with little loss is developed. For now, the only feasible baseline power plants are hydro, nuclear and fossil.

Generally solar is good as long as the sky is clear. Imagine what would happen to a 100% solar economy hit by a month of thick clouds. I don't think relying on something as random as the weather for your main energy supply is a good idea. It's OK e.g. when you want to power farm machines, because if there's no power you can wait, but powering cities with it doesn't seem wise. I also think that green activists should stop pretending they can do without nuclear power (at least those of them that do), because right now they can't, and telling everybody not to invest in nuclear and wait until we come up with adequate energy storage technology is making the global warming worse by preventing substantial CO2 emission reductions.

Re:Let me guess... (0)

Anonymous Coward | more than 5 years ago | (#23470758)

Hydroelectric power plants need not provide base load constantly. They can be stopped and started very quickly and provide a great way of evening out power supply. Generate power from wind when it blows , from the sun when it shines and top up the power supply from hydro when it is needed at other times.

Re:Let me guess... (1)

evilviper (135110) | more than 5 years ago | (#23469576)

For instance if you want solar the solar thermal systems are pretty cheap to build and have decent efficiency.

If you're talking about passive solar heating... They're an okay option, but don't provide any cooling (which is needed most when it's sunny out). What's more, as PV panels keep getting more efficient, so too do heat-pumps, which require electricity, not heat (...ignoring inefficient and expensive gas absorption units).

If you're talking about generating electricity via steam or the like, the laws of thermodynamics don't work out well with such small (single-household) installations, and besides that, require maintenance. On an industrial scale, these work well, and are slowly being developed and invested in now that energy prices are so high.

Re:Let me guess... (5, Interesting)

AdamTrace (255409) | more than 5 years ago | (#23468208)

Remember, solar power is generally available HERE and NOW.

I just invested in a PV system for my house (in sunny SoCal). As a computer geek, I asked our guy if it was stupid to invest, since there always seem to be efficiency breakthroughs on the horizon.

He reminded me that efficiency generally meant "smaller" and perhaps "cheaper". But since my roof was plenty adequate for what I needed, "smaller" wasn't really an issue. Cheaper will ALWAYS be the case, as it always has been.

Don't get frozen by the thought that solar power isn't worth investing in today. It totally is.

Adman

Re:Let me guess... (0)

CrackedButter (646746) | more than 5 years ago | (#23468438)

True I can agree with this, I'm ready to plunk down some cash on a powermonkey and powerchimp for my needs and around the corner is an even bigger version to complement my future purchase. www.powermonkey.com

Re:Let me guess... (3, Funny)

Belial6 (794905) | more than 5 years ago | (#23468548)

Sounds just like computers. I need to get one of those one of these days. Just as soon as they stop getting smaller and cheaper.

Re:Let me guess... (0)

Anonymous Coward | more than 5 years ago | (#23468692)

Ha I was just shopping around for solar panels maybe 6 months ago and it would have taken 35 years for them to pay for themselves in energy if they even lasted that long.

Re:Let me guess... (0)

Anonymous Coward | more than 5 years ago | (#23468878)

Do you even know how to factor in predicted increases in energy costs?

Re:Let me guess... (2, Interesting)

Anonymous Coward | more than 5 years ago | (#23468910)

Not only here and now. I started homesteading in 1979 and been off the grid, but not without power since then -- the tech was already good enough insofar as solar panels go. Batteries, on the other hand...we do OK with what there is. What makes good panels (such as I have) expensive is not the silicon part. It's all the rest, which has made my panels last from then until now, still performing like new -- I couldn't guess the eventual lifetime. All it's going to take is more people putting their money where their mouth is, instead of using theoretical improvements as an excuse to wait forever.

My systems now run a campus with 4 buildings, a large computer network, a machine shop, an electroplating line (not all at once, there's only a couple of us to use it all). Is that finally good enough? Not to the oil trolls, the people who won't pay for power upfront, or who think that if we just tax those other guys enough (and who pays for that, really?) someday soon I'll be able to buy a magic box to clip to the antenna on my Toyota and it will the run on freely available hydrogen...I have permits for all kinds of dangerous things -- but can't even buy hydrogen, evidently in reality it's more dangerous than guns, high explosives, various chemistries...the list goes on.

Don't slashdot me all at once at
www.coultersmithing.com

Re:Let me guess... (1)

Oktober Sunset (838224) | more than 5 years ago | (#23469312)

Waiting for cheaper can be a fallacy too tho, if you buy today and then in 5 years time, the price drops, well, you have been selling electricity for 5 years already, so how much did you make in the meantime?

Re:Let me guess... (1)

Firethorn (177587) | more than 5 years ago | (#23469592)

This is almost exactly the argument I used to convince some people to finally jump on the computer wagon.

Sure, it'll be cheaper and more powerful in the future. But they were running a business and the expected savings would pay for the systems in less than two years with an expected lifespan of at least five.

Re:Let me guess... (2, Interesting)

Anonymous Coward | more than 5 years ago | (#23469922)

Thank you thank you thank you! I've lost count of the number of times I've heard the "solar is almost ready, but it's only x% efficient, so best to wait a little longer when it'll be cheaper/smaller/whatever" argument repeated over the years. Yes, just like any other technology solar cells will get better as time goes by... so the "don't buy until we reach nirvana in $\lim n \to \infty$ years time" argument can be equally applied to pretty much any technology. Like, say, computers, cars, refrigerators, home theater systems and microwave ovens. So would you indefinitely delay purchase of the items on this list in response to this argument? Of course not! If the technology does the job, then you buy it. This applies to to cars, to computers, to microwave ovens... and to solar cells.

Re:Let me guess... (0)

Anonymous Coward | more than 5 years ago | (#23470594)

>> If the technology does the job, then you buy it.

Only if it is the cheapest way to solve the problem. Until the cost of fossil fuels goes up (some more) it's still a cheaper way to generate energy than solar is. Personally, I'd like to see a huge tax on energy to encourage this to happen sooner, but until the crossover, forget it.

Re:Let me guess... (2, Funny)

rossy (536408) | more than 5 years ago | (#23468270)

... then they would be 99.9999999% efficient and cost less than crackers.
Yes, but would they be individually wrapped?

Re:Let me guess... (1)

Dishevel (1105119) | more than 5 years ago | (#23468818)

... then they would be 99.9999999% efficient and cost less than crackers.
Yes, but would they be individually wrapped?
My crackers come 2 to a package. :)

Re:Let me guess... (0)

Anonymous Coward | more than 5 years ago | (#23469370)

Hopefully not.. that's a big waste of packaging (probably petroleum based plastic).

Re:Let me guess... (1)

Anne_Nonymous (313852) | more than 5 years ago | (#23470462)

>> But I'm not bitter, nooooooo.

So you're saying they can take their hairy solar cells and stick 'em where the sun don't shine?

Sheeit Negro, that's all you had to say! (2, Interesting)

gandhi_2 (1108023) | more than 5 years ago | (#23467810)

What's really awesome is that PV cells have undergone constant improvement in lab performance for 20 years, but since nothing ever gets put into production, the industry is held in a constant state of "early adoption" and we get screwed like perpetual "early adopters".

Know what would rawk? A 5 year moritorium on new PV cell research so we could get some actual PV cell production going.

Lab advancements != commercially viable (4, Insightful)

QuasiEvil (74356) | more than 5 years ago | (#23467892)

The problem is that a large portion of the lab performance-enhancing techniques are so insanely expensive that they *can't* go into production. Many of them - particularly exotic materials or multi-junction cells - are prohibitively expensive to make, given the meager performance improvements. I think Nanosolar has the right idea for now - craptastic cells made cheap. Who cares if they're large if they're incredibly inexpensive?

Re:Lab advancements != commercially viable (2, Insightful)

dunezone (899268) | more than 5 years ago | (#23468080)

Yeah but this is like any technology. A few days ago there was an article on why touch table tops are just now coming around. Thats because 30-40 years ago when they were developed they were developed in labs and were extremely expensive. Now with the advancement in technology that produced them its feasible for this technology to be manufactured/developed/sold.

Give this technology another 20-30 years, maybe even less, and the advancement of production will drop the price.

Nanowires are nice and everything... (2, Informative)

Hankapobe (1290722) | more than 5 years ago | (#23467854)

but what is really needed is a photovoltaic that will release two electrons for every photon. If any of you material guys out there do that, you'll be a gazillionaire! That will really make photovoltaics productive enough to really complete with other alternative energy source - assuming fossils fuels don't go up much higher than they are now. Photovoltaics need to get down below $0.15 kwh on the roof (the heat from a typical roof reduces photovoltaic's efficiency by at least 10%).

Re:Nanowires are nice and everything... (3, Interesting)

skintigh2 (456496) | more than 5 years ago | (#23468106)

Barely related... but as a South Texas resident, I wonder how much less I could run my A/C every year just because of the shade provided by solar cells on my roof? I believe I first used my A/C this year in February, so even a small decrease could be significant over the year.

I also always wondered why people don't advertise how much cooler CFL bulbs are than incandescent bulbs. I replaced 480W of lighting in a bathroom with 72W (replaced 60W clear bulbs with 9W vanity CFLs) and not only is it brighter and the light softer (and thus makes ladies feel prettier when doing whatever it is they do for hours in bathrooms) but it's a lot cooler. And they will pay for themselves in roughly 13 months.

And similar swaps make a really significant difference when sitting under the 5-bulb light that is just above the dining table. A friend of mine used to unscrew some of the bulbs when she did homework.

So basically now I save electricity while saving electricity.

Re:Nanowires are nice and everything... (2, Interesting)

lgw (121541) | more than 5 years ago | (#23468238)

Ahh, but that's because you live in Texas. Residents of lesser states are often concerned primarily with heating a room instead of cooling it. The difference is particularly huge in a batroom with a well-lit mirror, where 300W of heating in a small poorly-ventilated room could send the temperature over 100 in minutes - the CFLs are a glorious change, and available in whatever color temperature suits your fancy.

Now we just need affordable dimmable CFLs for that dining table fixture, and low-wattage CFLs with the same wonderful very-warm color temperature that you get from dimming a 300W floor lamp down to 3W, which does as much as alcohol for making your partner look more attractive. ;)

Re:Nanowires are nice and everything... (1)

brainnolo (688900) | more than 5 years ago | (#23468622)

A bit offtopic, but let me ask. In the US you really commonly use 300-400W bulbs? I've never seen anything more than 200W and 60-100W are most common in Italy. Either you rooms are very big, or your nights are very dark.

Re:Nanowires are nice and everything... (1)

slazzy (864185) | more than 5 years ago | (#23468712)

300 watt halogen floor lamps are somewhat common, otherwise most bulbs are 40-60-100 watts

Re:Nanowires are nice and everything... (1)

Chris Burke (6130) | more than 5 years ago | (#23468754)

That's a total of multiple bulbs, I'm certain. Which isn't that uncommon around bathroom mirrors or living/dinning room tables. E.g. the ceiling fan at my house (rarely used) has 3 100W bulbs.

Re:Nanowires are nice and everything... (2, Informative)

aliloln (973288) | more than 5 years ago | (#23469950)

No, they are talking about 300W halogen floor lamps (single halogen bulb fixtures). There are even 500w halogen bulbs. Google Halogen 300w and you'll find the bulbs.

Re:Nanowires are nice and everything... (0)

Anonymous Coward | more than 5 years ago | (#23468782)

No, they are talking about light fixtures that have several bulbs which when added together consume that many watts

Re:Nanowires are nice and everything... (2, Funny)

lgw (121541) | more than 5 years ago | (#23468928)

It was two different examples. 6 or even individual bulbs in a bathroom fixture are common (I've never been sure why, not needing to apply makeup). Also, 300W halogen floor lamps are common, and it's really hard to find a florescent replacement for those: nothing is bright enough, and when you turn down the dimmer on the 300W bulbs to where you can barely see them, you get the color temperature of firelight, which is very nice at times.

Also, in Texas, your average living room is larger than Italy, but that's a different topic. :)

Re:Nanowires are nice and everything... (1)

pjt33 (739471) | more than 5 years ago | (#23468950)

I think that "floor lamp" means what I know as a standard lamp: a bulb on a 6 foot pole with a reflector which points up, so the light is diffused off the ceiling. A friend has one whose bulb gets pretty hot - I'm not sure what power it uses, but when a fly lands it on you smell burning fly.

Re:Nanowires are nice and everything... (1)

ErikZ (55491) | more than 5 years ago | (#23470724)

Bulbs. I have 6 light bulbs in my bathroom that I replaced like he did.

Re:Nanowires are nice and everything... (4, Funny)

Facetious (710885) | more than 5 years ago | (#23468366)

I believe I first used my A/C this year in February
You own an Anonymous Coward? That would be sweet. I would task mine to read and summarize /. for me.

Re:Nanowires are nice and everything... (0)

Anonymous Coward | more than 5 years ago | (#23469264)

Depends on the composition of the roofing material. If the roofing material is something like Dura-Last, a white PVC type material, attaching solar panels directly to or slightly above such material will be a thermal disadvantage to the house as a whole compared to a roof with black asphalt shingles.

Re:Nanowires are nice and everything... (1)

rcw-home (122017) | more than 5 years ago | (#23470432)

I wonder how much less I could run my A/C every year just because of the shade provided by solar cells on my roof?

Your average silicon PV cell is 12% efficient. That means that for every watt of electricity out, 7 watts goes into heating up the cell, and very little gets reflected back out (since they are black).

A white or light-shaded composition shingle roof would reflect about 30% of the light energy hitting it. While an asphalt shingle generates no electricity, it would absorb 20% less heat than the PV cell.

Hopefully you have a little bit of an air gap between your PV cells and your roof.

Re:Nanowires are nice and everything... (2, Informative)

NeutronCowboy (896098) | more than 5 years ago | (#23468530)

Now it's been a while since I dealt with Physics and all that, but... release 2 electrons for one photon? How would that work? Photons knock electrons out of their bonds by imparting enough energy into the electron so that it moves into the conduction band. However, photons are either absorbed or not - this is not billiards.

Re:Nanowires are nice and everything... (1, Informative)

Anonymous Coward | more than 5 years ago | (#23470364)

What you're looking for is a multiexciton creating material. There is a decent amount of research going into it right now. Generally, a high energy photon which is more than twice the bandgap creates a high energy exciton, and somehow (competing theories right now) the relaxation process generates low energy excitons.

Dramatic efficiency improvements unlikely. (4, Informative)

BlueParrot (965239) | more than 5 years ago | (#23467904)

If I am not completely mistaken "classical" semi conductor cells can reach efficiencies of 40%, meaning that even with perfect 100% efficiency you would get at best a factor 2.5 improvement. Of course, 100% efficiency is an impossibility and thus I think we can safely assume that these cells will never reach more than 80%-90% efficiency, which would be an improvement of a factor of 2 over current technology. Now last estimate I saw was that in Europe solar cells work out to be about 4 times as expensive as wind power (which is itself rather pricey ), so even assuming the 100% efficiency, efficiency gains alone cannot make solar economical.

Add in to this that a large part of the cost of solar is the energy needed to produce the cells, which means that if you get that energy from a more expensive power source, the price of the cells will increase. I.e, if one started to replace relatively cheap generation capacity with more expensive solar cells, then the cost of energy, and hence the cost of the cells, would increase.

It would therefore appear to me that for solar to have a chance to become competitive what is needed is focus on lowering the cost of producing the cells, because the gains from improving their efficiency cannot offset their presently large price, and it appears unlikely that pushing for higher and higher efficiencies will be possible without making the cells more expensive.

Re:Dramatic efficiency improvements unlikely. (4, Informative)

clonan (64380) | more than 5 years ago | (#23467982)

Currently availible non-specialty cells (the cells used for space etc are not used for general power) are typically between 5 and 15%.

Therefore getting to the 80-90% range would result in a 5-18X improvment.

Since solar is currently 4X, that means it will drop to .2-.8X of CURRENT power costs.

Now remember that hydro is essentially 100% tapped. Wind has a much more limited range and is already approaching the likley maximum efficiency. Nuclear is great but will take some time to spin up. Oil/natural gas prices are climbing rapidly and coal is becoming more expensive to mine and or clean.

Solar PV provides a great load matching power source that will help reduce an individuals demand on the system even if it doesn't complely remove the need for other power sources as well.

Re:Dramatic efficiency improvements unlikely. (1, Interesting)

timmarhy (659436) | more than 5 years ago | (#23468046)

solar could maybe provide 10% of our needs at most. it can't supply base load, which is something nuclear can do very well. don't tell the tree huggers that though, they want to continue to live in their dream world.

Re:Dramatic efficiency improvements unlikely. (1)

clonan (64380) | more than 5 years ago | (#23468070)

personally I would love to see throium reactors until fusion actually shows up.

While I am not a "tree-hugger" I am a "tree-shacker-hander"

Re:Dramatic efficiency improvements unlikely. (4, Informative)

Anonymous Coward | more than 5 years ago | (#23468200)

Photovoltaics can't supply base load now, but that doesn't that you can't get a solar plant to supply base load. The trick is to instead, use thermal energy. We can store the excess thermal energy overnight to continue generating power in the dark, until the sun shines again. Check it out http://en.wikipedia.org/wiki/Solar_thermal_energy [wikipedia.org]

Re:Dramatic efficiency improvements unlikely. (1)

clonan (64380) | more than 5 years ago | (#23468786)

The primary benifit to solar thermal is that it is a mature technology and is about 40 percent efficiency plus we are decent at storing heat energy without loss.

The downside is that we are unlikley to improve much because of Karnat restrictions.

PV has a Karnat limit of about 98 percent. Therefore while at the moment thermal is better for large power plants, PV will eventually pass thermal. We are already pretty close efficiency wise to storing electricity cost effectivly.

Thermal is great for now.

Re:Dramatic efficiency improvements unlikely. (1)

rcw-home (122017) | more than 5 years ago | (#23470514)

PV has a Karnat limit of about 98 percent.

Maybe you mean Carnot [wikipedia.org]? More importantly, if you have a source for this assertion, I'd be very interested in reading it.

Re:Dramatic efficiency improvements unlikely. (1)

Tweenk (1274968) | more than 5 years ago | (#23468958)

When your sky looks like this [wikipedia.org] for several weeks (not that uncommon in Europe), you have a problem.

Re:Dramatic efficiency improvements unlikely. (1)

clonan (64380) | more than 5 years ago | (#23469044)

Yet Germany, which is one of the worst for solar, still generates a huge amount of it's power from currrent solar tech and the percentage is growing.

Germany produces more power from solar than the whole US.

Re:Dramatic efficiency improvements unlikely. (1)

Firethorn (177587) | more than 5 years ago | (#23469838)

'Huge' is now defined as 3% now [boston.com]?

They may be the world leader, but I'd argue that it's not helping them as much as nuclear power is helping France, which, on average is a electricity exporter.

Re:Dramatic efficiency improvements unlikely. (4, Interesting)

c6gunner (950153) | more than 5 years ago | (#23469088)

solar could maybe provide 10% of our needs at most. it can't supply base load, which is something nuclear can do very well. don't tell the tree huggers that though, they want to continue to live in their dream world.


Just to be contrary: at least in theory, solar COULD supply base-load. All you need to do is integrate the Earth's power grids. Then you'd have a more or less constant amount of current available throughout the grid.

Of course, this isn't practical - even ignoring the political implications, transmission losses would create serious problems. Getting away from AC current and using DC for all grid transmission could fix part of that problem, but that's not likely to happen any time soon.

And yes, you're certainly right about nuclear. Realistically, it's our best option at this point in time. That's one thing that France got right.

Re:Dramatic efficiency improvements unlikely. (0)

Anonymous Coward | more than 5 years ago | (#23470118)

Just to be contrary: at least in theory, solar COULD supply base-load.
All we need are solar power satellites [wikipedia.org].

Oh right, NASA's in charge of the space program. Scratch that.

What, me bitter?

Re:Dramatic efficiency improvements unlikely. (3, Informative)

BlueParrot (965239) | more than 5 years ago | (#23468382)

Currently availible non-specialty cells (the cells used for space etc are not used for general power) are typically between 5 and 15%.

Therefore getting to the 80-90% range would result in a 5-18X improvment.

Since solar is currently 4X, that means it will drop to .2-.8X of CURRENT power costs..


I said 4X WIND POWER costs. Not current power costs. Britain's Royal Academy of Engineering estimates the cost of wind power at roughly 3 times that of nuclear, so even if you achieve 90% efficiency that would put you at roughly twice the cost of nuclear generation ( assuming 15% efficiency for present cells ). Now, to give an idea of how hard 90% efficiency would be to reach, the Sun's average surface temperature is 5778K , meaning a solar cell at 300K could at best reach 95% efficiency without violating the laws of thermodynamics.

That is, ignoring ANY other problems you are closing in on the theoretical limits allowed by the laws of physics if you are to get such efficiencies, and you have to do this without increasing the costs of your cells. Any dust on the cells and you can forget it. Protective glass coating is a no-no since it would absorb in the UV range. Heck, simply finding a material that is reasonably transparent at all the relevant wavelengths could be tricky. Add in to this that you cannot use any expensive/toxic/rare elements, that the cells should have to last for a long time, that they should survive a wide range of temperatures and be able to handle a reasonable level of abuse, and it becomes far from certain that it is even possible to reach 80% efficiency, let alone to do so in the foreseeable future.

Re:Dramatic efficiency improvements unlikely. (1)

clonan (64380) | more than 5 years ago | (#23468916)

You are correct..You did say Wind power.

But the cost of power is based on more than cell efficiency.

For instance, nanocell solar cells are proven and produce power at 0.15 cents a KWH. this is done at about 7 percent efficiency. Coal power typically costs about 0.10 cents a KWH. This is possible because the cells are so cheap and can be placed in "useless" areas like residential siding and roofs. This tech is expected to reach rf percent efficiency at the current price point in 5-10 years.

There is enough unused space on roofs etc to provide several times our power usage right now AND do it at about a third the price of coal plants.

Remember, caol plants are already close to thermodynamic top efficiency at 40 percent efficient.

In a few decades you may be able to buy a gallon of PV paint that will cover a wall with 50 percent efficient cells at $20 a gallon (I am exaggerating on the price since I don't know and it really doesn't matter).

Remember we have an avearge of 4 KWH falling on every dquare meter every day. Even 50 percent efficiency on the wasted space would provide all our energy needs for the predictable future.

Re:Dramatic efficiency improvements unlikely. (1)

Firethorn (177587) | more than 5 years ago | (#23469868)

Coal power doesn't cost 10 cents a kwh. It's more like 4-6 cents, before distribution grid costs. Unless you go off the grid, you're still going to have that, as the power lines need to be maintained.

Of course, clean coal is much more expensive, quite possibly making it more expensive than building nuclear plants. The level of cleaning/scrubbing making coal clean is expensive.

Re:Dramatic efficiency improvements unlikely. (1)

clonan (64380) | more than 5 years ago | (#23470392)

Argue with my electric bill.... I pay 10.5 cents per KWH and I am slightly better than my state (Georgia).

Coal prices vary but the average has NEVER been below 7 cents a KWH (adjusted to today's dollar) before distribution costs. Those that are that low are typically from non-profit co-op type organizations.

For profit power companies charge anywhere from 8 cents up to 15 depending on market forces (again average).

Finally even is you WERE right and it did cost 4-6 cents before distribution costs, we are talking about power at the wall and pricing for residential off-grid solar. the 4-6 cents then gets line maintenances and transmission losses which together can be substantial.

In the end, financially Solar is still not a viable option for MOST people. However if you live in a sunny are where central power is relatively high solar is ALREADY a financially viable option. As the technology improves, and it is improving quickly, solar becomes cost effective for more people. Right now I am about even financially purchasing power vs generating power with solar. In 2-3 years it probably won't be a contest and I will gradually move off grid. (Probably solar water heater on year then grid tie solar the next and finally fully off grid).

As efficiency goes up and price goes down more people will move towards solar and away from centrally generated power.

Re:Dramatic efficiency improvements unlikely. (1)

Belial6 (794905) | more than 5 years ago | (#23470510)

10.5 cents per KWH? Man, I wish I could get power that cheap. My last bill had me paying 23 cents KWH for a good portion of the bill.

Re:Dramatic efficiency improvements unlikely. (1)

kesuki (321456) | more than 5 years ago | (#23468784)

hydro isn't 100% tapped, there are tons of places around the world where new hydro electric plants are going up, maybe in America the market was saturated early, but if we put in hydro plants in many countries in Africa, those countries won't have to put in as many coal fired plants at technology gets cheaper, etc.

wind is nowhere near tapped.... i think the Department of energy once found in a study that wind power plants could provide up to 40% of the energy needs of the US, overall, the problem though, is that the states where wind power is really viable, are far away from the major population centers, putting up massive wind farms to power all of north Dakota would be easy, but north Dakota would never ever have the money to install that many wind farms...

there are countless places where wind power is so predictable and reliable that those regions could get almost all their power from wind, but the very high upfront cost, compared to the 'artificially low' price of coal, makes it unlikely for those regions to go wind.

Wind turbines can pay for themselves, easily, but there are things (tornadoes, etc) that make them a 'risky' bet, if your wind farm stands for 20 years you've paid off expenses, but if a F5 tears them down in year 3 you're hosed...

remember, windy places are usually in tornado country, so tornadoes are the 'fear, uncertainty, doubt' factor that keeps energy companies (thinking only of the bottom line) from turning to wind power...

Solar PVs are never going to be cheap as long as they require pure silicon, even if this technology helps significantly (if it ramps up, if it can be cheaply mass produced, big ifs, there) PV will still be an 'expensive' power source, home owners buy PV because they 'pay less than buying from the grid' but that price supports a lot more than the 'cost' of producing the energy, so if this tech works, in a few years the demand for cheap, home installed PV will grow way beyond production capacities, but it still will be way more expensive than coal, it will only save homeowners from paying 'full retail' cost for energy... they won't use this new solar PV technology to power cities, it's still too expensive...

Re:Dramatic efficiency improvements unlikely. (1)

Firethorn (177587) | more than 5 years ago | (#23469820)

Since solar is currently 4X, that means it will drop to .2-.8X of CURRENT power costs.

Do you happen to have a source on this? All the times I've figured it, it's around 10X as much.

4X might be with some of the high levels of subsidies and such. Or a large solar thermal installation, which photovoltiacs don't figure into.

Or maybe it's compared to retail electrical prices, and doesn't include support equipment such as the inverter.

Re:Dramatic efficiency improvements unlikely. (1)

clonan (64380) | more than 5 years ago | (#23470210)

I was quoting the parent of my comment.

However with nanosolar's thin film cells the price can drop to about 1.5X coal (although space could become an issue).

Currently the payback period for a full off-grid residential solar system is on the order of 7-10 years. (Cited all over the place) This is in line with the roughly 4X for conventional silicon cells.

Re:Dramatic efficiency improvements unlikely. (1)

argent (18001) | more than 5 years ago | (#23468412)

Even given your calculations (and I don't think I'm really happy with all the assumptions) solar power is often usable where wind power isn't, and vice versa, so it's not an "either or" situation.

Re:Dramatic efficiency improvements unlikely. (1)

aztektum (170569) | more than 5 years ago | (#23468684)

If you're talking strictly about the monetary economics, then I think what we really need to do is rethink the world's concept of economics.

At SOME point the bullet has to bitten as far as cost goes somewhere. Oil and coal aren't going to stick around for ever.

Re:Dramatic efficiency improvements unlikely. (0)

Anonymous Coward | more than 5 years ago | (#23469258)

Actually that is exactly backwards. A majority of the cost of installing a photovoltaic (PV) system is independent of the type of PV, as I recently saw in an NREL presentation. Think of things like labor, transportation, maintenance, etc. It's such that the only way we're going to reduce the cost of the cells significantly is by making them more efficient, so that we don't need as many installed!

Thus, the best way to improve cost is by finding more efficient PV cells. It's initially counterintuitive, but data supports that conclusion.

Re:Dramatic efficiency improvements unlikely. (1)

Firethorn (177587) | more than 5 years ago | (#23469782)

While increasing the efficiency of a solar cell can indeed make it cheaper, in that if the increase in efficiency doesn't significantly increase the cost of a cell, making it so you need half as many, half as much mounting equipment, etc... It doesn't really matter.

I agree with you, the significant obstacle isn't the efficiency of solar panels. It's the cost of them, more so than the space they take up.

If we could produce solar panels that were half as efficient as current panels for the cost of a ream of paper(for the area), that were still able to have the lifespan, it'd be a no brainer in many cases. If we were able to make panels, even minimally efficient, that were about the same cost and durability as shingles, it'd be easy.

But that's not the case.

Already been done in nature (1, Funny)

Turken (139591) | more than 5 years ago | (#23467968)

Last I heard, polar bears are already nature's hairy solar collectors. So all we have to do is hunt them down for their skins to make super efficient solar panels so that we can stop the global warming and thus save all the polar... umm...

Re:Already been done in nature (2)

MountainLogic (92466) | more than 5 years ago | (#23468840)

Polar bears make very poor harry solar solar collectors. Their white fur has a very high albedo [wikipedia.org] and their high latitude habitat results in high Angle of incidence [wikipedia.org]. Generally speaking, grizzlies and black bears are a much better choice of harry solar collectors given their fur color and more equatorial habitat. So the correct solution is to hunt down all the grizzlies and black bears for their skins to make super efficient solar panels so that we can stop the global warming and thus save all the polar bears. There is also the case of the ghost bears [pbs.org], but I'm not clear on their IR albedo.

They already invented these (0)

Anonymous Coward | more than 5 years ago | (#23467970)

They call them "cats".

I hope nobody is planning to touch these things (1)

LuminaireX (949185) | more than 5 years ago | (#23468108)

Handling broken glass is bad enough, now we have engineered nano-shards of it? I hope nobody falls or steps on these

Re:I hope nobody is planning to touch these things (0)

Anonymous Coward | more than 5 years ago | (#23468218)

I hope all them green hippies fall into them!

Re:I hope nobody is planning to touch these things (1)

toby34a (944439) | more than 5 years ago | (#23468442)

An even better question is what happens to these things after a hailstorm... in a lot of the Midwest/South hailstorms happen fairly often... would these PV cells break? And with nanowires lying around, would that act as a nice lightning attractor? Anyone know if hailstorms can knock out PV cells?

Could have swore (0)

Anonymous Coward | more than 5 years ago | (#23468722)

I spotted the same story last week [slashdot.org].

Tin whiskers? (1)

fabu10u$ (839423) | more than 5 years ago | (#23468998)

FTFA:

At UC San Diego, scientists were able to grow nanowires directly on an inexpensive indium tin oxide conductive surface.
So now tin whiskers [nasa.gov] are good?

Wow, ANOTHER solar cell breakthrough (4, Insightful)

GodfatherofSoul (174979) | more than 5 years ago | (#23469368)

Wake me up when there's actually a cheap product. These articles need their own icon; maybe Bigfoot, the Easter Bunny, Santa Claus, the Loch Ness Monster, or La Chupacabra.
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