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Towards a 50% Efficient Solar Cell

timothy posted about a year and a half ago | from the bounty-from-the-roof dept.

Power 129

necro81 writes "IEEE Spectrum magazine has a feature article describing DARPA-funded work towards developing a solar cell that's 50% efficient, for a finished module that's 40% efficient — suitable for charging a soldier's gadgets in the field. Conventional silicon and thin-film PV tech can hit cell efficiencies of upwards of 20%, with finished modules hovering in the teens. Triple-junction cells can top 40%, but are expensive to produce and not practical in most applications. Current work by the Very High Efficiency Solar Cell program uses optics (dichroic films) to concentrate incoming sunlight by 20-200x, and split it into constituent spectra, which fall on many small solar cells of different chemistries, each tuned to maximize the conversion of different wavelengths."

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129 comments

No problem with this (1, Insightful)

Dyinobal (1427207) | about a year and a half ago | (#41341541)

Republicans would have no issue with this. It's military spending and that is fine, but if we ever want to invest in solar in the USA for purely clean energy purposes they'd call it wasteful spending and all sorts of crap.

Re:No problem with this (5, Insightful)

Firehed (942385) | about a year and a half ago | (#41341663)

Know your audience. As long as DARPA's research comes to the public eventually (we got the internet, after all) it's still beneficial. Quite possibly delayed and almost certainly more expensive than it should be, but slow and expensive progress is still progress.

Re:No problem with this (0, Troll)

TubeSteak (669689) | about a year and a half ago | (#41342267)

DARPA? You mean the Government?
Obviously private industry already did it faster and cheaper without government subsidies.

Re:No problem with this (4, Informative)

Anonymous Coward | about a year and a half ago | (#41342633)

No, he means forward-looking scientists working for government money (so, just like it should have been). So far the general public was the greatest beneficiary of DARPA projects. Computers, Internet, GPS to name the few...

Re:No problem with this (2, Informative)

Anonymous Coward | about a year and a half ago | (#41343025)

I am not sure you understand what DARPA is. They don't do the research, they read proposals submitted by companies, universities, non-profits, etc, and allocate US tax dollars to whoever they think is most likely to successfully develop the technologies they need. For example, the solar cells noted in this article are being developed by University of Delaware, using DARPA money.

Not new with DARPA (3, Informative)

Geoffrey.landis (926948) | about a year and a half ago | (#41343677)

I'm surprised that DARPA is getting all the credit here; the approach isn't new with DARPA.

That approach is known as the "spectrum splitting" approach. Some older work was the NASA "rainbow concentrator" array concept:
http://ntrs.nasa.gov/search.jsp?R=20110024141 [nasa.gov]
http://www.techbriefs.com/index.php?option=com_staticxt&staticfile=/Briefs/June03/NPO21051.html [techbriefs.com]

In general, spectral-splitting concepts do need to track the sun, and so they're envisioned more for concentrator systems than for flat-plate arrays.

Re:No problem with this (0)

JesseMcDonald (536341) | about a year and a half ago | (#41342655)

As long as DARPA's research comes to the public eventually (we got the internet, after all) it's still beneficial. Quite possibly delayed and almost certainly more expensive than it should be, but slow and expensive progress is still progress.

Unless, of course, it comes at the expense of the same result being achieved by someone else at a lower cost and/or in less time, or even other, completely unrelated, results which may be valued more highly. Whether it is beneficial for DARPA to do the research depends on the opportunity cost, even if the research ultimately produces usable results.

Naturally, when your source of funding is taxes, the (externalized) opportunity costs are never given any serious consideration.

Re:No problem with this (0)

Anonymous Coward | about a year and a half ago | (#41344809)

>we got the internet, after all
No, no we didn't. Internet is completely different to ARPANET. I mean on levels of black and white different.

The internet isn't even remotely decentralized or safe from nuclear attack. Hell, the internet has already been taken down several times by accident!
It isn't safe from its own operators, never mind a nuke. A nuke in the middle of some main nodes would absolutely destroy communication, and it likely wouldn't automatically fix itself either since most peoples servers are controlled manually for the most part when it comes to massive blackhole situations when DNS systems fail for whatever reasons (DDoS, hacking, accidental changing)

Just because SOME of the researchers who worked on it doesn't mean it was derived work. Packet-switching isn't exactly rocket surgery, it is the only logical system you could use to deal with the distances involved and all the interconnecting wires.

This common misconception is such a pet peeve of mines.

Re:No problem with this (1, Troll)

Charliemopps (1157495) | about a year and a half ago | (#41341945)

Governments do not "invest", Governments move money from one place to another... VERY inefficiently.
How are Obama's solar investments doing? Oh, that's right, they taxed you... took your money, then gave it to some businessmen that promptly filed bankruptcy and drove off in their BMWs. Congrats.

Re:No problem with this (2, Informative)

Anonymous Coward | about a year and a half ago | (#41342265)

Except in the case of Spacex, where that model is dandy and fine, right? Which side of the Space Nutter camp are you on??

"As of May 2012, SpaceX has operated on total funding of approximately one billion dollars in its first ten years of operation. Of this, private equity has provided about $200M, with Musk investing approximately $100M and other investors having put in about $100M (Founders Fund, Draper Fisher Jurvetson, ...) [22]. The remainder has come from progress payments on long-term launch contracts and development contracts. NASA has put in about $400-500M of this amount, with most of that as progress payments on launch contracts."

Re:No problem with this (0)

Anonymous Coward | about a year and a half ago | (#41342337)

You are more obsessed with "Space Nutters" than said (imaginary) people are with space.

The tantrum you will throw in response to this post will prove me right.

Re:No problem with this (0)

Anonymous Coward | about a year and a half ago | (#41342545)

I am obsessed with a thing called "reality". The perception that you have of my rebuttals of your demented world view as "tantrums" really tells me all I need to know.

Re:No problem with this (0)

Anonymous Coward | about a year and a half ago | (#41343475)

I am obsessed with a thing called "reality".

You violently hate reality. You hate it because it does not contain any of the "Space Nutters" over whom you obsess. This is proven by your habit of constantly lying about other people and their statements in order to pretend they are actually the people you invented. You insist on seeing "Space Nutters" everywhere because you want them to be there.

The perception that you have of my rebuttals of your demented world view as "tantrums" really tells me all I need to know.

You have never, even once, rebutted anything. You cannot and will not show a single instance of this happening. Your efforts to do so will fail, and will only further prove you to be a liar.

Furthermore, you do not know what my "world view" is. You are taking your fantasies of "Space Nutters" and projecting them onto me just as you do others here. You are pretending I am saying things that I am not, and never have. You are doing this consciously, willingly, and repeatedly. This is what makes you a liar.

Your posts absolutely are tantrums, without exceptions. Each and every one of them is 100% emotional content. You have never once made a statement of fact or responded rationally to questions or criticisms, and indeed when asked to do so have reacted with further emotional abuse and lies. There is no case where you have not done this. Not one.

The tantrum you threw in response to my previous post proved me right. The tantrum you will throw in response to this post will further prove me right.

Re:No problem with this (0)

Anonymous Coward | about a year and a half ago | (#41343659)

Redefining terms during a debate is intellectually dishonest. Your definition of a "tantrum" is obviously far different from a normal person's.

" because it does not contain any of the "Space Nutters" over whom you obsess."

Either I obsess over Space Nutters, or they don't exist. You can't have it both ways. Space Nutters are very simply people who think sci-fi is the same as engineering, usually sprinkled with quasi-religious mumblings about how the species is doomed on this rock and we must colonize the galaxy as a consequence. That there is no such technology, and indeed, no physical possibility of ever building such technology, doesn't stop these people in the slightest. If that isn't delusional and opposed to reality, what is?

"The tantrum you threw in response to my previous post proved me right."

Whatever helps you sleep tonight, my friend. You will sleep right here, on this planet, with everyone else. And you, and everyone else, will never ever sleep on Mars, or colonize asteroids, or eat comets, or jizz a light-year long stream of species-seed into the universe either.

" Each and every one of them is 100% emotional content."

Yup, like my informative post about the reality of Musk's financials up there?

Re:No problem with this (0)

Anonymous Coward | about a year and a half ago | (#41344175)

Redefining terms during a debate is intellectually dishonest.

I haven't done that, and you don't believe that I have.

Your definition of a "tantrum" is obviously far different from a normal person's.

My definition of "tantrum" is entirely consistent with a normal person's, and an absolutely accurate description of every single post you make.

Either I obsess over Space Nutters, or they don't exist. You can't have it both ways.

Yes I can, because those facts are not mutually exclusive. Space Nutters do not exist, and you obsess over them anyway. Their non-existence makes your obsession all the more pathetic.

Space Nutters are very simply people who think sci-fi is the same as engineering, usually sprinkled with quasi-religious mumblings about how the species is doomed on this rock and we must colonize the galaxy as a consequence.

And they don't exist. You've never met one. Every single one you've ever "encountered" has been a strawman you've projected onto people saying things you didn't like but couldn't refute. The "Space Nutter" is your way of pretending you've refuted them. But you never have, never will, and never can.

And even if you really did meet a real live Space Nutter? One who really does believe and espouse all the things you dishonestly ascribe to everyone who questions or disagrees with you? You would still lose the argument to them, because you're just that bad at it. That's why you've never made a factual rebuttal even of the "Space Nutter" position, let alone one ever advanced by a real person. You ignore your opponent, attack a strawman in his place, and lose anyway.

You will sleep right here, on this planet, with everyone else. And you, and everyone else, will never ever sleep on Mars, or colonize asteroids, or eat comets, or jizz a light-year long stream of species-seed into the universe either.

I never said I would, or implied it. And you know it. Again, you are projecting onto me what you want me to be saying. You desperately wish I was suggesting such things, to the point that you are willing to lie about me having said them.

Yup, like my informative post about the reality of Musk's financials up there?

It was not informative. It was an excuse you gave yourself to put words into the OP's mouth. Pure emotion through and through.

You will now prove me right again.

Re:No problem with this (1)

jamstar7 (694492) | about a year and a half ago | (#41343961)

Read what you wrote. NASA paid the 400-500 mil for launch capabilities, i.e., delivered assembled vehicles to stand up on the pad, fuel, and go.

Re:No problem with this (5, Interesting)

hawguy (1600213) | about a year and a half ago | (#41342321)

Governments do not "invest", Governments move money from one place to another... VERY inefficiently.
How are Obama's solar investments doing? Oh, that's right, they taxed you... took your money, then gave it to some businessmen that promptly filed bankruptcy and drove off in their BMWs. Congrats.

In this list of recipients of the DOE's 1705 Loan program, 5 of out 26 are listed as being in serious financial difficulty, the majority of the projects on the list are on-track.

Direct costs of the war in Iraq were $800B, by the time all direct and indirect costs are accounted for (interest, injured and wounded, veteran care and pay), it could hit $4T. The Loan Program cost $34B (and that's only if all $34B loans are defaulted on).

So, for somewhere between 5% and 0.8% of the cost of war that we shouldn't have started, the US Government can help to move us toward alternative energy sources, and off of foreign oil (I know we have domestic sources for much of the oil we use, but since it's a global commodity, any oil we consume means more that volatile middle eastern states will sell)

I'm not sure that the vetting process for all companies is fair and balanced, but I do think it's a useful program.

Re:No problem with this (1, Interesting)

JesseMcDonald (536341) | about a year and a half ago | (#41342729)

So, for somewhere between 5% and 0.8% of the cost of war that we shouldn't have started, the US Government can help to move us toward alternative energy sources, and off of foreign oil...

This may become a reasonable argument when you find a way to ensure that spending on alternative energy sources (and other projects) comes instead of, rather than in addition to, the money wasted on war. The "balanced budget amendment" proposal would be a reasonable place to start. Until then, massive overspending in one area cannot possibly justify spending other areas, no matter how small the latter might be by comparison. Quite the opposite, really; when you're that far over budget to begin with, any additional spending requires more justification, not less.

Re:No problem with this (2, Insightful)

ShanghaiBill (739463) | about a year and a half ago | (#41343275)

Direct costs of the war in Iraq were $800B, by the time all direct and indirect costs are accounted for (interest, injured and wounded, veteran care and pay), it could hit $4T. The Loan Program cost $34B.

This is a logical fallacy. You can't prove that something makes sense just by pointing out that something else is even stupider.

Re:No problem with this (3, Insightful)

RobbieCrash (834439) | about a year and a half ago | (#41343915)

Are you suggesting that we shouldn't be looking into alternative energy sources?

Private industry hasn't exactly done a whole lot to do anything other than prolong our dependence on fossil fuels. The oil, and oil related, industries are bigger than ever, more money than ever is spent on refining more and more difficult sources of crude. Oil sources that 15 years ago were thought would never be cost effective are now major suppliers in the whole chain.

Solar power has made slight inroads, but only on a personal level. There's no significant widespread power generation through solar. We're NIMBYing wind turbines. Everyone is reluctant to invest in tidal power.

Everyone just keeps pouring more and more money into oil. Spending money thinking about how to stop doing that is sensible, even if 90% of it goes nowhere. Only spending money on things that are proven to work is what got us here, if private companies aren't willing to risk failing, then fucking A rights the government should help out.

Re:No problem with this (0)

Anonymous Coward | about a year and a half ago | (#41345055)

"Private industry hasn't exactly done a whole lot to do anything other than prolong our dependence on fossil fuels."

You REALLY think that's the case? And not, say, the physical reality that oil is energy-dense, comes out of the ground (less and less readily every year), is a liquid at STP, can be handled by people with double digit IQs, and can power a 747 with 400 people aboard across the ocean in 6 hours?

It's almost as if you think that business just hasn't tried hard enough to magically "find" something better... It's the other way around. The fact that we did find oil allowed such businesses in the first place. You can't just wish for something physical and make it true. There will never be a substitute for oil that will allow the lifestyle we have now. It's very simple. If there WERE such substitutes, why did it take the discovery oil to allow the lifestyle in the first place?

Re:No problem with this (1)

jcr (53032) | about a year and a half ago | (#41343759)

>In this list of recipients of the DOE's 1705 Loan program, 5 of out 26 are listed as being in serious financial difficulty,

Does that seem like a low level to you? I can tell you that any private lender looking at that many of his loans going bad would be in deep shit.

-jcr

Re:No problem with this (1)

ajaxlex (658555) | about a year and a half ago | (#41343825)

I don't think that a Lender is the right analogy. Rather, the Govt is an investor, where the benefits are measured in repaid loans PLUS jobs created PLUS new technologies developed PLUS strategic resource concerns alleviated. Investing in startups means taking different kinds of risks than traditional lenders do - higher risk of default, but bigger payouts when things succeed.

Re:No problem with this (1)

hawguy (1600213) | about a year and a half ago | (#41344105)

>In this list of recipients of the DOE's 1705 Loan program, 5 of out 26 are listed as being in serious financial difficulty,

Does that seem like a low level to you? I can tell you that any private lender looking at that many of his loans going bad would be in deep shit.

-jcr

Of course they are risky investments, if their business plan was so sound that they were able to get traditional loans, they'd just get traditional loans.

The government is acting more like a VC firm for these companies, and the average silicon valley VC firm has around a 50% success rate.

Re:No problem with this (1)

DamonHD (794830) | about a year and a half ago | (#41344859)

My expectation of VC success rate is ~20%, having several times been in receipt of VC money (and arguably succeeded once!)...

Rgds

Damon

Why couldn't these companies get private loans? (1)

bradley13 (1118935) | about a year and a half ago | (#41344557)

There's a reason these companies came to the government: they could not get private sector financing. Why not? Most likely, because they have no convincing business case. However, they have good contacts in the government, so they get to waste your tax dollars.

Note these tidbits from a report written for the House Oversight Committee: [house.gov]

- "The Government Accountability Office (GAO) found that the DOE loan guarantee program was riddled with program inefficiencies"

- "the absence of government intervention the private sector builds the infrastructure to assess risk, the federal government has neither the expertise nor the incentive..."

- "...once the government subsidizes a portion of the market, the object of the subsidy becomes a
safe asset. Safety in the market, however, often means low return on investments, which is likely to turn venture
capitalists away. As a result, capital investments will likely dry out and innovation rates will go down"

- "loan guarantee programs are unable to save failing industries or to create millions of jobs,
because—he explained—the original lack of access to credit markets is caused by serious industrial problems, not
vice versa. If an applicant’s business plan cannot be made to show a profit under reasonable economic assumptions, private lenders are unlikely to issue a loan. And they would be right not to."

- "the systematic economic harm done by rewarding companies that forgo value creation in favor of pursuing
financial benefit through the political system creates long term consequences for our economy and our country"

The fact that the government is wasting less money on this cronyism than it is wasting on useless wars is irrelevant. It is still waste, and it is still our money they are wasting.

Re:Why couldn't these companies get private loans? (1)

RabidReindeer (2625839) | about a year and a half ago | (#41345119)

There's a reason these companies came to the government: they could not get private sector financing. Why not? Most likely, because they have no convincing business case.

That's because in this day and age, a "convincing business case" isn't "Give me funding for R&D and I can probably exceed your wildest expectations eventually", it's "We'll give you a guaranteed 6 billion dollar payback next quarter". Corporations have all but abandoned long-term thinking and speculative research in pursuit of the largest profit in the shortest interval.

Governments, for all their faults, are not expected to show a profit (and, in fact, if they do, it probably means there's something amiss), don't live from quarter-to-quarter, and are therefore at liberty to pour money down assorted ratholes knowing that few of them will pan out. AND, when something does, they'll then unload whatever discoveries have been made to private enterprise.

It may not be the best solution around, but it's better than any of the alternatives.

Re:No problem with this (0)

Anonymous Coward | about a year and a half ago | (#41345245)

We still need tech advances in alternative energy. Subsidizing manufacturers of current tech does not get us there. We need basic R&D, which this program does not fund. The entire premise is flawed.

Re:No problem with this (0)

Anonymous Coward | about a year and a half ago | (#41343319)

Governments invest:

The US paid for a highway system in the 1950s that made zero ROI for itself for decades.

China spent money on infrastructure and airports, as well as laying fiber. You can watch streaming shows in real time from Shanghai to the rice paddy in almost every nook and cranny of the mainland.

As for Obama, yes, people sneer about what he did with the car industry, but GM is still making cars and its assets are not a part of some offshore conglomerate or holding company. If I buy a GM van, it will be a GM van, not a Dodge/Mercedes/Freightliner/Fiat monstrosity like the Sprinter.

I hate arguing for Obama, but he was handed the reigns of the country plunging into the worst economic times since the 1920s. The fact that we are not having massive tent cities [1] shows that he actually did something positive.

[1]: Other than Occupy, and the tents popping up in front of the local Apple store.

Re:No problem with this (0)

Anonymous Coward | about a year and a half ago | (#41343075)

We did invest in solar:

1: We had a number of companies make high yield panels.
2: China hacked them and stole their trade secrets.
3: China used the fact they are sitting on rare earths and started selling panels for less than it cost to make them.
4: Congress stood there and watched an industry get destroyed. Compare this to Harley where Congress swooped in with tariff after tariff to protect them.
5: US solar companies got shut down, high density battery technology gets sold to China.

I don't blame China -- they know that they would be in a strategic disadvantage if the US stopped spending trillions in camel country. However, the Congress violated their oath of office by not enforcing trade practices.

Re:No problem with this (1)

jcr (53032) | about a year and a half ago | (#41343767)

started selling panels for less than it cost to make them

If that were true, then it would basically be a gift from China to their customers.

-jcr

Re:No problem with this (0)

Anonymous Coward | about a year and a half ago | (#41343875)

It's called dumping. Give some number of customers a discount, so when your competitors are driven out of business you can charge all future customers a premium.

Research better use of $ (-1)

Anonymous Coward | about a year and a half ago | (#41341561)

I would much rather our government fund research, than to spend that same money trying to prop up a company. Once the research has found something viable, give that knowledge to any company in the US that wants it, and let them compete on an open market.

drone not soldier (0)

Anonymous Coward | about a year and a half ago | (#41341589)

soldier would still be marching on his or her stomach

Screw soldiers, NASA will love this. (3, Interesting)

Anonymous Coward | about a year and a half ago | (#41341689)

There's basically two ways to get power in space. One involves plutonium, the other high efficiency solar cells.
Since launch costs are related to weight, anything that increases panel efficiency, even if expensive, is great
for solar applications.

Re:Screw soldiers, NASA will love this. (0)

Anonymous Coward | about a year and a half ago | (#41342145)

Screw NASA. I love this.

Re:Screw soldiers, NASA will love this. (2, Informative)

Anonymous Coward | about a year and a half ago | (#41342231)

The solar (photovoltaic) panels used in space are already very efficient and use some of the most expensive materials such as being made out of Gallium Arsenide (GaAs) with multiple doped layers to collect at different valence levels. Panels used in space also receive sunlight that doesn't pass through the atmosphere allowing for higher power gains.

The problem has always been with getting high efficiency rates on earth without the high cost.

Re:Screw soldiers, NASA will love this. (0)

Anonymous Coward | about a year and a half ago | (#41342939)

There's basically two ways to get power in space. One involves plutonium, the other high efficiency solar cells .

Quibble, solar cells are really only good in the inner solar system due to the inverse square law [wikipedia.org].

Just sayin'.

The end justifies the means (3, Insightful)

deatypoo (1837038) | about a year and a half ago | (#41341725)

When the US starts paying what other countries pay for fossil fuel (as any European could say), then maybe solar power research will skyrocket. Until then, as it's not even currently appealing profit-wise, it's quite sad to say but only military applications and some rare initiatives (often subsidized) remain and that's just because soldiers can't be carrying their weight in oil to fuel the devices they use and batteries are still inconvenient. Let's give it a few more years, but recent events in the middle east should help a few make up their minds.

Re:The end justifies the means (1)

SeaFox (739806) | about a year and a half ago | (#41342047)

When the US starts paying what other countries pay for fossil fuel (as any European could say), then maybe solar power research will skyrocket.

So why isn't this research a hot field in Europe?

Re:The end justifies the means (2)

manu0601 (2221348) | about a year and a half ago | (#41342803)

So why isn't this research a hot field in Europe?

Because the hot field can be another research. France is a top player at nuclear energy, for instance.

Re:The end justifies the means (0)

Anonymous Coward | about a year and a half ago | (#41342965)

Yes, but Germany is planning to shut down their nuclear plants...

Re:The end justifies the means (2)

DamonHD (794830) | about a year and a half ago | (#41344871)

Germany (and others) for example already *has* a lot of *installed* solar PV.

But yes, research is going on in the EU too.

Rgds

Damon

Re:The end justifies the means (1)

gewalker (57809) | about a year and a half ago | (#41342433)

The US generally pays the same for fossil fuels as any other country in the world -- O you mean the US should raise taxes on fossil fuels to the levels seen in Europe, etc. so that the end-user has to pay a painfully high price. There are a number of different possible ways to reduce your carbon footprint if that is the goal. Tax policy is usually best left to the locals -- taxation without representation seems to be a bit of a sticking point here in the US.

I believe we should be reduce our carbon footprint by quite a bit, but I think the idea of taxing fossil fuels to double costs smells worse than an oil refinery and I'll tell my congressmen to vote against it. I might even use strong language.

Re:The end justifies the means (1)

strangeattraction (1058568) | about a year and a half ago | (#41342593)

Just raise them high enough to pay for the unfunded wars which we are only in because of energy dependency. Oops then we would be paying what they pay in Europe I guess. Our 2 parties seem to give of only 2 choices Tax and spend Democrats and No Tax Just Spend Republicans.

Re:The end justifies the means (1, Interesting)

hairyfeet (841228) | about a year and a half ago | (#41342977)

The simple fact is, whether anybody likes it or not, is that we simply haven't found ANY tech that can replace oil when it comes to the amount of energy per unit. Last I checked oil gives you a return of something like 30 to 1, most of the other techs are around 3-5 to 1. that isn't even close folks.

Then there is the problem of the NIMBYs, that frankly have a living shitfit if you do ANYTHING anywhere near them. Look at China, they are gonna have a good 25 nuclear reactors online in the time it takes the USA to get ONE through the 560 levels of paperwork and NIMBY bullshit. The smart way to go would be a combination of nuclear, molten salt and solar panels, wind and tide power generation cutting the living hell out of fossil fuel usage so pretty much the only thing we'd need it for is vehicles, but that will never happen here thanks to NIMBY.

Frankly I truly believe we could solve our energy problems within the next 15 years but sadly the whole damned thing has gotten too political. Instead of doing what will be best for the country you have lobbyists pushing blank checks for pointless programs like cap&trade, you've got NIMBYs having a shitfit if you build ANYTHING and the greenies are nearly as bad only they'll claim your new plant is gonna kill a frog or something. The whole damned thing here is so fucked up.

Re:The end justifies the means (0)

Anonymous Coward | about a year and a half ago | (#41343639)

What would go a long way in solving this technology is some means of storing energy in a battery that is even an order of magnitude worse than gasoline, by volume (as opposed to weight.)

Take a gallon of gasoline. It has around 35,000 watt hours of energy in it. A typical lithium battery has 128 watt hours of energy per gallon of volume. If we could come with something in the 3000-10000 range for watt hours of energy, this would completely change our daily life.

1: We can chuck the inefficient Otto cycle engines that waste heat out the exhaust and use electric motors which get their peak torque at 0 RPM.

2: We can use any energy source for battery charging.

3: The RV and auto industry would be completely changed. No generators or gasoline needed for a long camping trip in the back country.

However, any battery technology that we end up with in the US is ignored... or sold to China.

Without batteries, energy generation is half the issue.

unfortunatley... (1)

queazocotal (915608) | about a year and a half ago | (#41341907)

In order to do this, it relies on the sun being a nice bright disk.
If you try to split the image of the sun on a prism, it works well.
If you do the same with a cloudy sky, it totally fails,

So, this technique will not wWork at all during light cloud.
In many places, that more than halves the output.

Re:unfortunatley... (0)

Anonymous Coward | about a year and a half ago | (#41342209)

<Sarcasm> That's ok, we currently are only at war in sunny places so shouldn't matter much. </sarcasm>

PV works on cloudy days, too. (1)

Anonymous Coward | about a year and a half ago | (#41342359)

Too many people still believe (and want others to believe) that PV output drops to zero at the first sign of a cloud, but it simply isn't so.

My array is something like 15% efficient, give-or-take a few percent. Even on cloudy days it manages to charge my battery banks and power my loads.

Granted, the output decreases as the density of cloud increases, but, even on the most dismal and rainy days, there is still usable output from the array.

It's true that some places aren't exactly ideal for PV. (Seattle?) However, most other locations - those that aren't particularly prone to prolonged periods of thick cloud and heavy rain - manage quite well.

It's time to stop telling yourself that "Solar power just doesn't work!!!!!1111eleventyoneone" and go talk to people who actually know something about it.

Re:PV works on cloudy days, too. (0)

Anonymous Coward | about a year and a half ago | (#41342587)

Too many people still believe (and want others to believe) that PV output drops to zero at the first sign of a cloud, but it simply isn't so.

Too many people do. The post you responded to (apparently without reading) doesn't -- GP's argument was that the separation & concentration of bands to wavelength-optimized cells only works for parallel incoming rays. While this would be true for a simple prism or diffraction grating, I expect they're using more sophisticated means to avoid precisely that problem.

No. (3, Informative)

mosb1000 (710161) | about a year and a half ago | (#41342535)

If that were true, this would only work if the sun were at a very specific angle. But that's not how it works. It concentrates light from the entire sky into a narrow beam which is then split into different wavelengths. It says that right in the summary.

Re:No. (2)

Squirmy McPhee (856939) | about a year and a half ago | (#41345065)

It concentrates light from the entire sky into a narrow beam which is then split into different wavelengths. It says that right in the summary.

No, it doesn't say that in the summary. It says (incorrectly) that dichroic films are used to concentrate sunlight 20-200X, but nothing accurate about how it achieves that concentration. TFA says that for the concentrators to work, they would have to be pointed at the sun.

This is consistent with my personal experience. I've never seen a concentrator that can collect light from the entire sky and deliver it in a tight, focused beam. It's part of the reason concentrator systems have never quite managed to live up to their economic promise -- the diffuse portions of the solar spectrum go unused, reducing available energy by about 20% even in cloudless locations, and output drops to near zero as soon you have a few clouds or some haze.

And the dichroic films are used to split the light into its constituent parts, a bit like a prism. They play no role in the concentration of the light (though that is not your error).

Re:unfortunatley... (1)

dbIII (701233) | about a year and a half ago | (#41343017)

There are some photovoltaics that work well when it is cloudy.

Re:unfortunatley... (1)

jamstar7 (694492) | about a year and a half ago | (#41344007)

They work okay when it's cloudy. Hell, a Junior Scientist Kit solar cell will still put out some power in an indirectly lit room. It'll put out more in direct sunlight.

Trying again (1)

dbIII (701233) | about a year and a half ago | (#41344243)

There are some photovoltaics that work better on wavelengths that are blocked less by clouds than the normal silicon cells. If you expect a lot of cloud cover then those are the ones you pick for that job. They cost more because they are not a byproduct of making microprocessors like the silicon cells, but they have been available for probably a longer time than the poster complaining above has been alive.

LOL Military (0)

Anonymous Coward | about a year and a half ago | (#41341927)

Soldiers looking for a solar source of a few watt-hours of charge energy while traveling around in a 2 ton SUV carrying a million watt-hours in the tank.

LOL idiot (0)

Anonymous Coward | about a year and a half ago | (#41342581)

... who thinks he knows more about military logistics than DARPA.

Here's a hint regarding one of the several reasons you're dumb to say what you did: Gasoline is kind of expensive.

Re:LOL idiot (1)

jcr (53032) | about a year and a half ago | (#41343787)

Hate to break it to you, but DARPA's not a logistics organization.

-jcr

Current generation is still good (0)

Anonymous Coward | about a year and a half ago | (#41341979)

I am getting a 25ftx5.5ft solar array installed to produce 1.7kW of power (in perfect conditions). It cost $10,000 installed, ~$7,000 after tax rebate. It should provide 80-100% of the power I use each month, but I am a energy efficient guy. It should produce 225 kWh a month I'm estimating. But it is 12% efficient if you count the inverter ~97% and the panel at 13%. (It is still more efficient than 0 like most people.)

If DARPA can triple the efficiency, I could produce the same amount of power with only a 8ft by 5ft array. But that isn't important in my application.

If I had a sailboat and needed to be energy independent and not use fuel to power the electronics on board, this would be a big improvement.

Re:Current generation is still good (1)

icebike (68054) | about a year and a half ago | (#41342625)

With a larger view than just your project, doubling the efficiency MAY make a HUGE difference to the solar market as a whole.

But You can't tell from just the output side of the equation, you also need the cost side.

For fun, lets assume it can be brought in with mass production for the same 10,000 to cover the same area you installed.
Maybe you get all your summer cooling for free. Maybe you charge your battery operated car.

That's where I see the big advantage. If we can start getting a significant portion of our automotive power, for simply the capital investment costs, no continuing consumables, we are way ahead. In Australia, a survey found most people willing to make Solar roofs mandatory [energymatters.com.au] in new construction.

Its the same equations you are working on your project taken to a grand scale. Solar is already cost effective in some places, marginally cost effective in many more places, With with twice the efficiency it becomes phenomenally more cost effective in huge sections of the world.

Re:Current generation is still good (1)

Billy the Mountain (225541) | about a year and a half ago | (#41343235)

You should consider shopping around because for the bare panels you can easily find 300 watt panels for $400 in the U.S. And if you estimate the installation and other goodies, let's say that doubles the cost, you are still talking about $5000 installed.

Yeah, maybe (1)

Anonymous Coward | about a year and a half ago | (#41342005)

but that still means it's 50% not efficient. I don't know, I'm just in a pessimistic mood tonight.

Re:Yeah, maybe (1)

icebike (68054) | about a year and a half ago | (#41342649)

Even a half glass of water gets a thirsty man's attention.

50% efficiency as something approaching today's cost is probably enough of an improvement to start a world wide movement toward Solar.

Re:Yeah, maybe (0)

Anonymous Coward | about a year and a half ago | (#41344009)

Actually, it get worse then that efficiency ratings for solar panels are counted at 25c/77f which is pretty cold considering where you would want to mount most solar panels. Now, you know why PV is pretty much dead in the water outside of space/goverment funded applications. Also, solar thermal is a joke because most solar thermal plants only need to produce 50% of there power form the sun but still get to charge as if 100% came from the sun.

Cue yet another Solar Cell dream article... (0)

Anonymous Coward | about a year and a half ago | (#41342093)

Is science just filled will bullshit these days? Here's an idea, instead dreaming of the 50% solar cellfor the year 2030, just focus on better manufacturing methods for the 20% cells? How about increasing the durability of the 20% cells?
How about giving larger incentives for homeowners and business to buy solar cells?

Re:Cue yet another Solar Cell dream article... (4, Interesting)

icebike (68054) | about a year and a half ago | (#41342779)

Is science just filled will bullshit these days? Here's an idea, instead dreaming of the 50% solar cellfor the year 2030, just focus on better manufacturing methods for the 20% cells? How about increasing the durability of the 20% cells?

Lets try the old car analogy... heck, it almost fits.

Instead of working hard toward developing more fuel efficient cars, we should have found better ways to manufacture the 60's vintage cars and continued to accept the 8mpg that was common then.

See how dumb that sounds?

What's wrong with research? It is after all what got solar from 5% efficiency to where it is today.

I'm not convinced its wise to build massive amounts of not-very-cost-effective solar installations when twice the capacity might be available in 5 years. (Finished and installed Solar is in the mid teens, not the laboratory figure of 20%).

Re:Cue yet another Solar Cell dream article... (1)

HornWumpus (783565) | about a year and a half ago | (#41343669)

How about addressing the GP's point. Not what you wish he had said. You attacking strawmen sounds really dumb BTW.

The fact is efficiency is only part of the story. Efficiency has to be measured per dollar to reflect market reality. $/peek watt installed is one traditional rule of thumb way (we're looking for $1/peek watt installed).

Cutting the cost of 20% efficient cells by 60% is much like increasing the efficiency to 50% at the same cost (installation costs do matter, but I'm squinting at the problem and ignoring them). We're nowhere near being out of rooftop space.

In the real world you pursue all paths of research that are economical reasonable.

Re:Cue yet another Solar Cell dream article... (2)

Daetrin (576516) | about a year and a half ago | (#41343831)

He did address the GP's point. The GP said "Here's an idea, instead dreaming of the 50% solar cellfor the year 2030, just focus on better manufacturing methods for the 20% cells?".

I agree with you that pursuing all paths of research is good, however the GP didn't say "also", they said "instead." And both you and the GP seem to be missing the point that although cheaper low efficiency cells are good, they can't cover every case. Roofs aren't the only place people want to put solar cells. Sometimes you have a limited area of real estate to work with, at which point the efficiency, i.e. the power density, becomes rather important.

Now, hopefully (0)

Anonymous Coward | about a year and a half ago | (#41342411)

DARPA has provisions in the work that prohibits it being sold to other nations or companies owned by foreign interests esp. China.

Don't be a PV efficiency snob (4, Informative)

TrumpetPower! (190615) | about a year and a half ago | (#41342439)

Developments like this are awesome, because they open up the possibility of doing exactly what the summary describes -- using solar power to recharge things where size / weight / surface area is at a premium.

But those sorts of scenarios are few and far between. Most of the time, cost is the limiting factor, and these high-efficiency designs are always costly.

That's okay, though: PV panels are already plenty efficient for their desired function in most cases [ucsd.edu].

A typical location within the U.S. gets an annual average of 5 full-sun-equivalent hours per day. This means that the 1000 W/m solar flux reaching the ground when the sun is straight overhead is effectively available for 5 hours each day. Each square meter of panel is therefore exposed to 5 kWh of solar energy per day. At 15% efficiency, our square meter captures and delivers 0.75 kWh of energy to the house. A typical American home uses 30 kWh of electricity per day, so we’d need 40 square meters of panels. This works out to 430 square feet, or about one sixth the typical American house’s roof (the roof area of a two-car garage). What’s the problem?

Cheers,

b&

Re:Don't be a PV efficiency snob (1)

Anonymous Coward | about a year and a half ago | (#41342569)

Price.

Re:Don't be a PV efficiency snob (1, Interesting)

TrumpetPower! (190615) | about a year and a half ago | (#41343191)

Don't be a price snob, either.

If we wanted to go 100% solar for electricity generation over the next 50 years, it'd only take about as much as we're currently spending on federal government pensions. No small chunk of change, to be sure, but peanuts compared to the other big projects our society doesn't even bat an eye on.

(Assume $2 / watt installed, not much below the current bottom end but well above what such huge economies of scale would push it to. Assume 1 MWH per year per kW of panels, quite pessimistic -- I'm in Arizona, and I'm getting 2 MWH / year / kW, and Olympia, the dreariest part of the country, gets more than half the sun-hours we do here. Now plug in the Wikipedia figures for annual US electricity consumption, divide by 50, and compare with budget figures.)

Cheers,

b&

Re:Don't be a PV efficiency snob (1)

Anonymous Coward | about a year and a half ago | (#41343251)

Assume $2 / watt installed

That is rather low, rather 80% low.

Including wiring and batteries, and battery housing, and battery maintenance, typically it costs around $10 per watt initially and an additional $2-5 per watt every five years thereafter just to replace the batteries. Did I mention batteries?

The current cost of a complete solar solution is significantly higher than the cost of an average house and would take more time than an average person lives in any one house to recoup the cost.

Re:Don't be a PV efficiency snob (2)

Anonymous Coward | about a year and a half ago | (#41343465)

The return on investment for PV just doesn't make sense. It is non-existant. You could spend a fraction of the cost of PV insulating everyone's attic, replacing windows, buying tubes of caulking, or changing furnace filters and save tons of energy. The program would actually payback!

PV is a marketing statement more than a practical energy saving strategy.

Re:Don't be a PV efficiency snob (1)

HornWumpus (783565) | about a year and a half ago | (#41343679)

Does insulation, double glazed windows, caulking and new furnace filters make hippie chicks puddle?

There goes that idea. I bet you don't even own a hybrid.

Re:Don't be a PV efficiency snob (1)

Anonymous Coward | about a year and a half ago | (#41343231)

$6 per watt average installed cost = no payback. And you still need a grid connection.

Re:Don't be a PV efficiency snob (0)

Anonymous Coward | about a year and a half ago | (#41343245)

I call BS. The factor that makes solar pointless for all but specialty items (power for remote locations) is that the cost of making not just the silicon, but the other parts of the panel and power network FAR outweigh the energy gotten back. So, for every kWh of electricity you get from that panel, you actually have put in two to 20 over its operational life.

Lets get real here: Solar has its uses, but as a mainstream energy source, be serious. A coal plant is a lot more efficient when one puts together the costs of making what is used for the energy generation. At least a coal plant puts out more energy than it cost to make it.

Re:Don't be a PV efficiency snob (1)

nocain (2730619) | about a year and a half ago | (#41343695)

So I am missing something because this does not add up, 40 meters squared is nowhere near 430 sq feet, unless my drunken math is that bad or I am missing something entirely, hoping since its from UCSD and titled do-the-math.... I get 1 meter about 3.3 foot so 40x3.3=132feet so 132ft x 132ft area... thats a lot bigger than my 2 car garage, maybe they meant 2 airplane garage?

Re:Don't be a PV efficiency snob (1)

Anonymous Coward | about a year and a half ago | (#41343783)

Yes, you are missing an education. Assume 1m=3ft, then 1msq=9ftsq so 40msq=360ftsq. Right in the ballpark.

Re:Don't be a PV efficiency snob (0)

Anonymous Coward | about a year and a half ago | (#41343823)

Yes, your drunken math is bad. Go back to your calculations and do a dimensions analysis to see what went wrong.

Re:Don't be a PV efficiency snob (0)

Anonymous Coward | about a year and a half ago | (#41344985)

No worries, I moderated you funny. 40 squared meters. Hahaha.

Re:Don't be a PV efficiency snob (0)

Anonymous Coward | about a year and a half ago | (#41344039)

there are no 15% efficiency mounted commercially available panels even panels claiming to get close to that much efficiency do so only at 25C which means they get a lot less efficient when the amount of sunlight hitting them increase. Test I've seen show around a 40% loss at 50c which is what many panels will reach in 25c weather. No to mention cook eggs on a side walk weather many places receive.

Why focus on solar? (2)

evilviper (135110) | about a year and a half ago | (#41342749)

Why would the military focus so heavily on solar power? I mean, the research is a very good thing, and will be a huge boon for satellites, and maybe electric vehicles as well, but for soldiers, they have a lot more options available.

The main thing which comes to mind is the backpack which converts motion into electricity, which happens to have a side-effect of altering one's stride into a more efficient motion as well:

http://www.msnbc.msn.com/id/9245155/ns/technology_and_science-science/t/backpack-generates-its-own-electricity/ [msn.com]

This could be supplemented by a set of foot-pedals, so if the soldiers are stationary, they could assign one guy to generate the power they need... If they're stationary and not marching, I'd suppose the workout might even be welcome.

These options have the added advantage of working just as well in high latitudes, bad weather, and during sandstorms, and not requiring soldiers with other concerns to deal with panels hanging off their pack, and needing to be oriented to catch the sun.

Re:Why focus on solar? (0)

Anonymous Coward | about a year and a half ago | (#41342935)

From your link: "It’s true that you burn a few more calories when you walk with the backpack than a traditional backpack of the same weight."

They go on to explain how it's better to carry more food than more batteries. However, this says that that is not the only option. Instead of carrying food or batteries, you could carry a solar panel. On a long deployment, this could mean that you still have power and food longer (since the solar panel doesn't get used up the way that batteries or food do). In fact, you could still have power after you stop moving to conserve food.

You may be correct that the tradeoff isn't worth it. However, in order to determine that, you need both systems.

Re:Why focus on solar? (1)

evilviper (135110) | about a year and a half ago | (#41344655)

Your complaints really aren't relevant to the real world. Soldiers aren't in a situation of facing starvation, where burning "a few more calories" will be an issue. They would cease to be a fighting force long before that point. And besides, solar panels on everything adds weight, too.

You may be correct that the tradeoff isn't worth it. However, in order to determine that, you need both systems.

No, it's pretty damn easy to calculate the possible benefit versus the alternatives. You can also calculate 60% efficient, 70% efficient solar panels as well.

Re:Why focus on solar? (-1)

Anonymous Coward | about a year and a half ago | (#41343005)

how about micro-nuclear power packs, or nuclear batteries as i like to call them. strap one to every soldier. embed gps and a remote detonation device into them. if we lose communications with the soldiers or they get captured, we give islamic terrorists a taster of their own suicide bomber medicine.

iran is the beast. china is the dragon.

Re:Why focus on solar? (0)

Anonymous Coward | about a year and a half ago | (#41343233)

Because soldiers already carry a metric fuckload on their backs, and adding a backpack energy generator could very well break them?

Re:Why focus on solar? (3, Interesting)

Squirmy McPhee (856939) | about a year and a half ago | (#41345121)

Why would the military focus so heavily on solar power?

It's not just solar, they are also very interested in wind, geothermal/ground source, and biofuels. But they think solar and wind have the most potential for their purposes (it's mostly only the Air Force interested in biofuels, for fueling their planes).

As for why, well, 80% of the convoys run in Iraq and Afghanistan are fuel convoys. On average, a soldier died or was wounded in one of every 46 of those convoys in 2010. And by the time you take into account the cost of the fuel and the expense of moving it, the military is paying something like 5-10 times the price you pay at the pump when you fill your gas tank.

What is this fuel used for? Some of it is used to power vehicles, of course, but the vast majority of it is used to provide electricity at remote and forward bases. They dump it in a generator, burn it, and wait for another convoy. On the other hand, the sun and the wind come to many of their locations without the need for a convoy.

The upshot of all of this is that with sufficient energy densities, the military could spend a whole lot more on solar panels and wind turbines that would seem justifiable to the average homeowner and still have it be economical -- I mean, just think of the money and lives that could be saved if a base could reduce the number of convoys it needs by 80%.

For all of that, you probably don't need cells with 50% efficiency, and I guess that's why TFA focuses on soldiers' gear instead of base power.

Your concern about a soldier contending with solar panels hanging off his back is a bit misplaced, I think. TFA says that at 50% efficiency, a 10-cm square panel is all that would be needed. That is already smaller than a single standard silicon cell in production today (standard is 15-cm square). And if you're worried about bad weather, sandstorms, and distractions then I would think that the last thing you want is a mechanical device with moving parts like foot pedals.

Great! (2)

amightywind (691887) | about a year and a half ago | (#41342773)

A 50% efficiency would merely make solar energy a lousy energy source, not a ridiculous one.

Re:Great! (1)

jamstar7 (694492) | about a year and a half ago | (#41344053)

Not if they can get the costs down. If they could produce a 50% efficient PV cell for what they spend today, solar would start looking viable, even without massive subsidies and tax rebates that keep the current cells just barely around breakeven in cost vs output ratios. At the moment, without tax rebates and subsidies, solar is way too niche to work properly.

Unless you like paying 2 bucks a kilowatt hour...

Re:Great! (0)

Anonymous Coward | about a year and a half ago | (#41345235)

Yes I do. I'm even paying $5.88 for the first year per kWh. The next year, the number gets divided in half. The year after that it goes down again. And repeat for 40-50 years. Because it is all up front cost. It might not be cost comparable to the 'pollution-tax free' dirty power sources for 12-15 years, but it is a long-term investment, and one less bill to worry about.

It is worth it to not make any air pollution, and take some money away from the energy companies.

Now, there are a lot of other things the government (mostly state, local, HOA, and utility oversight) needs to do in order to make it cheaper. Instead of taking 4 months to get a system installed, it should take 2 weeks to get the permits, interconnection agreement, and approvals.

Solar "Efficiency" (0)

Anonymous Coward | about a year and a half ago | (#41342845)

It is my understanding that most of this quoted Efficiency numbers are quite useless in real life??? Because to get a large amount of power you need a lot of sun light but since sun light = heat you move away from the quoted Efficiency simply put to get max efficiency you would need to build your panel near the poles but since you don't get more dispersed light you loose. Efficiency numbers are given with the panel at 25 C am sorry but on a summer day any where with a decent concentration of sunlight your going to see ambient temps over 25 and a black panel is going to heat up to like 50+ C.

Something wrong with this picture (2)

Shavano (2541114) | about a year and a half ago | (#41342877)

And this is going to be cheaper than triple-junction cells? And DARPA is going to be in charge of making it cheap?

I'm not holding my breath.

Very nice (-1, Offtopic)

oliva23 (2730669) | about a year and a half ago | (#41344047)

my best friend's half-sister makes $70 every hour on the laptop. She has been unemployed for five months but last month her paycheck was $21307 just working on the laptop for a few hours. Read more site on this web http://doiop.com/s09ci0 [doiop.com]

O, come on. (0)

Anonymous Coward | about a year and a half ago | (#41344369)

I'm tired, tired, tired of this. Every few weeks someone comes up with a solar cell technology, design, whatever that increases efficiency by xx%. If you believe some of them, efficiency should be well over 100% by now. Yet, in practice, you'll be lucky to find cells with efficiencies approaching 20%. It is worse than the miracle cancer cures that seem to come out every few months.

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