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Towards a 50% Efficient Solar Cell
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."
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.
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.
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.
Any sufficiently advanced incompetence is indistinguishable from malice.
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.
but that still means it's 50% not efficient. I don't know, I'm just in a pessimistic mood tonight.
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.
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.
Cheers,
b&
All but God can prove this sentence true.
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.
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 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.
Sig Battery depleted. Reverting to safe mode.
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/
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.
Slashdot gets worse every day... Pipedot: News for nerds, without the corporate slant
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%).
Sig Battery depleted. Reverting to safe mode.
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.
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.
That was the turning point of my life--I went from negative zero to positive zero.
100% more expensive, brok brok brok.
Good leaders run toward problems, bad leaders hide from them.
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.
John McAfee 'It was like that time I hired that Bangkok prostitute; to do my taxes, while I fucked my accountant'
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
http://www.techbriefs.com/index.php?option=com_staticxt&staticfile=/Briefs/June03/NPO21051.html
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.
http://www.geoffreylandis.com
Hate to break it to you, but DARPA's not a logistics organization.
-jcr
The only title of honor that a tyrant can grant is "Enemy of the State."
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.
This Space Intentionally Left Blank
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...
Understanding the scope of the problem is the first step on the path to true panic.
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.
20% is already close to the 30% efficiency of a nuclear power plant.
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:
- "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.
Enjoy life! This is not a dress rehearsal.
He didn't say ignore efficiency. He said focus on manufacturing and make incremental improvements. 'instead dreaming of the 50% solar cellfor the year 2030, just focus on better manufacturing methods for the 20% cells?'. He then gave an example of an incremental improvement.
Incremental improvements where how 50's cars turned into modern cars. Breakthrough thinking got us the 'Tucker'. Before anybody defends the Tucker realize that it was made with an aviation engine. Does anybody think putting helicopter engines into cars is remotely economical?
John McAfee 'It was like that time I hired that Bangkok prostitute; to do my taxes, while I fucked my accountant'
And you'll be refilling that battery with energy made HOW?
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