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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.
soldier would still be marching on his or her stomach
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.
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.
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.
but that still means it's 50% not efficient. I don't know, I'm just in a pessimistic mood tonight.
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?
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.
DARPA has provisions in the work that prohibits it being sold to other nations or companies owned by foreign interests esp. China.
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.
... 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.
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
A 50% efficiency would merely make solar energy a lousy energy source, not a ridiculous one.
an ill wind that blows no good
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.
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.
100% more expensive, brok brok brok.
Good leaders run toward problems, bad leaders hide from them.
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
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.
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.
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.
at 25% efficiency, you only get 8,250 watt hours out of that gallon of gasolene. Moreover, that gallon of gas once burned has ZERO watt hours left. Meanwhile that 128 watt per litre battery is ready to charge and recharge and get you moving again.
1000 watt hours per litre would be absolutely effective. After four refills, you'd have regained any lost capacity and still have the same ready to do all over again.