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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."
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.
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.
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.
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.