

Breakthrough could double solar energy output - pwg
http://www.latimes.com/news/local/environment/la-me-gs-breakthrough-double-solar-energy-output-20111216,0,3897047.story

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ars
This is not a new invention - it's called a multi junction solar cell.
(Although this may be a cheap way to do - that part may be new.)

A photon needs to be above a critical energy to generate an electron - any
energy above that is lost as heat. Any photons lower than that energy are
unusable and also lost as heat.

A multi junction solar cell has multiple layers, each one capable of handling
a different energy level.

For extra credit have the photon create an electron, then get emitted again
with a lower energy only to be captured a second time by a lower layer.

But these type of solar cells cost a lot to make, so are mainly lab
curiosities and are not used commercially much except in very specially
applications where the cost is worth it.

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jpdoctor
> _This is not a new invention - it's called a multi junction solar cell._

The photon absorption mechanism of multi-junction solar cells is still energy-
transfer via electron-hole pair production.

This paper is utilizing excitons for the energy transfer, which truly is a
different beast.

[One liner description of excitons: It is a positive and negative charge bound
together by electrostatic attraction. It acts a lot like hydrogen with a hole
taking the role of the proton.] (OK, that was two lines.)

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alexholehouse
Original article in Science Daily is here;
[http://www.sciencedaily.com/releases/2011/12/111215141617.ht...](http://www.sciencedaily.com/releases/2011/12/111215141617.htm)

Original paper is here; <http://www.sciencemag.org/content/334/6062/1541>

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andrewfelix
Everyone do yourselves a favor and read these instead.

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bane
I'll believe it when the headline reads "Breakthrough _doubles_ solar
energy..." not "could".

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hristov
If I read the article correctly it seems that his improvement in experimental
conditions is about 42% which is still very impressive.

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karamazov
"loads more electrical power"? "it's way cheap"? This sounds like it was
written for a college newspaper by a freshman.

~~~
anthonyb
I also liked "much of the energy delivered by sunlight comes in the form of
“hot” electrons"

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jurjenh
I think the biggest statement in the article is _The bottom line? Commonly
used studies have listed dollars-per-watt of electricity as high as $7.61.
According to Dr. Pearce, the real cost in 2011 is under $1 per watt._

That used to be the figure at which it would become feasible to convert to
mass generation through solar... Maybe the timing is off, it came quicker than
a lot of people expected, or else there are other factors still to be solved
(availability?)

Should be an interesting space to watch over the next 2-5 years, now that
we've reached the $1/watt mark...

~~~
fpp
This is indeed another confirmation of what I've heard earlier this year that
1kw can now be build for about $1000 (including inverters / control devices) -

now put this knowledge into context -

One of the biggest solar plants currently being planned / projected / soon to
be build is in Greece with about 20km2 of area donated by the Greek state to
build solar plant(s) up to 10+ GW (the numbers are only a few months old so
not much change in efficiency here).

This should finally also make it clear to everyone what really is wrong with
renewables & the "energy industry" today.

Simple arithmetic shows you that the consortium of the usual suspects (large
energy conglomerates, quangos / PPPs, banks & private equity) is cutting
themselves a premium of at least 100% for financing etc. And that does not
include the frontloading of other cost, tax free revenues etc.

At the same time smaller decentralized plants are being hindered with changes
in legislation, feed-in tariffs, planning permissions and ridiculously high
building cost. At least here in Europe.

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sneak
I would be very concerned if the solar energy output doubled. I don't have
nearly enough insulation in my house, and I'm rather fond of the oceans.

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MichaelApproved
Like all other "breakthroughs": it sounds great but I'll only get excited
when/if it's actually been commercialized and available for purchase.

~~~
arctangent
This is a very good point.

There are lots of "breakthroughs" which are genuinely incredibly useful, but
not commercially viable (yet, or ever).

Until these things are viable commercially it is best not to get too giddy
when hearing about them.

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strstr
If only they defined what they meant by 'output' in the title to make it less
sensational.

Most readers will likely interpret this as energy, which is not the case. The
author meant output of electrons per photon absorbed. (The breakthrough is
that high energy photons can be absorbed with less loss of energy by
converting them into multiple electrons.)

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DiabloD3
Heh, another thing that the mass media tries to get me excited with, and just
baits and switches with more of that good ole coal and oil.

Who cares if they discovered it if I can never buy it.

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fungi
according to a rerun of the a speech by the australian climate change
commissioner to the national press club i watched a bit of yesterday,
depending on where you live the current cost curve of solar energy will place
on par with brown coal in 2018.

technological development will only accelerate change.

think it was this speech <http://www.npc.org.au/speakerarchive/tim-
flannery.html..>. old media == no stream or even a transcript :\

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Maxious
Might be this one, no transcript though:
[http://www.abc.net.au/tv/bigideas/stories/2011/02/08/3131960...](http://www.abc.net.au/tv/bigideas/stories/2011/02/08/3131960.htm)

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JohnnyBrown
They described the plastic as 'organic', hopefully this means it comes from
somewhere other than from petroleum - does anyone know enough to comment?

If it means organic as in 'carbon-based compound' then it's just redundant.

~~~
stan_rogers
Pentacene is synthesized from benzene, and the primary source for benzene is
currently petroleum. It doesn't _have to be_ , but benzene has always been a
relatively cheap "garbage" byproduct of other products (first coke, then
petroleum fuels). It is unlikely that over the long term extraction of fossil
fuels would be a cost-efficient means of deriving chemicals that are now
heavily subsidized by the primary products; bacterial synthesis would probably
much more practical. That is to say one shouldn't dismiss non-fuel
petrochemicals simply because the current cheapest source is petroleum -- it
won't always be unless the demand for petrochemical fuels (or coal/coke)
remains high. Ironically, then, things that are now petrochemicals could spell
the end of the petrochemical industry if they contribute to a reduction in
demand for fuel.

