[ExI] solar is looking better all the time: was RE: Efficiency of wind power

[Eugen Leitl]

On Tue, Apr 19, 2011 at 01:25:38PM -0400, Mr Jones wrote:
> Did any of you happen to catch this yet?...
> 
> http://michigantoday.umich.edu/2011/04/story.php?id=7980&tr=y&auid=8154157

Yes.
 
> The light must be shone through a material that does not conduct
> > electricity, such as glass. And it must be focused to an intensity of 10
> > million watts per square centimeter.
> 
> 
> How difficult a task is this?  Are the optics required difficult to come
> by/produce?

Nanometamaterials/photonic crystal patterning are hard problems on
their own. Semiconductors, particularly in quantum dot form can
be pretty cheap and made from nonscarce/nontoxic elements.

Long-term we're likely to see interesting new approaches (e.g. rectennas
scaled into VIS/NIR) with quantitative efficiency, but we're again
looking at fabrication issues. This will be probably done by autoassembly
or outright machine-phase which are both comfortably far off.
 
> I think I saw somewhere in the article 10% efficiency.  What are current
> solar panels rated at?  What efficiency do we need to attain to make solar
> ubiquitous?

In PV you're looking at ROI and EROEI integrated over lifetime.
Efficiency is typically negatively correlated to that, so as long
as you're above some minimal (~2-5%) efficiency with all other factors
compensating for it you're in the clear.

Best commercial efficiencies are ~20% IIRC, best lab is approaching
50%, but that's concentrated multujunction/tuned bandgap stacks made
from unobtainium.

Trend see http://upload.wikimedia.org/wikipedia/commons/7/74/PVeff%28rev100921%29.jpg

-- 
Eugen* Leitl <a href="http://leitl.org">leitl</a> http://leitl.org
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