[Tfug] OT: Big Oil? Windows Vista!

[Ronald Sutherland]

On Wed, May 28, 2008 at 9:05 AM, Hubert M Bath <bathhm at laposadagv.net>
wrote:

> "one will be able to buy a solar panel that is the size of a laptop for
> several hundred dollars that will be able to power your house, in say 5
> to 10 years...."
>

hehe... it will absorb neutrons to drive fission reactions... way cool.


> My (emphatic) vote is that this *is* impossible, at any price.  The
> arrays of PV cells large enough to generate of couple of Kw  currently
> cover dozens of square feet. My son, who designs and sells PV
> installations on the Big Island of Hawaii says that 2KW output after
> conversion from DC to AC requires 153 ft^2 of PV cells.  Full output is
> available 5 hours per day.  20% is the efficiency in conversion from
> radiation to DC.
>
>  Solar radiation density at the surface of the earth is taken to be
> 1000 w/m^2. [ Solar constant = power per square meter at the top of the
> atmosphere is about 1350 watts. ]
>
> So apparently 1000 watts/m^2 is available at the earth's surface.  A
> laptop has an area of about 0.12 m^2.  So the laptop, collecting and
> converting at 100% efficiency could generate 120 watts.  That's all the
> energy that is available.  Enough for a very small house.
>
> Regards,  Hu Bath
>

Spectrolab makes some very efficient Solar cells, >28%

http://www.spectrolab.com/DataSheets/TNJCell/utj3.pdf

but they cost a lot and there price will never drop to a competitive level
with single junction silicon PV. The materials are more exotic than silicon
and much higher energy input is required to process the multiple
semiconductor structures. However they are nice for space craft. It is
possible to concentrate solar radiation on PV but it is very important to
keep the PV temperature as low as possible. The two panels I got six years
ago are monocrystalline silicon, which is to this day the most efficient
commercially available product. Back then it was Siemens sp75, then shell
oil sold them for a while, and now the improved solarworld version (it has
even less info on the datasheet).

http://www.mrsolar.com/pdf/shell/Solarworld758085.pdf
(ouch 415$ each, I payed about 500$ for both 6 years ago from mrsolar)

A test of commercial PV:
http://www.solarworld.de/fileadmin/content_for_all/pdf/test_ergebnisse/photon-test-2007-en.pdf

I found the company that makes the 20kW Stirling engine, and they even had a
job posted for a test engineer... hehe... I sent them my resume.

http://www.stirlingenergy.com/
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