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From: keithl@loop.uucp (Keith Lofstrom;;;628-3645)
Newsgroups: sci.energy,sci.electronics,sci.physics
Subject: Re: solar cells
Message-ID: <1991Jan3.072059.20842@loop.uucp>
Date: 3 Jan 91 07:20:59 GMT
Organization: Launch Loop, Portland OR
Lines: 60

>|  Solar power: no digging, no processing, energy is converted from 
>|sunlight, no remains.

Most solar cells are made with processes that are similar to those used to
make integrated circuits.  A big IC fab turns out on the order of a million
wafers a year, and turns out tens of thousands of gallons of liquid toxic waste
and hundreds of thousands of cubic feet of gaseous waste in the process.  
A million 6 inch wafers is about 20,000 square meters.

Assume an average insolation of 400 cal/cm2-day -- or about 180 watts/m2
average, for a flat plate collector without tracking.   Given a collection and
storage efficiency of 14%, that's about 25 watts per square meter.  So, this
million wafer plant is turning out about 500 Kw of generating potential a year.
If the cells last 20 years, that's 10 Mw-year of power per those thousands of
gallons of toxic waste.  Scaled to nuclear plant size, that's millions of
gallons of waste per year for the same amount of power.  I'd rather take a few
cubic meters of high-level radwaste any day.

Safety?  Ever see the results of a fab fire?  A co-worker had a wall clock 
that had barely survived a silane fire.  Interesting Salvadore Dali effect.
When I was with my former employer, we had building evacuations about twice
a year.  Rule of thumb:  safety costs money.  As prices go down, safety may
go down, too.  Imagine hundreds of fab fires a year...

That same silicon area could be turned into about 100 GW of power controller.
Some friends are working on controllers that will save about half the motor
power use on the New York subway.  Other folks are working on reprogrammable
motors for the Detroit's assembly lines - smart controllers could save about
30% of power use.  I saw a paper once on a smart power controller for the
off-hook detection for telephones;  this circuit saves about 3 watts per
phone.  There's a lot of phones out there.  So why waste all that silicon
processing capability on such trivial power savers as solar photovoltaics?

Conclusion:  Solar cells are an expensive joke for residential and bulk
industrial power.  They are O.K. for satellites, mountaintops, toys,
calculators, and other niches.  

*H*O*W*E*V*E*R* - they do have one saving grace, and one that I think makes
the whole thing worthwhile:  the folks that DO install residential solar power
systems will find themselves with a trickle of power and not much money left.
So, if they want to survive, they will have to be fiendishly clever about
efficient and cost-effective power use.  And the rest of us will benefit from
the hard-won knowledge here, even if those gaining that knowledge suffer
greatly for it.

Nothing succeeds at keeping a determined person at a task as effectively
as telling them how ridiculous they are.  So for all of you solar folks
that I have made RAGING MAD, please take that emotional energy and make
something impressive with it.  You are free to flame at me, but you will
bring about an energy revolution faster by building inexpensive and
attractive energy-saving products, rather than sounding off about evil
power companies and energy company conspiracies like a paranoid flake.

And if any of those products require efficient, cost-effective use of
silicon, give me a call ;-)

-- 
Keith Lofstrom  keithl@loop.uucp ...!sun!nosun!loop!keithl (503)628-3645
KLIC --- Keith Lofstrom Integrated Circuits --- "Your Ideas in Silicon"
Design Contracting in Bipolar and CMOS - Analog, Digital, and Power ICs