[SGVLUG] Off-topic - home guerrilla solar systems

[Dustin Laurence]

On Sat, Feb 24, 2007 at 12:50:43PM -0800, David Lawyer wrote:
> 
> content.  I've read that PV will cost more for electricity so if
> that's the case then it's a loser.

On general grounds I am not in favor of using cost-return rather than
energy-return to value solar systems.  On the other hand, the paper you
linked looks interesting and, at a glance, apparently argues that when
people count energy-return for PV's they undercount.  If so, then I
would argue that the message is not to adopt cost-return, but rather fix
the energy-return calculation.

One reason is that I've never seen a cost-return calculation that has
the guts to charge a sizable portion of the defense budget to the cost
of oil.  Unless a sizable chunk of the taxes I pay each year is counted
as part of the cost of grid electricity, then that calculation is badly
undercounting as well.

Just as a back-of-the-envelope thing it's a bit complicated.  The annual
military budget is ~$5.3*10^9 for FY 2007, and the population is about
3*10^6, or about $1700 per person per year.  Or, since taxes are not
linear, you can do better by calculating 3.7% of your taxes as your
military share.  Heh, don't you wish it were that easy?  You need to add
in the supplementary spending bills that are actually paying for Iraq
and Afganistan, and the black budget that isn't in the official DoD
budget.

But that's just getting started.  You need to estimate what fraction of
that is directly related to foreign energy, which isn't easy and is
probably violently disputed.  If you are especially morally opposed to
war then you may need to guesstimate some sort of fudge factor to
represent how much more you like this energy (and if you say infinite I
won't believe you as very few people would do *anything* to avoid it,
just as few people would actually live without, say, toilet paper no
matter what).  Then you have to realize that this is just the extra real
cost of fossil energy for any purpose, and factor it in to all energy
cost.  Oops, better do it just for fossil fuel, hydroelectric is
different.  Now increase not only the cost of grid electricity but also
the electricity used to create the PV cells.

That should keep you out of trouble for a couple of weekends. :-)

Note that I'm therefore talking about social cost, not individual cost.
Economically we are set up so that the most efficient individual
strategy is generally to burn your share of ancient sunlight.  Right
now, if money is your God then you should go worship him with burnt
offerings at the pump and meter like everyone else.  Solar power, like
the biodiesel I burn, is for people who are trying to buy something else
with their money.

On the other hand, nothing reduces costs and increases efficiency like
manufacturing in the greatest possible volume.  So one good effect of
adopting a technology early is that you *may* help push it over the
hump.  I said may--you need to be willing to risk wasting your
investment, if the technology, economics, or politics ultimately pulls
the market a different way.

Finally, on PV's specifically, I know 20 years ago it was quite true
that you lost more energy than you gained from solar cells, so they were
worthless except for situations were grid power was inconvenient
(spacecraft, remote installations, radar beacons on buoys far away from
shore...).  My impression was that efficiency had probably increased
enough to fix this, but I have not attempted to be really sure of it.

> installation will last.  You also need to include the cost of
> batteries.

As others have said, this isn't true.  The grid already exists whether
you use it or not and is paid for, so it's an excellent idea to utilize
it as an energy storage device and a bad idea to use energy to make
batteries that are a waste disposal problem when they die.  Also, when
you pay for your grid connection the power company has to maintain it,
and their uptime record is excellent.  If you have batteries, it's
another system *you* must maintain (and therefore costs time as well as
money).

Another good reason is that energy is not the only issue.  We live in a
desert here in SoCal.  I think we get enough hydroelectric power to make
it independently worthwhile to save water with a solar system by
releasing less water from the reservoirs (but if someone has a better
idea on the relationship of drinking water to power generation in
California, I welcome better information).  In other words, if I'm right
about the connection between power and drinking water, then spending the
energy elsewhere to make the PV cell is as good as transporting water
here, and much cheaper.

Don't you long for the simple days when good citizenship just meant
voting, cleaning up after yourself, volunteering for the fire
department, and serving in the military if there was a war? :-)

Dustin

-- 
The small binary attachment on every message I send is my PGP digital
signature, not a virus.  If you don't know what that is, you can ignore it.
If you do, my keyserver is pgp.mit.edu.
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