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Re: Solar Energy



Stephen Lajoie <lajoie@eskimo.com> wrote:
>Will Stewart  <will1000@ix.netcom.com> wrote:
>>meron@cars3.uchicago.edu writes: 
>>>nick@vu-vlsi.ee.vill.edu (Nick Pine) writes:

I do? I don't see anything quoted below that I wrote. Perhaps the >>>s
got confused somewhere... But as long as I'm here...

>>Kindly provide information showing the areas of the country that are
>>subject to two straight weeks of rain in a given year.  Now, what
>>percentage of the country is that?

I dunno. 30%? We seem to get 2 weeks of cloudy weather in January fairly
often around Philadelphia. Who cares, and why?

>At what reliability? We are talking probabilities here. How many sigma do
>we want to go out? And it doesn't have to be just rain; it can be simply
>cloud cover, snow cover or fog.

I'd like to know more about that. Norman Saunders, PE, estimates yearly backup
heat requirements of his solar houses based on house heating loads, the size
of the thermal store, and Gaussian weather statistics. I don't understand his
method, but his "100% solar houses" are nearly so, with predictions of backup
heating required every 40 years, in New England. Some of them have no backup
heating systems at all. He has elaborate temperature records from data logger/
fan controllers in these houses, with track records going back over 12 years.
This is sort of like 100 year flood predictions, with less dire consequences,
like having to wear a sweater indoors once every 40 years :-)

He doesn't use PVs or solar thermal panels, just glass, containers of water,
fans and insulation. I'd rather use plastic instead of glass, and I think
one could do almost as well without the fans, but it would cost more to build.

>[Cloudy weather] happens on a regular basis in these areas. It has less 
>of a probability in other areas but it CAN happen ANYWHERE, it is just a 
>matter of probability.

Then let's treat it as such, with numbers. It's not a disaster. It just
increases one's backup heating bill a bit. How much? Or drives purists to
wearing sweaters indoors. How often? I'd like to see numbers, not hand-waving.

>Maybe for the unreliable systems you envision, yeah, you don't have too
>many areas. But if you are trying to match the reliability of the grid,
>that would be another story. 

I think of the sun as fairly reliable. Moreso than the electrical grid.
It's been working longer, with no serious outages lately, and no major
repairs. It is very predictable, on a long time scale, and it seems to me 
that with proper statistics and careful design, we can build more houses
with thermal storage, that do not have any other form of heat. These might
be called "solar houses," a hundred years from now. 

>>Now, just because a tiny percentage of the country might have rain that
>>lasts two weeks, solar electrical generation is infeasible everywhere? 
>>I think your implications require re-examination.

It's nice to see the word "electrical" above.

>As usual, you ignore probability and reliability simply because it runs 
>counter to your beliefs.

Versus just talking about them? :-)

Nick