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Re: Solar Energy



Stephen Lajoie <lajoie@eskimo.com> again conflates solar thermal and
electrical energy, while miscalculating the US energy pie: 

>>> But, you neglect the losses in the battery...

About 10%, BTW. You have to put in about 10% more energy in charging a
battery than you get out when discharging it. Not very important, I'd say. 

>... I note that there is no large scale 
>presence of solar energy in the U.S., less than 1/2 of one percent.

Au contraire, I think that with proper accounting, over 99% of the
energy present in the US would be called "solar."

>>... it looks worse, i.e., less economical, when you insist that solar must
>>exist completely independent from the current structures. 

"Solar" what?

>Excuse me for using good engineering practices.

OK, but I haven't seen that yet.

>I didn't know that solar engineers were suppose[d] to throw that book out.

Ie economics? Some of us don't.

>But when you crunch the numbers, solar just doesn't cut it.

"Solar" what? A 2 year payback for space heating seems nice to me. Regardless
of context, it still seems unfair to baldly state these conclusions in
overly-general language. It gives some economically-practical solar
applications a bad name, among undiscerning readers.

>Only by considering a completely independent solar energy system can the 
>cost of reliability be factored into solar.

Bullshit. Users want reliable electricity, say an availability of at least
0.999999, ie an expected outage period of less than 30 seconds a year, with
or without the grid. It's cheaper to do it with. But a properly-designed 
solar-electric system with enough batteries and some redundancy (eg two
inverters) can be more reliable than today's grid, at a higher cost.

>Solar, in some cases, is practical in limited and small scale systems to
>supplement power grid usage.

This seems unlikely, even with synchronous inverters instead of batteries
and inverters, assuming you mean "economically-practical." Economically-
practical solar electric systems tend to be far from the grid. 

>While this lowers demands on the grid when the solar conditions are
>favorable, the variation in the power demand on the grid becomes greater,

Agreed.

>with the peak power requirements becoming just as
>high as if there were no solar.

I doubt the peak power requirements would be just as high. It seems to me
that if a lot of people made solar electricity, and used a few batteries,
the peak power requirements for the grid would be lower than if that were
not the case, not counting the fact that solar-electric people tend to be
electrically frugal. How often do you think everyones' batteries would all
be discharged at the same time? That's possible, but not too likely. Once
in a hundred years? It would be interesting to try to work out some numbers
and probability distributions. 

>The effect is to pass on more of the non-recurring cost to the other grid
>consumers.

Sure. And that's one of the reasons utilities have minimum monthly bills,
eg to cover the cost of meter reading, even if the reading this month
is the same as the reading last month.

>But consider, what if everyone had a solar system? The advantage over your 
>neighbors would be lost. The cost of the grid, which is needed to provide
>the reliability, would increase for everyone,

It seems to me that the cost of the grid would stay the same, but the
cost of centrally generating the electricity would decrease, because
there would be less of that needed.

>and this would be the hidden cost of solar. 

Of "solar" what?

>Thus people would buy more solar, and the grid would increase in cost more,

No. The cost of wires and poles and transformers does not increase if
people make solar electricity and sell it back to the grid. In fact, it
may decrease, if there is more electrical energy being decentrally generated
in an area, so there is less transport capacity needed from the outside,
on a statistical basis. 

>until the entire energy system went to hell, and power became unreliable. 

Seems to me that in principle, decentralized electricity sources should
make the network more reliable, not less reliable.

Nick

(Still hoping someone will send me an a.e.r. charter or description,
so I can start creating sci.a.e.)