[Greenbuilding] is it ever sensible to use PV to heat water?

[Reuben Deumling]

On Fri, Mar 23, 2012 at 11:32 AM, Steven Tjiang <steve at tjiang.org> wrote:

> Reuben, why are virtues of banking deceptive?
> I understand the grid issues but in my opinion, we are no where near
> having enough PV to have those problems.  when we get there.....that's a
> good problem to have (and solve).
>

The scale is a secondary matter. I don't like sleight of hand when it comes
to the subjects we cover here on this discussion list. If someone tells me
(as Martin Holladay just did) that PV heated water is 'better' than solar
thermally heated water because it is 'cheaper' then I want to know why he
thinks it o.k. to think of the grid as a battery when it isn't. It doesn't
store solar energy for six months or even six minutes. It is a trick that
generally works fine in the summer (especially in places with summer peaks)
but not in places that are cloudy during the winter peak.

... pumped storage is clever, but that is not what we're doing, and it is
itself costly and not without losses. When someone (Holladay) says 'the
grid' he is not talking about pumped storage. Besides pumped storage
doesn't solve the six months lag I'm interested in in this context, though
it is great for diurnal fluctuations.
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