On Sun, 27 Jan 2008 13:16:18 +0000 someone who may be The Natural
Philosopher wrote this:-

No solar collector needs direct sunlight to proiduce useable heat. In
pathetically small quantities.

As opposed to merely *rather* pathetically small quantities.

Yawn.

Meanwhile those with an open mind heat nearly all their hot water in
summer with the panels you appear to despise so much, produce a
significant proportion of it in spring and summer and produce some
of it in winter. No doubt you would claim that they are all
imagining this hot water.





--
David Hansen, Edinburgh
I will *always* explain revoked encryption keys, unless RIP prevents me
http://www.opsi.gov.uk/acts/acts2000/00023--e.htm#54

On 2008-01-27 16:02:49 +0000, David Hansen
said:

On Sun, 27 Jan 2008 13:16:18 +0000 someone who may be The Natural
Philosopher wrote this:-

No solar collector needs direct sunlight to proiduce useable heat. In
pathetically small quantities.

As opposed to merely *rather* pathetically small quantities.

Yawn.

Meanwhile those with an open mind heat nearly all their hot water in
summer with the panels you appear to despise so much, produce a
significant proportion of it in spring and summer and produce some
of it in winter. No doubt you would claim that they are all
imagining this hot water.

Nobody is disputing that there is *some* heat produced.

The equation is a simple one.

How much heat is produced in the course of (for example) a year from
such a panel?

How much would the gas to produce the same amount of heat cost?
Project that cost forward assuming an increase in gas prices.

The write down the cost of the boiler over its lifetime and the cost of
the solar panel over its lifetime.

That provides the data for the cost of a system using only gas and one
using the panel as well and one should be able to calculate the total
cost of ownership and use of each.
Clearly, there will be some operational cost saving between using gas
plus solar vs. gas only.
That's the cost argument. One could even do it on an operational cost
basis only, ignoring the capital cost.

The other arguments on appearance, feel good and interest in tehnology
are valid in themselves.

However, let's have some honesty here and a clear justification of the
economic arguments if there are any.

In article ,
David Hansen writes:
On 27 Jan 2008 13:29:58 GMT someone who may be
(Andrew Gabriel) wrote this:-

For a few
people, energy payback might be a consideration, but photo-
voltaics really struggle to produce more energy during their
lifetime than they consume in manufacture,

It is a common claim, but still an incorrect one. It may have been
true in the 1970s, but that was a long time ago and engineering has
moved on since then.

Not much. In spite of much research, their efficiency has
only doubled in the ~50 years since they were invented, and
almost none of that was recently. Research now is tending to
look for alternative materials as no further headway was being
made with silicon. There are a few, but a big problem (literally)
is that you tend to need a lot of material to make large receptors.
Whilst silicon is cheap and in plentyful supply, it's just the
processing of it into sufficient purity which is expensive. For
anything else that turns out to work well, it's unlikely there
will be the volumes of raw materials available in the first place,
making them more expensive before you even start with the
processing of it into sufficient purity.

It is some sort of step function improvement in efficiency or
reduction production cost which is needed to make photovoltaics
more viable, but that's just not shown up yet, although there is
much research looking for it.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

On Sun, 27 Jan 2008 11:15:27 +0000, Andy Hall wrote:

On 2008-01-27 10:33:03 +0000, David Hansen
said:

On Sun, 27 Jan 2008 10:00:25 +0000 someone who may be Andy Hall
wrote this:-

Televisions and kitchens are not sold on the basis of a payback
period. Solar panels, to a great extent are.

Nice try, but incorrect.

Really?

Do tell.

You mean that they are sold as roof decorations?

If it's not feel good or look good and isn't payback, it doesn't really
leave a lot, does it?

I think you may have missed out something from the list? There is club
membership. I suppose it comes partly under the feel good category. Club
membership, is equivalent to something like "I feel good, because I'm
part of a group who let each other know that they are part of something
_different_.". If they can also raise their status in the eyes of others
by doing something _different_.

A solar assisted hot water system can easily save it's material, running
and maintenance, resource costs - the problem is that in a post
industrial economy it can't, at present, save it's installation cost.

--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at http://www.diyfaq.org.uk
Gas fitting FAQ http://www.makewrite.demon.co.uk/GasFitting.html
Sealed CH FAQ http://www.makewrite.demon.co.uk/SealedCH.html
Choosing a Boiler FAQ http://www.makewrite.demon.co.uk/BoilerChoice.html

On Sun, 27 Jan 2008 13:13:49 +0000, The Natural Philosopher wrote:

David Hansen wrote:
On Sat, 26 Jan 2008 11:48:14 -0000 someone who may be "Pete Smith"
wrote this:-

I looked in to it for hot water, but it's of no use in the winter !
It's too cold!

What is too cold?

Te sky is too cold.

The exterior temperature? Solar panels work on the
sun, not the external temperature.


Exactly. Something that is in such short supply in winter, that peopl
need vitamin supplements..


In the winter it is highly likely not to be sunny enough to produce all
the hot water one needs. However, the heating that is provided means
less other fuels are needed.

On a bright winter day a well insulated house which has been warmed up
by the boiler can be maintained at a reasonable temperature by a solar
panel for the daylight hours. This does involve a heating system
designed for this.


On a sunny winters day, my room that has been warmed up by the boiler,
simply needs the curtrinsns drawing back to absorb far more sunlight
than a stupid panel on the roof.

In the summer you don't want scalding hot water.

Any properly designed solar system will have at least one thermostatic
mixing valve on the hot water system.

Why not use curtains?

Should it be necessary to control the store temperature there are a
variety of ways of doing this.

The solar panels charge huge batteries which power the inverters.

That rather depends on the system. You have described a solar only
island system. However, such systems generally have other means of
charging the battery as well. They also practice energy efficiency and
so tend to avoid electric fires.

A grid tied system has no battery. In effect it uses the grid as a big
battery.

Lord. All this cost an complexity and heavy use of energy to produce
less energy than the things took to make.

It reminds me of the 'we will never run out of oil' brigade. True, but
when it takes more energy to get it out of the ground than is released
by burning it, you do end up with some absurd economics.

Not something *you* would be bothered by, mind you.


True, the oil companies stop pumping long before that point is reached
because of all the other overheads. This means there is quite a lot of
reserves which are held back until the price of oil is sustainably high
enough. Therefore there will a longish transition period from oil to
other sources of energy, which currently are not worth the effort.



--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at http://www.diyfaq.org.uk
Gas fitting FAQ http://www.makewrite.demon.co.uk/GasFitting.html
Sealed CH FAQ http://www.makewrite.demon.co.uk/SealedCH.html
Choosing a Boiler FAQ http://www.makewrite.demon.co.uk/BoilerChoice.html

"Ed Sirett" wrote in message
...
On Sun, 27 Jan 2008 11:15:27 +0000, Andy Hall wrote:

On 2008-01-27 10:33:03 +0000, David Hansen
said:

On Sun, 27 Jan 2008 10:00:25 +0000 someone who may be Andy Hall
wrote this:-

Televisions and kitchens are not sold on the basis of a payback
period. Solar panels, to a great extent are.

Nice try, but incorrect.

Really?

Do tell.

You mean that they are sold as roof decorations?

If it's not feel good or look good and isn't payback, it doesn't really
leave a lot, does it?

I think you may have missed out something from the list? There is club
membership. I suppose it comes partly under the feel good category. Club
membership, is equivalent to something like "I feel good, because I'm
part of a group who let each other know that they are part of something
_different_.". If they can also raise their status in the eyes of others
by doing something _different_.

A solar assisted hot water system can easily save it's material, running
and maintenance, resource costs - the problem is that in a post
industrial economy it can't, at present, save it's installation cost.

But nor can many items people buy regularly.

Look, today it was very cold but the sun was out. Our boiler became full of
water at 31C. What was the average temperature of mains water?

If, say, it was 10C then we saved fuel to heat ours through 20 degrees.

People simply don't understand :-)

Mary



--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at http://www.diyfaq.org.uk
Gas fitting FAQ http://www.makewrite.demon.co.uk/GasFitting.html
Sealed CH FAQ http://www.makewrite.demon.co.uk/SealedCH.html
Choosing a Boiler FAQ http://www.makewrite.demon.co.uk/BoilerChoice.html

On Sun, 27 Jan 2008 12:36:20 +0000 David Hansen wrote :
Reasons for installing them have been explained before. The fact
that some reject these reasons does not make them invalid, no
matter how much some huff and puff.

Very true. But the opposite is true also: the fact that some people
are convinced of their validity does not make them valid.


--
Tony Bryer SDA UK 'Software to build on' http://www.sda.co.uk

"Andrew Gabriel" wrote in message
...
In article ,
David Hansen writes:
On 26 Jan 2008 17:02:39 GMT someone who may be
(Andrew Gabriel) wrote this:-

Hot water system which is DIY installed is the only
thing at the moment which is even remotely viable.

If one measures viability only in terms of simple payback period.

For most people, that will be the only measure. For a few
people, energy payback might be a consideration, but photo-
voltaics really struggle to produce more energy during their
lifetime than they consume in manufacture, so there's no big
win there.

For a really few geeks like me, I'll pay extra just for my
own opportunity to play with the technology. E.g. I invested
in a condensing boiler long before they were mandatory and
when they were at a price premium, because the technology
interested me and I wanted to try designing a heating system
to make good use of one (which I did).

If I had a south facing roof, I would be interested in
playing with some type of solar energy project on the same
basis. However, with my roof ridge running north-south so
it's never going to work well, and needing scaffolding in my
neighbour's garden, and the outlay (even DIY'ed) with no
prospects of any realistic savings, it really is a complete
waste of effort even at the geek level.

I installed air-con with heat-pump heating a couple of years
ago, and that looks to provide viable heat. It claims 3.5kW
for 1.2kW power consumption. It's very difficult to measure
what it produces; it does output more heat than a 2kW fan
heater but I haven't got more than 2kW to compare it with
so I don't know if it reaches 3.5kW. It is limited to quite
a narrow range of outdoor temperatures -- above about 12C
and I don't seem to need it, and below about 5C and you
can't use a heat pump air exchanger as it will ice up and
waste energy defrosting itself. For quickly heating one room
it's very good, but as an energy saving measure, it's probably
a non-starter. If prices of such units drop to the level they
are in some countries where they are more common, then they
would be viable for DIY installs.

Of course if one does this then there are many things one shouldn't
install as they have infinite simple payback periods. A new
television or kitchen are examples.

Take the cost of a kitchen (I think mine was around £4k, but
as I did it piecemeal, I never actually added it up) and
divide by, say, 15 years life, and that's around £260/year,
i.e. it's costing me less than £1/day for a kitchen. That
seems like very good value.

For some values of 'value'.

"Andrew Gabriel" wrote in message
...
In article ,
David Hansen writes:
On 27 Jan 2008 13:29:58 GMT someone who may be
(Andrew Gabriel) wrote this:-

For a few
people, energy payback might be a consideration, but photo-
voltaics really struggle to produce more energy during their
lifetime than they consume in manufacture,

It is a common claim, but still an incorrect one. It may have been
true in the 1970s, but that was a long time ago and engineering has
moved on since then.

Not much. In spite of much research, their efficiency has
only doubled in the ~50 years since they were invented, and
almost none of that was recently

If the research you read was differnt would you be persuaded?

"AJH" wrote in message
...
On Sun, 27 Jan 2008 09:57:52 +0000, David Hansen
wrote:

On Sat, 26 Jan 2008 22:45:10 +0000 someone who may be AJH
wrote this:-

I'm convinced he never saw any savings simply because he left
his gas dhw system configured as before.

Changing the settings on other water heating systems is part of the
installation process of anybody who knows what they are doing.

I know but the installers didn't do it because the basic operation was
a hard sell with a grant kickback for the installers.

The net effect was it was only while we had the opportunity to talk in
hospital in the weeks prior to his death ( whilst we socialised in his
later life he distanced himself from his kids and didn't confide in
us) that he said he had monitored his gas use and couldn't see the
solar contribution. A visit back to the house, which still had two
lodgers, so showed the reason was simply that the dhw timer was still
topping the tank up at 23:00 after most washing activity was finished,
and then in the morning the gas came on at 6:00 at about the time the
lodgers were getting ready for work and stayed on till 10:00. Hence by
the time the panel was able to provide heat from its non optimal SSE
orientation the tank was still full of hot water. By late afternoon
the panel was shaded when the evening wash period started.

That sounds like a serious lack of insulation.

Apart from the price I'm sure it was a reasonable installation if run
properly but most punters just expect to turn a tap or push a button
and get instant results.

Yes. But what DOES give instant (economic) results?

"Mike P" mike@askme wrote in message
...
On Sun, 27 Jan 2008 11:10:38 +0000, Si $3o&m head
down on the keyboard, banged out this message:

.. xxIn message , Mike P
.. writes
.. xxhe alledgedly was told it does not need sunlight and it will use
.. xxantifreeze, not water.
.. xx
.. xxantifreeze in the water that circulates through the outdoor solar
.. xxcollectors is sensible.

Obviously .... too me and many others, but maybe not to an 80 year
old.

LOL!

You might think differently when you're 80 :-)

Mary

"David Hansen" wrote in message
...
On Sun, 27 Jan 2008 13:16:18 +0000 someone who may be The Natural
Philosopher wrote this:-

No solar collector needs direct sunlight to proiduce useable heat. In
pathetically small quantities.

As opposed to merely *rather* pathetically small quantities.

Yawn.

Meanwhile those with an open mind heat nearly all their hot water in
summer with the panels you appear to despise so much, produce a
significant proportion of it in spring and summer and produce some
of it in winter. No doubt you would claim that they are all
imagining this hot water.

I have a good imagination. Spouse does not.

We experience the same benefits of our installation.

Mary





--
David Hansen, Edinburgh
I will *always* explain revoked encryption keys, unless RIP prevents me
http://www.opsi.gov.uk/acts/acts2000/00023--e.htm#54

"Dave Liquorice" wrote in message
ll.net...
On Sun, 27 Jan 2008 10:48:48 +0000, Mike P wrote:

but the no cooling period off is worrying and he alledgedly


was told it does not need sunlight and it will use antifreeze, not
water. The mind boggles!

Why? Thermal solar panels don't need direct sunlight to work, you get more
energy collected on bright sunny days but you stiill get some on dull
overcast ones. Any decent system will circulate a antifreeze mixture so
you don't have to drain it down in the winter...

Ours doesn't. We don't need to drain it.

Why? http://www.solartwin.com/questions_a...hp#reliability

Mary

In message , Mike P
writes

I am asking on behalf of my partners father ..... who is 80 years old
and has just put a down payment on a £5000 system for hot water.
I am not convinced it is a good idea.
He is convinced it will put value on his house when he sells up to
downsize.

My father was of the same opinion and it took some robust words from me
following a thread I started about a year ago here


--
geoff

In article ,
"Mary Fisher" writes:

"Andrew Gabriel" wrote in message
...

Not much. In spite of much research, their efficiency has
only doubled in the ~50 years since they were invented, and
almost none of that was recently

If the research you read was differnt would you be persuaded?

Not sure that's a sensible question. I've kept an eye on
the research to see if there's anything on the horizon.
The research is largely irrelevent though -- it's how they
perform now that governs if I would be persuaded now. The
lack of progress is disappointing, but I'm aware it's not
for want of trying -- lots has been done and it's had
serious money behind it from areas such as the space
industry and energy industry, something which other
renewable sources really struggle for.

If they were more efficient or significantly cheaper, I
might be persuaded. They don't even need to payback from
my perspective -- remember I said I'm geeky and do try
things out for the sake of it, but they need to be
significantly more attractive in some aspect before I
would do so.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

On Sun, 27 Jan 2008 20:04:42 GMT someone who may be Tony Bryer
wrote this:-

Reasons for installing them have been explained before. The fact
that some reject these reasons does not make them invalid, no
matter how much some huff and puff.

Very true. But the opposite is true also: the fact that some people
are convinced of their validity does not make them valid.

Correct. However, some people have only become convinced after
studying the issue, including the thermodynamics, and thus putting
their initial scepticism to rest.

There is much bull**** talked about such things, much of it by those
who appear to have an aversion which borders on the unacceptable
face of religion. There is also much bull**** talked about them by
the unacceptable face of the installation industry, the double
glazing approach. However, the latter bull**** can be cut through to
discover those, which includes some in the installation industry,
which offer a good service.


--
David Hansen, Edinburgh
I will *always* explain revoked encryption keys, unless RIP prevents me
http://www.opsi.gov.uk/acts/acts2000/00023--e.htm#54

On 27 Jan 2008 18:00:37 GMT someone who may be
(Andrew Gabriel) wrote this:-

It is a common claim, but still an incorrect one. It may have been
true in the 1970s, but that was a long time ago and engineering has
moved on since then.

Not much. In spite of much research, their efficiency has
only doubled in the ~50 years since they were invented,

One also needs to consider the energy involved in manufacture.



--
David Hansen, Edinburgh
I will *always* explain revoked encryption keys, unless RIP prevents me
http://www.opsi.gov.uk/acts/acts2000/00023--e.htm#54

On Sun, 27 Jan 2008 20:30:58 +0000 someone who may be AJH
wrote this:-

Insulation doesn't feature in the discussion about how the gas and
solar inputs clash. In fact it was a modern insulated tank and I doubt
it lost more than 1kWhr of heat in the 24 hour period.

Did it feel at all warm to the touch? If it did then it didn't have
enough insulation.

The point was the system stayed permanently satisfied by the gas
system because of the heating periods, so the panel was never able to
contribute.

An installation problem.

What I forgot to mention was that whilst the solar coil was at the
bottom of the tank the gas heated coil was almost directly above it.
The problem would have been mitigated had the gas coil been nearer the
top of the tank.

A design problem.




--
David Hansen, Edinburgh
I will *always* explain revoked encryption keys, unless RIP prevents me
http://www.opsi.gov.uk/acts/acts2000/00023--e.htm#54

On Sun, 27 Jan 2008 11:30:59 +0000 someone who may be AJH
wrote this:-

Hence by
the time the panel was able to provide heat from its non optimal SSE
orientation the tank was still full of hot water.

Nothing wrong with the orientation. Anything from SW to SE will give
good results compared to the ideal direct southerly orientation.
What was wrong was the installation, in particular the setting of
controls. A good installer will return to check that everything is
working well.




--
David Hansen, Edinburgh
I will *always* explain revoked encryption keys, unless RIP prevents me
http://www.opsi.gov.uk/acts/acts2000/00023--e.htm#54

On Sun, 27 Jan 2008 17:18:44 +0000 someone who may be Andy Hall
wrote this:-

That's the cost argument.

That's a financial cost argument. However, money is not the only
cost, as the inhabitants of low lying areas are already discovering
in a very real way.



--
David Hansen, Edinburgh
I will *always* explain revoked encryption keys, unless RIP prevents me
http://www.opsi.gov.uk/acts/acts2000/00023--e.htm#54

On Sun, 27 Jan 2008 20:14:53 -0000 someone who may be "Mary Fisher"
wrote this:-

Why? Thermal solar panels don't need direct sunlight to work, you get more
energy collected on bright sunny days but you stiill get some on dull
overcast ones. Any decent system will circulate a antifreeze mixture so
you don't have to drain it down in the winter...

Ours doesn't. We don't need to drain it.

Why? http://www.solartwin.com/questions_a...hp#reliability

Indeed. Neither are drainback systems like
http://www.imaginationsolar.com/system.htm

Even if not using any of these approaches, a good controller can be
set to circulate water if the collector is close to freezing. This
will use a little heat from the store, but not much as the
circulation will only operate for short periods. This is only likely
to be a particular issue on a DIY flat plate collectors which are
not insulated properly.


--
David Hansen, Edinburgh
I will *always* explain revoked encryption keys, unless RIP prevents me
http://www.opsi.gov.uk/acts/acts2000/00023--e.htm#54

On 2008-01-28 08:38:30 +0000, David Hansen
said:

On Sun, 27 Jan 2008 20:04:42 GMT someone who may be Tony Bryer
wrote this:-

Reasons for installing them have been explained before. The fact
that some reject these reasons does not make them invalid, no
matter how much some huff and puff.

Very true. But the opposite is true also: the fact that some people
are convinced of their validity does not make them valid.

Correct. However, some people have only become convinced after
studying the issue, including the thermodynamics, and thus putting
their initial scepticism to rest.

There is much bull**** talked about such things, much of it by those
who appear to have an aversion which borders on the unacceptable
face of religion. There is also much bull**** talked about them by
the unacceptable face of the installation industry, the double
glazing approach. However, the latter bull**** can be cut through to
discover those, which includes some in the installation industry,
which offer a good service.

Where are the disinterested sources of information?

By this I mean disinterested from the commercial sales aspect and also
from the eco sales aspect......

David Hansen wrote:
On Sun, 27 Jan 2008 13:16:18 +0000 someone who may be The Natural
Philosopher wrote this:-

No solar collector needs direct sunlight to proiduce useable heat. In
pathetically small quantities.

As opposed to merely *rather* pathetically small quantities.

Yawn.

Meanwhile those with an open mind heat nearly all their hot water in
summer with the panels you appear to despise so much, produce a
significant proportion of it in spring and summer and produce some
of it in winter. No doubt you would claim that they are all
imagining this hot water.



Not at all. we were not talking about summer.

When I spend all of what - 20 quid on hot water?

Frankly, its the least of my outgoings.

Mary Fisher wrote:

If the research you read was differnt would you be persuaded?

If the moon were made of green cheese would you invest in crackers?

Andrew Gabriel wrote:
In article ,
"Mary Fisher" writes:
"Andrew Gabriel" wrote in message
...
Not much. In spite of much research, their efficiency has
only doubled in the ~50 years since they were invented, and
almost none of that was recently
If the research you read was differnt would you be persuaded?

Not sure that's a sensible question. I've kept an eye on
the research to see if there's anything on the horizon.
The research is largely irrelevent though -- it's how they
perform now that governs if I would be persuaded now. The
lack of progress is disappointing, but I'm aware it's not
for want of trying -- lots has been done and it's had
serious money behind it from areas such as the space
industry and energy industry, something which other
renewable sources really struggle for.

If they were more efficient or significantly cheaper, I
might be persuaded. They don't even need to payback from
my perspective -- remember I said I'm geeky and do try
things out for the sake of it, but they need to be
significantly more attractive in some aspect before I
would do so.

You only have to do the overall maths for watts per square meter to
discover that in THIS country, they haven't a hope of ever doing more
than a few tenths of a percent of the winter energy needs.

Sure they can on a sunny day, net you a tankful of hot water. So could
doing two hours exercise on a treadmill hooked up to a generator in all
likelihood.

David Hansen wrote:
On 27 Jan 2008 18:00:37 GMT someone who may be
(Andrew Gabriel) wrote this:-

It is a common claim, but still an incorrect one. It may have been
true in the 1970s, but that was a long time ago and engineering has
moved on since then.
Not much. In spite of much research, their efficiency has
only doubled in the ~50 years since they were invented,

One also needs to consider the energy involved in manufacture.



Indeed. So why don't you?

Mary Fisher wrote:
"Ed Sirett" wrote in message
...
On Sun, 27 Jan 2008 11:15:27 +0000, Andy Hall wrote:

On 2008-01-27 10:33:03 +0000, David Hansen
said:

On Sun, 27 Jan 2008 10:00:25 +0000 someone who may be Andy Hall
wrote this:-

Televisions and kitchens are not sold on the basis of a payback
period. Solar panels, to a great extent are.
Nice try, but incorrect.
Really?

Do tell.

You mean that they are sold as roof decorations?

If it's not feel good or look good and isn't payback, it doesn't really
leave a lot, does it?
I think you may have missed out something from the list? There is club
membership. I suppose it comes partly under the feel good category. Club
membership, is equivalent to something like "I feel good, because I'm
part of a group who let each other know that they are part of something
_different_.". If they can also raise their status in the eyes of others
by doing something _different_.

A solar assisted hot water system can easily save it's material, running
and maintenance, resource costs - the problem is that in a post
industrial economy it can't, at present, save it's installation cost.

But nor can many items people buy regularly.

Look, today it was very cold but the sun was out. Our boiler became full of
water at 31C. What was the average temperature of mains water?

If, say, it was 10C then we saved fuel to heat ours through 20 degrees.


Yes, now do the 'maths' mary - you may need to take of your socks,
because the numbers sometimes go above ten, and see how MUCH you really
saved.

People simply don't understand :-)

Indeed!

Ed Sirett wrote:
On Sun, 27 Jan 2008 13:13:49 +0000, The Natural Philosopher wrote:

David Hansen wrote:
On Sat, 26 Jan 2008 11:48:14 -0000 someone who may be "Pete Smith"
wrote this:-

I looked in to it for hot water, but it's of no use in the winter !
It's too cold!
What is too cold?
Te sky is too cold.

The exterior temperature? Solar panels work on the
sun, not the external temperature.


Exactly. Something that is in such short supply in winter, that peopl
need vitamin supplements..


In the winter it is highly likely not to be sunny enough to produce all
the hot water one needs. However, the heating that is provided means
less other fuels are needed.

On a bright winter day a well insulated house which has been warmed up
by the boiler can be maintained at a reasonable temperature by a solar
panel for the daylight hours. This does involve a heating system
designed for this.


On a sunny winters day, my room that has been warmed up by the boiler,
simply needs the curtrinsns drawing back to absorb far more sunlight
than a stupid panel on the roof.

In the summer you don't want scalding hot water.
Any properly designed solar system will have at least one thermostatic
mixing valve on the hot water system.

Why not use curtains?

Should it be necessary to control the store temperature there are a
variety of ways of doing this.

The solar panels charge huge batteries which power the inverters.
That rather depends on the system. You have described a solar only
island system. However, such systems generally have other means of
charging the battery as well. They also practice energy efficiency and
so tend to avoid electric fires.

A grid tied system has no battery. In effect it uses the grid as a big
battery.

Lord. All this cost an complexity and heavy use of energy to produce
less energy than the things took to make.

It reminds me of the 'we will never run out of oil' brigade. True, but
when it takes more energy to get it out of the ground than is released
by burning it, you do end up with some absurd economics.

Not something *you* would be bothered by, mind you.


True, the oil companies stop pumping long before that point is reached
because of all the other overheads. This means there is quite a lot of
reserves which are held back until the price of oil is sustainably high
enough. Therefore there will a longish transition period from oil to
other sources of energy, which currently are not worth the effort.



Longish in what terms?

a decade or two?

David Hansen wrote:


There is much bull**** talked about such things, much of it by those
who appear to have an aversion which borders on the unacceptable
face of religion. There is also much bull**** talked about them by
the unacceptable face of the installation industry, the double
glazing approach. However, the latter bull**** can be cut through to
discover those, which includes some in the installation industry,
which offer a good service.



Gosh, you have summed your position up in a nutshell Dave.

Mary Fisher wrote:
"AJH" wrote in message
...
On Sun, 27 Jan 2008 09:57:52 +0000, David Hansen
wrote:

On Sat, 26 Jan 2008 22:45:10 +0000 someone who may be AJH
wrote this:-

I'm convinced he never saw any savings simply because he left
his gas dhw system configured as before.
Changing the settings on other water heating systems is part of the
installation process of anybody who knows what they are doing.
I know but the installers didn't do it because the basic operation was
a hard sell with a grant kickback for the installers.

The net effect was it was only while we had the opportunity to talk in
hospital in the weeks prior to his death ( whilst we socialised in his
later life he distanced himself from his kids and didn't confide in
us) that he said he had monitored his gas use and couldn't see the
solar contribution. A visit back to the house, which still had two
lodgers, so showed the reason was simply that the dhw timer was still
topping the tank up at 23:00 after most washing activity was finished,
and then in the morning the gas came on at 6:00 at about the time the
lodgers were getting ready for work and stayed on till 10:00. Hence by
the time the panel was able to provide heat from its non optimal SSE
orientation the tank was still full of hot water. By late afternoon
the panel was shaded when the evening wash period started.

That sounds like a serious lack of insulation.
Apart from the price I'm sure it was a reasonable installation if run
properly but most punters just expect to turn a tap or push a button
and get instant results.

Yes. But what DOES give instant (economic) results?


Knitting a jumper.

Payback time probably under a winter.

On 2008-01-28 08:58:42 +0000, David Hansen
said:

On Sun, 27 Jan 2008 17:18:44 +0000 someone who may be Andy Hall
wrote this:-

That's the cost argument.

That's a financial cost argument. However, money is not the only
cost, as the inhabitants of low lying areas are already discovering
in a very real way.

OK, so are you here making the connection that I think you are? i.e.

- Solar panels = "reduced carbon" energy
- Therefore reduction in carbon emission
- Therefore less climate change
- Therefore less flooding of low lying areas

This is shortening, simplifying and perhaps not in the order that you
might present it.

I'm not going to counter it with the teaspoon and Titanic argument either.


However, let's assume that the prospective purchaser believes that
buying a solar panel for his hot water affects the "cost" for the poor
sods living in low lying areas.

This is actually falling into the feel good category because the money
spent is being considered as affecting the well being of others,
present and future as opposed to benefiting the spender directly.
It could then be considered on the same basis as charitable giving to
flood relief to Bangladesh for example. Then one has to wonder
whether the £5000 spent on the solar panel system would have been put
to better use as a charitable donation, especially when grossed up with
the tax contribution.

Could it be that the solar panel represents an enormous and lasting
equivalent to the paper sticker I get when I put money in the
collecting tin in the high street?

On Mon, 28 Jan 2008 09:18:54 +0000 someone who may be The Natural
Philosopher wrote this:-

Yes, now do the 'maths' mary - you may need to take of your socks,
because the numbers sometimes go above ten, and see how MUCH you really
saved.

Excellent, personal abuse.


--
David Hansen, Edinburgh
I will *always* explain revoked encryption keys, unless RIP prevents me
http://www.opsi.gov.uk/acts/acts2000/00023--e.htm#54

On Mon, 28 Jan 2008 09:16:54 +0000 someone who may be The Natural
Philosopher wrote this:-

If they were more efficient or significantly cheaper, I
might be persuaded. They don't even need to payback from
my perspective -- remember I said I'm geeky and do try
things out for the sake of it, but they need to be
significantly more attractive in some aspect before I
would do so.

You only have to do the overall maths for watts per square meter to
discover that in THIS country, they haven't a hope of ever doing more
than a few tenths of a percent of the winter energy needs.

It is certainly true that the peak output of solar PV panels does
not coincide with peak electrical demand. However, that does not
mean they are pointless.

Sure they can on a sunny day, net you a tankful of hot water.

You appear to be mixing up PV and hot water panels. Whether this is
accidental or deliberate I leave for others to decide.


--
David Hansen, Edinburgh
I will *always* explain revoked encryption keys, unless RIP prevents me
http://www.opsi.gov.uk/acts/acts2000/00023--e.htm#54

"David Hansen" wrote in message
...
On Mon, 28 Jan 2008 09:18:54 +0000 someone who may be The Natural
Philosopher wrote this:-

Yes, now do the 'maths' mary - you may need to take of your socks,
because the numbers sometimes go above ten, and see how MUCH you really
saved.

Excellent, personal abuse.

Well, I wouldn't have seen it if you hadn't replied :-)

(I always read your posts)

Mary

"Andrew Gabriel" wrote in message
...
In article ,
"Mary Fisher" writes:

"Andrew Gabriel" wrote in message
...

Not much. In spite of much research, their efficiency has
only doubled in the ~50 years since they were invented, and
almost none of that was recently

If the research you read was differnt would you be persuaded?

Not sure that's a sensible question. I've kept an eye on
the research to see if there's anything on the horizon.
The research is largely irrelevent though -- it's how they
perform now that governs if I would be persuaded now. The
lack of progress is disappointing, but I'm aware it's not
for want of trying -- lots has been done and it's had
serious money behind it from areas such as the space
industry and energy industry, something which other
renewable sources really struggle for.

If they were more efficient or significantly cheaper, I
might be persuaded.

Early motor cars were neither. Those who bought them were pleased with
them - and more R&D was done on the back of that.

It might happen again :-)

By the way, we live on the state pension but could afford a dhw panel.
They're not that expensive.

Mary

"AJH" wrote in message
...
On Sun, 27 Jan 2008 20:09:44 -0000, "Mary Fisher"
wrote:

That sounds like a serious lack of insulation.

Insulation doesn't feature in the discussion about how the gas and
solar inputs clash. In fact it was a modern insulated tank and I doubt
it lost more than 1kWhr of heat in the 24 hour period.

The point was the system stayed permanently satisfied by the gas
system because of the heating periods, so the panel was never able to
contribute.

I suspect that most people who get a solar dhw system change the rest of
their lifestyle to suit. That would include adjusting 'heating periods',
surely.

David Hansen wrote:
On Mon, 28 Jan 2008 09:18:54 +0000 someone who may be The Natural
Philosopher wrote this:-

Yes, now do the 'maths' mary - you may need to take of your socks,
because the numbers sometimes go above ten, and see how MUCH you really
saved.

Excellent, personal abuse.


Ditto.

After your hilarious comments about 'religion'

This whole topic is too important to be left to touchy feely qualitative
analysis.

If people can't do the maths and the real analysis, they shouldn't comment.

Its like going into the supermarket, and buying tow to get one free..and
then letting it rot in the cupboard. That isn't saving money. That's
being a gullible fool.

Which by and large is what most people who buy so called 'green'
products, are.

BECAUSE its something I consider important I HAVE spent a total of
several MONTHS looking into 'green' technology and the like, doing a LOT
of sums, and double checking the results.

Using strict cost benefit analysis both in cash and energy terms.

And frankly the answers are depressing and scary. Almost none of it
makes a measurable difference to overall carbon footprint, and a lot of
it actually makes things worse, and the one thing that actually DOES
have the potential to make a real positive difference is shouted down by
religious greenies. On QUALITATIVE grounds. It makes them FEEL BAD.

Let's take solar power.

The UK is about 30M hectares in surface area.

A hectare is 10K square meters, so thats 300G meters square.

WE have a peak winter energy consumption as a nation, of around 300GW.

In winter, the average insolation is less than 600Wh per day, or 25W/sq
meter.

That means we need to totally cover the entire area of the UK with solar
panels at 4% efficiency, to generate our energy needs.

In summer, when we don't need the energy, its a lot less. But that's no
great help is it?

In terms of cost, a decent nuclear power stations is around £1000 a Kw.

So unless that one meter square solar panel is actually costing less
than around £2.50 (at 10% efficiency)..its money better spent elsewhere.


Its also rank hypocrisy, or naivete of the first order to claim that you
personally are 'green' when everything you use , eat buy and consume, is
produced by a system that isn't.

As I pointed out to the woman in the checkout at the 'green' till in
Waitrose, that the plastic used in one carton of cream was ten times the
amount in the plastic bags used to carry the shopping home in. Howevr
all I got was teh blank incomprehension of those that don't like to be
told that they are basically involved in a futile feel good marketing
exercise, and their cherished beliefs have no more chance of stopping
global warming than fitting a CFL bulb does.

Its only by doing the nummbers, that you can actually whittle down the
bull**** to what really actually DOES save energy and works.

We have juts had a thread on wood burning, and the US contributor and I
both came to a reasonably similar figure that 5-10 acres per house is
what it takes to heat a small home, sustainably.

There are about 30M households in the UK.Pretty staggering for a country
of 60M people, but that's apparently the way it is. 10 acres is arond 4
hectares, so we would need to devote something like 120M hectares to
wood growing just to heat our houses. Thats 4 times the total land area
of the united kingdom. Right. Great idea.

The latest greatest windmill projcet, a '1GW' windfarm at a cost of
£1.5bn, won't actually produce 1Gw at all. Since thats its PEAK output,
when the wind is exactly the right strength. Typically it will produce
about 15% of that. Average. Which makes it about 4 times as expensive AT
LEAST as a nuclear power station. To do the total country copmplete
energy needs, we need about 1800 windfarms JUST like it. A staggering
conclusion.

Never mind the cost issues of maintaing all those windmills out there in
the sea..

Whereas we can run the WHOLE COUNTRY, on just 100 5GW nuclear power
stations.

The simple answer is this. You need a staggering amount of kit - often
exceeding the total area of the country, to collect the very low energy
density energy from 'renewable' energy. I.e. energy from the sunlight we
get, whether its biofuel or direct solar. Or windmills, or water power.
We are a society that actually uses something like 10% of the
equivalent energy it gets from all the sunlight falling on it, to keep
itself running. Whilst with excruciatingly expensive technology we might
reduce that a little, we cannot slash it in half, or anything like it,
at the population density we have. Nor can we contemplate slashing the
population in half either.

We have built this society by using energy - energy borrowed from
natures piggy bank of fossil fuels. It's running out. If it is NOT
replaced, we will revert to the sort of lifestyles and population levels
of - say - Tudor England.

No renewable energy source has the sort of levels of energy we need to
counteract this: we have no geothermal energy to speak of, we have some
possibility of using some tidal energy, but at massive adverse and
unknowable effects on tidal ecosystems.

Using natures Stellar piggy bank and raiding the fusion store, gives us
a few hundred billion years of energy, but we cant yet do it
economically, if ever.

The ONLY thing we have left is a couple of million years of nuclear
fission energy.

Its not the best solution. Its the ONLY solution.

Nothing else can replace fossil fuels in the UK. Not one other
technology has a *prayer*, even. Windmills are a distant ugly and hugely
expensive second best. Maybe in practice they might to 10% of the job at
enormous expense and totally transform the whole nature of the seascapes
and landscape in so doing.

Solar power has its place in sunnier climes. Stuck in a low population
low latitude desert, it starts to make sense. Not a lot, but some.

I don't have any axe to grind in this apart from simply not wanting to
be involved in the sort of chaos and civil war that would accompany the
return of the UK to a pre industrial society. I have no involvement with
the power generation industry, or any other industry, I am not part of
any lobby or group.

I simply did the sums, using the facts as available, not as wishful
thinking. I wish we did NOT have to contemplate nuclear power. But at
least its problems are practicably soluble, Whereas that doesn't ring
true for any other way to crack the nut.

Certainly not any technology that relies on direct or indirect solar
energy falling on the UK landmass. There isn't enough of it.

In fact, there is a puzzle, in that the earths actual temperature is
more than can be accounted for by the solar radioation and its initial
temperature post formation, leading to a lot of speculation that it is
in fact a large fission reactor in its own right.

So you may owe the life of the planet to nuclear reactions anyway. Makes
it a bit stupid to worry about siphoning off a little to heat your
tootsies doesn't it?

The Natural Philosopher wrote:
....
In fact, there is a puzzle, in that the earths actual temperature is
more than can be accounted for by the solar radioation and its initial
temperature post formation, leading to a lot of speculation that it is
in fact a large fission reactor in its own right.

Isn't there a large molten iron core that makes up the difference? Been
there since year dot, or thereabouts, cooling all the time.

But out of curiosity, what happened to all the research into fusion
reactors? Anyone else remember ZETA?


--
Mike Scott (unet at scottsonline.org.uk)
Harlow Essex England

On Mon, 28 Jan 2008 11:41:08 +0000 someone who may be The Natural
Philosopher wrote this:-

This whole topic is too important to be left to touchy feely qualitative
analysis.

Indeed.

Some may claim to have spent months doing calculations. However, if
it was a mine's bigger then yours competition they should realise
that some have spent years and decades doing the same.



--
David Hansen, Edinburgh
I will *always* explain revoked encryption keys, unless RIP prevents me
http://www.opsi.gov.uk/acts/acts2000/00023--e.htm#54

"Mike Scott" wrote in message
...
The Natural Philosopher wrote:
...
In fact, there is a puzzle, in that the earths actual temperature is more
than can be accounted for by the solar radioation and its initial
temperature post formation, leading to a lot of speculation that it is in
fact a large fission reactor in its own right.

Isn't there a large molten iron core that makes up the difference? Been
there since year dot, or thereabouts, cooling all the time.

There are other theories now.

But out of curiosity, what happened to all the research into fusion
reactors? Anyone else remember ZETA?

There was a programme about it last week on R4.

I remember ZETA well, the problem was containing the temperature.

Mary