On Tue, 26 Feb 2013 03:19:54 -0800 (PST), willie eckerslike wrote:

He was not too bothered, though, because he was selling to the grid.

The export price is only 3p/unit. With an installation that old I think he'll
be getting paid 43p/unit for *everything* his panels generate wether it's
exported or not. He may well be deemed to export 50% of that total generation
as well so gets 46p/unit for half of it *and* if he uses it himself doesn't
have to buy power at say 10p/unit either, 56p/unit...

My father has solar heated oil filled panels on his roof, which heat
the water in his hot water tank. From my experience of those, when the
sun shines, even on a spring or autumn day, the water gets very hot.

Not heard of oil filled solar thermal panels, it's normally water with a lot
of antifreeze (unless you have a drain back system). 30 mins of solar
thermal activity so far today, it's not a particularly bright day either.
Delta T across the thermal store was about 20 degrees and with a 3l/min flow
rate through the collect that's something over 4kW. I have a couple of spare
1-Wire temperature sensors I think I'll attach them to the flow/return of the
solar loop will be able to see how much energy it yields then.

If I had the choice, I think I would plump for my fathers' hot water
system, but my appliances are all cold fill, so would need to be
replaced which makes it a non-starter for me.

Not sure you'd find any appliances with hot fill these days. With washing
machines the use of bio based low temperature cleaning agents means that they
have to cold fill and heat as most domestic ho****er is too hot for the bio
bits... Even if using non bio agents, heating mains water at say 15C to 40C
in on step is better than heating 15 to 60+ and cooling it. They don't use
much water either so hot fill may just fill the pipe with hot water with very
little actually entering the machine.

--
Cheers Dave.
Nr Garrigill, Cumbria. 421m ASL.

"Dave Liquorice" wrote in message
ll.co.uk...

Current UK demand 49.53 GW coming from:

For anyone wanting to monitor it for themselves:

http://www.gridwatch.templar.co.uk/


JGD

Tidal is not available all the time but at least it's predictable.

Once we have enough tidal generators spread around the coast, it will be
available all the time.



Malcolm

Indeed, for a relatively small island we are lucky with the range of tide times.

It's worth making the point that most SolarPV generation does not appear in any official generation statistics. I'm not just talking about individual houses, where there is normally just a total production meter for the FIT, the export is simply not measured, or even off grid production, but even quite large systems.

Take a look at http://www.theoldehouse.co.uk/page/solar_energy.html I know the family who run the farm and have been there a number of times. They have a largish farm (by Cornish standards) quite a large number of holiday cottages, leisure centre with pool & hot tub. So their power usage is substantial.

The have a 250kw SolarPV system which generates about 250,000kwh per annum.
Being a farm and holiday complex which is busiest in summer, much of this is used on site, only a small proportion is exported, but it is only the small proportion exported which gets in the statistics. The panels also provide useful shelter for the sheep. There are many such setups in Cornwall, going through the County it's surprising how many farms now make use of SolarPV.

No land has been taken out of agricultural use, the panels also provide useful shelter for the sheep.


Graham
Penzance

On Monday, February 25, 2013 3:52:07 PM UTC, Dave Liquorice wrote:
On Mon, 25 Feb 2013 10:28:21 -0000, Ken Cook wrote:



Any guidance much appreciated.



If you are happy about the ethics involved and that it is pure money

investment scheme and nothing to do with saving the planet then fine. I'll

just regard you as a rich leech on society.



The ethics are that the money that pays the FIT is raised from a levy on

everyones electricity bill from the very poorest up. The poor can't afford

the required capital investment so are effectively locked out of joining in

but still have to pay.



As a money based venture either it is economically viable or it is not. The

FIT payments distort the market, by paying seriously over the going price for

wholesale electricity. Solar PV would not be economically viable without the

FIT payments.



The electricity generated is not "green" even the best PV panels are not much

more than 30% efficient, if that and efficiency drops as they get hot (like

in summer). Also because of the variable and unpredictable nature of the

power produced conventional plant has to be kept on "hot standby", burning

fuel. to provide backup so any pretence that this is "carbon free" power is

just that, a pretence.



There is quite a high energy input in their manufacture and transport from

China. I seriously doubt that Solar PV ever becomes energy positive, ie the

system has produced more energy than was consumed in manufacture, transport,

installation, maintenance and disposal.



--

Cheers Dave.

Nr Garrigill, Cumbria. 421m ASL.

Well said, Dave. Like wind power it is just a money making scheme that lines the pockets of the people that can afford it and robs the people who cant.. The poor end up subsidising it - higher bills and falling ethics. I sincerely hope that when the revolution comes and it is coming (see Beppe Grillo in Italy) the people will take back what is rightfully theirs and those that complied with this disgraceful con lose out when the government contracts and feed in tariffs are declared void.
No sympathy. IT WILL SERVE YOU ALL RIGHT!!!!!

On Tue, 26 Feb 2013 15:48:52 +0000, Malcolm wrote:

What about heat pumps? Output input every time?

When installed and running yes (though air source are crap overall
with airtemps between about freezing and a few degrees higher).

From personal experience, I disagree.

With which bit? Crap performance of air source heat pumps with air temps just
above 0C or contesting "Output input every time" on a cradle to grave
basis?

--
Cheers Dave.
Nr Garrigill, Cumbria. 421m ASL.

On Tue, 26 Feb 2013 08:31:40 -0800 (PST), Graham Easterling wrote:

Tidal is not available all the time but at least it's predictable.

Once we have enough tidal generators spread around the coast, it will
be available all the time.

Indeed, for a relatively small island we are lucky with the range of
tide times.

But where do you *build* all these tidal systems?

The have a 250kw SolarPV system which generates about 250,000kwh per
annum.

250kW is a miniscule drop in an ocean at 0.00025 GW. But even that drop, when
added with the other dropsn needs some other form of dispatchable generation
capacity to back it up when the sun goes behind a cloud or simply because
it's dark. The costs of this back up capacity is not bourn by the wind mills
or solar PV that makes the grid need it.

--
Cheers Dave.
Nr Garrigill, Cumbria. 421m ASL.

The have a 250kw SolarPV system which generates about 250,000kwh per
annum.


250kW is a miniscule drop in an ocean at 0.00025 GW. But even that drop, when
added with the other dropsn needs some other form of dispatchable generation
capacity to back it up when the sun goes behind a cloud or simply because
it's dark. The costs of this back up capacity is not bourn by the wind mills
or solar PV that makes the grid need it.

Cheers Dave.

Nr Garrigill, Cumbria. 421m ASL.


It is a very small drop, but get a lot of drops and you can start a Boscastle!

I completely take your point about the need for backup. It is however better to have a carbon emitting station working on reduced output for much of the time, only peaking when 'renewable' input is low, than having it working flat out all the time. (at least from an environmental perspective)

The need for backup reduces somewhat if you have a wide range of widely spread renewable options. Wave power hasn't been mentioned yet, but there are a number of projects, including the Wave Hub at Hayle. It currently only has a max capacity of 20mw, but this is easily upgradeable, as the cables come ashore at the old Hayle coal fired station, so much of the infrastructure to transport the power is in place. http://www.wavehub.co.uk/about/ (There are few days a year when there is little swell off west Cornwall, there's been a lovely wave for much of the time recently http://www.cornwallcam.co..uk/

I actually don't think our opinions are massively apart, just looking at things from a rather different angle.

Graham
Penzance (just 19m asl.)

On Wed, 27 Feb 2013 01:34:48 -0800 (PST), Graham Easterling wrote:

It is a very small drop, but get a lot of drops and you can start a
Boscastle!

But even all the drops if you covered the country in PV panels isn't enough
energy, even mid-day, mid-summer with no cloud anywhere.

I completely take your point about the need for backup. It is however
better to have a carbon emitting station working on reduced output for
much of the time, only peaking when 'renewable' input is low, than
having it working flat out all the time. (at least from an
environmental perspective)

But the efficiency of the dispatchable conventional plant falls as you reduce
it's output. So a plant running at 80% may well be burning just as much gas
as one running at 100%.

The need for backup reduces somewhat if you have a wide range of widely spread renewable options.

No every watt of direct wind, wave, tidal, PV renewable energy needs a watt
of backup as you do not know if those sources are going to be available at
any given time. Tidal is a bit different but will still have periods of low
output (neap tides).

About the only reliable renewable energy sources are the indirect ones, like
bio-mass and bio-gas. Where there solar energy is captured and stored, just
like oil, coal and gas except the turn around time from capture to use is
measured in tens of years or less, rather than millions. But the energy
captured per unit area is very low, so you need vast areas of land to grow
these fuel crops... Use of suitable waste as an energy source has a place as
well.

But no matter what renewables will struggle to provide the reliable energy we
have all become accustomed to. What is needed is a radical change in energy
use, ie reduce it. Renewables then stand a chance of providing it. Instead of
spending millions of pounds on subsidising commercial wind mills or funding
PV based monetary investment schemes(*) they ought to be ensuring that the
energy we do consume isn't wasted by, say, ensuring that *all* buildings are
properly insulated.

The "Green Deal" is available for everyone (I think) but TBH I'm not sure how
well it is going to work in practice. Take up essentially relies on people
feeling guilty about their energy use. IMHO the vast majority haven't a clue
about how much energy they use, the bill comes in they pay it, they might
whinge a bit when the price goes up but about all they can do about that is
to see if there is a cheaper supplier. As they don't have a clue about their
energy use seriously looking to see if they can reduce they amount they
consume is "too difficult". If they do look the primary motivation is a large
energy bill, are they going to opt to *increase* that energy bill via the
Green Deal? And if buying the Green Deal stays with the property, the new
owners *have* to take it over.

Wave power hasn't been mentioned yet, but there are a number of
projects, including the Wave Hub at Hayle.

Wave power seems to be in the same camp as fusion. As they were saying before
the 1970's "it will be commercially available 10 to 20 years".

It currently only has a max capacity of 20mw,

20 what? The unit is named after James Watt so has a capitalised symbol, ie
"W". Lowercase "m" is milli for 1/1000th or do you mean uppercase "m" for
1,000,000?

20 MW is also very little and would require backup as the waves aren't always
there.

but this is easily upgradable, as the cables come ashore at the old
Hayle coal fired station, so much of the infrastructure to transport
the power is in place. http://www.wavehub.co.uk/about/

"Wave Hub provides shared offshore infrastructure for the demonstration and
proving of arrays of wave energy generation devices over a sustained period
of time."

So it's a 25 year leased test bed rather than a commercial venture. Not going
to be much help in the next few winters...

Upgrade to 50 MW "once suitable components for operating the cable at 33kV
have been developed." So like wave and fusion not anytime soon...

And I wonder how well the cable risers from the sea floor to the sea surface
cope with the constant flexing/stressing, in salt water, at tidal and wave
frequencies?

I actually don't think our opinions are massively apart, just looking
at things from a rather different angle.

Quite possibly. You are glass half full, I'm glass half empty. Probably
influenced by how much energy renewables can be reasonably expected to
provide, how practical it is to realise that energy, how practical it is to
move that energy to where it is used and then add in time scales and cost.

Trouble is there are lots of stupid ideas out there How about this one?
Encircle the globe with a 10 mile wide strip of PV cells (avoids the night
problem), but how do you construct that across the oceans, how do you get the
power from the daylight side to the night side?

Have read "Without Hot Air"?

http://www.withouthotair.com/

(*) Would those that have installed or are going to install PV systems done
so if the payment for all the electricity generated was set at a 5p/unit
premium above their grid buying price? No index link and no guarantee?

--
Cheers Dave.
Nr Garrigill, Cumbria. 421m ASL.

On Wed, 27 Feb 2013 09:01:49 +0000, Malcolm wrote:

With which bit? Crap performance of air source heat pumps with air
temps just above 0C or contesting "Output input every time" on a
cradle to grave basis?

Both. We've had low temperatures the last few days and nights and are
living in a warm house, with the air source pump only on during the
day.

Have you measured how much heat it has produced and how much energy it has
consumed? With air temps just above freezing the collector ices up, ice is a
good insulator, the unit has to regularly defrost the collector. This is what
gives them crap performance under such conditions. It'll still churn out the
heat but with a poor COP.

Any evidence of cradle to grave energy costs?

--
Cheers Dave.
Nr Garrigill, Cumbria. 421m ASL.

On Thu, 28 Feb 2013 20:21:32 +0000, Malcolm wrote:

With which bit? Crap performance of air source heat pumps with air
temps just above 0C or contesting "Output input every time" on a
cradle to grave basis?

Both. We've had low temperatures the last few days and nights and are
living in a warm house, with the air source pump only on during the
day.

So? Evidence for an air source heat pump having a good COP with air temps
just above 0C. And that you gte more out from the heat pump than you put in
ove the cradle to grave measure?

Do you actually have one of these units yourself?

Not particularly relevant, you have one. What is the COP with say an air temp
of 2C and 80% RH?

Part of the house has storeage heating, which I hate. I'd like to replace
that with something a little more controlable and cheaper. I've been looking
at air source heat pumps, but the drop in COP with low air temps is a major
drawback when we spend quite significant periods (weeks) of the winter with
air temps 5C and high humidty, mist/hill fog.

Assuming a COP of 3.5 under ideal conditions droping that to 2.5 means the
input energy to get the same output goes up by 40%, either that or you get
cold...

--
Cheers Dave.
Nr Garrigill, Cumbria. 421m ASL.