Solar

[Doctor Drivel]

But have and designed many systems. You just guess. And a bad guesser at that.

** snip babble **

[David Hansen]

On Thu, 24 Nov 2005 22:00:05 +0000 someone who may be Peter Parry wrote this:-

You are asserting that there is not an adequate amount. This is based on one twenty year old system that you have experience of (and perhaps you are disappointed with).

On the other hand one can see what people with more modern systems have to say. You asserted that the two comments on the Solartwin web site could not be relied on (but your assertions could be relied on).

Well, the comment below has not been put on the Solartwin web site and neither is there a link from Solartwin to the pages concerned. They are

and from which the following comment is taken, "On a sunny day in mid June when the system was first running it heated a full tank to 70oC".

So, even if your particular system does not collect adequate amounts of energy that does not mean that all solar water heating systems don't collect adequate amounts of energy.

[Peter Parry]

Yes.

Please read this slowly as I've now said it three times and you seem to have difficulty comprehending it.

The measured results I obtained were consistent with the measured results obtained by the DTI when they tested "more modern" systems (including your pet Solartwin). There was no appreciable performance difference between the system I installed then and systems being installed now. Moreover the control system was considerably more capable than most of the rather noddy ones which seem to come with commercial systems these days.

I wasn't "disappointed" in it - it behaved exactly as predicted and was an interesting experiment. However, it ultimately saved nothing. Despite the very low installation cost (because of the source of the materials) over its whole life it never recouped even that low cost.

"More modern" in this field is in many respects no different from "more modern" of 20+ years ago. The collector tubes I had then were producing the same performance as identical "modern" ones.

I'm really not interested in perceptions, only reality. The measurements I took over ten years were in line with those obtained by the DTI - the performance was measured - why do you find it so difficult to understand this simple fact?

I said the two comments you quoted were possible made up, that if they were true were selectively quoted and in any case were subjective. My statements are based upon objective, reproducible measurements. Why do you have this aversion to measurement?

On a sunny day in mid June my system could do likewise, it couldn't (nor can his) in mid December.

There wasn't an adequate amount of energy to collect all the year around. The technology had nothing to do with it. Again you show this distaste for figures.

The maximum amount of energy in ideal situations in the UK varies from about 0.5kWh/m2 in the winter to 5kWh/m2 a day in the summer. A solar hot water system has a total collection efficiency of around 30 to 70%. Let's assume the higher figure. That equates to 350W/hr of energy per sq/m per day. For a typical 2sqm panel installation that's 700W/hr a day.

Assume a daily household requirement of about 100L of water at 60degC and an input temperature of 10degC in the winter. The specific heat of water is 4.2Joules per gram per deg C so the energy required (in kJ) is 4.2 x volume in litres x temperature rise in deg C. In our example 4.2 x 100 x (60-10) = 21MJ or 5,800W/hr a day. In the winter therefore the solar heater can provide no more than 12% of the required energy. This is for an absolutely perfect site. If the panel isn't aligned due south it can drop by 50%. If the panel isn't cleaned frequently it can drop by another 5-10%.

In the summer the same collector can manage 7,000W/hr a day, more than is needed and of course the excess cannot be stored. Each day you throw away the equivalent of nearly two days worth of winter energy gain.

Heating water in the summer is simple - I've achieved higher temperatures than 70degC with plastic bag. Heating adequate amounts of water to acceptable temperatures all the year around is completely beyond the capability of a modern commercial domestic solar heater.

Compare Tony's figure of GBP15 energy saving per year with other yearly energy savings you could make :-

Double Glazing - GBP82 Energy Efficient dishwasher - GBP13 Energy efficient Fridge Freezer - GBP35 Energy efficient Fridge - GBP15 Upgrading ;loft insulation - GBP58 Replacement condensing boiler - GBP 256 (Figures from the Energy Saving Trust)

Overall Solar water heating saves trivial amounts of energy and money. In energy terms the cost of manufacture, shipping the major components around the world and installation probably comfortably exceed the useful energy they collect in their lifetimes. The only thing they do is help the crazy political game - if you move manufacturing to China you "save" CO2 from the UK's "balance sheet". You actually contribute far more CO2 to the world supply of course but if it's CO2 made in China it doesn't matter and it doesn't count in the fairyland of Kyoto - absolute insanity.

[meow2222]

>> These are listed in Annex C to the report.

IIRC you said it did not provide a satisfactory supply of hot water, and did not pay back its installation cost. That would seem to me to make it inadequate on both grounds.

I would very much expect so, yes. If I had to generalise, I would generally say forget about commercial solar systems if youre serious about solar. Commercial setups seem to appeal more to people that just want the feelgood factor and dont want any hassle like maths, ROI, building a system or anything like that.

If you want a serious system design, alt.solar.thermal is the place to go. But expect a lot of reading and thinking before coming to a decision on design, be clear what your goals are, and listen to Mr Pine.

NT

[meow2222]

I agree with a lot of what you say, if not this bit. What you say further down does not support this conclusion either. It only tells us that your system, and many others with similar performance, arent upto it for winter use.

theres a key problem right there, 2sqm. 2sqm is ok for summer, but not winter. For winter one needs more area and more efficiency. Not 10x as much though, as will be explained below.

But recognise that that is not a necesarily true figure. Household water consumption can vary widely depending on whether the householder wants to conserve or not. Aeration, turning water off while soaping up in the shower, and a shower or whole house drain heat exchanger will all make a significant difference to hot water consumption.

will be higher if a drain heat exchanger is used.

ONLY if you install an inadequate panel of course! :) And do nothing to conserve energy use in the first place. You might just as well install a half square metre panel and then complain theres not enough sun for summer solar hot water.

one does not normally install them that far off, so thats not a real world problem with installed solar systems.

it can and there are systems that do it, but I would fully agree it isnt worth doing.

a non problem

Yes... but note how you slipped the word 'commercial' in there. You might as well have said competent performance is beyond the ability of any incompetent system.

one woud have to be upgrading from something fairly ancient to achieve that sort of saving.

ditto

I dont see how a condensing boiler will save me the entire annual spend on gas.

agreed! At least when applied to single domestic dwellings anyway.

It does something very sensible. Selling solar DHW makes a market with money available for businesses. This makes it more attractive, and provides funds for a business to develop the technology further, and that is what is needed today. You have to have a market for anyone to invest funds, and you have to invest funds to develop better technology. Its all part of the process.

I quite agree with your core message: solar domestic DHW is not something to invest in today.

NT

[Peter Parry]

You will have to blame celestial mechanics for that I am afraid. There simply isn't enough solar energy available in the UK for much of the year to make solar water heating worthwhile.

[David Hansen]

On Mon, 28 Nov 2005 17:19:07 +0000 someone who may be Peter Parry wrote this:-

An interesting swerve. Now there isn't an adequate amount of energy all year round to fully heat the hot water cylinder. Gosh!

Actually, that isn't news.

[Peter Parry]

More area = more cost = more CO2 used in manufacture and shipping across the globe. The equation never balances.

Of course you can reduce water consumption dramatically. There is no requirement to wash at all, it has little health benefit. I've spent many weeks living on one or two litres of pretty disreputable water a day with no harmful effect.

Whether you can convince Sun readers to become even more malodorous is of course a different matter and when you start looking at trying to add a waste water heat exchangers to an existing build the sums get silly.

I'm not sure how you reach this conclusion - 70% overall efficiency is beyond most systems. You can keep adding panels of course but the economics stay the same.

Not really - just spend the money you were going to waste on solar panels on more effective ways of conserving and gaining energy.

One does if the roof is in the wrong direction as most are.

Most people are not going to make their own - so it is the performance of commercial systems which matters. I can make a solar heating system which will give me hot water 365 days of the year. To do so makes no economic sense whatsoever and no sense at all from an energy point of view.

Not really, quite a few Fridge/Freezers of 5 years old or more can be replaced by modern equivalents to give this sort of saving.

Did seem high I must admit.

Funnily enough that was exactly what was said in about 1975. In the meantime the "technology" (there really isn't that much involved) has progressed minimally and costs have stayed high. Exactly the same has happened in countries where solar energy has long been far more attractive than it ever will be here. There is a well established worldwide market in solar heating and it hasn't driven development or cost reduction to any significant extent so this argument does seem rather implausible.

The market has existed in many countries for centuries, you simply can't develop what isn't there to develop. In countries with lots of sun, solar water heating has existed for years and uses crude and quite adequate technology. In countries like the UK nothing is going to make up for thee fact there simply isn't adequate solar energy for most houses for most of the year.

[David Hansen]

On 28 Nov 2005 12:06:58 -0800 someone who may be [e-mail] wrote this:-

Agreed. That is one of the issues the Sustainable Development Commission's report on micro generation covered.

One of the long-standing failings of the training of engineers in the UK is that we tend to have an over-reliance on figures and try and airily dismiss such "social" arguments.

[Doctor Drivel]

to only use machines as a last resort. All proven and a part of the design: Since 1961 A school near Liverpool has been heating itself.

[Sam Nelson]

Is it warm yet?

[Alan]

Hi Graham,

I have looked extensively at solar water heating. I could bore you to death with figures and calculations but my opinion is that at todays prices you will never see payback on a commercially installed system. I have looked at DIYing it and worked out a payback of 20 years (not counting running and maintenance costs) and that is comparing it to oil which is comparatively expensive. As a commercialy installedl system (even with a grant) is much more expensive than DIY then your payback time is even greater than that. I should also mention I am in central Scotland so I guess you might have more sun than me and perhaps a better payback...

As energy prices increase, the payback time gets better so my advice to you is to revisit this in a few years.

You didn't mention your motivation for looking at this. If environmental then it maybe makes sense but I don't know the energy costs in the manufacture of these.

You also didn't mention how many people you are looking to heat water for or if this is a retrofit or part of a new build. Payback is better on a larger system and installation cheaper on a new build.

Alan.

[Peter Parry]

Strong on issoooes they are. Short on facts unfortunately. Pity they don't seem to know what "sustainable" actually means.

That's because the "social arguments" are largely nonsense spouted by agenda driven propagandists who don't have a sustainable argument.

How does importing machines made from materials made in heavily polluting plants and manufactured by poorly paid, almost slave, labourers help socially?

How do we reduce carbon emissions by buying vast quantities of equipment which in their lifetime save far less energy than was involved in their manufacture?

The "social argument" is one of desperate foolhardiness; save (insert country here) from Kyoto and screw the world.

[Doctor Drivel]

How about using cheap Navitron equipment. They have dropped the price of Solar equipment like a stone.

[David Hansen]

On Tue, 29 Nov 2005 19:24:06 +0000 someone who may be Peter Parry wrote this:-

Strong on all sorts of facts about how micropower influences people's attitudes to energy.

A mildly amusing assertion, but incorrect.

That is one of my concerns about evacuated tubes. As currently most are made in China that is not in alignment with the local production agenda of many environmentalists.

[Peter Parry]

So it's attitude that influences the amount of CO2 emitted by energy generation is it? Hadn't realised that.

Hardly, look at the makeup of your "Sustainable Development Commission". Led by Baron Porritt, Eton educated lawyer and son of the ex Governor General of New Zealand. Green Party founder and well known campaigner against almost anything. Closest he has been to "social housing" is studying a photograph of one.

Of the 14 other members of this so called "independent" commission one is an unsuccessful Labour party parliamentary candidate, one a paid consultant for a company that makes money promoting "environmental awareness", one a Media Studies lecturer, one a teacher of tourism and non-formal education. Another heads a company designing "sustainable energy" equipment, yet another is an expert in consumer behaviour and a professional playwright. One is apparently an expert in "facilitator networks" using "community visioning" and runs a company selling the service (whatever it may be).

More than a half of them are members of one or more of the Labour Party, the Green Party, Greenpeace, Friends of the Earth and other groups with vested interests. More than a quarter run companies selling the services or products they are promoting.

Oh, it does also have a token scientist.

Independent?

[David Hansen]

On Wed, 30 Nov 2005 09:59:37 +0000 someone who may be Peter Parry wrote this:-

Is that a crime now?

What vested interests to Greenpeace and Friends of the Earth have? Is being a member of either a crime now?

So, even if these were all involved just to promote their services or products they would not have an overriding influence. Thank you.

[Alan]

Yes, Navitron prices make it at least close to practical but it is still expensive. I'd love to know how good they are - how can Navitron be so cheap? Is there a catch? Anyway, my calculations are done using Navitron pricing - =A3395 for the collector + =A3100 delivery then =A3200 for a dual coil cylinder then a controller, temp sensors, pipes, pump etc you are looking at the best part of a grand for the bits. I recon I can save =A350/year with SDHW which is where I get the 20 year payback without including maintenance costs. Yes, spiraling fuel costs will reduce this and I am sure I could save some of the costs for instance by using a solar panel to drive the pump

- no need for the diff controller/sensors or even by making my own controller. Any commercially installed systems I have seen are twice this price although maybe using Navitron panels will reduce this but even with a grant this will still be more expensive so not a short term proposition. It is criminal that grants are not available to DIY'ers. There should be a law against DIY-ism.

[David Hansen]

On 30 Nov 2005 05:40:02 -0800 someone who may be "Alan" wrote this:-

ISTM that the premium for such systems is £1000. Against this is a grant and reduction in VAT.

I entirely agree, as well as the discrimination over VAT. I think this is another example of the administrators taking over and driving out those who know what they are talking about. All very much "New" Labour claptrap.

[Peter Parry]

Hardly, although they may be working on making not being a member of it a crime to go with the crime they have invented of fitting a telephone extension in your kitchen. The pork barrel politics don't do much for the claim of "impartiality" though.

Promoting their own narrow agenda. Greenpeace in particular have a long history of dishonesty and trying to suppress and sabotage work and studies which may reach conclusions that don't suit them.

Now making that so is quite tempting. Making deliberately publishing misinformation a crime would certainly get rid of both of them pretty quickly. It would get rid of all politicians as well so unfortunately it's never going to happen.

Oh I think they could rely upon their like minded mates to help :-).

How does this motley collection of unqualified political placemen and serial part time committee sitters count as impartial? Or has impartial been redefined as not allowing preconceptions to be affected by facts? This group of entertainers may not be faced with that problem of course as they assiduously avoid anything factual.