Solar

Has anyone here had domestic solar water heating installed? I know this is the DIY group but I'm looking for someone to do it for me. Googling has produced a number of companies and trade associations but there's nothing like a personal recommendation (or warning).

I'm on the Somerset/Wiltshire border (some companies only seem to work in certain parts of the country).

Thank you.

Reply to
Graham Harrison
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Commercial solar HW systems are a great way to throw your money away. Suggest looking at solar flat plate space heating, less cost, more heat gain. Try alt.solar.thermal for info & expertise.

NT

Reply to
meow2222

Looks like I've got quite a lot of research to do. Thanks.

Reply to
Graham Harrison

On 22 Nov 2005 14:54:03 -0800 someone who may be snipped-for-privacy@care2.com wrote this:-

They are certainly not going to have a short payback period. However, the same is true of double glazing. There are plenty of other reasons for installing solar hot water systems than payback period.

Far more expensive if one is going to produce enough heat for a house. A major problem is that the heat is available in the summer, but needed in the winter. It might make a contribution in spring and autumn, when there are relatively sunny days and cold nights. Such heating is ideal in warm places with cold nights, such as deserts.

I suggest the original poster looks at two companies:

1) if they have no requirement for extra water storage and their existing cylinder is well lagged.
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which involves less work. 2) if they want extra water storage or their existing cylinder is not well lagged.
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which involves more work but produces a better result.

Both avoid mains powered pumps, which has many advantages.

Reply to
David Hansen

My parents house had it (self install - DIY cost about GBP500 in total using some very expensive glass vacuum collectors found in a scrap yard - it was finding the collectors which caused the thing to be built!) and a neighbour later had a commercial one fitted. Over

20 years neither broke even or got remotely near doing so. Both houses had virtually ideal south facing roofs of appropriate pitch.

Two reports worth looking at are

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do at least put some figures on the likely effects of these units (something the manufacturers studiously avoid doing).

From those tests the amount of energy from the panels tested came to roughly in the range 3,400 to 4,800 MJ per year. 1kw/hr (1 unit of electricity) = 3.6 MJ so that is between 945 and 1,330 kw/hr per year in ideal locations. If they are not south facing and at the right angle that figure can reduce by 50%.

Assuming 1,100 kw/hr is contributed per year the equivalent fuel costs are roughly:-

Gas (2p per kW/hr) = GBP22 Electricity (9p peak rate) = GBP99 Electricity (3p off peak rate) = GBP33 (These figures do not include any standing charge)

The saving achieved by using solar water heating in ideal situations is therefore in the order of only GBP22 to GBP100 per annum.

As the installed cost of commercially fitted solar panels is in the region of GBP3,000 to GBP5,000 or more it is not surprise that the manufacturers so carefully avoid any mention of how much energy the things actually (don't) produce and the fact they can never pay for themselves as the payback period is considerably greater than the system life.

Reply to
Peter Parry

On Wed, 23 Nov 2005 12:41:15 +0000 someone who may be Peter Parry wrote this:-

Incorrect.

Solartwin make quite a lot of one of the reports you mentioned.

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"Where's the evidence of this 20%?

"A recent UK government-funded study of eight solar water heating systems at Milton Keynes confirmed what has long been suspected: that the environmental benefits of solar can be substantially improved by eliminating mains electricity. ( Side by side testing of eight solar water heating systems 2001 DTI/Pub URN 01/1292)

"In this study, flat plate solar hot water systems negated an average of 17% of their potential global warming benefits (i.e. CO2 savings) by using mains electricity.

"For partial-vacuum tubes ("solar tubes"), their loss averaged even higher, at 23%.

"In other words, if you run mains-powered solar for ten years, its electricity consumption deletes its CO2 saving by about two years.

"Solartwin?s environment-centred solar water heating design brief specifies a solar electric pump. So your CO2 savings won?t retreat two steps after advancing ten."

Solar water heating is much like double glazing. If you do it just to save money then you are not going to do very well out of it. However, if you do it for a whole range of other reasons then the investment makes perfect sense.

Reply to
David Hansen

far cheaper in fact. They do not produce all the heat for a house, but a substantial percentage. Far more than a commercial DHW panel ever would.

heat is available in winter too, and it is this level the system is designed for.

it makes payback even poorer.

NT

Reply to
meow2222

It would take a not especially well designed system to waste 17% or 23% on electricity. What you dont mention here is that using a solar panel to provide power means more embodied energy used in manufacturing the thing, plus more cost to pay back.

no, but you start from a position further back, due to embodied energy in the panel. Youre also further back financially.

correct :)

it doesnt, for one simple reason: you can spend less, invest less embodied energy, and receive greater returns with solar space heating.

NT

Reply to
meow2222

Indeed they do - most misleadingly. As with all other manufacturers they also, as I stated, avoid real figures like the plague and have no link to download the report they quote. Instead there is a rambling missive about vague greenery and a wholly ridiculous claim that the value of your house will go up by at least GBP1,000 and your boiler get two years of extra life.

20% of what? They present it as if it is a huge saving, in fact the performance of their product is pretty middle of the road in a bunch which collectively are dire.

Which fails to mention that the benefits are minimal to begin with -

17% of 2/3 square root of sod all is still sod all.

The loss was exactly the same - this is simple dishonest use of percentages to make a marketing point.

It is nothing like double glazing. Double glazing brings with it a number of other advantages such as better noise insulation, less condensation and improved comfort within rooms by eliminating draughts. Solar water heating has no advantages at all over any other form of water heating, however, as well as making no economic sense is visually unattractive and also a very unreliable heating source.

Solar water heating will never make sense in the vast majority of situations in the UK.

Reply to
Peter Parry

It is best to look here as the prices are highly competitive:

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Reply to
Doctor Drivel

Try the Thermomax panels from Navitron - I gave the link. An array of those and a large thermal store supplying very low temp UFH and it may be viable.

The UK has about half the sun of north America in winter. The most cost effective way to save energy is:

  1. Insulate as much as possible: cavity wall, 1 foot in the loft, foam against the side of the foundations (easy to do, just digging).
  2. Make the house as air-tight as possible: spay-in Warcell in the loft, sealed triple glazing and doors, ect. Seal up chimney breast.

Then use solar as DHW only.

Reply to
Doctor Drivel

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> and

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> These do at least put some figures on the likely effects of these

As energy has taken a price hype, the figures may be rather out of date. These 20 year old systems may start to pay for themselves big-time.

Reply to
Doctor Drivel

It will if it is designed and built into new homes, renovations and extensions. If it is made mandatory the capital cost will plummet and it will be viable.

Reply to
Doctor Drivel

Oddly enough, I find myself almost agreeing with Drivel. I've no idea who Navitron are, but Thermomax make a good product. If they can get them to work cost-effectively in Northern Ireland, they ought to work in Somerset!

Reply to
Andy Dingley

Tell us something. Why install an array of highly priced commercial panels/tubes, plus plumbing system, plus UFH, when you could just as well install panels that are nothing more than glazed frames with black cloth, add holes in the wall and dampers, and harvest stacks of heat directly without all that nonsense in the way. You'd get twice the output for half the money.

Re storage, you dont use any. Theres a temperature comfort range, the day time heating takes it to however high your comfortable with, and temp drops very slowly in the evening. If it drops to the lower end of your chosen range, the CH tops up.

NT

Reply to
meow2222

Dramatic price reduction is the one barrier with SDHW, and one thats addressable in the years ahead imho.

Mass produced freezeproof moulded panels can be fitted into the roof so that they replace an area of tiling, thus cutting their effective cost for new builds. Add suitable control as part of some standard CH controllers and the control costs drop. Instead of one collector per house, install a large bank of panelling on flats to supply a communal HW source, and the paperwork and organisation costs per flat drop, and diversity kicks in, ensuring quick recovery. Include a set of minimum cost unglazed panels for prewarming cold incoming water.

Etc.

If solar cost 1/4 the price it would be worth it today. Energy costs are on the up, and there are many ways to cut solar costs once it gets out of the gimmick league. Also manufactured goods costs are coming down every decade. I reckon they might well become widespread in time.

NT

Reply to
meow2222

On Wed, 23 Nov 2005 18:01:06 +0000 someone who may be Peter Parry wrote this:-

Something I said in my posting.

Really. So not burning gas or electricity and thus reducing greenhouse gas emissions is not an advantage? Not running a boiler all the year round is not an advantage? Fascinating.

I suspect we are getting to your real motives now. Do you think that a panel built into a roof

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is unattractive?

Owners of modern systems seem happy with them, perhaps you are thinking of some of the earlier systems (still sold, sadly) with pre-heating cylinders and the like.

As others have said, mass production and installation in new buildings will even change the economics. Meanwhile the other advantages remain.

Perhaps you would like to study the recent report on sustainable heating systems by the Sustainable Development Commission. This gives the best view on the subject recently.

Reply to
David Hansen

You are on about an air heater in a conservatory. Good choice and v good. But you need a conservatory.

The Navitron Thermomax panels are cheap and will produce heat when the flat plates will not.

Reply to
Doctor Drivel

I don't believe it. If you spent £500 20 years ago and you haven't recouped the cost? Do some sums. That is £25 a year. A DHW solar setup will save more than £25 in energy costs a year, unless they don't use much DHW at all.

Reply to
Doctor Drivel

'Sums' is all it is - like a five year old could do. An adult brain would consider things like interest.

500 quid invested 20 years ago could have given a return of far more that 25 quid a year in the early years.

Get your nurse to explain it to you when she gives you your medication before putting you outside in your bathchair. And make sure she gives you an extra blanket.

Reply to
Dave Plowman (News)

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