B&Q Solar

[EricP]

Sounds familiar. It was in Bristol and they charged £9000+ for a couple of panels, and the plank gave them £3000 up front.

[John Rumm]

Why do you say that?

I don't see that the percentages that you save are really relevant though. The (financial) analysis seems quite simple: For every kWh of "free" energy you get from solar, that is one less you need to pay for in terms of fossil fuels.

How many usable kWh do you get out of your system per year do you think?

[John Rumm]

This is true, and is a valid reason.

However doing the full resource analysis that includes raw materials, energy to manufacture, transport, install, service, and finally decommision and dispose of, is actually quite difficult.

The danger is that with many "green" systems that only reclaim relatively small amounts of energy, you never recoup these costs in the lifetime of the product, so the nett impact of the whole exercise can be negative - not only financially, but environmentally as well.

[David Hansen]

On Tue, 10 Oct 2006 19:10:40 +0100 someone who may be Andy Hall wrote this:-

In another thread on this group someone is lamenting having followed fashion and installed halogen downlighters in his kitchen. There is a sizable market for such things, but they don't make money or save money (for the customer). I point this out to illustrate that people can do things for other reasons, not to recommend others do it.

I accept that and hope the manufacturers of halogen downlighters soon find that out. Sales of 4x4s seem not to be affected by such considerations though.

However, money is not the only reason for installing such things and even if it was installing such things as an early adopter so that the price will come down is a slightly different thing.

[David Hansen]

On Tue, 10 Oct 2006 19:06:33 +0100 someone who may be Peter Parry wrote this:-

I suggest that you know little about religion. Questioning is a most important part of many religions, an example would be the critical relationship with God in the Jewish faith. Of course there are zealots in all religions, including those whose religion is science. It is also worth remembering that the Roman Catholic church has in the past and is still a great supporter of the scientific aspects of astronomy, something zealot "scientists" tend not to mention.

Would they really. Given their history of being involved in issues to do with the sea I rather doubt it.

"It's all too difficult.", "Noting I will do will make any difference.", "Others should act before I will." and the like are commonly heard statements. If everybody followed that line then nothing would ever be done, but fortunately not everyone does.

[David Hansen]

On Tue, 10 Oct 2006 18:14:21 +0100 someone who may be Peter Parry wrote this:-

There are a number of assumptions in those figures, but they don't negate the figures I assembled from the Navitron web site.

Some do, though not many. That this is the case is simply another example of government mismanagement.

I made the point to ensure that anyone reading it could be quite clear that the figures are a minimum simple payback period. I have always stated that such a system is a long term investment in such terms.

However, simple payback is not the only reason one does things.

[David Hansen]

On Tue, 10 Oct 2006 21:23:16 +0100 (BST) someone who may be "Dave Liquorice" wrote this:-

Depends what one calls sales puff. However, it is dealt with directly in the FAQs, which anyone interested can read for themselves.

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During the winter months when most of the hot water will be generated by the boiler, what happens if there is enough sun to set the pump in action. At which time there is not enough thermal energy to heat up the water sufficiently so that when it is returned to the hot water tank it reduces the temperature there?

A: The pump runs only on solar energy in the form of electricity. It has no temperature sensor, only a high pressure bypass in case the panel or its pipes are frozen. In response to your question: First - best not to have the hot water system on all day since this is wasteful anyway and does not allow for optimum solar performance. Most boilers have separate timers for this, but not all. Ideally time the boiler to add heat to the domestic hot water after 4pm. Second, even in winter some hot water is made by Solartwin, not all by the boiler as you say. Third - the panel is well insulated and so will still raise the temperature of water going into it since it collects heat from the sun and not the air. Fourth - at 100% sun and a water input temperature of 50C and air temperature of freezing our mathematical model (based on extensive tests at Napier University) suggests that the water will still leave the panel at least 10C hotter than when it went in. Fifth - if they really want to put cold water in under these circumstances they can connect a second cylinder behind the first and draw water off it! This will also allow for more summer hot storage and is a neat solution for people with AGAs and Rayburns.

====================================================================

[Bob Mannix]

Or maybe they are people who can't afford the extra expense and are looking for ways to save money. Sometimes greenery/organic eating can be a better-off person's hobby.

The only real answer to the current biosphere's present woes (the planet, of course, will be fine whether we are here or not!) is for half of the population to die (randomly spread). One can't help feeling sometimes that nature tries its best (Aids, Ebola, TB - safety valves built in to the system?) but we have advanced a bit quick recently and are one step ahead.

There, that's cheerful!

[David Hansen]

On Tue, 10 Oct 2006 19:07:02 +0100 someone who may be Andy Hall wrote this:-

You are assuming that money, in the form of simple payback period, is the only criteria for doing or not doing something. However, it isn't.

Continue to only look at simple payback period for as long as you like. It has come down and will come down, but if simple payback period was the only criteria for doing things many things would not be done.

Next contestant please.

[David Hansen]

On Wed, 11 Oct 2006 05:55:58 +0100 someone who may be John Rumm wrote this:-

It is indeed quite difficult. However, that has not stopped people doing such analysis and concluding that solar panels are worth fitting for life cycle environmental reasons.

[Mary Fisher]

Our income is considerably less than the national average, we're officially poor.

We eat far better than most people and as much organically produced food as possible.

It's not a hobby, we have no time for those :-)

Mary

[Mary Fisher]

But not always from what Mary has said I think she has a direct system.

cell powers small pump that circulates the secondary water in the cylinder through the collector. All you need to do is bung in a couple of T's into the cold feed (to collector) and the expansion pipe (from collector).

We needed to put a cylinder in because before solar we had a multipoint system.

It wasn't that but that's far less than other figures which have been bandied around by people who haven't got the systems but think they know everything.

the pump circulating your expensive traditionaly heated hotwater

?

the panel, thus cooling that water?

It hasn't happened to ours.

you'll need a softener another £800 thank you very much.

If you're in a hard water area you need a softener anyway, don't you?

We don't.

doesn't make money?

Do you work for nothing?

Mary

[Mary Fisher]

I'm not a contestant as you know but when we've completed a year I'll post what money we've saved. There will no doubt be those who question it but I'm not a liar and can't be bothered arguing with anyone who calles me one.

Mary

[Mary Fisher]

Indeed - and many commercial businesses too, not just gullible householders.

Mary

[John Rumm]

I can think of a few reasons one may decide to invest in many of these technologies:

1) Making or saving money will figure obviously in many cases 2) Doing something that has an environmentally less harmful effect that employing an alternative is another 3) Providing some facility / luxury that was not previously available. 4) Arriving at a solution for a particular problem set 5) Being "trendy" perhaps

I am sure there are more

True. But what are the motivations for solar water heating though?

(1) Is the easy one - but seems difficult to use as a justification in this case[1]. Note also that "cost" can also give a fair indication of environmental impact in many cases since it will include aspects relating to energy consumption, raw material, and distribution costs involved.

[1] Even where a payback can be shown, is it the most "bang for your buck", or could you get a faster or better payback on say extra insulation?

(2) would be a good reason - if it genuinely is the case - however as I mentioned in another post, working out the true environmental impact of a manufactured product through its full life cycle is very difficult to do, and always open to debate. Can anyone demonstrate that hot water production on a micro scale is environmentally less destructive than for example using other energy sources when you take into account all of the factors?

(3) Seems unlikely in these days of CH and multipoint etc - i.e. hot water supply is easy to arrange by any number of methods.

(4) Would be the clincher in a few specific examples - like very remote sites with no access to mains energy services, or perhaps providing hot water in your shed on the allotment!

(5) Sadly, this is probably a big driving factor.

Not really a contest is it? Given this is a DIY group, we are well placed to capitalise on emergent technologies like these since we can in many cases implement them at a fraction of the commercial costs. However to make it worth doing there needs to be some benefit to someone - either directly or indirectly. It is all well and good saying "there are other reasons", but it would help if those promoting the idea would explain some of theirs.

[John Rumm]

And many have done the analysis and concluded the opposite... who do we believe?

Larger scale commercial installs are often far easier to justify on traditional cost grounds alone.

However bear in mind that even companies are run by gullible householders!

[David Hansen]

On Wed, 11 Oct 2006 09:06:56 +0100 someone who may be "Bob Mannix" wrote this:-

People looking for ways to save money should research the subject. If they do then they will be advised that things like insulation are the first step. It states that in the Friends of the Earth Scotland green homebook that I have, which must be at least ten years old by now.

Before I answer, what do you mean by greenery?

As for organic eating, if one buys organic vegetables in a supermarket that have been flown from the other side of the world then that will be expensive (and not good for the environment). If one grows them oneself that will not be expensive.

[David Hansen]

On Wed, 11 Oct 2006 12:36:13 +0100 someone who may be John Rumm wrote this, which I have re-arranged:-

Given limited resources and an "unimproved" house there are plenty of things to do before solar water heating. People like me have said so for years and it says so in information provided by the various organisations. However, that is not a reason for not doing it in other circumstances.

Only up to a point.

It has been done a number of times, bearing in mind the limitations of such studies that you outlined. I have already indicated the reasons behind centralised electricity systems in the past and how this is changing. This is not a new debate, the discussion on centralised and decentralised boilers providing heating and hot water has gone round the circle several times.

Only with some people.

[Mary Fisher]

Indeed - unless they are foods which can't be grown here. I can't grow oranges :-(

In any way.

Mary

[David Hansen]

On Wed, 11 Oct 2006 12:43:32 +0100 someone who may be John Rumm wrote this:-

I have yet to see a convincing one (and I have seen many). The arguments expressed by the antis in this group have been very unconvincing, so far. Time will tell whether they are convincing in the future.

A company of any size would be well advised to employ an engineer to consider such things. I can remember when people said that basic insulation measures were a waste of time and money. The nay-sayers have moved on to other things now, but their line is the same.