Solar Power-is it worth it?

driller_killer

Cardew wrote: »

Firstly, I am fully aware of the correct terminology for units of Energy. What I stated was

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Nothing wrong with that! They can be so defined.

As the OP said he 'wasn’t interested in the power the systems produce but how much hot water,' I genuinely did not know what he meant; indeed I thought he might be confusing solar electricity generation with solar DHW.

So your assumption/accusation of rudeness was incorrect!

No it wasn't. You said "i do not understand what you mean by power" As you've attempted to bluff an answer above, why did you post an inflammatory answer like this?

Secondly British gas do not charge “4.1p to 4.8p” Their standard tariff price for all secondary units(after the first 1,143kWh per quarter) is either 2.391p or 2.709p and on their Click 5 it is 2.601p – after first 670kWh per quarter(all prices include VAT but exclude discounts)

Lets start with the British Gas figure first. I checked that amount today.

Rate 1 went to 4.861p per kWh from 3/4/08, replacing the previous figure of 4.111 per kWh.
Rate 2 went to 2.929p per kWh from 2.322p per kWh.

This is stated of page3 of my invoice ****82174, customer reference ****66193

Do you want to continue arguing the point over this?


I did say you need to factor in boiler efficiency a couple of times - if you wish to read carefully.

Let us get to the more important issue.



I quite like that quote – I don’t think I have seen one more out of context – you must have political ambitions!!! And you accused me of not reading posts!!

The 50% is of DHW is for a house using the UK average of 3,000kWh per year.

I have gone to great lengths(using the data you provided) to say that a 3 panel system will produce approx 3,000kWh.(you are presumably not going to dispute that figure?)

Somehow you manage to get that 3,000kWh to be worth £720 and base saving calculations on that figure. So you are pricing each kWh at 24pence!! –
That makes Economy 7 electricity and an Immersion heater seem a bargain at around 4p/kWh!

Cardew, WELL DONE on completely missing the point of my post.

Yes, the figures i use to calculate DHW are simple, its a shame you don't follow them.

As i stated right at the beginning, i would consider my own personal consumption of hot water to be normal or even below average for a small family (that's why i accept that 50% of my DHW is viable from solar i.e. YOUR figures). Remember i gave the details of physically how much water i was using. If you like, i will get into the shower with Mrs driller_killer and measure exactly how many litres of water we get through. She might not like that though.

Lets put it another way.
Are two showers of 8mins and 10mins, plus a shallow lukewarm bath excessive?
Is that a ridiculous amount of hot water?
Would it, in your words, be considered (wait for it) average? Or even below average?

If the answer to the last question is yes, then using your figures of 50% DHW from 3000 kWh of panels is perfectly correct. (what you put in bold above)

What you singularly fail to understand is that it i am getting clobbered by my LPG boiler. It is THIS that makes solar panels APPEAR cost effective. In reality, i can see that its a very poor boiler that needs attention first.

Just what bit of this do you not understand?

I've kept stressing through my post that people need to consider their own personal circumstances, yet you persist in citing averages.

Like i've now said for the THIRD TIME, solar panels will have a very long payback on my roof because i'm addressing the weakest part of my system (the boiler and fuel) first.

You answered your question for me yourself.

The current set up means i pay according to your figures 24p kWh.

I expect the bill for all the LPG for heating and water to be £3300 this year to September.

The point of my calculations was to show you and others and statistics can be deliberately misinterpreted. Shame you went for it. To all the other people reading this forum, read behind the headlines on solar and do your own maths. If i was selling solar to someone in similar circumstances to myself, i would be quite right to suggest an annual saving of £720. What i wouldn't say was that there were other cheaper methods to achieve an even greater saving

In the real world I suspect you won’t be able to use some of that DHW in the summer.

And you know my family do you?

I won’t even dignify your simplistic economic calculations by explaining how silly they are – I suspect you won’t fool many!(we can discuss those calculations separately if you wish)

I asked you:


You have studiously avoided any answer.

P.S I have no mortgages and am not contemplating getting either solar heating or electricity; but thank you for the advice!

Great, anymore financial advice you require, please let me know. Make sure you read it carefully though. On second thoughts, just make sure you read it.

bobmedley

Please, please show us how you are going to save money (you claim £1,800 over LPG?) using wood pellets and paying £12,000 for the privilege:eek:

They are a bigger scam than solar & if you show your figures, then I will show you mine:p

In fact, you appear to be spending £16,500 in total when it seems you only needed to change your LPG boiler for a newer, more efficient one at c£800 plus fitting - you must be very wealthy.

mech_2

(Your quoting is broken).

driller_killer wrote: »

Lets start with the British Gas figure first. I checked that amount today.

Rate 1 went to 4.861p per kWh from 3/4/08, replacing the previous figure of 4.111 per kWh.
Rate 2 went to 2.929p per kWh from 2.322p per kWh.

This is stated of page3 of my invoice ****82174, customer reference ****66193

Do you want to continue arguing the point over this?

I think this proves Cardew right. The unit value of any kWh you are likely to save is not in the 4.1p to 4.8p range at all.

As i stated right at the beginning, i would consider my own personal consumption of hot water to be normal or even below average for a small family (that's why i accept that 50% of my DHW is viable from solar i.e. YOUR figures). Remember i gave the details of physically how much water i was using. If you like, i will get into the shower with Mrs driller_killer and measure exactly how many litres of water we get through. She might not like that though.

Lets put it another way.
Are two showers of 8mins and 10mins, plus a shallow lukewarm bath excessive?
Is that a ridiculous amount of hot water?
Would it, in your words, be considered (wait for it) average? Or even below average?

If it's below average, then the idea that you would not be able to use all the heat in summer seems perfectly valid to me. Panels that collect 3000kWh a year will probably be collecting 15kWh a day in the height of summer. I think using all that heat is a tall order if you have average (or lower) consumption.

If the answer to the last question is yes, then using your figures of 50% DHW from 3000 kWh of panels is perfectly correct. (what you put in bold above)

Actually it seems like a fairly random guess. How do we arrive at this assumption?

tabath

driller_killer wrote: »

Ha ha! I wish i was using a lot of hot water. Believe it or not, all that LPG produces is enough hot water for 1 shared bath between the kiddies and 1 shower each for my wife and I per day. That said, the second shower is lukewarm! Clearly, the system is inefficient.

It'll cost around £12000 for a new pellet boiler installed. 3 panels have been priced at £4100. I'm convinced of the former, but not the latter. I could go down the route of a condensing LPG boiler (£3000), but i think the writing might be on the wall for certain fuels. We seem to be being 'developed' back to the Victorian age.

In working out my solution, i'm trying to look to the future. Having been in the house for only a year, i do not intend to move for the next 15. (Quite like where we live!) We have two little children, soon to be three, so the things that i'm considering are:

1) My family will drastically increase its use of hot water as they grow up and to a lesser extent, heating
2) Future fuel costs. Will they ALWAYS go up? Well yes, i think they probably will
3) The weak excuse of a government that we have that cynically exploits anything to do with carbon in order to raise more tax.

Having done my sums, it'll be about 11 years for solar to payback (on a wood pellet boiler) at current consumption and costs. If we use more or fuel costs more or Brown taxes more, my time to payback will come down.

Is it worth it? Don't know.

where did you get £3000 for an lpg condensing boiler????

Cardew

Lets start with the British Gas figure first. I checked that amount today.

Rate 1 went to 4.861p per kWh from 3/4/08, replacing the previous figure of 4.111 per kWh.
Rate 2 went to 2.929p per kWh from 2.322p per kWh.

This is stated of page3 of my invoice ****82174, customer reference ****66193

Do you want to continue arguing the point over this?

Most certainly I do:

If you look at the BG website the figures I quoted are exactly correct for both Standard tariff and Click 5.

See: http://www.britishgas.co.uk/pdf/Standard gas prices.pdf

I wonder if you have a non-domestic tariff?

In any case it doesnt excuse you trying use Tier 1 primary unit price as the basis of your(flawed) calculations.

Do you wish to continue arguing the point over this?

If the answer to the last question is yes, then using your figures of 50% DHW from 3000 kWh of panels is perfectly correct. (what you put in bold above)

I simply don't follow that statement!

You keep avoiding the central issue that 3 solar panels totalling 6 square meters are only capable of producing approx 3,000kWh. It doesn’t matter what your system is or how much, or how little, DHW you use, you are not going to save more than that amount of energy.

Even allowing that you could use all the DHW they will produce in the summer months(several full tanks) - and most people wouldn’t be able to use it all – your savings will still be:
(using ‘domestic’ BG gas prices on their most expensive standard tariff and taking boiler efficiency at a very low 60%)

3,000 x 2.709p x 60% = £135 and that hypothetical figure is drastic over-estimate of the real time savings.

I repeat £50 savings for a gas CH house will be good.

The point of my calculations was to show you and others and statistics can be deliberately misinterpreted. Shame you went for it.

Absolute classic!

Have we all got that! - I mean really understood that?
An admission that all his above posts are complete rubbish and a wind up?

Somehow I think you are being just a teeny bit disingenuous!

I prefer to think that you have been persuaded of the complete lack of logic in your posts, and do not have the grace to admit that is the case.















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wpp34

Wow, I didn't realise this was such a heated topic!! (sorry about that) Thanks for the support driller, and I do happen to know the difference between power, energy, work etc but as I said I am only interested if I can get DHW and use less gas. As to the efficiency of the boiler I know in my case it is very poor as it is a 20 year old Rayburn Gas Ranger. In case anyone doesn't know what that is, it is an old style range cooker and has two gas burners, one for cooking and one for the hot water and central heating system. Most of the year the cooker is switched off and we just use the boiler.

More background to my original post is that I am also considering the option of adding a condensing boiler to the system but want to keep the Rayburn as it looks nice in the kitchen and we do like to cook with it in the winter. As it has to have a gravity feed sort of bypass for the hot water it produces when the cooker is on (I'm not good on the technical side so no need to correct this!) and we need to keep the hot water cylinder. I think the plumbing required to add a new boiler is quite complicated and I've been told to budget on around £3000 as a starting figure if it is possible to have such a hybrid system.

An alternative was to look at other ways of getting hot water and hence the request for information about solar power (oops should that be energy and lets go back to good old cgs and ergs.....).

The financial arguments are also interesting. In my case I will not have to borrow and am more than happy if my monthly bills are reduced in the long term. However, Cardew, how do you set about demolishing the claims that adding a solar water heating system can add up to 9% to the value of your house. Now if I lived in a £300,000 house that would be £27,000 and even I find that one hard to swallow. Makes my unbelievable £340 seem quite reasonable to me.

Cardew

wpp34 wrote: »

Wow, I didn't realise this was such a heated topic!! (sorry about that) Thanks for the support driller, and I do happen to know the difference between power, energy, work etc but as I said I am only interested if I can get DHW and use less gas. As to the efficiency of the boiler I know in my case it is very poor as it is a 20 year old Rayburn Gas Ranger. In case anyone doesn't know what that is, it is an old style range cooker and has two gas burners, one for cooking and one for the hot water and central heating system. Most of the year the cooker is switched off and we just use the boiler.

More background to my original post is that I am also considering the option of adding a condensing boiler to the system but want to keep the Rayburn as it looks nice in the kitchen and we do like to cook with it in the winter. As it has to have a gravity feed sort of bypass for the hot water it produces when the cooker is on (I'm not good on the technical side so no need to correct this!) and we need to keep the hot water cylinder. I think the plumbing required to add a new boiler is quite complicated and I've been told to budget on around £3000 as a starting figure if it is possible to have such a hybrid system.

An alternative was to look at other ways of getting hot water and hence the request for information about solar power (oops should that be energy and lets go back to good old cgs and ergs.....).

The financial arguments are also interesting. In my case I will not have to borrow and am more than happy if my monthly bills are reduced in the long term. However, Cardew, how do you set about demolishing the claims that adding a solar water heating system can add up to 9% to the value of your house. Now if I lived in a £300,000 house that would be £27,000 and even I find that one hard to swallow. Makes my unbelievable £340 seem quite reasonable to me.

I have posted on a couple of other threads about the problems of adding a third source of heating(Aga/Rayburn/Baxi etc) to a CH system.( a hybrid as you put it) Essentially you have a safety problem and/or a backpath for hot water.

I have such a system(with a Baxi) and wish it had never been installed that way.
Merely something to be aware of!

As for the 9% well that is absoutely correct.

However the 'up to' you put in italics says it all. 0.001% is covered by that qualifying statement is it not! So for your £300k house that statement covers an increase in value of between £3 and £27k!

I seem to have been cast in the role of the MSE solar sceptic, with justification I suppose.

However I have been looking at these systems for many years. I first was interested in solar for a large swimming pool as solar can be more effective heating large quantities of water a few degrees.

However for all uses they are simply not cost effective IMO - I wish they were.

I believe the long term future of solar will be for electricity generation, all it needs is the panels to be manufactured at some realistic price, and the Government get involved and stop the inevitable Cowboy firms getting into 'rip off' mode.

Incidentally to borrow, or take money from savings, is irrelevant to the principle of working out the economics of fitting solar. To take £4,500 from savings invested at 5% after tax, is still £225 pa in lost interest. Compound that interest etc

Also do people seriously think these systems will be maintenance free? Plumbing, pump, electronics, panels mounted on a roof etc etc

All this for savings of ???

wpp34

Cardew wrote: »

I have posted on a couple of other threads about the problems of adding a third source of heating(Aga/Rayburn/Baxi etc) to a CH system.

Cardew I've down a search for posts you mention but you have so many I can't find the right one! Can you provide a link please?

Cardew

wpp34 wrote: »

Cardew I've down a search for posts you mention but you have so many I can't find the right one! Can you provide a link please?

http://forums.moneysavingexpert.com/showthread.html?t=643447&highlight=Baxi+open+fire+explosion

Just a tip on searching in MSE. If you go to advanced search as I did and put down a couple of words(in this case I put Baxi, Open fire, explosion) it will bring up the relevant posts.

moo2moo

To stir you all up again I paid considerably less than £4500 for my installation with thermal store. Almost £2000 less.

30 tube panel £900.
300l Thermal Store £1200
Copper piping lets call it £100
Fernox Alphi 11 £15 (anti freeze for inside the pipes)
Expansion tank £10
Hi-temp pipe insulation - £15 (to buy a bottle of whiskey as a thank you rather than the £45 per 2m length we were quoted)
6 lengths of builders strapping to attach the panel to the roof and 12 v.v.v. big coach bolts through the roof trusses. £25)
Throw in the lead free solder, copper pipe joints, pressure relief valve and blow torch £40
External Heat dump - free via Freecycle
Pump for heat dump £60
Resol controller and temeprature sensors £210

We're not your average DIY'ers but even so it wasn't beyond someone with a reasonable understanding of plumbing. It was installed on a single story roof so no expensive scaffolding to consider, we borrowed some builders tressels from a friend.

Total cost £2575.

Wet underfloor heating went in at the same time. Basic kit from Screwfix £350 (now £399), pipework £50, controller £25, 3 sheets re-inforcing mesh with 6" grid (to hold pipework in position) and 2000 tie wraps £50.

Accepting Cardews worst case figures that this will save me £120 per year then the solar install (£2575) will pay for itself in 23 years assuming I buy mains gas at 4p / KWh. However since I buy the rather more extortinately priced LPG from Flogas which is currently at the 50p/l mark assuming I reduce my LPG usage by 400l per year (just a random figure.. although Driller_Killer used this amount in 2 months) saving £200 then this quickly reduces to 13 years. Lower usage, quicker payback. Using Driller_Killers figures (flawed though they may be by an elderly boiler) as an example even if my solar system was only operational for 4 months of the year (May-August) then the savings would be £400 per year or payback in 6.5 years. On the otherhand if Flogas double the cost of LPG again over the next 2 years (as they have since 2006) then my actual savings will be more like £800 per year. Payback in 4 years.

Solar won't suit everyone. But for those of us on LPG its an option worth considering.