Non-diy Solar Panels

aislingw

Hi, I hope someone can advise us one way or the other, we are putting on an extension and part of the plan from the very start was to put on dhw solar panels. However, now that they're due to go on very soon, we've started looking at the numbers. In the winter we have plenty of hot water and in the summer we only put on the immersion for about 2 hours every 2 days. Maybe we're particularly stink but a shower every 2 days is enough for us and the kids are small and only have baths 2 or 3 times a week. A quick calculation on this - 2 hours of immersion at 2.5kw * 60 days (ie, mid-may to mid-sep, every 2 days) - and calculating at 20 cent a unit, which it's not, I come out at 60 euro a year and that's hitting 100 year payback time.

Even allowing for 3 hours every day - to allow for older kids wanting showers every day etc etc, it's still 33 year payback - not allowing price increases beyond 20 cent though, which I'm sure will happen, so ok, maybe it'll be down to 25 years... don't know... but still where do people get these 5-7 year payback times? Admittedly during the summer we do end up boiling the kettle etc for hot water for dishes etc, but still, I'm dubious. We are definitely going for a pellet boiler, so we could always have stuff zoned and just put it on for hot water an hour a day and would that not do the job? Theoretically I would love to have the panels, and am not thaaaat pushed on payback time but the budget is starting to be stretched a lot and we really don't want to be too much of a sucker...

So basically, who has panels, how do they work? Are they really the business, are you saving loads of energy? Flat or tubes? We have trees in front of us which basically limit us to the summer months for now until the neighbour gets the finger out - would tubes be of any use in this situation. Heard somethign about them working from ambient light rather than direct sunlight. Have seen the thread about diy panels, but not sure hubby would be on for that, he's had enough of the diy for a while - did the (poroton) blockwork on the extension himself. Sometimes we say we'd prefer to put the money into a SP generator.

Sorry for the ramble, I hope someone has some insight into this....

Aisling

CJhaughey

Hi Aislingw
We am taking the jump with a 6.3 m2 panel and a 400l tank from Solaris in Macroom co Cork.
I hope that it will give plenty of hot water in the summer and a good boost in the winter. It is a flat panel installed with a 3kw immersion for boosting.
I think that you really have to look at the bigger picture while it may be affordable right now and by the sounds of it you are pretty good with economising on DHW than you are probably all right in the short term. But come January next year it will be a requirement for all homes to be energy rated.
This will take into account all the inputs and outputs in your home.
and may prove to be the single biggest thing to affect house prices.
I cannot give you any details on running costs as the system is not installed yet, but I will certainly post them as soon as it is commissioned.

Mothman

Hi Aisling,

I've given a detailed reply below, but in short from what you've said, I think your thinking is good, and since you don't use much hot water, then getting free hot water (after initial capital cost) is of little benefit. But as kids grow up, they may be less frugal, but then if they don't know any other way..... life's full of ifs and buts

8 yrs ago I installed in my new house a very similar system to what CJhaughey is getting. Also got it off Solaris, in the early days of the company. It is a 6 m2 300l tank system.

We certainly use plenty more hot water than you, with daily baths, showers, hot plumbed washing machine, other general cleaning etc. The backup is the immersion, using night rate elctricity. The immersion is rarely on from end of April to mid September. One sunny day in summer will heat at least 200l water to 80C!! The insulation around the tank will give the water hot for days.

From September to April, the immersion heats the top half of tank overnight, which is plenty for a days hot water, leaving the bottom half to be heated by the collectors. If it is a sunny day then, then the thermomstat won't allow the immersion to come on the following night. A sunny day in winter can heat the water to 40C+, but remember the water coming into the tank is a lot colder as well, (18C in summer, 8C in winter)

Because of our hot water usage, I feel I make quite good use of the system. If a sunny day is forecast in Spring or Autumn, I'll often turn the immersion off. Have got caught out a couple times when it remained cloudy :rolleyes:

Issues with my system are few. The main one is that it is installed at too low an angle which is 30deg. This is my roof pitch and I integrated the collectors into my roof. I have to drain off hot water during sunny spells in summer

For this reason I'm delighted to see CJhaughey getting a 400l tank, and I'd even consider a bigger one! At the time I was getting my system Solaris were out on a limb by suggesting 300l tank. Other suppliers at the time were suggesting 150-200l tank which made no sense to me at all. The tank has 2 coils in it. The bottom one for the solar collectors, and the top one for another heat source which I don't use, but is available should one be using a burner of any sort.

At the time I considered the tubes as well. There was no Irish supplier and I actually went England (no irish supplier at the time) to look into the system. I love the technology, but the bottom line was that it was going to cost more for half the area of collector and that was with a 150l tank!!! No brainer at the time.

I've reason to look into solar collectors again as I'm involved in a residential development. I haven't got today's figures yet, but was talking to a tubes rep at the Sustainable building show last week, and he nearly made my blood boil (not the only rep to do that at the show) He was criticising me strongly for having gone with flat plate technology 8 years ago, and saying that I'd have been better off paying more for half the area :mad: :mad:

I don't know what the bottom line difference is between tubes and flat plate, but when tube reps are giving you comparison figures, it'll be against poor flat plates, and they'll say it is twice as good per area, a flat plate rep told me 8-9%. I suspect it's somewhere in between.

In a typical flat plate system, the collectors themselves only make up less than 40% of the purchase price. The tank makes up a large proportion, and the controls and plumbing bits the rest.

So what I feel is my ideal system would be to add in extra collectors (doesn't add hugly to price) mount the collectors at a very steep angle of 60% or more to face the winter sun (mid winter sun is less than 25deg above horizon) and I think one could get 80%+ annual hot water needs. I haven't put this idea to any of the solar WH suppliers yet, but it makes sense to me. What would be needed by increasing the collector area (even if angled steeply away from summer sun) is overheating protection. This system seems to have an answer for that.

Here is a list of suppliers to the Irish market. Its a PDF file from Sustainable Energy Ireland website.

As for which collector, perhaps flat plate near the coast and tubes inland. The coastal margins on average get a load more sunshine than inalnd areas, and while tubes perform better when sun is not shining, the flat plate are pretty much equal in performance when sun is shining.

As for financial payback, it depends of what heat source you are replacing. I worked out my payback to be 30yrs at best. I'm replacing night rate electricity, which is cheap, but lets off a load of CO2. The financial payback has shortened because of the considerable rise in prices, and electricity cost will continue to rise as will pellet stove fuel etc.



A long post but I had the time and it may be of help to others

xonencentral

Aisling,

I have to agree with CJ's philosophy on it might not make sense now but me thinks the econmomics will change very fast and it might be akin to buying that house in 1990 for 10 grand that seemed very expensive at the time.

My theory is that when carbon producing fuels and goods are taxed and that tax keeps going up, renewable product will be in short supply and prices will go through the roof, so I'm getting in now while eveyone else is just talking about it and before it all goes belistic because I am one this people who thought house prices were mad in 1990, "what an idiot".

Worrying (realism) Quote from the G8:
The carbon taxes will raise the prices of the different energy carriers depending on their carbon concentration. Coal is levied more than petroleum and gas. The relation is about 4:3:2. Nuclear and renewable energy is not taxed at all. Higher energy prices will reduce energy demand and carbon emissions. Further energy prices will spread all over the economy and raise the prices of all goods depending on their direct and indirect energy inputs. On the other side wages will be reduced, because the government uses the tax revenue to lower social security contributions. This effect lowers costs and in reaction prices especially in the labour intensive sectors. Structural change will be induced, which favours labour intensive industries and depresses energy intensive industries.

It's not just econonics anymore that should be helping you make this decision, you should consider environmental responsibility for carbon emmissions, etc and if you don't; me thinks the government will dive into your wallet in a fashion that will have Eddie Hobbs up in arms. :eek:

aislingw

Oh, listen, when we got into this it was all environmental responsibility - it takes us forever to make any sort of decision as it all has to get weighed up - are we better off using natural slate that had to be shipped from Spain or locally made ferrocement thingies? Are we better off using timber-frame, poroton or locally produced concrete blocks.... etc etc. We thought we were going to get a certain pellet boiler which was half the price of everything else, but turns out it's not great, so now have to pay twice as much, so it's just at this point in a build, the money is starting to get tight and we were wondering were we just jumping on a green bandwagon - the hubby is quite concerned that the trees across the road are going to be a major liability but I reckon they won't affect the panels during the summer and we're not really banking on them to do much in the winter anyway....To be honest, the lads are doing the roof at the moment and they have put mounting brackets for panels up already - but dh especially is having pre-panel jitters. I'm more in favour and trying to convince him. I have been reading waay too much peak-oil stuff recently and I think he thinks I'm obsessing, which I am, but that it's just my latest phase and that it's not going to be that bad and we should save our money. We were at that sustainable building show too and picked up an old copy of local planet which had a load about peak oil in it which I'm going to try and get him to read. He's very much anti using oil to heat the house etc but I don't think he gets the full ramifications of the situation. I think he's just getting sick of the fact that all the green options are so much more expensive and he thinks we're being taken for a ride and everyone else is just moseying along regardless....

Anyway, thank you all for the input. It's great to get some reasoned, knowledgable feedback!

saibhne

Hi Guys,
Very informative - thanks! any chance you could let me know how much I could expect to pay for the system you are talking about?

Cheers!

S.

CJhaughey

My quote installed is ~5k
hope this helps.

Newshound

I agree that the payback for solar is outrageous.
There should be grants for this.

We had to make this decision a while ago and our research told us us that plain old night time esb is the way to go for your water.

Ok prices will go up, carbon tax will be introduced, but i am betting my bottom dollar that we'll cope. there are so many houses that use esb in this country that the price will never be allowed to rise so high as to punish the population enough that they cant afford hot water.

The energy rating on houses i believe will have zero effect on the purchase price of houses. Rooms the size of a cardboard box, wiring tec that needs replaciing dont even have an effect on the price of houses. There will be a big deal made about it for a while but it will fizzle out.

While i would love to have everything in my house environmentally friendly and looked into all sorts of ways to do this, i have come to the conclusion that i can afford to be environmentally friendly, which really pisses me off.

saibhne

CJhaughey wrote:

My quote installed is ~5k
hope this helps.

Thanks CJ

Mothman

CJhaughey wrote:

My quote installed is ~5k
hope this helps.

Which is only marginally more than what I paid back in 97, so in real terms I think the price has dropped a little.

CJhaughey

I am really looking forward to seeing the system setup.
I have learnt so much from watching the Builders build our Scanhome and asking them questions during the 3 day build.
Hopefully when the Solar Install happens I will learn as much again.

aislingw

Well I think I've re-persuaded him, thanks to you all!! Our roof is relatively small and we have just put on shiny new slates that look great so we're going to stick to the tubes and go with the smaller area.

CJ - mad jealous - looked at those scandinavian homes back in 97 or so but around here sites are mad expensive and pp very hard to come by so we ended up buying an old cottage and extending instead, but really would have loved what you're getting... Hope it all turns out exactly as you wished!

Mothman

aislingw wrote:

Well I think I've re-persuaded him, thanks to you all!! Our roof is relatively small and we have just put on shiny new slates that look great so we're going to stick to the tubes and go with the smaller area.

Sounds a good plan. I think it is quite easy to extend either by getting the 3m2 head but only putting in 2m2 of tubes now, or just by adding another unit later.

Must be worth bearing in mind when getting the unit installed, to allow for expansion, just in case.

CJhaughey

Update,
Panels, 400l Tank, and all the gubbins arrived yesterday.
Tank is one heavy piece of work with lovely Orange vinyl zip-on lagging jacket.
Looks the part if nothing else.
Panels a a lot bigger than I imagined them to be.
Pics of install coming soon.

bandraoi

you know you don't just need to look at your financial pay back time but also your environmental pay back time.

The impact of the manufacture of the solar panels will be greater than the impact of the manufacture of a conventional power generator per unit of energy produced. If your solar panels aren't going to be used only to produce a small amount of energy, then the net environmental effect may be worse from the solar panels.

CJhaughey

How do you calculate this?
The frames of the Panels are timber.
The glass is, well ...glass.
what are the environmental costs of that?
I cannot see how the panels would be any more environmentally costly than (timber) window manufacture.

I would like to see your information regarding net environmental cost of solar panel manufacture vs Peat based power generation.

Bill2

CJ,

a you installing the solar system yourself, getting the supply company to do it or is your plumber doing it. Just interested to know if it's a DIY job or strictly for the professionals, am going down this road soon and interested to know, i've been quoted €1100 plus vat to install a similar system.

Bill..

css

Guys, is there a limited life expectancy on solar panels? Does the performance degrade on them after a period of time?

Keeks

CJhaughey wrote:

My quote installed is ~5k
hope this helps.

What is included in the quote? Parts, labour etc.....?

xonencentral

What are you getting for the 5K, seems kind of cheap given the systems I have looked at, (never mind the installation cost).

Can you point me in the right direction.

CJhaughey

Sorry for the late reply, Ihave been away for the last few days.
Answers:
I am pretty sure that you can install the system yourself, I just wasn't too keen as I have never seen one installed, and little tricks may be the difference between an efficient system and a poor running one.
The price is for Flat Panels 6.3m2, a 400l tank the solar controller/pump unit and expansion vessel, a gallon of anti-freeze fluid, a big box of Flashings, TR301 differential unit with sensors auto air vent and valves and other bits and pieces. and the labour to install it.
What is not counted is the Pipework and the scaffolding AFAIK as the pipework depends on the length of run.
Roofers will be here soon and put the scaff. up so panels installed at the same time.

Mothman

bandraoi wrote:

you know you don't just need to look at your financial pay back time but also your environmental pay back time.

The impact of the manufacture of the solar panels will be greater than the impact of the manufacture of a conventional power generator per unit of energy produced. If your solar panels aren't going to be used only to produce a small amount of energy, then the net environmental effect may be worse from the solar panels.

I do think this is a fair point to raise, if it is for evironmental reasons that one is making decisions on. But if coming from this angle, the only logical solution that I can come to that is best for the environment is for me not to exist at all... :rolleyes:

If as CJ mentions that if it's a choice of Peat based power or solar water panels, then to m e it's a no brainer, and to think that we are all sudsidising peat generated power... :mad:

a you installing the solar system yourself, getting the supply company to do it or is your plumber doing it. Just interested to know if it's a DIY job or strictly for the professionals, am going down this road soon and interested to know, i've been quoted €1100 plus vat to install a similar system

I installed my system ( which is similar to CJs) myself. Though getting supplier to install should incur a lower VAT rate.

Guys, is there a limited life expectancy on solar panels? Does the performance degrade on them after a period of time?

I do think this a an issue that is not getting enough thought these days. I would expect everything indoors (tank, plumbing, control gear) to last a lifetime (whatever that means ) The collectors themselves, I'm hoping 30 years, and yes I would expect efficieny to drop a little. Mine are in 8 years now, and today, although it's not very sunny, my 6sqm of collectors have heated 150l water from 16C to 44C(by 14:40) and that is with some hot water usage as well.

CJhaughey

That sounds encouraging Mothman, what sort of sun conditions do you need to generate useful hot water? Today is very overcast but actually quite warm, I realise that it is dependant on Sunlight but how much is needed?

Mothman

CJhaughey wrote:

That sounds encouraging Mothman, what sort of sun conditions do you need to generate useful hot water? Today is very overcast but actually quite warm, I realise that it is dependant on Sunlight but how much is needed?

Oh you do need sunshine with the flat plates. A bright day without sunshine may raise temperature a handful of degrees. Looking at the suncard (I record sunshine for Met Eireann) for today, there was more sunshine than I thought, though it was hazy at best, and there was a gap of 2 hours during the middle of day. There was about 5.5hours, and the water in bottom of tank got to well above 50C

It's the bright days with little sunshine where the tubes come into their own