Lets Talk Solar - opinions please!

John T Carroll

mp31 wrote: »

OK thanks for that - it's a relief to know they are not doing that sort of stuff.

Sorry one more question (I should ask them all together but I can't think of them all at the same time ) - how is the system performing in this latest 'heatwave' that we are having. OK, I know it's a stretch to call it a heatwave but I'm guessing that your hot water tank is full of really hot water and so what happens to all the heat coming from the panels on the roof? Does it get diverted to a radiator somewhere in the house?

As its a combined system Space Heating/Domestic Hot water heating then one would need to have an EXTERNAL heat dump of anywhere between 25 and 50 KW depending on the solar array sizing......its a question that Freddyuk has asked more than once "what do you do with the heat in the summer", I know that Kingspan make a HP400 array with a snap disc that closes at 90C, this might do the job but will Kingspan still give that 20 year guarantee if you inform them that your system will be stagnating almost every day for up to 4 months of the year? as the tubes will still reach very high temperatures even if the water doesn't. I would be very surprised if the proposed system has anything like this fitted so if you want to avoid stagnation without that external heat dump then you may have you settle for a very hot house for the summer.

Slieve

There is no dump. What you would do in summer is turn all but one or two rads off and the excess hot water goes into them. Although this summer I left it running at full pelt and had a lovely warm house and loads of hot water. What I had intended to do was to leave the bedroom rads on medium so the rooms would be warm at night, but the bad weather put paid to that.

andy99

For what its worth my immersion stopped working a year ago due to a faulty thermostat. We relied on the condenser boiler to heat the water in the 300l Tank. In summer months I simply turned off the radiators and let the oil boiler heat our hot water. We use a lot of hot water and thus I was amazed to find that our oil usage seemed to be minimal. We live in the same house for the past 30 years and I keep a record of oil fills--thus I have a good feel for what we are using versus other years. The house is about 3000sq feet and we have used less tan a fill in the past 12 months. This despite the fact that my family hit the ON switch for the Oil boiler whenever they feel like it. Admittedly the house is triple glazed and well insulated--while still being mostly built in 1983. One of my friends who is an electrical engineer calculated that it would take about 30 years to recoup the money a solar hot water system would cost and by then it would be well wrecked. I started the process of going Solar 18 months ago--thus the bigger new hot water cylinder but now there is definitely no way I am going to put up the panels. Not unless I move to somewhere sunnier.

John T Carroll

Some of our country colleagues might be interested in this.

Wearb

John T Carroll wrote: »

Some of our country colleagues might be interested in this.

10 year payback and that assumes, no maintenance or repair costs after installation. Maybe worthwhile.

There was a system developed for dairies that used the cooling of the warm milk as a source of heat for the hot water. Wonder if that gained any legs.

andy99

Folks I do not know why Dairy farming has come into the equation. I was just stating, as an older person with all those years of making mistakes, that these systems are all hyped up while really not worth all the hassle. I firmly believe that solar will never pay itself off. It s also very complicated and liable to leaks etc. In 1983 I put in an ordinary system complete with gun barrel piping--it should have been a recipe for disaster but is still perfect today albeit with a new condenser boiler, Our newly extended house of 3000 sq feet is easily heated by an ordinary Stanley bon-boiler Stove and a 1000 litres a year in the condenser boiler. I still calculate that were I to fit a rolls royce solar system it would only save me about €200 per year. There is no way I am fitting a Solar anything unless I can get it free--too many valves/software gadgetry to go wrong and too much cost at the beginning.
Insulate like mad, build 2500 sq feet and get a stove--my advice for all you young folk.

MicktheMan

andy99 wrote: »

were I to fit a rolls royce solar system it would only save me about €200 per year.

For anybody who actually measures / monitors their dhw cost, this is 100% true but you won't hear any solar salesman telling you this. Claims of 5,6,7 year payback on solar thermal is complete bs.

In fact, if you run the numbers, you will find that the cost of heating the water is a lot less than the actual cost of the water in the first place when proper metered billling starts.

Best to concentrate on the efficiency of the current water heating system and reducing actual water use rather than solar thermal.

Wearb

Insulate or have a good pre insulated cylinder and insulate pipe work. After that heat only the amount you need for the day and heat it as close to the time of first usage as possible. This applies whether you use gas, oil or electric to heat your water.

I am not convinced about the merit of solar at all. Maybe if you are in the habit of using lots of power showers in the sunny summers, but even then you would have to cut back in the winter or you would negate the savings made on solar in the summer.

John T Carroll

Wearb wrote: »

Insulate or have a good pre insulated cylinder and insulate pipe work. After that heat only the amount you need for the day and heat it as close to the time of first usage as possible. This applies whether you use gas, oil or electric to heat your water.

I am not convinced about the merit of solar at all. Maybe if you are in the habit of using lots of power showers in the sunny summers, but even then you would have to cut back in the winter or you would negate the savings made on solar in the summer.

Would agree with most of the above even though I have a modest F.Plate solar system myself. I didnt install it until my almost 40 year old cylinder started leaking, the system cost me a net €2700 four years ago and I reckoned at the time that my pay back would be around 19 years. I would think that the F.Plates are good for 25 to 30 years, the system never stagnates (due to the "inefficiency" of the F.Plate) so I reckon the glycol is good for 7 or 10 years, it still is the same colour as the day it was put in, I will change it myself unless I'm wheelchair bound for about €50, the circ pump is probably the only item that may need renewing within 10 years or so?. I certainly wouldnt spend any huge sums on a solar installation but in my case I really only installed it as I have a great interest in all enery devices, I really couldnt care less whether there was/is a payback or not. It was probably the most satisfying €2.5 grand that I have ever spent in my life. I suppose one (including myself) can be a bit too cynical in knowing the cost of everything and the value of very little.

Wearb

John T Carroll wrote: »

Would agree with most of the above even though I have a modest F.Plate solar system myself. I didnt install it until my almost 40 year old cylinder started leaking, the system cost me a net €2700 four years ago and I reckoned at the time that my pay back would be around 19 years. I would think that the F.Plates are good for 25 to 30 years, the system never stagnates (due to the "inefficiency" of the F.Plate) so I reckon the glycol is good for 7 or 10 years, it still is the same colour as the day it was put in, I will change it myself unless I'm wheelchair bound for about €50, the circ pump is probably the only item that may need renewing within 10 years or so?. I certainly wouldnt spend any huge sums on a solar installation but in my case I really only installed it as I have a great interest in all enery devices, I really couldnt care less whether there was/is a payback or not. It was probably the most satisfying €2.5 grand that I have ever spent in my life. I suppose one (including myself) can be a bit too cynical in knowing the cost of everything and the value of very little.

Yes, I agree that the satisfaction of getting hot water for "free" does have its rewards.

You said that you would replace the glycol yourself. Is there a way of doing it without special equipment?

John T Carroll

Wearb wrote: »

Yes, I agree that the satisfaction of getting hot water for "free" does have its rewards.

You said that you would replace the glycol yourself. Is there a way of doing it without special equipment?

The recommended way is to hire the equipment if possible but there are lots of ways of skinning a cat, I helped a friend of mine nearly 10 years ago to change the glycol in a flat plate array, we used one of those ten euro "drill pumps" (the one that is attached to an electic drill), a bit messy in getting the pressures right etc but we got there and his system is running away fine. However, from a health and safety point of view, I would recommend that you get a professional in to change it, it wont break the bank.

MicktheMan

Wearb wrote: »

Yes, I agree that the satisfaction of getting hot water for "free" does have its rewards.

But that's the point, it isn't "free".:)

John T Carroll

MicktheMan wrote: »

For anybody who actually measures / monitors their dhw cost, this is 100% true but you won't hear any solar salesman telling you this. Claims of 5,6,7 year payback on solar thermal is complete bs.

In fact, if you run the numbers, you will find that the cost of heating the water is a lot less than the actual cost of the water in the first place when proper metered billling starts.

Best to concentrate on the efficiency of the current water heating system and reducing actual water use rather than solar thermal.

That's interesting.....cost of heating vs water cost, I actually did a few calcs recently and came up with the cost of heating a litre of water from 10C to 60C using oil at 60 cent/Litre and with 80% boiler efficiency as 0.41 cent/Litre, the combined metered cost of water supplied + water removed is €3.7/M3 or 0.37 cent/Litre so except I,ve put the decimal place in the wrong place then its important to conserve both Water and Energy.

MicktheMan

John T Carroll wrote: »

That's interesting.....cost of heating vs water cost, I actually did a few calcs recently and came up with the cost of heating a litre of water from 10C to 60C using oil at 60 cent/Litre and with 80% boiler efficiency as 0.41 cent/Litre, the combined metered cost of water supplied + water removed is €3.7/M3 or 0.37 cent/Litre so except I,ve put the decimal place in the wrong place then its important to conserve both Water and Energy.

When you consider that you don't use hot water at 60 degC but rather something like 42-45 degC, the heating cost per liter drops accordingly.

John T Carroll

MicktheMan wrote: »

When you consider that you don't use hot water at 60 degC but rather something like 42-45 degC, the heating cost per liter drops accordingly.

Quite true, the heating cost of useful water at say 43C will then fall to 0.27 cent/litre or 73% of the cost of the supplied water.

air

John T Carroll wrote: »

That's interesting.....cost of heating vs water cost, I actually did a few calcs recently and came up with the cost of heating a litre of water from 10C to 60C using oil at 60 cent/Litre and with 80% boiler efficiency as 0.41 cent/Litre, the combined metered cost of water supplied + water removed is €3.7/M3 or 0.37 cent/Litre so except I,ve put the decimal place in the wrong place then its important to conserve both Water and Energy.

I think you did let the decimal point wander.

Kerosene is about 58c / litre at present and contains approx 3500kJ per litre
Heating a litre from 10C to 60C uses (60-10)=50C*4180=209kJ
209kJ/3500kJ=.0059L = 60mL of oil =€0.34c or allowing for 80% effiency as you did €0.42c/litre

At 41 cent a litre a 100 euro bath would costing people €41 in oil costs based on your figures

John T Carroll

air wrote: »

I think you did let the decimal point wander.

Kerosene is about 58c / litre at present and contains approx 3500kJ per litre
Heating a litre from 10C to 60C uses (60-10)=50C*4180=209kJ
209kJ/3500kJ=.0059L = 60mL of oil =€0.34c or allowing for 80% effiency as you did €0.42c/litre

At 41 cent a litre a 100 euro bath would costing people €41 in oil costs based on your figures

I stated the cost as 0.41 c/Ltr? above, dont know whether you are pulling my leg or not but a "100 euro" bath would need to have a capacity of 24,390 Litres, my house is far too small to accomodate this but its OK I know what you mean and I have an excellent sense of humour. John

air

Apologies I misread & we had both come to the same result in fact.

John T Carroll

air wrote: »

Apologies I misread & we had both come to the same result in fact.

No problem, your figures are spot on.

imokyrok

These guys are coming to me tomorrow after meeting them at Bloom. I'm very skeptical. We use little hot water so Im more interested in heating. My dream would be to have constant 18 degree heat throughout the house without spending more than I currently do being very frugal with the gas and bloody cold as a result. Dream on I guess.

garyh3

imokyrok wrote: »

These guys are coming to me tomorrow after meeting them at Bloom. I'm very skeptical. We use little hot water so Im more interested in heating. My dream would be to have constant 18 degree heat throughout the house without spending more than I currently do being very frugal with the gas and bloody cold as a result. Dream on I guess.

LOL My Mother In law also saw them at blooms.

They came round to my house a few years back.

The System uses Solar and is topped up by gas when the solar cannot meet the required temp. I sure it will meet your needs but at what price. I think I was quoted 20,000+ Euros. They were a little pushy well the guy I was speaking to was. It looks a good system but I don't know if you can justly the price... Id be interested to see what they say now.
let us know how you get on.

imokyrok

garyh3 wrote: »

LOL My Mother In law also saw them at blooms.

They came round to my house a few years back.

The System uses Solar and is topped up by gas when the solar cannot meet the required temp. I sure it will meet your needs but at what price. I think I was quoted 20,000+ Euros. They were a little pushy well the guy I was speaking to was. It looks a good system but I don't know if you can justly the price... Id be interested to see what they say now.
let us know how you get on.

Will do. I have them warned not to try any hard sell tactics.

andy99

Have done a lotta research and I think Solar is useful if you use a lot of hot water. I am going to wait until technology is better/cheaper. BTW did a big insulation job on house 2 years ago and put in stove --oil bill on nearly 3000sq ft house which dates from 1983 is nearly halved. At the moment my payback would be about 20 years!!

freddyuk

We want to know
1. How many standard tubes are installed. Are they all in series or parallel and series?
2. What capacity DHW cylinder
3. What is the expected payback time (based on their written estimation of your usage and the average annual generation expected)
4. What happens in summer when the sun is out and the cylinder is up to 60c. ( and if you are away on holiday). Will they include a by pass circuit.
5. Will there be a TMV installed for the DHW supply

If they give you written information you can post it and get a second opinion.

Mannin

V good questions.
They are v careful not to give written undertakings on payback etc.
In the hot weather it is possible to dump to radiators ,however there is no clarity as to provision for same.There is a blow out valve.

Recommend all these matters are dealt with , in writing,prior to start.

imokyrok

I have to admit I'm impressed after the spiel on the central heating and water system. The system is daylight activated rather than direct sun so the walls in the house build up to minimum 16 degrees all year around. the gas or oil then would give the extra boast in the 7 months cold period.

I'm very frugal with my heating because I have a lowish income and a biggish house to heat so I'm basically cold a lot which plays havoc with my chronic pain condition. My ideal would be to have a home at 18 degrees minimum 24/7.

Now the sums as best as I can calculate IF the minimum 50% savings in utility bills (electricity and gas) is factual and I take out a loan over 10 years I would be paying out about 125 euro a month extra above and beyond current expenditure for those ten years. So I have to decide if the better quality of life is worth it for the extra money.

Does anyone know of finance companies that give home improvement loans over a longer period than ten years? I own my home outright so no mortgage - but low income so the extra 125 is significant for me. And of course it could be more as fuel prices are expected to rise and carbon taxes too.

TTTT

20 grand would buy a lot of insulation.

imokyrok

Yes it would. I had a chat with a friend who is a civil engineer who works a lot in the middle east and he says even there the technology and the savings don't mesh for solar energy. He's very dubious and thinks insulation and upgrade of the boiler when it finally dies would be better value for money. He's going to look at the claims they make on their website and come back to me.

freddyuk

You will not get any useful information off their website. That is the whole point of using pressure selling tactics. You need to ask the questions and get the information when they sit down with you. The website just makes spurious claims without any had facts to back them up.
As said £20,000 to gamble on them coming up with a solar thermal system that heats your house all year is madness as it will not happen and be financially viable.
Sadly we do not have anything factual to go on to help you.

MullChildmind

imokyrok wrote: »

These guys are coming to me tomorrow after meeting them at Bloom. I'm very skeptical. We use little hot water so Im more interested in heating. My dream would be to have constant 18 degree heat throughout the house without spending more than I currently do being very frugal with the gas and bloody cold as a result. Dream on I guess.

I met this crowd at a festival 2 years ago. I am (very mean) lol Well not mean but frugal like you.

The initial cost was a lot, and I was concerned if I was making a mistake. Almost immediately my bills dropped, and the hot water was great.

We don't know how much we have saved yet, because we never bother looking into that. But we will be in this house forever .

Its hard to judge my electic bill as it is estimated, but it's about 40 euro cheaper a month from what I see. We ordered 1 tank of oil this year, last year we ordered 3 - 2 fills and a top up.

So I'd hazard a guess that I am saving about 1200 a year? But I am not sure yet. I will find out as we got it installed in August so I can compare the last two years

I am just happy that we have it, and doing our bit