New Kingspan solar panels on Nationwide

Anthonyk2010

I was wondering if anyone saw kingspan solar panel on nationwide last night. It was called Thermomax and instead of a long manifold at the top of the panel, each solar tube had it own small manifold at the top of the tube, each small manifold clicked in to each other so you could add and take each tube as you wanted, going to be a headache moving pipes. Interesting idea, not sure if it would make a difference. Anyone see it?
RTE realplayer might have it.
Also I noticed that the Kingspan tube was a single layer of glass with a copper fin welded to a copper rod in a vacuum.
Which is generates more heat single or double layers tubes or does it make a difference?

muffler

Please type your comments rather than copy and paste or alternatively copy and paste to the default Boards.ie format.

quentingargan

Yeah, I saw that alright. Since the manifold of a vacuum tube system lasts indefinitely, I see no reason to have a twist-and-click system for each tube. Now your 30 tube panel has 29 extra connections to potentially give trouble over the next 40 years.

The plus side is that you can size the system more precisely - most tubes come in units of 10 tubes, so if you wanted 25 for some reason, you'd have to opt for 20 or 30.

Single glass tubes have a small flatplate inside them, whereas flasks effectively have a circular one. The flatplate is optimised at noon, so the noonday efficiency is higher (and this is often played on in the sales pitch) but the curved glass tends to end up with the same efficiency overall. So much of a muchness there.

The other difference is that at the end of the life of the tube (typically 15 to 20 years), there is a more expensive replacement. Flasks can be replaced for about €5 each, whereas when the vacuum goes in a single-layer system, you have to replace the whole gubbins.

Anthonyk2010

Is there a solar panel that you pour a liquid in to each tube? someone at work was telling me that they knew someone who had to fill each tube with a liquid.

They spilled some on there lawn and burned the grass, any truth in this?

quentingargan

Anthonyk2010 wrote: »

Is there a solar panel that you pour a liquid in to each tube? someone at work was telling me that they knew someone who had to fill each tube with a liquid.

They spilled some on there lawn and burned the grass, any truth in this?

I've heard of people filling vacuum flasks with oil to increase conductivity between the heat pipe and the collector glass, but I wouldn't recommend this. If the panel goes into stagnation, this oil can go to 220 degrees centigrade.

muffler

quentingargan wrote: »

this oil can go to 220 degrees centigrade.

:eek:

Not good for the environment

reverenddave

i dont know if i'd trust this type (if its the one i'm thinking of)
as eventually the glycol in the tube can become stagnant very quickly
i think the life span of even the best glycol is 3-5 years after that it just turns into a brown sticky mush
and instead of just topping up your system with new glycol
you need to buy new tubes

i think i'll pass on these ones
yet another inferior kingspan product

quentingargan

reverenddave wrote: »

i dont know if i'd trust this type (if its the one i'm thinking of)
as eventually the glycol in the tube can become stagnant very quickly
i think the life span of even the best glycol is 3-5 years after that it just turns into a brown sticky mush
and instead of just topping up your system with new glycol
you need to buy new tubes

i think i'll pass on these ones
yet another inferior kingspan product

Ah, a bit of confusion here. The system that was filling the tubes with a fluid was a flask system, and they were filling it with oil. Hence Muffler's incendiary interjection.

Glycol is only used as antifreeze in the plumbing circuit which brings heat from the manifold down to the cylinder. Yes - it has a limited life, and what isn't understood by many in the industry is that it doesn't survive very high temperatures, so it does get damaged, particularly in systems that overheat. But thats for another day.

reverenddave

is this the ''flask'' system in the new kingspan ones ?????????



as this has always been my understanding of evacuated tubes

quentingargan

Nope. They use a single layer of glass with a flatplate inside it.

The flask system is also known as the Sydney Tube and is by far the most popular vacuum system worldwide.

The issue here is that one company tried to improve on it by suggesting filling the flask with oil. That's the bit to avoid. Flasks themselves are great, cheap and easy to replace (about €5 each if you break 'em) and very efficient.

Just don't fill them with oil. Q

reverenddave

quentingargan wrote: »

Nope. They use a single layer of glass with a flatplate inside it.

The flask system is also known as the Sydney Tube and is by far the most popular vacuum system worldwide.

The issue here is that one company tried to improve on it by suggesting filling the flask with oil. That's the bit to avoid. Flasks themselves are great, cheap and easy to replace (about €5 each if you break 'em) and very efficient.

Just don't fill them with oil. Q

i'll be keeping my oil else where


oh By the way i'm looking at a slide show of your house tomorrow (i think he said your house anyway)
doing a green building course in the city Mike Holden is the lecturer

Merch

reverenddave wrote: »

is this the ''flask'' system in the new kingspan ones ?????????



as this has always been my understanding of evacuated tubes

Which of these types are available in Ireland, I thought only the type in the lower image, where the fluid in the manifold actually passes through the tube,
If a tube is to be replaced in the type in the lower image doesn't the system have to be drained as the two tubes going into the evacuated tube are NOT connected, so if a tube has to be replaced or is damaged then the system will leak fluid?? is that correct?

The first image shows a type that has the heating component separate from the fluid in the manifold, it looks to me as if this would be easier to maintain (when maintenance/or a repair is needed)

Where are the type in the first image available? are they similarly priced to existing types?

quentingargan

Merch wrote: »

Which of these types are available in Ireland, I thought only the type in the lower image, where the fluid in the manifold actually passes through the tube,
If a tube is to be replaced in the type in the lower image doesn't the system have to be drained as the two tubes going into the evacuated tube are NOT connected, so if a tube has to be replaced or is damaged then the system will leak fluid?? is that correct?

The first image shows a type that has the heating component separate from the fluid in the manifold, it looks to me as if this would be easier to maintain (when maintenance/or a repair is needed)

Where are the type in the first image available? are they similarly priced to existing types?

You have shown two types here - a U tube, where the fluid flows through the flask, and a Heat Pipe, where a self contained pipe transfers heat to the manifold through evaporation. Both are available from various companies in Ireland, but the heat pipe is more common.

There is one company making outlandish claims for the efficiency of their U tube system which they claim is designed in Ireland. We found that their TUV cert was a forgery:eek:. In practice, there is little to choose between both systems.

The issue with U tubes (or other direct flow systems) is that in the event of a power cut, the way they go into stagnation can be problematic unless the system is carefully designed. For that reason, many companies are reluctant to sell them over the counter, but most suppliers can get them. Just be sure to go through the layout of the plumbing very carefully if you are thinking of using them. You also need to use slightly different settings on the controller.

Price wise, the U tube can be slightly more expensive because of the higher price of copper.

Q

Anthonyk2010

quentingargan wrote: »

There is one company making outlandish claims for the efficiency of their U tube system which they claim is designed in Ireland. We found that their TUV cert was a forgery:eek:. In practice, there is little to choose between both systems.
Q

I heard a company make a claim like that on pat kenny radio show last year, are they one in the same company?

reverenddave

quentingargan wrote: »

There is one company making outlandish claims for the efficiency of their U tube system which they claim is designed in Ireland. We found that their TUV cert was a forgery:eek:. In practice, there is little to choose between both systems.

Q

from your experience quentin what is the highest output panel on the market that you know of ?????

i know a guy in wexford that imports tubes from italy an they have been certified independently in germany (wolfsburg) and Ireland i think SEAI in dublin
and both came back @ 733Kwh/msq of aperture area per annum

quentingargan

Anthony - may well have been the same company - they had quite a media razzmataz, but not worth naming and getting banned over.

Reverandave - The most efficient ones I have seen are ones with reflectors behind the tubes. These perform brilliantly in tests when they are new because light falling between the tubes gets reflected back into the tubes again. HOWEVER, after a few years, the back of the tubes on any systems I have seen are filthy and the performance would rapidly degrade.

SEAI doesn't do any testing as such - they just read the cert from the testing organisation and if that's OK they list the product on their website.

Most other panels are within a whisker of each other. Some will have a better zero loss efficiency, but a poorer heat loss coeficient and vice versa.

Where I think most systems lose efficiency is in poor installation. Controller not properly set up, insulation not doubled up at the cylinder, slight gravity circulation from the cyliner either to the header tank or the heating system - all that sort of stuff.

Anthonyk2010

quentingargan wrote: »

Anthony - may well have been the same company - they had quite a media razzmataz, but not worth naming and getting banned over.

Reverandave - The most efficient ones I have seen are ones with reflectors behind the tubes. These perform brilliantly in tests when they are new because light falling between the tubes gets reflected back into the tubes again. HOWEVER, after a few years, the back of the tubes on any systems I have seen are filthy and the performance would rapidly degrade.

SEAI doesn't do any testing as such - they just read the cert from the testing organisation and if that's OK they list the product on their website.

Most other panels are within a whisker of each other. Some will have a better zero loss efficiency, but a poorer heat loss coeficient and vice versa.

Where I think most systems lose efficiency is in poor installation. Controller not properly set up, insulation not doubled up at the cylinder, slight gravity circulation from the cyliner either to the header tank or the heating system - all that sort of stuff.

i understand what your saying Quentin.

on the reflectors, can you install them to a panel that never had them?

quentingargan

Anthonyk2010 wrote: »

i understand what your saying Quentin.

on the reflectors, can you install them to a panel that never had them?

Well, you could, but they are parabolic in shape and usually designed to match the spacing of the tubes.

However, they also dramatically increase the wind loading of the system. The mountings used with most tubes assume minimal wind loading because the wind passes easily between the tubes. Imagine two sheets of plywood and you get the idea.

If you have an accessible roof (I have a grass roof and could clean these regularly), then it might be a worthwhile improvement.

reverenddave

quentingargan wrote: »

If you have an accessible roof (I have a grass roof and could clean these regularly), then it might be a worthwhile improvement.

wouldn't a bit of rain do most of the cleaning work for you ??????

quentingargan

reverenddave wrote: »

wouldn't a bit of rain do most of the cleaning work for you ??????

No - thats the problem with reflectors as I see it. The rain washes the front of the tubes just fine, but the dirty water runs to the back of the tubes and you get this green - brown gunge on the back of them after a few years.

Anthonyk2010

Is there a suppiler in Ireland that would have reflectors seperate from the panel. I'd like to look in to them more.

championc

With the system I have on my roof, there isn't very much space between each tube. Therefore, the only time when you would get sun around the sides of each tube is when the sun would be directly overhead and in line with the tubes. My tubes have a fin arrangement inside so maybe the flask type don't have this allowing for the sun to get around to the rear.

quentingargan

The system you have ChampionC, consists of a small flatplate attached to a heat pipe and sealed within a vacuum tube. This system would never respond to reflectors because the absorber is the black coating on the flatplate.

It behaves quite differently to the Chinese flask, working best at noon, with efficiency falling off either side of noon. Flasks have a round reflector inside and show a lower noon efficiency but their output increases either side of noon by up to 40%. Reflectors work with flasks (initially at least, while they are all nice and clean).

The advantage with flasks is that the vacuum is held within a single glass flask with no seals or welds to fail. When the vacuum is eventually lost, replacements are a lot cheaper than the system with a flatplate inside it...

championc

Hi Questin,

By any chance do you have a sample data output from a Chinese Flask system from a sunny day which would then show the heat gain / rise. Below is a graph from my system and it would seem that the system is behaving at an equal rate right across the day. As you can see, the data is from 15 June 2010 which would seem like it was a day of clear blue skies, I'm sure other potential buyers would welcome to ability to compare technologies.

quentingargan

championc wrote: »

Hi Questin,

By any chance do you have a sample data output from a Chinese Flask system from a sunny day which would then show the heat gain / rise. Below is a graph from my system and it would seem that the system is behaving at an equal rate right across the day.

I don't have any datalogger readings for our systems. Have been meaning to rig one up becuause there's a nice iPhone App that goes with it and can give you two days data on your phone. Yuppy I know..

But I am slightly mystified by the straight line - when you think about it, this probably shouldn't happen because morning and evening the sun is at a more oblique angle to the collector. I suspect that the increasing input towards noon is being offset by the roof angle being less than optimum for June. So if your roof was at, say, 45 degrees, then in the morning and evening, the sun is at the optimum height, but not the optimum horizontal angle. That would straighten out the line in the manner shown.

championc

quentingargan wrote: »

But I am slightly mystified by the straight line - when you think about it, this probably shouldn't happen because morning and evening the sun is at a more oblique angle to the collector. I suspect that the increasing input towards noon is being offset by the roof angle being less than optimum for June. So if your roof was at, say, 45 degrees, then in the morning and evening, the sun is at the optimum height, but not the optimum horizontal angle. That would straighten out the line in the manner shown.

I completely agree but you can generally never really argue with raw data. It looks like my type (taking care not to mention specific brands since the mods don't seem to like that sort of thing) is very well designed to be able to take the sunshine from side angles. Certainly the data would seem to imply this anyway. Here's the same data showing just the top of store temperature. You can see that the lines are slightly flatter at the beginning and end - but not by much so it seems very impressive.




C

quentingargan

The real raw data is the EN12975 testing which happens in independent laboratories. This shows that for the type of panel you have, the optimium efficiency is at noon, and the fall off either side of that is shown by what is called Incidence Angle Modifier on either side of this, with IAM figures for every 10 degrees.

The IAM chart for a typical flask system will show an increase. In the case of some systems, the multiplier is 1.4 or more at an angle of 60 degrees. That is real test data from a well callibrated lab.

The overall efficiency is about the same. Your system will show optimum efficiency of about 78% or so, and the flask will show it in the mid-60s. When you multiply both by their IAM, you get in or around the same result. I'm not suggesting that one system is more efficient than the other, though I do get narked when I hear sales people claiming a comparison of 78% -vs- 66% efficiency without explaining IAM on the doorstep:rolleyes:

In relation to the original question though, I think the point is that reflectors only work with flasks - and only when they're clean. There is no need and no benefit to using reflectors with the system you have.

championc

It's amazing but when I zoomed in closer on the data, you could actually tell (just about) that the most efficient time was at about 12:15 - 2 deg rise over 10 mins whereas more like 2 deg over 15 mins either side of 12:15. I have to say though I'm very impressed with the performance once the flatplates are hit by the sun.

Data Logging is great to be able to spot any system problems.