Really they need to be on separate primary circuits.
Hmmm... Have you seen the prices of the Chinese import ETs ?
To be honest, while what you say was true 10 years ago, the difference in cost per area is now pretty small, and the prices we quote to end users are much the same per area for FP and ET, because while ET is slightly more expensive, installation is easier and safer in lifting and handling terms, if not actually quicker.
Nice ! I know somebody who lived in an 8' by 12' shed with poly urethane wall insulation from an old container truck, and aluminium foil wall paper. Excellent !
Think you were robbed !
Hmmm... We generally get pretty near peak output for a few hours a year even without OPT regulators.
About right.
:)
Depends how much you need, but yes, what did you expect ?
Yes - though it doesn't seem to be much of a problem on open frames in the UK.
outer envelope part silvered to concentrate sun onto the inner tube.
Yes, thats what I mean. The FP makes warm water, then this goes to the final high temp circuit with ETs.
I suppose thats true of professional installs on rooftops, I'm thinking more of diy installs, where the cost for a decent area of tubes is way above that of flat panels, and makes a real difference to ROI figures.
Flat panels can give much better performance at ground level or on a flat roof, as 1 or 2 reflectors are easily added to give anything from
1-2 suns. Equipment on a flat roof ditto, mounting the panel either at an angle from roof to wall or else flat on the wall, reflector below.
I guess the ultimate is a 3 zone system, with a drain heat exchanger providing the 1st stage of heat input, flat panels the 2nd (with reflectors for best performance), and vac tubes the last. Perhaps one day the equipment will be cheap enough for this to be the done thing.
I installed a system a few weeks ago. My vacuum tube array collector is vertical on the gable end. I was faced with a cylinder replacement and decided to go solar rather than stay limited to fossil. The whole batch of kit and pipes came to =A31100. I was dubious about the effectiveness of having the panel vertical so I have used 4 "L" brackets to mount it to the wall. If I find it lacks performance when the spring comes round I can simply extend the bottom brackets with mild steel bar. with the present dull weather we do notice an elevation of the temperature of the cylinder bottom by about 15 to 20 degree C on many days (the sensor is about 300mm above the base of the cylinder) It will be interesting to see what happens to our energy bill over the next twelve months. Obviously I would like a decent saving but its an experiment with a potential for economy
I installed a system a few weeks ago. My vacuum tube array collector is vertical on the gable end. I was faced with a cylinder replacement and decided to go solar rather than stay limited to fossil. The whole batch of kit and pipes came to £1100. I was dubious about the effectiveness of having the panel vertical so I have used 4 "L" brackets to mount it to the wall. If I find it lacks performance when the spring comes round I can simply extend the bottom brackets with mild steel bar. with the present dull weather we do notice an elevation of the temperature of the cylinder bottom by about 15 to 20 degree C on many days
Yes, so do we. Today, with the outside temperature at 6C (and overcast sky) we had water at 25C. That's not hot enough for Spouse's washing up or my baths but it's fine for hand washing and it means that the boiler won't need to be on as long to raise the water temperature to his acceptable level.
The array is approximately five feet by five feet but this is interspaced by the gaps between the tubes so meaningless really. The tubes are about five feet long and 2.5 inches diameter
I'm not so much concerned about the angle of incidence of the solar radiation since the net effect of having the tube angled or square on to the sun is minimal, its still illuminated. What I was concerned about was degradation of the convection currents within the reduced pressure fluid inside the fairly narrow copper collector core tubes. As I said I am treating this as an experiment and may alter things around to see how it responds
Because I strongly suspect that there will be cheaper ways to achieve the same thing, because the UK doesn't have that many cold but bright days, because the sun doesn't shine when we need space heating, because passive solar design is more cost effective.
universities, and there is a Nu Aire system on sale in the UK that we have looked at installing for somebody, and the Carbon Trust have waxed a bit lyrical in some of their training about merging all sorts of streams of low grade heat to heat space, but all of these things seem to require a lot of capital cost and super insulated buildings to be viable, and they also require buildings to use, in some cases, whole walls as solar collectors which again rather begs the question, would passive solar be cheaper ? It also raises planning issues, which knowing the UK, may take decades to resolve.
But that's my whole point. At least in the UK, the prices are now pretty similar.
Not sure why the same can't be true of ET systems ?
I guess the bug bear with that is getting end users to keep the reflectors clean, especially if they are flat.
Maybe. My understanding is that the people who have tried these in the UK have not found them cost effective, and I'm not sure what the regulatory position is either.
Guess energy prices may have changed the first of those at least !
Possibly. We've done cylinders / heat stores that go
Oil
Wood
Solar
and have also considered
Oil
Solar
Heat pump
Or more likely, energy prices will be high enough to justify it.
I'm all ears as to what those are. I've not yet found anything cheaper or with better payback than solar flat plate speace heating. (with one possible exception that I dont like)
No need, we have enough insolation to make it work and pay its way. Space heating performs significantly differently to the more well known dhw because the output temp is much lower, and much more efficient mesh absorber panels can be used.
the sun shines every day, and there is a simple way to use it to provide evening heat.
Unfortunately that one is too vague to know what you mean
maybe, but none of that is applicable to the solar space heating I'm referring to.
would what passive solar design be cheaper than what? Cheaper to install, run, or what?
Perhaps in some circumstances, but not across the board.
With vac tubes it makes no difference whether theyr flat to the wall or not, as long as the tubes run horizontally. One simply rotates the tube to face the incoming sun angle, and each tube sees exactly the same regardless of panel mounting position. This holds true so long as the panel mounting angle isnt so far off that tubes start to shade each other.
Well, the first problem would be getting planning consent to build one in the UK, but hands on experience of solar in dull winder weather just suggests that the watts aren't there !
I know of one or two people that get a good solar contribution, but they've used heat stores and huge collectors, had big capital investment, and still have to burn some other fuel.
I suspect that a COP5 or better ground source heat pump in a super insulated building with good PASSIVE solar characteristics would be a better deal, simpler and with less kit !
Do tell ?
I'm not convinced that we do in winter. I'd like to see your calculations on this if you've got any ?
And these are more efficient in exactly what sense ?
Yes - but many of the work best in orbit.
Well go away and look it up then !
No - but they are all worth looking at.
The sorts of buildings that seem to be shown on the web sites you keep pointing at.
Well - none of them should cost much to run if the sun shines should they ?
So are you looking at home made panels ? How many UK householders want to make their own ?
And no - not only Navitron. I was comparing Zen flat plat (or Filsol for that matter, or Imagination) with Focus and Apricus.
As a fraction of an installed system price, the difference is pretty small.
Well some have mirrors behind them, but many don't. As a generalisation that doesn't seem too accurate.
The glass is frequently self cleaning, but above all, is unlikely to tarnish. When inclined, leaves etc are also inclined to fall off ! My point was that you might need to "keep the reflectors clean", especially if they were horizontal.
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