Solar Panels

I read somewhere on a site that supplies both tubes and panels that in Germany panels make up 75% (?) of all units installed.They are less "ugly" and although they take up a little more space the difference is marginal.

I personally think a larger (modern) flat panel is much more visually appealing than a big array of tubes.

Pete

I don't know the answer, but I had colleagues who were facing a similar choice and went to the Centre for Alternative Technology for advice:

I would say that with efficiencies down around the zero mark in our benighted climate , it probably makes little difference.

Anyway as long as the birdshit goes black eventually..

Did you read hat article in one of the weeklies where the blokes panels sludged up after a year. He got them serviced. The annual service cost twice as much as the estimated fuel bill saving ;-)

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On the face of it, tubes have significant advantages, but things are never as simple as they first seem. Fact is tubes cost way more than flat plates, hence for the same money you get far more flat plate than tube, and can thus achieve much better payback with flat plate.

So pros and cons on both sides. The article also explains how to improve panel performance. Dont forget that what counts in the end is total power output per cost in, and in no way are tubes 'the winner' in this. No simple answer, sorry!

NT

May I ask why? Given that domestic hot water is a small proportion of a typical house's energy consumption then unless your house is already insulated and draught-proofed to Scandanavian standards and has the most efficient heating controls, condensing boiler and appliances and you're not on mains gas I'd question the economic/ecological case for solar DHW.

Hmm, not my experience. I have 2x20tube panels which cost less than I was quoted for flat panels (£600 for the tubes, £750 for the equivalent panels). A lot depends on where you buy the collectors. I got mine from someone who was honest and imported them from China, I've seent he same untis sold as "German" which seems to mean "Made in China, exported to Germany, sold on again to the UK" the price for those units was £3000 for two arrays of 20 tubes, but on inspection, the units were identical.

For a hot water supply in a barn I used a panel I made myself for £50. It's not as efficient as the tubes and weighs a lot more. OTOH for that price it's possible to make a very big array of flat panels.

It seems pointless using solar just for DHW. However using it to feed a large thermal store seems a very good idea, and IME it is a very good idea. OTOH the farm doesn't have mains gas, and oil for water heating is currently the same price as diesel and propane isn't that much cheaper.

The main headache with solar is educating family and guests to fit their use of hot water into the cycle of when hot water is available, that is shower, bath, wash and do the laundry in the late afternoon. Also finding a washing machine with hot water fill is a PITA.

he equivalent

You can always find someone charging silly prices. Panels are very DIYable.

quite so - and thats where they win. Efficiency may be inconsistent but when they perform, a large area can output a whole lot at very low cost.

NT

he equivalent

You can always find someone charging silly prices. Panels are very DIYable.

quite so - and thats where they win. Efficiency may be inconsistent but when they perform, a large area can output a whole lot at very low cost.

NT

We chose a flat panel and installed it ourselves more than two years ago. Any dirt washes off in the rain. The glass is very tough and unlikely to be broken.

Ours is a direct system, rather than transferring heat from a fluid to water, the water in silicone piping is heated. It's pumped round the system by an integrated pv panel so no mains power is used and when the sun isn't shining - i.e. when water doesn't need to be moved - it doesn't run.

We've been very satisfied with ours, it heats water even in winter. Our gas bills plummeted after we installed it. Even if the water is only 20C (that's unusually low by the way) we know that the boiler doesn't need to heat mains water more than necessary.

Remember, too, that experience does count more than opinion :-) If you want to know more please mail me.

Mary

Let me stick my neck out here Mary and hazard a couple of guesses: (1) that you're the sort of people who put on a jumper rather than the central heating when it gets chilly, and (2) that your boiler and hot water cylinder are pretty ancient and prodigiously chuck heat into the house and out the flue for ages while heating the water in the cylinder. If so then your water heating costs would be a relatively high proportion of your total heating costs. If you'd spent the money you spent on your solartwin on a condensing boiler instead you might have found that your gas bills plummeted even further.

Quite presumptuous, aren't you!

Good tubes always beat panels, on everything except cost. However that's enough to make or break installation actually taking place, so it's a hard choice. All you can really say is that you need to run the numbers for your site, your system and your budget. Anything else, even someone else's first-hand experience, is just hand-waving in comparison. It's a pretty exact science, or ought to be if you do it right.

Well, she did claim to save more than a normal person actually spends on heating water

... but then you're new and wouldn't know these things

Nothing wrong with that.

Not necessarily, her circulation is probably buggered and she doesn't feel the cold, my old mum got to be like that. However my dad kept stumm (for a quiet life) sadly he died 20 years before she did of Cardio Respiratory failure. :-((

H2O >> Duck's Back to a "Classicist" like MF.

Don't you try confusing her with facts.

Derek

I have a photograph of Mary and Spouse. Chavs, they ain't :-)

I wouldn't stand within reach of her and say that ;-)

It would have been a bit of a shock if he'd been clean-shavem, wouldn't it? ;-) In fact it was mildly disppointing that he isn't more facially hirsute.