Any forum members heat their hot water with a flat plate solar water heater?

I've done all the usual energy saving stuff and the next biggest cost to tackle is water heating in the summer which is presently electric. I saw this http://www.solarfriend.co.uk/ and apart from the size and weight appears to be the best design I've seen although I would do the plumbing and storage slightly differently.

However the pumps and controls look decidedly iffy and if you read his diary require constant attention.

would be delighted to see pics and hear experiences with your installations.

Cheers!

I,m not sure how these things get water hot enough to be any good.

I had a spa pool, 2m x 2m, to heat I purchased a solar panel from the USA, this was 6m x 1m which was basically tow header tanks with I would guess 100 little tubes going between each end.

I made a 1" box frame to hold it included a foil backing and stuck on the south side roof of my house, just used a standard central heating pump to circulate water and plumbed into the pool.

On the hottest days I measured a 2c degree rise in temperature from the intake to outlet, pool water never got above 35c as just open.

So my setup was much bigger then this, unless you can remove all heat loses in the tank and pipework I struggle to see how it would get hot enough for a decent shower.

Regards Mark

I would steer well clear of any home made kits. Stagnation temps in solar panels can reach in excess of 250 degrees. Only correct equipment should be used. You can't solder joints as these cold potentially melt. Normall heating pumps are a big no no as well as they will not take the temps.

Kits are becoming more affordable so take a look at those

Cheers

Col

I have installed some vacuum tubes from Navitron...They feed into a thermal store. Really good bit of kit and gets PROPERLY hot so much so we have to dump some heat on really hot days...

Would not go the DIY route.... buy some vacuum tubes... the rest can be DIY

quote:

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Originally posted by mark chandler
I,m not sure how these things get water hot enough to be any good.

I had a spa pool, 2m x 2m, to heat I purchased a solar panel from the USA, this was 6m x 1m which was basically tow header tanks with I would guess 100 little tubes going between each end.

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Agreed, my system was close to what is being described in the DIY example given in the original where they are just pushing water through plastic tube.

So I would see this in the cold being a good way of also cooling the water, you need vacumn tubes and a much better approach to get real gains.

DIY such as this is okay for pool heating but not suitable for a household system.

Regards Mark

I have 4 panels on the roof of my house (pro install: Sun User). They were installed by the previous owner and were an unknown when we took ownership.

They are superb during the summer and regularly get the water above 70 degrees C.

I'm not sure about the comments above - it's plumbed with plastic pipe and a standard heating pump. The high capacity tank sinks the heat.

I have heard this before but find it hard to believe, the water temp could not go above 100c unless pressurised and then it would need to be a very high pressure to reach temperatures hot enough to melt solder.
Paul

quote:

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Originally posted by Locost_col
I would steer well clear of any home made kits. Stagnation temps in solar panels can reach in excess of 250 degrees. Only correct equipment should be used. You can't solder joints as these cold potentially melt. Normall heating pumps are a big no no as well as they will not take the temps.

Kits are becoming more affordable so take a look at those

Cheers

Col

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Paul,

The systems are pressurised, the stagnation temp is the temp in the solar collector when there there is no demand and the circulator pump is not running. With bright sunshine beaming down they can easily reach these temps. The solution in the pipes is 50% glycol not just water.

Solder melts at 225 so although I've never seen it it is possible..

Col

Pure water would have to be above 25atm of pressure to still be liquid at 225deg C. Scary.

Hi, Yes i've just installed a 3 flat panel in roof system, it's not rocket science but you do need to do the calculations to prevent stagnation.

Soft solder is not allowed,the systems run glycol under pressure and it's possible to get spot temp's mainly on the hot exit from the last panel that could cause joint failure. (this is covered in building regs).

The current recomendation is to use the stainless corrugated pipe. It's easy to work with and you don't need a special tool to flare the ends.

The other thing to think about is your existing hot water system, ideally this works best using a cylinder designed for solar, the solar coil is a lot larger than a standard coil and is at the bottom of the tank, secondary heat is provided by a second coil 1/2 way up the tank for your boiler connection. One other thing to watch out for is the fact that you cant normaly use a combi boiler, as most do not accept pre-heated water.

You also don't need an expensive fill/flush unit, there is a hand held pump for glycol filling that you can use instead.

Have a look at the following site
h2 solar

the owner (anthony) is very helpful and there is a lot of information on the site.

Roger

I built my own as per a web site I found using hot water radiators painted black and fitted in wooden boxes with toughened glass on the front. Extremely easy to make and cost about £160 each panel. Mine sit on the ground in front of the house and heat the hot water tank using the separate coiled copper pipe in the water tank that's usually for boilers. No risk of melting solder joints! if it was that hot melted joints would be the least of your worries

Was about the simplest thing in the world to knock together and is very effective when the sun is out, hot enough to scold, if it's not sunny though you get very little or zero heat.

Mine is not pressurised or needs to be but has a header tank in the loft to cope with expansion of the coolant which is simply car antifreeze

I didn't use a pump as I found the water circulates very well all by itself, probably helped by the panels being on the ground and about 1m lower than the hot water tank, there is only 4m of pipe to the tank


[Edited on 5/11/12 by Mr Whippy]