Some more on Solar Water Heating

[La Guerriere]

This is a completely different question. If one has a residence secondaire and a solar system, what happens to the excess heat ? I am not arguing about the economics (which probably don't work out) but practicalities of what happens when the sun is out and nobody is at home for a few weeks. Polite answers please and no squabbling ....

[Pierre ZFP]

I assume the whole system gets hot then cools, gets hot then cools etc

Whether this has a detrimental effect due to the 'hot' not being used I have no idea.

[Nick Trollope]

[quote user="La Guerriere"]This is a completely different question. If one has a residence secondaire and a solar system, what happens to the excess heat ? I am not arguing about the economics (which probably don't work out) but practicalities of what happens when the sun is out and nobody is at home for a few weeks. Polite answers please and no squabbling ....[/quote]

One needs somewhere to dump the heat - an accumulator (or a swimming pool) is usually the best bet. Otherwise the pressure circuit risks "blowing its top" (in basic terms).

I wouldn't recommend an undumpable solar system in an MS.

 

[La Guerriere]

I feared that this might be the case. What would you describe as an "accumulator" ? A swimming pool is not required as the cows would probably keep falling in it.

[Nick Trollope]

An accumulator is a large body of water - say 1000L+. Of course, this water can be used for all sorts of things (like washing the cows....)

 

[La Guerriere]

Ah, a drive-through cow wash. I shall have to check the market possibilities here in Normandie .... this could be the business opportunity I have been looking for .... we already have car washes for blue elephants

[Araucaria]

I am interested in this too.

But I thought that a normal solar heating system would have an expansion vessel built into the main heating circuit (the one through the panels/tubes). The accumulator will have one too (that is, the domestic hot water or heating circuit), as it too is pressurised. But presumably everything will get very hot!

I dimly recall an earlier posting from someone having problems with an overspecified solar heating installation (overspecified in the sense of too much panel area). And even if you have a pool to dump heat into - as opposed to cows - it's not really a good idea to overheat it.

[Nick Trollope]

Indeed so - to both points. As I say, these things need to be designed, not cobbled together from BricoDepot.

 

[Théière]

In the case of the brico and others the evacuated tube arrays do not have liquid inside them they connect to a collector at one end and that does have fluid inside as the primary run. the older style ones did have fluid inside and I remember a friend of mine in Spain saying you had to be careful as it boils.

 

[herbert]

WHY CANT I QUOTE??as others do??

I assume the whole system gets hot then cools, gets hot then cools etc Whether this has a detrimental effect due to the 'hot' not being used I have no idea.

That's what it should do. Once the water in the tank is too hot, say 90 degrees Celsius, there is a system that cuts off the pump, running the liquid in the panels. The vacuum tubes I have, survive more then 260°C my plumber told me and will cool down again at night and .. so it should be no problem

but

you should have seen me, when there was my first

electricity cut off and nothing worked and the Perigordan sun did her best. My plumber on the phone told me to keep cool and just have my aperitif. When electricity came back after seven hours by 6pm, the panels had only a temperature of 130°c (because the hotter they get, the more energy they send right back to the surrounding air).

Then the system did not start working ... (another telephone call to my plumber) of course it was not allowed until the liquid from the panels was cooled down enough not to ruin the tank. By 8pm

the system started working as good as ever and it was me, who was then cooled down by a bottle of white Bergerac

[roods]

I live in Cyprus where solar panels are part of the building regs, you cannot build a property without solar panels. Daytime temps here are in excess of 40deg C for most of the summer. There is a pressure relief valve built in to the system which will obviously vent off any excess pressure. Some holiday homes here are empty for months at a time. Nothing happens.

[UlsterRugby1999]

teapot -  I dont know that I fully understand what you are actually trying to say. My fault not yours I guess. I understood that evacuated tubes were superior to the others and that the ones that BricoDepot have on offer right now are, actually, more efficient than the older type and the poly & mono crystal types. No doubt I have misunderstood but thats what I have been reading.

Where I live (between the borders of S/E Vienne - Haute Vienne and Indre, I know of 2 families who have SIMILAR type systems and both have a total of between 2.5 and 3 m square of evacuated tube panels and they have too much hot water for approx 9 - 10 months of the year.

Why then does the BricDepot deal with 2.3 sq m of evacuated tubed panels and all the guarantess and the stated approval for fiscal rebates annoy so many people. Surely thay cannot be so crass as to sell their units if they wont do most, if not all, of the job.