Heat pump powered by photovoltaic panels

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Capt_Maloche
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by Capt_Maloche » 09/10/07, 09:53

I no longer know who asked this question:
What happens when the water storage is at 90 ° and there is still radiation?

Well, it's simple, at these temperatures the yield is terribly degraded, and it is the losses from the solar panels that stabilize the installation
This is why we prefer traditional panels to vacuum sensors.
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Christophe
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by Christophe » 09/10/07, 10:18

Ok for the recommendation, so it's almost an obligation?

For "overheating" I do not really agree: even if the performance so degraded that does not prevent the sensor (same plane), therefore the fluid, to continue to receive the radiation and therefore to increase in T °. ..at least at the panel level ... after that is another story. But it is the panel (and its lifespan) that interests me precisely ...

I believe that the plans are "standardized" to withstand a T ° of fluid of 140 ° C.

Is it for this reason that when we talk about solar coverage as a% of needs, we try not to exceed 80%?

When you say you prefer plans to vacuum, does that indicate that there is a not insignificant risk? Hey, speaking of vacuum, did you know that there are some "at the top" where each tube is in fact a heat pipe, so a mini fridge circuit by absorption? I'm not talking about the price ...
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saulnews
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by saulnews » 09/10/07, 19:08

thank you for the advice
the project has lead in the wing ..... and why not two solar collectors
my DHW tank is already pre-equipped
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Christophe
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by Christophe » 09/10/07, 19:11

Solar thermal I guess? Well in this case go for it!

But that has very little to do with the original question : Cheesy:
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saulnews
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by saulnews » 09/10/07, 19:14

absolutely.
only imbeciles do not change their mind especially after good advice
thanks to the site
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emlaurent
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by emlaurent » 09/10/07, 22:46

Capt_Maloche wrote:I no longer know who asked this question:
What happens when the water storage is at 90 ° and there is still radiation?

Well, it's simple, at these temperatures the yield is terribly degraded, and it is the losses from the solar panels that stabilize the installation


It is certain that at some point we will reach a thermal equilibrium where the losses (radiation and convection) will balance the solar gain and the temperatures will stabilize. Only, the panels are designed to have little heat loss and to best convert solar radiation into heat in the fluid:
- the flat panels have rear insulation and the collection surface has been treated to be low-emissive.
- the vacuum panels have insulation due to the vacuum of the tubes

So, when we do not consume enough and / or there is too much radiation (in summer), it is necessary to evacuate the heat from the fluid (when the temperature of the balloon reaches the maximum of the resistance).
Hence the installation of a discharge loop (copper S tube or cast iron radiator in the cellar) to dissipate the excess.
Another solution: cover part of the collectors with a curtain (e.g. wood)

The smartest use this heat to heat their pool or to dry wood !! : Lol:
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emlaurent
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by emlaurent » 09/10/07, 22:55

Christophe wrote:Is it for this reason that when we talk about solar coverage as a% of needs, we try not to exceed 80%?


I don't know if this is the reason, but covering 50 or 60% of these needs with solar is doable at a "reasonable" cost. If we want to go up to 80%, it will cost much more and if we want to go up to 100% (total autonomy), it becomes unrealistic at a correct cost because we must consider extreme cases, like in very winter. cold, no sun for 1 week ...
It then takes a large balloon to store over several days and a lot of sensor area! Finally, the additional cost will only be useful a few days a year!

Going from 80 to 100% costs more in bcp euros than going from 40 to 60
: Shock:

Emmanuel
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Christophe
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by Christophe » 09/10/07, 23:00

We agree on the principle of the need to evacuate "excess" calories (unless the solar system has been dimensioned as accurately as possible ... but a vacation period in summer for example is not never to be excluded ...)

emlaurent wrote:Hence the installation of a discharge loop (copper S tube or cast iron radiator in the cellar) to dissipate the excess.



Ah OK!

Never seen or heard of such a loop ... it does not appear on any of the solar diagrams that I have been able to examine ...
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emlaurent
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by emlaurent » 09/10/07, 23:42

Christophe wrote:We agree on the principle of the need to evacuate "excess" calories (unless the solar system has been dimensioned as accurately as possible ... but a vacation period in summer for example is not never to be excluded ...)


It is an interesting dimensioning problem especially by involving the costs in Euros in addition to energy constraints.

emlaurent wrote:Hence the installation of a discharge loop (copper S tube or cast iron radiator in the cellar) to dissipate the excess.

Never seen or heard of such a loop ... it does not appear on any of the solar diagrams that I have been able to examine ...

It can have other names: overheating radiator, ...
See details here
http://www.sebasol.ch/radiateur.asp

A+
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by Capt_Maloche » 10/10/07, 00:30

Yes, and above all there is a valve responsible for spitting in steam if necessary

The average of 50 to 60% of solar cover is a balance between investment, storage size, average performance and above all climatic conditions (we can do 100% at the equator or in the desert !!)
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OUCH, OUILLE, OUCH, AAHH! ^ _ ^

 


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