My (large) solar thermal project

Solar thermal energy in all its forms: solar heating, hot water, choosing a solar collector, solar concentration, ovens and solar cookers, solar energy storage by heat buffer, solar pool, air conditioning and solar cold ..
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dede2002
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by dede2002 » 16/01/14, 08:30

It is the addition of DHW needs and circuit losses, according to figures from the Simsol report.
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Philippe Schutt
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by Philippe Schutt » 16/01/14, 20:54

yes, I saw that, I thought there was a special meaning ...
So in the cold months you do not use all the solar kwh, or is it the loss due to the inclination of the panels?
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dede2002
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by dede2002 » 17/01/14, 00:45

including...

I don't know why I wouldn't use everything, there are a lot of parameters in the Simsol calculation.

I am thinking of the fact that the exchanger transmits less power when there is less difference in temperature, at the end of balloon charging.

There is approximately a 30% difference between the energy available and that used.
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dede2002
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by dede2002 » 17/01/14, 15:01

Revoila a table with 4 simulations on the same basis.

With 60 ° or 80 °, and 4kW / K or 20 kW / K for the exchangers.
We note that by increasing the temperature we increase the production in the summer, and by increasing the power of the exchanger we increase the production in the winter.

Image

A+

:D
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by Philippe Schutt » 18/01/14, 08:35

And by reducing the delta to 10 ° or less, it also gathers a few kwh in winter?

After, it seems to me that the vacuum tube panels allow to have warmer water in winter, even if it means reducing the flow. Provided they are cleared of snow and defrosted. I believe Christophe had put a file online on this subject.
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PITMIX
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by PITMIX » 18/01/14, 09:22

Hello
By experience in the Paris region, I found that it is possible, when the weather is right, to use the solar water heater from the beginning of March to the end of October without additional energy. My installation could correspond to the table, low power, high temperature.
Outside these periods, the solar angle and the duration of sunshine are too low.
To optimize performance, the circulator (s) must be automatically regulated in flow.
Effectively, to make up for this lack of power in winter, more sensors are needed. Useless in my case, because I do not have the ad hoc installation, but beneficial in yours since you will be able to store the excess heat in the heating tanks to increase the DHW autonomy in bad weather in summer or at night .
Given your project I think the best is to provide as much power as possible, the temperature will follow.
Concerning the vacuum collectors they have the capacity to heat very quickly with the least ray of sun, but they have no inertia in the event of brief cloudy passage. To avoid losses, a very efficient and fast DT ° regulator is required. Personally I installed in addition a light sensor. They are fragile.
The flat sensors last and age better in my opinion, have more inertia and heat less so less stress.
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dede2002
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by dede2002 » 19/01/14, 08:05

Hello to both of you,

The thermostat is set (by default) to 7 ° - 2 °, I tried 4 ° - 2 ° the difference is minimal.

From what a panel seller told me, the tube collectors would not lend themselves to self-draining, inlet and outlet are upstairs.

And going to snow-clear on my roof would be rather suicide bomber given the height and the difficulty to access it.

I actually plan to put as many panels as possible on the roof, above the small chimney that will serve as a duct and which opens directly next to the balloons.

Lower, I should run the sheath along the facade, exposed to frost and significantly longer, or abandon the idea of ​​self-emptying, but there I would have a serious problem of overheating in summer.

In the Simsol report I found the solar irradiation values ​​of the panels, significantly higher than the horizontal solar irradiation value. I'm going to integrate that into the table to compare.

A+ :D
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PITMIX
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by PITMIX » 19/01/14, 12:25

dede2002 wrote:or abandon the idea of ​​self-draining, but there I would have a serious problem of overheating in summer.

A+ :D


Hi dede2002
Yes the seller is right. I also think that the problem with self-emptying, with vacuum tube collectors, is the overheating of the collectors.
Besides, I thought that in the event of a cut in regulation on domestic hot water at 60 ° C you would switch to the central heating tanks without draining the sensors?
Is there no risk of overheating the flat collectors in the event of emptying in the middle of a sunny day?
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dede2002
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by dede2002 » 19/01/14, 16:20

I think it is the liquid which is sensitive to overheating, not the sensor itself even if it is only filled with air ...?
The temperature should stabilize around 200 °.

This is what I read on this forum and elsewhere.

Yes I think to switch to the buffer once the ECS at 60 °, but in summer everything will be hot quickly.
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by PITMIX » 19/01/14, 17:42

200 ° C is still not bad, I'm afraid of premature wear of the seals.
Are there any contraindications according to your seller?
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