Choose solar collectors: plans or vacuum tubes?

[jean63]

I open the debate after having gone through the APPER site where the solar specialists in self-construction, with group orders at attractive prices.

For now, I can deliver these comparisons between planar and vacuum sensors:

http://www.apper-solaire.org/2techno.htm
et
http://www.alpilles-solaires.fr/CP_CSV_ ... rtout.html

It's not that easy:

Performance / Price Report:
Once the performances have been calculated, you can then define the quality / price ratio.
You divide the power obtained by the price, then you get a power to the Euro invested.
For the same final power, your budget will be decreased.

Example with DT of 20 ° C located in Paris (vacuum tube collectors):
Sensor A: 280W / m² with a total price for 5m² of 700 Euros.
Sensor B: 230W / m² with a total price for 4m² of 600 Euros.
The reports give for sensor A 2,00W / Euro and for sensor B 1,53W / Euro.
The needs calculations show that you need 1000W average annual time, in this case, a sensor field A will cost you 500 Euros and a sensor field B 650 Euros.
Advantage to the one that is the most expensive (on the label, but -25% compared to the ratio surface / performance).

Example with 30 ° C DT located in Lyon (between 2 sensor technologies):
Sensor A (plan): 390W / m² with a total price for 1,8m² of 300 Euros.
Sensor B (tubes): 350W / m² with a total price for 4m² of 750 Euros.
The reports give for sensor A 2,34W / Euro and for sensor B 1,86W / Euro.
The needs calculations show that you need 1000W average annual time, in this case, a sensor field A (plane) will cost you 430 Euros and a sensor field B (tubes) 540 Euros.
Advantage flat sensor (20% difference anyway, it's not nothing ...).

Example with 40 ° C DT located in Marseille (between 2 sensor technologies):
Sensor A (plan): 340W / m² with a total price for 2m² of 350 Euros.
Sensor B (tubes): 380W / m² with a total price for 5m² of 700 Euros.
The reports give for sensor A 1,94W / Euro and for sensor B 2,71W / Euro.
The needs calculations show that you need 5000W average annual time, in this case, a sensor field A (plane) will cost you 2600 Euros and a sensor field B (tubes) 1850 Euros.
Advantage to the vacuum tube sensor.

We are waiting for the arguments .... mine will be coming soon.

[bham]

Ah very well Jean, I give you the latest doc from Frederic Mykieta, Alpilles solar:
http://www.alpilles-solaires.fr/CP_CSV_ ... ves_2.html

I will come back because now I have to go.
The Sunrain is the sous-vide sold by Apper and Paradigma, sold under the mark Trybasolar.

[Christophe]

1) Here is my vision of things:

So what about vacuum sensors? are they more efficient when there is little sun and an inclination / orientation not optimum?

For the orientation and the course of the sun: yes
For the sun: no. Without radiation, no panel "works".

We must reason not in "pure" performance but in performance smoothed over a year.

So in the end it's simple what to calculate is: cost under vacuum / service life - cost plan / service life = annual overcharge of vacuum - annual vacuum gain = interesting or not.
All of course in euros.

Example if the vacuum costs you 3000 € and it is 15 years and the plan costs you 2000 and 20 years, the extra vacuum is 100 € per year if it can recover less than 100 € per year it is not interesting.

Another way of seeing things:

If instead of recovering in the "best case for tubes": 70% (low margin for plans) you recover 90% (high margin for tubes) of the radiation in your region, say 1200 kWh / year, you earn therefore 240 kWH / year and per m² of panel. At 0.1 € / kWh, this makes a gain of 24 € / year for the benefit of vacuum tubes in this case, it is therefore necessary that the annual surcharge per m² tubes does not exceed 24 € so that they are "profitable" compared to plans.

You can have fun with the actual figures of viessman for example (the price of vacuum is scary) ... see https://www.econologie.com/solaire-therm ... -3678.html

2) I do not agree with the reasoning above that think about the installed peak power ... what counts is surplus energy and therefore the comparative financial gain that a vacuum panel provides and this is related to the investment ...

3) My preference is clearly for flat panels for the good reason that considering the depreciation periods and that what lasts is what is simple, the tubes are empty are unlikely to be competitive ... except isolated cases and bad exposure.

My conclusion on the subject

In addition, the best panel in the world will never recover more than the sun can give!

It is therefore better for the same investment:

a) a slightly worse performance
b) and more surface

Also avoid 1er price: it is not a guarantee of solidity and reliability so sustainable investment ... I say not to take the most expensive panels because it is outright billing!

Solar panels at 92% yield that will never be profitable because damn before are used for nothing except disgust people and spend public subsidies ... so also give directly money to your neighbor ...

[jonule]

+ 1

on the other hand can we rely on the performance of an installation during a heat wave for example?

[Christophe]

What a heat wave? You're crazy!

On the other hand the problems of overheating, rarely mentioned (unlike freezing) constitute a more important problem for vacuum, more fragile by "nature", than flat collectors ...

See technical data and comparative prices:
https://www.econologie.com/panneaux-sola ... -3679.html
https://www.econologie.com/viessmann-sol ... -3678.html

[Christophe]

Ah not bad this curve of your tone 1er link Jean:


If not for the instantaneous power readings done by the 2ieme comparatives, if they are interesting I do not think they are significant of actual use ...

Indeed; 300W / m² is a ridiculous power for the tube since on my installation in operation of sensor I measured at the end of April 2007 more than 50kW for 70m² is more than 700W / m² ...

ps: ok I understand better, the readings were done in November and February ...

[jean63]

What a heat wave? You're crazy!

On the other hand the problems of overheating, rarely mentioned (unlike freezing) constitute a more important problem for vacuum, more fragile by "nature", than flat collectors ...

See technical data and comparative prices:
https://www.econologie.com/panneaux-sola ... -3679.html
https://www.econologie.com/viessmann-sol ... -3678.html

Well, if the sous-vide resist well to overheating, they rise much higher in temperature; but hey, no experience in the long term because not enough recoil ...... except in China.

Too bad I had not yet opened this topic because on the apper site there are testimonials auto-installers of vacuum vacuum heat pipe that tested them in heavy heat.

I will try to find the evidence.

As soon as I have a moment I look at your price comparison, but I think that the vacuum Wiesmann must be very expensive compared to the sub-vacuum sold via APPER (China but good quality ... according to the words of buyers ..).

There is also a manufacturer of sub-vacuum in Grenoble (the only one in France and even in Europe), I forgot the name, the commercial came on this forum.

[jean63]

Ah not bad this curve of your tone 1er link Jean:


If not for the instantaneous power readings done by the 2ieme comparatives, if they are interesting I do not think they are significant of actual use ...

Indeed; 300W / m² is a ridiculous power for the tube since on my installation in operation of sensor I measured at the end of April 2007 more than 50kW for 70m² is more than 700W / m² ...

ps: ok I understand better, the readings were done in November and February ...

It's good that the yield is better in the cold season (this is the case of vacuum in the graph) and less good in the summer, but there must be something at the tilt and orientation.

What I would like is a very good performance in winter (at any time of the day even with a not optimal orientation / inclination) to complete the heating and incidentally the ECS, even if to dedicate a sensor to the ECS.

Frankly I would like to test them side by side connected and see on a season.

I'll remind you that RV45 has sub-voids and he is very satisfied, but he might be with plans too. Maybe he will regret in a few years when he will have to replace the tubes?

If I had a crystal ball .....

[Christophe]

Pkoi do you base yourself on a better return at all costs? I am afraid that you are on the wrong track ... take "2nd price" flat collector and you will be much more relaxed than with 1st price sous vide even if the "return" will be less good what matters is the financial return in the end no?

By the fact that the roof space is equal, did you find that the sous vide take up more space to make 1 m² of panels?

ESE for example, they are made in Belgium 30 km from us. They make a sort of "satisfied or refunded" guarantee but I don't know if it concerns individuals ...

[loop]

Bonsoir

Christophe thank you

http://www.ese-solar.com/ese/produits/p ... rbeurs.php

ESE for example, they are manufactured in Belgium at 30 km from us

thanks to you I may have found the ideal product for my self-construction / installation
Indeed, the absorbers proposed by this company are dimensionable in width and length

Solstrip is an absorber fin consisting of a standard thickness 0.2 mm copper sheet (other thicknesses available on request) coated with selective coating.
This sheet is continuously welded using ultrasonic technology on a standard diameter copper tube 8 * 0.5 (other sizes available on request).

I have a roof of barn very well oriented and inclined (45 ° full South), and a consequent surface (about 5 mx 20 m is not far from 100 m2)
This barn is covered with slate color steel tray
It is clear that having conventional planar sensors would be aesthetically questionable
On the other hand, I will see many sensors in the form of vertical bands, from the top to the bottom of the roof, which would be placed between the ribs of the sheets.
It remains to manufacture the casings and glazing, but it is not technically the most complicated
In other words, thanks to my sensors (I already see them on the roof) I will have the perfos of flat collectors with the look of tube sensors

Would anyone have any info on a self-build with these absorbers?

A+