Self-construction of a solar panel

[Philippe Schutt]

Following the message from Looping:

Hello
A solar panels manufacturer of sensors found this solution, between tubes and Plans
So the mockers!
It does not look so bad, but I do not read German
http://www.solarfocus.at/html/cpc_technik.html
A+

The link is no longer valid, take http://www.solarfocus.com/de/produkte/s ... -collector
I had fun making a sign in the same spirit, but to fix on the wall because I do not have a roof to the south

solar panel.jpg (166.48 KIO) Accessed 8200 times

Given the shadows of neighboring roofs, it is in the sun from 10h30 to 17h
surface: 0,8m2 and it is not under vacuum ... The reflectors are of course the shape it takes to return the rays on the tube for a sun 35 ° to 65 °.
it is connected to the primary of a plate heat exchanger, with a hot water loop pump currently set to 70L / h
The 150L flask (existing) is heated by thermosiphon from the secondary of the plate heat exchanger.

For now, it's not good:
-I can only recover 0.5kwh a day at best
- without drawing water during 1 sunny week the balloon does not exceed 34 °, the panel stabilizing towards 45 °.

I have already identified several causes:
-the window fogged up which created a deposit on the inside
I should have taken a glass of low reflection?
-I painted the tubes in black, it was better to blacken them by chemical treatment
-installing it vertically is a little exaggerated, with a sun at 60 ° the apparent surface is only 0,4m2
-the surface is too weak
-the pipes are long, in the 16m in all, insulated with 6mm thick foam. Maybe not enough ...

In any case, I discover many reasons that lead the yield of these things !!

[Philippe Schutt]

I was able to recover a classic plan panel out of service from Saunier-Duval. After summary repair, installation in place of my DIY.
So there is no photo, the efficiency is immensely superior. Having struggled to purge (it took + -15mn), I got steam on my fingers and a nice bulb. The self-built panel would never be mounted so hot.
So why?
these are the differences which in my opinion are the cause:
1. the surface: 2,4m2 or 3x more. necessarily, we get 3x more
2. low losses: on my panel, the glass was at T ° of water, in fact the whole panel emitted strongly towards the ambient environment. There, the glass is almost cold while the water comes out at 60 °. This shows that my reflectors were not good enough, although in "mirror" polished stainless steel. And these smart guys have stuck a plastic sheet (mylar?) On the back of the glass, which creates some insulation. Probably also a low reflexivity glass.

In conclusion, for an amateur manufacture the reflector system was a bad idea, it is better to absorb the radiation immediately. On the other hand, fixing the panels on a vertical wall works very well.

[wirbelwind262]

Bonsoir
industrial tubes are covered with a selective coating:
https://hal.archives-ouvertes.fr/jpa-00244742/document
https://www.lepanneausolaire.net/le-rev ... rbeurs.php

[A.D. 44]

Industrial flat panel not too darn:

Selective coating, thermal insulation of the bottom, and prismatic glass.

[A.D. 44]

Re,

That said, I really like your self-construction experience (even if, as you confirm, the result is often disappointing).

It is always instructive and it shows a real desire to embark on thermal solar.

Well done.

[Philippe Schutt]

In fact, by concentrating the rays of a 13cm strip on a 14mm tube, I hoped to have less re-emission than a flat panel, even treated super high-tech. Unfortunately, a large re-emission occurs before the rays hit the tube.
For example, I saw the reflection of the glass on the wall of the neighboring building. already a good bundle of energy that didn't even fit in the panel.
However, from a visual point of view, my panel seemed blacker than that of SD.
It seems to me that by tripling the size and improving everything a little and above all the glass I would reach an acceptable level.

on other points, the industrial panel is questionable, for example aluminum foil welded on copper tubes: with different expansions, all this was well deformed. personally, I would not have dared ...

[A.D. 44]

Difference between classic and extra white glass (low in iron).

Selective coating (low emissivity), sometimes with bluish reflections (not completely black)