Solar thermal collector autoconstruit: what solution?

[dedeleco]

This profiled sheet metal lost formwork is sturdy, and must be painted with care, if not rust by condensation, and made very tight on the edges, to keep the hot air inside.

The tube in 100m is much cheaper, about 50 m joined, enough to make 1 m2 and therefore a max of this black tube almost joined is cheaper, since the support, the insulation below and the film above, in spite of what is ; iron, wood, black plastic, will be more expensive.
The problem is to fold the 16mm tube at the ends, because then it bends when it closes. So winding it is simpler, unless you put it in line 10m long with the T-fittings or elbows of commercial drip tubes, to make 10m2 of linear sensors.

So the sheet allows for a very rigid support, but aluminum painted black is perhaps more resistant in the long term to humidity and not much more expensive?

The grooves if painted reflective (aluminum paint) allow a certain concentration of light on the pipe inserted in it (factor 2?) And a stronger T if the pipe does not touch the sheet?
But for this concentration, it would rather be vaguely parabolic grooves, in an insulator covered with thin aluminum sheets, which will make a concentration of the sun on the tube, if each groove is closed by the plastic film.

It is important to avoid the condensation of humidity inside, especially at night (the T decreases at night, therefore the pressure inside, which brings in a little humid air which condenses), because it reduces the efficiency , as for double glazing, so putting down a hygroscopic salt like CaCl2, or other absorbent, to change from time to time, with fairly good sealing, can improve.

I would tend to take a rigid insulation a few cm thick inexpensively, as a support, with a black film on it and the pipe attached to it in a few places, under the plastic film above, like:
http://www.apper-solaire.org/Pages/Expe ... index.html
can be rolled up into a square to fill the corners.

Castorama does not sell the right 16mm pipe, which is incompatible with other brands of drip.

[BobFuck]

This sheet looks thick and heavy (it is a concrete formwork), a sheet steel roofing bin is cheaper (but not the desired shape).

> I've been looking for a long time to make solar collectors with a price per m2 on
> lowest possible: can replace all ordinary roofs

Same. And I wonder if the obsession with the tube is a good idea after all. With a sensor which is not under pressure (therefore at atmospheric pressure), the price may fall further.

Finally, a sandwich with:

- insulation
- a waterproof bottom
- a material allowing the water to diffuse well (black felt or very fine mesh)
- a transparent top (mylar etc)
- and a "roof" in transparent panels from above (corrugated or not according to tastes)

should explode the minimum tariff ...

for example, I like the bagged sensors of this link:

http://www.builditsolar.com/Experimental/MTD/MTD.htm

but, it should be possible to make it even simpler ...

[chatelot16]

no the sheet for concrete floor that I mentioned is 0,5mm thick ... it should especially not more if not too much thermal inertia

I also thought of solutions with water between 2 films, but it is not easy ... how to fix to avoid that the wind can carry everything ... when the water circulates only in pipes we can put real screws between the pipes

with water between 2 plastic film you need a very flat support: plywood or osb ... finally the sheet is not much more expensive but at least well waterproof to protect as much from the rain as from a sensor leak thermal

the ply of pipes made for pool heaters are good but still too expensive

the 16mm thin pipe like 1mm is at a low price because it is not made for the handyman but for irrigation, so in very large quantities

[dedeleco]

This sheet looks thick and heavy (it is a concrete formwork), a sheet steel roofing bin is cheaper (but not the desired shape).

> I've been looking for a long time to make solar collectors with a price per m2 on
> lowest possible: can replace all ordinary roofs

Same. And I wonder if the obsession with the tube is a good idea after all. With a sensor which is not under pressure (therefore at atmospheric pressure), the price may fall further.

Finally, a sandwich with:

- insulation
- a waterproof bottom
- a material allowing the water to diffuse well (black felt or very fine mesh)
- a transparent top (mylar etc)
- and a "roof" in transparent panels from above (corrugated or not according to tastes)

should explode the minimum tariff ...

for example, I like the bagged sensors of this link:

http://www.builditsolar.com/Experimental/MTD/MTD.htm

but, it should be possible to make it even simpler ...

Completely agree, very interesting, a mylar bag is easy, because the mylar welds well when hot (and cuts well if a little too heated, and requires a lot of work in hours), a pneumatic mat sun is also a sensor, but the cheapest solution is very different depending on the means available, either personal DIY which requires using what is usual, recovered or sold cheap like this ready-made hose, easy to install quickly or the film mylar plastic, much longer to weld and mount waterproof, or industrial, which allows mass production of sometimes very complex at low prices. like photovoltaic cells or microprocessors.

One problem is not to change the roof of the house often imposed by urban planning rules.

The drip system then of this site, can be used on roof tiles, overheated by the sun, they put under a plastic film mylar or for greenhouse, posed above, not very visible, and thermally insulated from below, water being collected in a small gutter.
This can be a very simple and inexpensive solution, hardly changing the appearance of the roof, under this transparent film ??

He patented quite a few simple solutions of solar drips:
http://www.builditsolar.com/Projects/Sp ... atents.htm

[chatelot16]

for a solar collector to work in winters, it has to be waterproof ... running water on tiles only heats up in summer ... the slightest air stream causes wasteful evaporation all the heat

[dedeleco]

for a solar collector to work in winters, it has to be waterproof ... running water on tiles only heats up in summer ... the slightest air flow causes wasteful evaporation all the heat

Totally agree, and even in summer, evaporation consumes heat.
But we can try to seal the film placed on the tiles.
or better, put the water hose on the tiles at the bottom of the channel tiles channel under the film.

[BobFuck]

Since you are in full swing, we should start a subject "The cheapest possible solar thermal panel to put in quantities". What do you think ?

A google "plastic solar collector" gives a good harvest!

AMHA a good plan for finding a minimum of € per watt is found in pool heaters, adding insulation behind and a transparent front.

Extruded EPDM pipe plate (sold by the kilo!)

http://french.alibaba.com/product-gs/ru ... 19353.html
http://www.alibaba.com/product-gs/43031 ... ating.html
http://french.alibaba.com/product-gs/sw ... 22239.html
http://www.eurospapoolnews.com/nouveaut ... eating.htm

Here, the same, sold by a pool engineer with a substantial margin (50 € / m²)
This is the kind of thing that requires a group purchase from a wholesaler ...

http://www.piscinemateriel.fr/chauffage ... p-174.html
http://www.hydratechnique.com/47-chauff ... -sh09.html 20 € / m²

The copper tube on an aluminum or copper plate is very much more expensive, there is of course the apper-solar "gold mine" site, but even there we reach 150 € / m² ...

I also offer recycling centers as a source of raw materials: air / water exchangers (air conditioning condenser, etc.) or ... fridge condenser (which would go well in the sun behind a window with water passing through the small tube. ..)

[dedeleco]

The crucial tip at 30 € per 100m HT on:
http://www.france-arrosage.fr/iso_album ... 202011.pdf

polyethylene micro irrigation section.

Louis 14 would have liked to have this tip for Versailles instead of the lead ones !!

The rest is easy by recovering pallets, polyurethane insulating panels and films for anti-UV greenhouses.

The price depends on the lifespan of the panel and its aesthetics.

The hose has been resistant to the sun for more than 12 years in the PACA 83 region, as proven in my garden, for 12 years !!


This problem is solved !!

The only one left (almost solved by Uretek) is that of drill as cheaply as possible to thread this pipe underground and then do www.dlsc.ca , for less expensive per house, than a nice Okofen boiler !!

[chatelot16]

to circulate water if there is a positive pressure you need round pipes

to be satisfied with 2 parallel films I thought to put the circuit in depression with a layer of porous material between the 2 to allow the passage, carpet type

but no, it's a problem nest, the slightest leak puts everything down ... it does not pass very easily in the porous thing

the simple 16mm pipes on corrugated sheet are more secure

the epdm ply of pipes are interesting: the epdm is a very durable material resistant very well to UV and heat

remains to find how to order ... I do not understand anything with alibaba

[BobFuck]

The dedicated pipe in d.16 returns to 23 € / m² in jointed installation, which is not expensive, by spacing the pipes a little the price drops ...

> to circulate water if there is positive pressure, round pipes are needed

Yes. In addition, there is a disadvantage hidden in the "drip" sensor: it is necessary to pump more (therefore it consumes more electricity) because it is not under pressure.

> layer of epdm pipes are interesting: epdm is a very durable material
> very good UV and heat resistant

Yes...

Moreover, it should be possible (for a manufacturer) to glue 2 sheets of plastic together, by "printing" between the two a network of "tubes" ... that would make a sensor delivered in really cheap rolls. In short, like an air mattress, but with smaller tubes that communicate ...

> remains to find how to order ... I do not understand anything with alibabaes

It's a wholesaler and importer thing, you have to order a km of product;)