flat plate evacuated solar panel

Hello,
I am trying to figure how to make an evacuated flat plate solar thermal panel
( sort of this one: www.genersys-solar.com/downloads.asp ).
Main problem so far is how to keep air out (vacuum) .
What sort of o-ring should I use ?
Would it be possible to use Arduino to control internal vacuum and act a vacuum pump to keep it balanced in time ?



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lemonie7 years ago
You pump it out and leave it like that. Adding a pump to the system would detract from energy savings and add to cost.
How far have you got with it?

L
gabdab (author)  lemonie7 years ago
Hi,
yet have to start collecting items.
Adding a cheap converted pump for vacuum wouldn't add much, you can find little air compressors on ebay for like 10 $.
This is an how-to for converting to vacuum:
www.instructables.com/id/convert-a-tire-inflator-type-air-compressor-into-a/
As for microcontroller I plan to use an Arduino board (~30 $) which I would eventually use for solar tracking also.
Couple of thermal sensors and valves and the vacuum job is done ..
Problem is how to achieve a reliable vacuum in a 'metal box - glass panel' thing so not to over-depend on the vac pump ( energy consumption).
lemonie gabdab7 years ago
You don't want to have a controlled-pump on this: evacuate it and leave it sealed. Silicone sealant will probably do you if used correctly.

L
gabdab (author)  lemonie7 years ago
I guess so, as a matter of fact silicone sealant is used on aquariums also.

Aquarium's water pressure = flat panel's vacuum pressure ?
If this is the same it might work..

lemonie gabdab7 years ago
Negative pressure exerts a different type of force, but provided you have the panel sealed correctly I'm sure the sealant would hold a vacuum. Thin layer between glass and box, maybe 0.5 inch width, bead around the outside edge to be sure.

L
gabdab (author)  lemonie7 years ago
I guess 0.5 inch would work for the gasket bed and if I bead around the outside edge I could use one (gasket) on the bottom and one on the side of the glass to be sure that air won't get in ..

I have seen something online about how to make metal boxes , but never tried before.
I wish there was a way to metal forming with a metal press on a shoe string budget so to be able to achieve a no solder box, but I guess I will stick with folding a metal sheet .