Quote:
Originally Posted by Solar Mike
Hi
I have made many types of solar hot water collectors over the past 5 years or so, generally I have found its easier to use thin copper foil (0.25mm thick) fins soldered to the risers than using aluminum. Even though AL. is cheaper its long term reliability in this application is suspect (20 years +), ie the different rates of expansion between the differing metals will eventually work the fins loose, or cause corrosion failure if they ever come in direct contact. Copper foil is not that expensive, $26 per Kg here in NZ if purchased in a 50 Kg roll, will make many panels, go halves with someone else.
Cheers
Mike (NZ)
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Hi Mike,
The thing that discouraged me from the all copper collector with fins soldered to copper tubes was the time involved in the soldering. I did one small test collector, and it seemed like it was going to be a whole lot of work to do a full collector.
I did try to gather all the info I could on what the likely life of these aluminum fin collectors might be and put it all here:
Galvanic Corrosion with Solar Collectors Using Copper and Aluminu
I was encouraged enough by what I found to go ahead and make all my collectors in this way, and have talked a lot of others into doing the same -- so I certainly hope they hold up
Everything I was able to find from the ones made in the Maine Solar Workshops and the ones made by SunRay seems to point to very few problems.
I did take apart my 2 year old PEX and aluminum fin collector when I went with the new system. 2 years is not a long time, but every thing looked very pristene -- it was quite difficult to break the silicone bond between the PEX and the alumium. I cut right through the fin/PEX assembly in half a dozen places to see if there were any voids, and found none.
Gary