[RE-wrenches] copper roof

[Brian Teitelbaum]

Nik,

It's hard to tell from the photos, but are you seeing the same issue under the bottom edges of the other rows of modules going up the roof slope? From the images it looks like this is happening only along the very bottom row.

Is there enough spacing between the rows to allow water to drop through, or does all of the water on the array drop off of the bottom row?

I'm not an expert in galvanic corrosion, but it's my understanding that aluminum corrodes when in contact with copper, not the other way around. The AL is the anode and the CU is the cathode in a galvanic reaction, so the copper shouldn't corrode.

My guess is that it has more to do with the simple erosion caused by the quantity of water that is falling off that bottom row of modules. It may be just wearing off the patina that the copper naturally gets with age. If this is so, I suppose that it could eventually wear through the copper.

But that is just a guess.

Brian Teitelbaum
AEE Solar


From: re-wrenches-bounces at lists.re-wrenches.org [mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Nik Ponzio, Building Energy
Sent: Monday, September 16, 2013 2:10 PM
To: RE-wrenches
Subject: [RE-wrenches] copper roof

Dear Wrenches,

We installed a PV system on a copper roof several years ago. We used brass S5!-U clamps on standing seam and aluminum racking. We are now noticing some discoloration at the drip-line below the modules. See photos here:
https://picasaweb.google.com/109634809794570027207/CopperRoof?authuser=0&authkey=Gv1sRgCMv8n6rCl8e8Sw&feat=directlink

There is also a fair amount of discoloration from bird droppings but that doesn't seem to be the cause of the spots under the modules.

Does any know what's happening here, whether to be concerned about corrosion, and how to prevent this in the future?



--
Nicholas Ponzio
Building Energy
1570 South Brownell Road
Williston, VT 05495
802-859-3384 ext.15 (office)
802-318-4783 (cell)
http://www.BuildingEnergyVT.com

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