Anodized PV frames on copper roof in marine environment [RE-wrenches]

[EH Roy]

Gary,

Marine environments are a challenge and require paying attention to the
galvanic series everywhere two different metals touch.

A good example involves your module-to-module ground wire (if you use one
here). Anywhere copper and aluminum meet is a problem area. If you follow
the common non-marine practice of using a bare copper ground wire, you will
very likely encounter significant corrosion wherever that wire touches an
aluminum module frame or aluminum lug. I have had better results using USE-2
insulated ground wire (yes they make it in AWG #6), and attaching that to
the module frames with bronze lay-in lugs (only stripping the insulation at
the lug location). The lugs were bolted to the module frames with stainless
bolts and there was a stainless flat washer between lug and aluminum frame.
The insulated wire allows tie-wrapping to the aluminum frames or rails for
support between lugs.

I'll be very surprised if aluminum module frames look new after 20 years.
The advice I have been given is that anodizing will delay, not stop,
corrosion of aluminum in marine environments (and not for 20 years); though
once a patina of corrosion is formed on the surface that can help protect
the rest of the aluminum underneath.

Hope this helps.

E. H. Roy
Solar Works, Inc.
64 Main Street
Montpelier, VT 05663
1-800-339-7804 ext. 306
ehroy at solar-works.com

-----Original Message-----
From: Gary Higbee, Solutions from the Land [mailto:ghigbee at efn.org]
Sent: Thursday, February 21, 2002 4:47 PM
To: RE-wrenches at topica.com
Cc: Doug Boleyn
Subject: Anodized PV frames on copper roof in marine environment
[RE-wrenches]

Hi Wrenches,

I'm working on a PV design that may utilize a several kW array mounted on a
copper standing seam roof, and which is on the beach. We've located a clip
arrangement for the roofing, and hope to use arrays of Siemens ST40's,
which, with a custom mount, fit neatly in between the seams (with a small
gap under). The modules are to be mounted with SS bolts onto brass blocks
that attach to the roof seams.

The ST40's have a bronze anodized frame, and I'd appreciate any comments
those of you who have worked in marine environments have regarding the
long-term effects of salt air on PV module frames. This copper roof is there
for a long time, and we want the PV modules to be there (and looking good)
for a long time, too!


Do you think the bronze anodized frames will still look uniformly bronzed
after 20 years?

Are there any coatings you'd suggest? We've considered some sort of marine
paint or sealer on the frames, but then we've got color-shift issues and the
possibility of moisture building up under the coating.

Have any of you worked with copper or standing-seam roof mounts? Any tips?

If you have done module installs on metal roofs do you still ground each
module frame?

Thank you!

Gary

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
           Gary Higbee  (ghigbee at efn.org)
              (541)607-1818 (Eugene)
             (541)902-8544 (Florence)
Solar, wind, and hydro site analysis and system design
    Components dealer and installation assistance
              ~Solutions from the Land~
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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