Wrenches,
U.S. electricians have different rooftop wiring and conduit options that worked
successfully before PV and work well with PV. The same holds true for Europe.
I've seen bad and sloppy work on both sides of the pond. John Berdner and
others familiar with European wiring practices and double-insulated wire will
attest that are safe and have performed well for decades before PV. Let's face
it. Knowledgeable and discerning European customers would never spend billions
of Euros on gigawatts on poorly wired solar arrays. Sure, it drives good
electricians crazy to see European array wiring laying loose on roofs just as
it bothers us to see poor quality wiring anywhere. Email me off-list for German
wiring examples in a presentation about double-insulated wire.
Joel Davidson
----- Original Message -----
From: William Miller
To: RE-wrenches
Sent: Friday, October 09, 2009 5:31 PM
Subject: Re: [RE-wrenches] Rooftop wiring methods between multiple subarrays
Colleagues:
I think the correct answer is: there are no short cuts to good workmanship.
It requires intelligent design, a judicious selection of materials and careful
installation. EMT is appropriate in low corrosion environments, PVC if you can
control UV damage and accommodate expansion. There are aluminum and stainless
conduits for the extreme environments and demanding aesthetics. I am sorry
that there are no easy ways to pursue quality.
It is my understanding that the European model is to "plug and pray" with
quick connect cables, running them across roof tops and stapling them to
exterior walls. I don't know this for a fact, but if it is true, I hope that
market does not drive the US market towards reduced standards. I belive it is
short sighted to skimp on wiring methods with dangerous power feeds. I think
the loss of conduit boxes on modules is a direct result of European
installation techniques and a trend towards reducing labor costs. I welcome
information from those of you with experience in other markets to verify these
hunches.
William Miller
At 04:21 PM 10/9/2009, you wrote:
EMT needs to be "pickled" with vinegar or acid, to get the paint to hold.
I love it for inland work, but near the ocean, it'll rust through in 5 years.
I'm not sure how much more time paint would buy you.
Anybody use other plastic materials HDPE? Supposed to not have the
expansion problems of PVC.
R. Walters
[email protected]
Solar Engineer
If you have to run around the roof with EMT, you can protect it from rust
with a coat of paint.
Regards,
-Hans
Please note new e-mail address and domain:
William Miller
Miller Solar
Voice :805-438-5600 Fax: 805-438-4607
email: [email protected]
http://millersolar.com
License No. C-10-773985
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