[RE-wrenches] Rooftop wiring methods between multiple subarrays

[Joel Davidson]

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
    ray at solarray.com
    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: william at millersolar.com
  http://millersolar.com
  License No. C-10-773985




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