[RE-wrenches] Fwd: low voltage modules in high voltage applications

frenergy frenergy at psln.com
Tue Apr 27 09:29:58 PDT 2010


I hate to up you guys on this but you know the emails we get from our friends over there in PV, China??  They had 159,354 solar powered calculators that the "+" button didn't work.  OOOHH, what a deal we got on those little amorphous cells for the system we're installing at the local Building Dept!!

Bill
Feather River Solar Electric


  ----- Original Message ----- 
  From: John McNicholas - Key Power Services 
  To: Re-wrenches 
  Sent: Tuesday, April 27, 2010 8:21 AM
  Subject: [RE-wrenches] Fwd: low voltage modules in high voltage applications


  We have been working on a similar project - we picked up 10,000 solar pathway lights on the cheap and have removed the little modules..... been a bit tedious, but should be well worth the savings....


  John McNicholas
  NABCEP Certified Solar PV Installer ™
  Key Power Services, Inc.



  Begin forwarded message:


  From: Richard.L.Ratico at VALLEY.NET (Richard L Ratico)

  Date: April 27, 2010 9:30:05 AM EDT

  To: re-wrenches at lists.re-wrenches.org

  Subject: Re: [RE-wrenches] low voltage modules in high voltage applications

  Reply-To: RE-wrenches <re-wrenches at lists.re-wrenches.org>



  I second Mike's suggestion for sunglasses on startup. Wait, ........better go
  for welding helmets. Those DC arcs are bright. And I bet they didn't use listed
  electrical tape either! :-)  Thanks for sharing this one.

  Dick Ratico
  Solarwind Electric 

  --- You wrote:
  Typically those types of modules are rated for 30V.  Most 12v amorphous modules
  under 40 watts are rated for that.  I would recommend  sunglasses for startup.





  Mike

  mike at powerupco.com



  From: re-wrenches-bounces at lists.re-wrenches.org
  [mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Jeff Yago
  Sent: Tuesday, April 27, 2010 9:04 AM
  To: RE-wrenches
  Subject: Re: [RE-wrenches] low voltage modules in high voltage applications



  First let me say that we almost never work on failed systems, especially when
  its for somebody that picked our brains on pretense of buying a system, then
  they went out and bought everything on the internet, and when nothing worked
  they call us!

  Also, let me say that the following project has nothing to do with us other than
  a call from an electrician who is installing a grid-tie system for somebody I
  don't know who had a few general install questions and was hoping I would
  provide some guidance.  My advice was to run as fast as he can!   Here is the
  story-

  This commercial building owner went to Harbor Freight and purchased a trailer
  truck load of 12 watt battery charging modules.  You know the ones you see
  advertised to trickle charge a car or boat battery.  I have not actually seen
  the modules this guy purchased, but based on others I have seen they typically
  have a potted junction on the back with 3 feet of very limited insulation wire
  pair out with bare wire ends.  A few more questions and answers indicated these
  were made in China, had no label listing their ratings except indicating 12 watt
  at 14 volts.  The very large physical dimensions he gave for such a small
  wattage tells me they are those thin frame amorphous you see being sold to keep
  your truck or tractor battery charged.

  To make a long story short, this electrician said they had already mounted
  "hundreds" of these modules on the roof of a warehouse, and were wiring them in
  series for connection to a Fronius grid-tie inverter.  Also, he said the wires
  from each module was routed through a separate hole in the roof and then tied
  together.  I assume this was by the ol ball of electrical tape wiring method.

  Not counting the obvious code related problems with what they are doing, and the
  almost sure need to have a fire truck nearby when they start this thing up, does
  anybody know what a typical high voltage rating would be for this type of module
  and the small wire pair?    My guess is the small wire and/or the modules will
  quickly break down and start arcing, then the entire array will melt down which
  is what I told this electrician could happen.  However, since there is no label
  on the module, I am only going on gut feeling as to the voltage rating of these
  cheap modules which I am sure were clearly never designed for series wiring to
  achieve high voltage.

  Anybody know these ratings?  Should I sell tickets for the fireworks show?

  Thanks,

  Jeff Yago



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