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

[boB Gudgel]

Jeff Yago wrote:
> 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
>


Is there any way someone could get a picture of this installation for 
the "Hall of flame"  gallery ?

I can just see those separate wires going through the roof, but I can't 
print it.

boB





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