[RE-wrenches] finding array ground faults

[Carl Adams]

Marco,

I second Chris' suggestion.  Disconnect all strings at the combiner.  Check
VOC PV+ to ground, and PV- to ground on each string, and PV+ to PV-.  This
should point you to the faulty string.  If the string consists of 10
modules, each with VOC of 30 volts then you should see +300V from PV+ to
PV- (assuming negatively grounded array), and 0 volts PV+ to ground, and 0
volts PV- to ground.  If you find a string where you see +60V from PV+ to
ground, and -240V PV- to ground, your ground fault is on that string and is
likely between the 2nd and 3rd module as you move from PV + of the string
to PV-. (2 * 30V voc = 60V) (8 *30V voc = 240V).

Hope this helps
Carl
SunRock Solar.com



On Wed, Feb 6, 2013 at 12:57 AM, Marco Mangelsdorf <marco at pvthawaii.com>wrote:

>  Hoo boy....I’ve got a tough one here.  Trying to troubleshoot an array
> ground fault with a system that has 14 strings mounted on a metal roof with
> the whole roof and metal framed building being common to ground.****
>
> ** **
>
> Can anyone recommend any diagnostic tools out there to troubleshoot and
> locate ground faults?****
>
> ** **
>
> Thanks,****
>
> marco****
>
> ** **
>
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