Ground fault [RE-wrenches]

[Allan Sindelar]

----- Original Message -----
From: "Electrical Energy" <solar at eagle-access.net>
> This is a very informative thread.  I noticed on your web site that the
> negative lead measured - 48 volts to ground.  Was that after the wire was
> disconnected, or was there a grounding problem?

If these Carrizo modules are set up as Quad-Lams, 48V dc could be VOC on a
24V nominal array, as these Lams are about 6V VOC each. Is it a 24V system?
What are the specifics of the input current and voltage?

(Three in series won't always charge a 12V battery in hot weather, but four
is higher than needed. A Solar Boost lets you harvest that extra voltage--I
have seen a 50% boost in winter on a QL/SB50 setup; the MPPT trim pot was
maxed out.)

As the PV- and B- are isolated from each other at the SB50, a ground fault
could indeed send full array current from PV- through the controller to the
grounded B-, and overcurrent protection wouldn't catch the fault. Rick
Cullen, could this cause the fire?

Allan at Positive Energy

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