[RE-wrenches] SMA TL-22 insulation resistance error

[Dave Tedeyan]

Hi All,

I am curious to hear if anyone else has run into this:

This is the system I posted about a little while ago that had the
SolarWorld modules and all the module to module connectors were swollen and
melted. One of the inverters was giving an insulation resistance error, and
so after seeing the module connectors, I was sure that was the issue. We
replaced every single module connector with new MC4's, and then the error
came back!

My next step was to swap in the junction box which strings go to which
inverter to identify whether the issue was on the roof or somewhere between
the roof jbox and the inverter. (the issue was isolated to only 1 of 4
strings previously). Turns out the same inverter is faulting, which leads
me to believe that there may be an issue with the wires in the DC conduit.
Maybe they got damaged by a rough wire pull at the initial installation 7
years ago, and its finally degraded enough to cause a problem. The fault is
intermittent, only showing up once every couple weeks or so, so it is
difficult to catch it while the fault is active.

But my question is, could there also be something wrong with the inverter
itself? After spending a lot of time on this one, ideally, I would know
that replacing the DC wires will fix it. So I am curious if people have
done this, to still find that the issue was something internal to the
inverter.

Thanks!
-Dave

-- 
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Dave Tedeyan, P.E.
Owner | Sungineer Solar
p: he | him | his
a: 1653 Slaterville Rd. | Ithaca, NY 14850
w: www.sungineersolar.com <http://www.sungineersolar.com/>
c: (607) 270-0370
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