Has anyone noticed whether the location in the string or the array
voltage makes a difference in the failures? Is this more an issue at
higher array voltages (>600 v) and at points in the array that the
voltage would be highest? We primarily do low voltage (<200 v) off
grid systems, and have not seen any failures. But I'm wondering if we
need to go back and start looking for issues, as I can't promise that
every module connector matched the connectors we used, especially if as
has been reported, some manus used different connectors for neg and pos.
To further the problems, I've personally replaced what looked to be
counterfeit connectors on cheap 12 v modules. The connecting metal was
obviously inferior: very malleable and made such a poor connection that
it created an open circuit. Luckily this was at 20 v, and no melt down
occurred. Also Luckily, I didn't provide the module.
Ray Walters
Remote Solar
303 505-8760
On 9/4/19 4:26 PM, Jerry Shafer wrote:
Just to add, l had a lab and l did testing on connectors, we found
that most of the aec issues were under low light. This appeared to be
when iradiance was low and once the irads went up the issue was less
likely, this was because the Male-female contact was not tight enough
and under lower power it would arc instead of heating up and
expanding. I used a IR Camera but could see little change due to the
plastic.
Then l used an IV curve tester and shaded partially shaded the module
after several repeat testing the connectors got warm. I would suggest
making your own connector pull out tool to check the contact
pressures. This is where you may find your problem components. It
appears that early am testing had lower volts and the inverter pushed
the current up and causes the loose connector to fail due to the lower
volts.
This testing was done both in the field 1/2 meg and lab testing
results were very close.
The modules used for testing were Trina and the field inverters were
ABB and Fronius
Sorry for the long note
Jerry
On Wed, Sep 4, 2019, 2:52 PM Steven Lawrence <lawrenceste...@gmail.com
<mailto:lawrenceste...@gmail.com>> wrote:
Everyone,
Just to add to this, I've seen multiple melted connectors that
couldn't be traced to anything other than mixing manufacturers.
I've seen some connectors where you can clearly seeing arcing on
the pin itself and nowhere else. The crimps and the housing were
fine. I've postulated it had to do with slightly different metals
expanding/contracting at different rates. I've made it a very
hard rule at my company to never mix manufacturers of connectors.
When we order modules, we specifically have the PO call out the
manufacturer of the connector (can't just be "MC4 compatible").
Typically we order that same brand of connectors, but sometimes we
end up getting 6" jumpers made by a harness company (there are
some connectors out there that can only work with #12 wire. Can't
use them on #10 homeruns). It's drastically cut down on the
number of melted connectors. We've averaged maybe 1 or 2 on 6MW
projects over a year with this hard requirement versus 100+ we had
on a 1MW rooftop project that mixed multiple manufacturers.
Steven Lawrence
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