[RE-wrenches] Troubleshooting Stumper - Homerun Interference in Conduit/Inverter Turning Off/On Rapidly

[Matt Partymiller]

Thanks for all the questions and interest in my troubleshooting.

The polarities are definitely correct.  When testing wires at the inverter
with the DC disco off and fuses pulled, we see correct voltage on each
string.

We have tried using two clamp meters to measure current on each string
while operating the inverter with our homeruns in the conduit.  Using the
max function we never saw a meter get above about 1.5A (even less earlier
in the day).  String two seemed to be consistently lower but I really
wasn't sure if that was an inverter function or not as it ramps up towards
max power.  With the homeruns outside of conduit the inverter operates
fine and both strings show similar, but not identical, current.  Doing the
math it appeared each string was producing roughly half of inverter output
at that time.

To Jerry's question, the system did operate fine for about a week and 65
kWh.  The inverter then failed.  Our technician replaced that inverter
with a new Solectria 3.8 kW unit, restarted the unit, and noted the
problem.  With Solectria's help he arrived at the idea that we had a
faulty inverter, got a new one in, and noted the exact same error codes
and began trying to troubleshoot.  He left the third inverter installed
and also installed a new Tigo Cloud Connect and Gateway for the Trinasmart
system.

The modules are 255 Trinasmarts with the integral Tigos.  The folks at
Tigo insist the issue is not theirs and, given that either string works
fine by itself and both strings work fine when not in conduit, I tend to
believe them.  I just don't appreciate how having 20' of undamaged homerun
wire in conduit as opposed to free air can make an inverter stop
operating.

Thanks,

Matt



On Wed, September 7, 2016 8:58 pm, jay wrote:
> hate to ask the obvious here, but you mean to say that volts and polarity
> are correct on both sets of wires at the inverter when not connected?
>
> and
>
> 2. what wattage modules are you using?
>
>
> jay peltz power
>
>
>
>
>
>
>
>
>> On Sep 7, 2016, at 2:45 PM, Matt Partymiller
>> <matt at solar-energy-solutions.com> wrote:
>>
>>
>> Wrenches,
>>
>>
>> One of our systems is having an issue I have not encountered before
>> where the inverter switches between nighttime mode and interconnection
>> every few seconds.  I am hoping for some technical wisdom from the
>> community.
>>
>> We have an array of 20 TrinaSmart modules in two strings of 10.  The
>> array is connected to a Solectria 3.8 kW inverter.  The conduit run is
>> simple, all four homerun wires (#10 PVwire) in 1" EMT down to the
>> proximity of the Solectria inverter where the conduit switches to 1"
>> LFMC before entering
>> the inverter.  The run is about 20', straight down the side of the wall
>> before hitting the inverter.  A 600V jacketed communications wire was
>> also in the conduit but has since been removed and run separately.
>>
>> Our inverter is starting up, running for a few seconds, giving a low
>> voltage error, briefly showing nighttime mode, then going into startup
>> mode again.  Solectria was gracious enough to send us a new inverter
>> but we have the exact same issue.  They tell us their error codes (266,
>> 274)
>> indicate 0 volts.  The transition between low voltage error and startup
>> is almost instant.  Basically we have 20 seconds of start up, 5 seconds
>> of run, 5 seconds of error then repeat.  This is not a grid problem, the
>>  identical system next door works fine.
>>
>> In the process of troubleshooting, our technician pulled all four
>> homerun wires out of our conduit and meggered them.  They all tested
>> fine so he connected to the inverter.  The inverter worked fine.  The
>> technician verified grounding of the array and conduit, pulled new
>> homeruns back through the conduit, and reconnected to the inverter.  He
>> had the same error as before.
>>
>> He connected each string separately to the inverter by removing the
>> string fuses.  Either string will operate fine independently.  With
>> string one in conduit and either homerun of string two in conduit (but
>> not both) the inverter operates fine.  With string two in conduit but
>> string one outside of conduit, the inverter does not operate.
>>
>> I was certain the error had something to do with homerun roof wiring so
>> I
>> went out with the technician and removed and checked pretty much every
>> module.  Everything appears fine, all connections solid, all homeruns
>> have been remade at least once at this point.  Now I am stumped and lack
>> the technical knowledge to diagnose the problem.  I would be extremely
>> grateful if an esteemed wrench can provide technical support/advice.
>>
>> Thanks,
>>
>>
>> Matt
>>
>>
>>
>>
>>
>> Matthew Partymiller
>> Solar Energy Solutions LLC
>> (877) 312-7456
>> matt at solar-energy-solutions.com
>>
>>
>> _______________________________________________
>> List sponsored by Redwood Alliance
>>
>>
>> List Address: RE-wrenches at lists.re-wrenches.org
>>
>>
>> Change listserver email address & settings:
>> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org
>>
>>
>> List-Archive:
>> http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.
>> html
>>
>> List rules & etiquette:
>> www.re-wrenches.org/etiquette.htm
>>
>> Check out or update participant bios:
>> www.members.re-wrenches.org
>>
>
> _______________________________________________
> List sponsored by Redwood Alliance
>
>
> List Address: RE-wrenches at lists.re-wrenches.org
>
>
> Change listserver email address & settings:
> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org
>
>
> List-Archive:
> http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.ht
> ml
>
> List rules & etiquette:
> www.re-wrenches.org/etiquette.htm
>
> Check out or update participant bios:
> www.members.re-wrenches.org
>
>


Matthew Partymiller
Solar Energy Solutions LLC
(877) 312-7456
matt at solar-energy-solutions.com