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

Wed Sep 7 19:16:12 PDT 2016

im not sure why i am even suggesting this, but have you tried twisting the separate string's pairs before running them through the conduit?

todd

On Wednesday, September 7, 2016 6:55pm, "Matt Partymiller" <matt at solar-energy-solutions.com> said:

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