[RE-wrenches] Enphase intermittent breaker trippjng

[Jason Szumlanski]

I'm guessing I don't have a bad inverter problem since this is occurring on
two different strings. But I guess I can't rule it out.

I should also have mentioned that the breakers apparently trip in the
middle of the night more often than not. I know that because the envoy goes
offline. So this does not seem to be a power production issue. The
inverters should be sleeping at the time that the breakers trip.

I also ruled out rain. The first couple of times I suspected something got
wet, but subsequent tripping occurred during dry spells.

On Thu, May 21, 2020, 10:12 AM Chad Waits <chadwaits at netzerosolar.net>
wrote:

> Hey Jason,
>
> We have experienced this on multiple systems over the past 2 years. We
> have one system where 1 inverter pops an entire sub offline that has 72
> other inverters in it (screenshots attached). The only way we have been
> able to isolate the problem inverter(s) is to start first with isolating
> circuits, and then unplugging individual inverters until the culprit is
> found. We've had multiple cases escalated to top engineers and we have yet
> to get an explanation of what is going on. Obviously something in the bad
> inverter(s) is creating a catastrophic short but what is causing that has
> not been revealed to us.
>
> [image: Screen Shot 2020-05-21 at 7.10.24 AM.png]
> [image: Screen Shot 2020-05-21 at 7.09.59 AM.png]
>
> I'd appreciate anything you may find out in your investigations.
>
> Thanks!
>
> Chad Waits
> President-Net Zero Solar
> Cell: (520) 270-4873
>
>
>
> On Thu, May 21, 2020 at 6:57 AM Jason Szumlanski <
> jason at floridasolardesigngroup.com> wrote:
>
>> I'm trying to resolve an intermittent frustrating problem with and
>> Enphase IQ system. There are three AC Branch circuits of 9 microinverters
>> each coming into an Enphase AC combiner.
>>
>> What has been happening is one of the BR220 branch circuit breakers and
>> the combine CH240 breaker in the main backfed load center have been
>> tripping simultaneously. It has happened about four times in the last 6
>> months. It was always the same branch circuit breaker, so we kept
>> investigating that string, checking the junction box, trunk cable, and cap,
>> etc. Finally we swapped out the BR220 breaker.
>>
>> Fast forward 4 weeks, and we got another call. This time a different
>> branch circuit breaker and the main breaker tripped simultaneously. We
>> checked that branch circuit and could not find any fault. It seems unlikely
>> that two branch circuit breakers would be faulty, so we have now switched
>> out the CH240 main breaker in hopes that it is the culprit.
>>
>> I'm not totally confident in this resolution and I have my fingers
>> crossed. If that doesn't work, does anyone have any suggestions on another
>> diagnostic step? These intermittent problems are a major hassle. One
>> thought I had was to switch to a supply side interconnection with a fusible
>> disconnect. Maybe the intermittent fault would blow one of the two line
>> fuses so at least I could narrow it down to which line the fault is on if
>> there is in fact a fault.
>>
>> I have experienced two other tripping breaker issues with Enphase systems
>> in the past. Neither of them were systems I installed. One turned out to be
>> branch circuits that were not properly paired up and landed on different
>> breakers. Another time we had an inverter with an internal fault which
>> eventually"blew up" with a loud popping noise and smoke billowing out of
>> it. That happened after resetting a trip breaker multiple times. This case
>> seems to be unrelated to those issues. I'm perplexed.
>>
>> Jason Szumlanski
>> Florida Solar Design Group
>>
>>
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