Enphase IQ7+ inverters down for no apparent reason?

[solarintexas]

I have a small array of four Mission Solar 340W panels with IQ7+ micros that I installed five months ago and that has been working flawlessly ever since.
This morning I noticed on my egauge monitor that this array was only producing approx. 290W of power instead of the approx. 1100W it usually puts out. Also, this one microinverter had started up kind of late in the morning with the other three ones not producing at all. Yesterday, everything was normal! We had a storm and wind come through, but the panels worked fine the day after that storm. I have another array that is independent and that is producing power as always.

Here is what I did:
1. I checked the AC connection into my breaker box which is fine and has 251V.
2. I checked the Q cable under the panels with a non-contact voltage tester and also got line voltage to each panel.
3. I checked the Q cable wire connectors which seemed all tight and ok.
4. Put a clamp ampere meter around one of the phases in my breaker box to see if perhaps my energy monitor's CT was faulty. I registered no flow of current on either of the two channels.

Cycling the breaker does nothing. Tried it multiple times. I am puzzled that one of the four micros did produce some power this morning for a few hours. After I cycled the power, that microinverter would not come online anymore.

I have my micros registered with Enphase and might have to call them. I DO NOT have the Envoy system (due to the small system size not worth it for me). I have a distribution box in my attic and will double check if the transition from Q cable to Romex is tight, but I don't see why there should be a problem.

What could be going on with my IQ7+ inverters?

[SunEagle]

Sounds like either a loose connection or water intrusion due to the storm. Just because something works right after a storm does not mean it has not suffered some type of issue due to water intrusion.

[solarintexas]

I checked all remaining connections, and they are all proper. Oddly, a few hours after that, the panels came back online. Perhaps slight moisture intrusion in a wire connection that evaporated? I used all Enphase OEM connectors and followed installation instructions to a T. I have three pieces of Enphase field wiring: one termination cap, and one male and female connector plug. I suppose since they are field-assembled, they might be more at risk of leaking. I might want to keep an eye on them during the next severe weather event. However, they all have gaskets and are all tucked away under the panels, virtually completely protected from bad weather.

I checked all other variables such as frequency (59.98 Hertz) and voltage which were all in range. Let’s hope my panels will resume normal operation tomorrow.

[SunEagle]

I checked all remaining connections, and they are all proper. Oddly, a few hours after that, the panels came back online. Perhaps slight moisture intrusion in a wire connection that evaporated? I used all Enphase OEM connectors and followed installation instructions to a T. I have three pieces of Enphase field wiring: one termination cap, and one male and female connector plug. I suppose since they are field-assembled, they might be more at risk of leaking. I might want to keep an eye on them during the next severe weather event. However, they all have gaskets and are all tucked away under the panels, virtually completely protected from bad weather.

I checked all other variables such as frequency (59.98 Hertz) and voltage which were all in range. Let’s hope my panels will resume normal operation tomorrow.

Sounds like some water got into the connections. I hope all is working well now

[Mike90250]

If you are opening up connectors, proactively give each a dose of dielectric water proof jel. As O rings dry out and leak, that's likely where the trouble is

[bcroe]

Solar connectors are a a marginal so called weather proof design, and extra precautions
as Mike suggests will help. With some 300 connections in service, I have managed to
burn out several. Bruce Roe

[Will792]

Is it possible the panels junction box got water intrusion? You can do some troubleshooting by looking at LED lights in IQs.

[solarintexas]

My inverters are all back in service. The problem remedied itself. Oddly, the first full day of return to service, one of the four inverters came back online almost an hour after the others had started up already.
It might have been moisture intrusion. Before I open connections up, I will wait until the next weather event to see whether this repeats itself. There is also a slight chance of grid noise as this was an extremely windy period. POCO had warned about outages that, however, never occurred.

Mike, thanks for the tip with the gel. I didn’t know about it, but will purchase some to have on hand. Excellent advice.
I doubt that the O rings are dried out as they are brand new. I wonder if the other side, where the wire enters the field-wirable connector, is a more problematic leakage point as opposed to the connector plugs themselves. I will keep you updated if this occurs again. And no, my junction box is in the attic, and there was no water leak.

[Mike90250]

I'm pretty sure it was not "grid noise" and that moisture was getting in somewhere and the drying out. I can see 1 or 2 modules shutting down, but 4 at the same time is odd. Could they have been mounted in reverse and the leads funneling water into them ?

[solarintexas]

They are not mounted in reverse, Mike. And all the cables are neatly tucked away under them. No opportunity for water pooling at all. I installed everything myself. This is on a standing seam roof, although I am sure that doesn't really matter. I am still puzzled that all inverters went out of service. If moisture is responsible for this, then I suspect that the culprit could be the main line extension I did with the Enphase male/female field-wireable connectors. Are those prone to such early failure?
Regardless, if the next wet weather event produces similar results, I will take apart that connection and check for moisture intrusion.

These are the connectors in question:

https://store.enphase.com/storefront/en-us/field-wireable-connector-male

https://store.enphase.com/storefront/en-us/field-wireable-connector-female

[DanS26]

Dielectric grease, or tune-up grease, is a silicone-based grease that repels moisture and protects electrical connections against corrosion. ... The grease does not conduct electricity, so it shouldn't be applied directly to the mating surfaces (pins and sockets) of an electrical connection.

I use silver conductive grease on the mating surfaces themselves.

[solarintexas]

So, had another two major thunderstorm events, and zero problems! Heavier rain than before. The problem has not manifested itself again. I've decided to not take any connections apart at this point as I am now not fully convinced that moisture intrusion was the culprit.

When this originally happened, we had an extreme wind event. However, the heavy winds started after the rain had long subsided. It was no driving rain. Still a mystery what this was all about but glad to see everything is running normal.