Solar production: inverter failure?

I’ve had Sense solar installed for about 6yrs now and it’s been really helpful in identifying and diagnosing failing devices (sometimes after the fact), and I’m hoping it might be helpful with my current situation.

Twice in the past month, my SolarEdge inverter has tripped its breaker. Both times, there’s been a 1hr-ish surge in wattage read by Sense, at or near the rated production of the inverter (7.6kw - obviously why it’s tripping). Of course the installation company is going through the motions of checking failure codes (none that they’ve found), evaluating the breaker, etc. Meanwhile, I’ve got these signatures that I suspect point to a failing inverter, I’m just not sure how.

Any electrical specialists have any insight into what might be going on?

First time tripping the breaker:

Second time tripping the breaker:

A normal day of production in between trip 1 and trip 2:

Nothing has changed that I’m aware of. I had the roof done and panels removed/reinstalled back in March. Working fine as far as I can tell since then over the summer. Other than that, solar was installed 6yrs ago and has been working without issue.

Any suggestions on setting up a notification for when the breaker trips is a bonus.

Edit: Watching it die in real time. Fun.

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What model number SE do you have ?
How many panels of what wattage do you have hooked up to it ?
What rating is the breaker?
It looks like cloud focusing to me

It’s an SE7600A. 28 panels, I forget the wattage exactly. The breaker is rated at 40A.

I agree it looks like cloud focusing, but why are we suddenly tripping the breaker? Other instances of cloud focusing are relatively short lived, whereas these seem like they build up and persist.

Six years, nothing’s changed, no similar events despite days and days of with cloud focusing in the past. Now suddenly we’re tripping breakers with the only pattern being some surge in power coming from the inverter just before it trips.

SolarEdge and the installer seem to be focused on the breaker (for now); I guess I’m not sure why the breaker could suddenly be giving up the ghost. Lets hope its that simple :beers:

7600/240 = 31.66 amps max.
Take into consideration cloud focusing is x 1.25 = 36.9 amps.
You can run a 40 amp breaker normally at 44 amps for hours.
Since a breaker/fuse is a thermal designed unit, the environment plays a big part in this as well
eg: if the breaker is outside, outside temp is hot AND the breaker panel is in full sun, the breaker already gets so hot that it might pop at 32 amps.

Nothing ? are you sure?
It is getting hotter and hotter where I live.
You have build up of oxidization over the years on contacts that add milli ohms of resistance that will end up in higher temp when amps get forced through.

[quote] no similar events despite days and days of with cloud focusing in the past. Now suddenly we’re tripping breakers with the only pattern being some surge in power coming from the inverter just before it trips.

This has a lot in common with this thread on a different forum.

Also SE, he added panels/optimizers though after 8 years.
My nick there is fromport btw :wink:


This summer in Arizona, especially the past month, has been cooler than normal (105-110, vs 115+ last year). Quite a bit of rain and more frequent clouds over the past couple weeks.

When the roof was done this spring, they ran new wiring from the panels. I’d like to think they didn’t muck that up, but at best it could rule out aging wires.

Panel’s outside, north facing wall, as is the inverter. Tech is coming Monday to have a look.

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So now that I’ve had time to think on it, is the thought that maybe the breaker is getting too hot with the ambient temps and the sudden inrush of (otherwise normal) panel production, which explains why it trips when the power is surging like that? That would explain why it seems to be doing fine on clear days like today.

i.e. simply replacing the breaker and making sure the lines are fresh and free of oxidation at the breaker will do the trick?

Things are not always as easy as it looks.
Can you switch off the solar, maybe at night, remove the breaker
and take pictures/look at the bus bar underneath to see if you see any kind of discoloration (oxidation) where the breakers touch the bus bar
These are photos of a new sub panels I am installing so nothing much to see here:

and here on the contacts of the breaker itself:

If you see any kind of black, that would be bad

Although it’s certainly in my wheelhouse to do, I think I’ll leave this to the tech coming out next week. Easiest to just let them go through their diagnostic process :slight_smile:

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The tech came out and replaced the breaker…and in the process left my Sense disconnected, and disconnected my garage circuit. I had to go back in the panel and get both reconnected. Not sure any of it was worth it in the end. It remains to be seen whether a new breaker will correct whatever the problem is.