Microinverter Problem?

[mxyzptlk]

Hello all. New solar system owner here. I have a Sunpower 12.24kw system with X22-360-C-AC panels. I believe I have an issue. I have a few panels that stop working during peak sun periods during the day. It seems that once the panel output reaches a certain level the output drops to 0W. The panel will start producing again if it gets cloudy or when the sun is less strong. On a cloudy day these panels appear fine because the issue only occurs when strong sun (high W) occurs. See attached Max AC output of one of the problem panels during very sunny day. Also attached is the panel next to the problem panel for comparison. Anyone ever see this problem? Most likely a problem with the microinverter? I am still trying to get support to acknowledge there is a problem. My case with Sunpower was recently escalated, so hopefully they will find something soon. Anyone have ideas what the issue might be? panels_BAD.jpg
panels_GOOD.jpg

[bcroe]

That sort of thing is seen if you have rather high line voltage. When micro output increases, it pushes the line
even higher. If high enough, it may trip the micro voltage monitors. Check AC voltage at the micro outputs.
Bruce Roe

[Mike90250]

I wonder if that is a scheme the PoCo is using to apply negative feedback to solar ? (run the line voltage a tad high to kick inverters offline)

[mxyzptlk]

Thanks for some of the suggestions and feedback. Its always the same 4 panels/microinverters that are impacted. I just hope someone knowledgeable at SunPower will be able to identify the issue... and of course correct it.

[J.P.M.]

Thanks for some of the suggestions and feedback. Its always the same 4 panels/microinverters that are impacted. I just hope someone knowledgeable at SunPower will be able to identify the issue... and of course correct it.

Have you also contacted the installer ? They'll be involved anyway.

[mxyzptlk]

Have you also contacted the installer ? They'll be involved anyway.

Yep, I contacted the installer. Didn't get an answer I liked so it was suggested I could contact SunPower directly. The last two issues I went the 'contact SunPower direct' route and it worked out OK. It just takes a long time to get past the Tier I folks before you get to someone who can really dig into the issue. I'm hoping its something that can be fixed remotely (maybe an adjustable trip limit?). Of course the installer will be called in if its something needs to be swapped out.

[sensij]

Miswired is another possibility, or even just bad workmanship. Good luck... I would be asking sunpower to send one of their other partners to check it out, especially if there have already been other problems.

[solar pete]

We have this issue all the time, like everyday, seems high grid voltage is common in the states like it seems to be here. Mike you might be onto something

[bcroe]

I wonder if that is a scheme the PoCo is using to apply negative feedback to solar ?
(run the line voltage a tad high to kick inverters offline)

High line voltage seems to be the norm; its hard to get them to even stay below the upper legal limit. Then any losses
between the inverters and the meter add to the problem. Besides getting the line down, the (rather difficult) fixes are
program the inverter trip voltage higher, or use an auto transformer to knock a few volts off what the inverters see.

My original net meter wasn't installed for 12 weeks after I paid for it, keeping me from running all summer. There is no
reason the meter can't be installed immediately and be functional as soon as the array is complete. That backfired for
them; it was the only year they didn't get a bunch of surplus KWH from me. The other thing was extremely late PoCo
bills, some months not even received; I made a payment anyway to not allow any excuse. Bruce Roe

[mxyzptlk]

So the problem with the high line voltage - it would only affect certain panels? The same 4 panels tap out during very sunny days. I'm playing around with the graphs for this inverter during a problem time. It appears that when it stops producing, the voltage shown below goes over 60V. Not sure this is normal when the inverter shuts down or it shuts down because this value is above 60V. Sorry - I'm new to this and hate knowing there is a potential problem!

mppt_dc_v.jpg

[sensij]

The 60+ V reading is the open circuit voltage for those panels, and the expected value when they aren't producing.

Yes, with microinverters, it is common when there are wiring or line voltage problems for the same panels to be the first to trip out. There are several threads describing that condition on enphase based systems.

[bcroe]

The rise of perhaps 25% of panel voltage is normal when the load is removed. This has nothing to do
with the AC line, measure THAT or read it on an operating micro to verify the problem. Bruce Roe

[mxyzptlk]

The rise of perhaps 25% of panel voltage is normal when the load is removed. This has nothing to do
with the AC line, measure THAT or read it on an operating micro to verify the problem. Bruce Roe

Not sure I can measure what you are asking for from the SunPower site (or at least what I have access to). Only thing related is Avg. AC Voltage.

v.jpg

[sensij]

260 V is pretty high, and the fact that it is labeled "average" suggests there are higher resolution data points that could be exceeding the allowable voltage limit.

Troubleshooting this requires figuring out why the voltage is so high. It could be the grid, but bad connections or undersized wire are common when installers are taking shortcuts.

It is almost definitely not a problem with the microinverters or panels themselves.

[mxyzptlk]

Thanks for the feedback all. Once I hear from SunPower with their take on this issue I will post it here. Just a FYI. the 260V occurs on all the microinverters, but only a few shut off on my 34 panel system.