SolarEdge HD - replacement inverter having problems

[QuantumSlice]

We are on our second HD Wave inverter, the first one failed after a month. (could not hold the string voltage). The second one I installed in late November, it is holding voltages - but seems unstable. During the day is inexplicably drops power, then brings it back up. We do not have clean power curves during the day any longer.

Using the monitoring tool, i can see optimizer voltage drops during the day, the current chart during the day is very sporadic. I expect to see nice clean, stable trend lines - these are blue sky days i'm talking about.

System: Owner installed. 22 HIT 330W panels in 2 strings(12+10). 7.6Kw HD inverter. P400 optimizers. Located in Buena Vista Colorado.

I'll call the SolarEdge support line tomorrow, in the past they haven't been good teachers - just sent me the new inverter without explanation for example.

[JSchnee21]

Are you the installer or DIY? Who ran the DC wiring? Isolation error, short, fractured wire heating under load? How's your AC voltage? Any error messages -- from either the first or second unit?

[QuantumSlice]

I am a DIY installation here in Buena Vista Colorado. However I paid a local installer $500 for consultation and inspection. We both felt it was a solid job.
I basically have no reason to suspect my work quality. I am a retired technical professional, so felt i learned enough to do this job correctly.

I turned the system "ON" in late September, the first inverter failed in early November - you ask some specific questions regarding current state. Let me answer them.

1) I ran the DC wiring and the AC wiring. Two strings. 12 panels and 10 panels. Both strings had wires snapped together and held above the roof via clips. The strings go into a Soladeck box on the roof, In the Soladeck I terminated the roof string wires, and went into metal conduit down to the inverter. We bought and installed the isolation pieces for the terminal blocks to prevent arcing in the Soladeck across terminal blocks. All runs were very short, with oversized wires. I had DC surge protection on the first inverter, I removed these on my second inverter just in case they somehow contributed to the failure.

2) AC Volts. Attaching plot from yesterday. I am not getting much out of this plot myself.
AC_inverter_volts_20181209.PNG

3) Error messages... None that I can see now. (when the first inverter went down, i got an error message that only Solar Edge understood.. Inverter did not hold voltage down, was zooming over 400 DCV - they sent me a new inverter).

4) What made me suspicious? The inverter power is dropping out when it should not. See attachment for yesterday. The output from inverter, also string 1 and 2 power. It was a blue sky day all day, inverter should not be dropping power. See 11:00, 11:30, 12:30 times... Could this be a communication drop out???
InverterPower_20181209.PNG

5) Digging deeper... string 2.2...
I looked at optimizer behavior yesterday (plot shows moduel and optimizer voltage). I see three optimizers I don't like: 2.2.1, 2.2.4, 2.2.8. Note that none of these spikes lines up with the inverter power trip events.

S1_OptimizerModuleVDC_20181209.PNG


6) Digging deeper... String 2.3... I don't like optimizer 2.3.7 and 2.3.8 VDC responses.:

S2_OptimizerModuelVDC_20181209.PNG


7) Module current plots... what a mess these plots are(Power mimics the current plots below):

S1_OptimizerCurrent_20181209.PNG
S2_OptimizerCurrent_20181209.PNG

[QuantumSlice]

Oops, here is AC voltage from yesterday
: AC_inverter_volts_20181209A.PNG

[ButchDeal]

I am a DIY installation here in Buena Vista Colorado. However I paid a local installer $500 for consultation and inspection. We both felt it was a solid job.
I basically have no reason to suspect my work quality. I am a retired technical professional, so felt i learned enough to do this job correctly.

I turned the system "ON" in late September, the first inverter failed in early November - you ask some specific questions regarding current state. Let me answer them.

1) I ran the DC wiring and the AC wiring. Two strings. 12 panels and 10 panels. Both strings had wires snapped together and held above the roof via clips. The strings go into a Soladeck box on the roof, In the Soladeck I terminated the roof string wires, and went into metal conduit down to the inverter. We bought and installed the isolation pieces for the terminal blocks to prevent arcing in the Soladeck across terminal blocks. All runs were very short, with oversized wires. I had DC surge protection on the first inverter, I removed these on my second inverter just in case they somehow contributed to the failure.

2) AC Volts. Attaching plot from yesterday. I am not getting much out of this plot myself.
AC_inverter_volts_20181209.PNG

How far is your inverter from your meter?
What size wire was used to interconnect it.

That graph seems like your inverter is pushing up the voltage quite a bit and following production curve for the day indicates difficulty pushing the amps back to the grid.
It should be just slightly higher than the grid


Like this one that is working correctly:
Charts.jpg

[QuantumSlice]

So as a reality check, I went back to day #2 of operation in September 29th. This was a perfect day - smooth module current, smooth power and voltages. Went south from that day to now.

[QuantumSlice]

inverter is 12" from the shutoff box, then 6 more inches to the production meter. The production meter is a long distance from the street box, maybe 300'.

[QuantumSlice]

I used 8 gauge to the satellite 100 amp AC breaker box. This was maybe 20 feet from the production meter. The saellite breaker box was pre-existing, this is the long run to the street. I would suspect that run from satellite box to the street has the line drop.

[QuantumSlice]

I see your current is smooth, no drops. My current for yesterday drops current in sharp spikes just as the power dropped in my plot above. Going back to September, my plots look like yours. It seems to my the new inverter is not working correctly. I should go look at the questionable optimizers on other days, see if they had problems elsewhere. But the inverter #2 needs to go back I think.

[QuantumSlice]

Optimizer 2.2.1 is consistently showing voltage control problems. Let's see if I can talk SolarEdge into a replacement optimizer.

[QuantumSlice]

I opened the SolarEdge support case number, loaded the plots, wait and see what happens next. As a DIY person I am frustrated with these equipment problems. I can't imagine using this equipment to make a business model work. Also, the investment is sitting on my roof now for two months and hasn't produced at entitlement. I am rooting for all these companies to succeed, hope this clears up, I would like to be able to say good things about SolarEdge.

[ButchDeal]

I used 8 gauge to the satellite 100 amp AC breaker box. This was maybe 20 feet from the production meter. The saellite breaker box was pre-existing, this is the long run to the street. I would suspect that run from satellite box to the street has the line drop.

satelite breaker box?
You have a 7.6kw inverter interconnected to a 100amp MSP?
Did you derate the main breaker on that MSP?

[QuantumSlice]

Yeah, sorry, poor terminology. I have a 200 amp panel at the house, then a hefty line runs to the 100 amp panel in my garage. The solar is running off a 40 amp breaker in the garage. I did not change any of the service panels or main breakers other than adding my 40 amp breaker to the garage panel. My 8 gauge wire runs the 20 feet over to the garage panel and hooks into the 40 amp breaker. No breakers have ever tripped.

[QuantumSlice]

I wonder if I have a volt meter that will tell me the voltage drop story. A/C voltage at the garage panel, then the house panel. Might tell me something. Am i smart enough to measure 240 voltage at a service panel? No actually. I would hope the garage panel voltage nearly matches the inverter output voltage. There should be nearly zero loss between the two.

[QuantumSlice]

I think the AC voltage is okay, Before sunrise the house dryer outlet and inverter were at 243 VAC, at peak sun condition both outlets were showing 249 VAC. This implies little resistance all the way from inverter to fairly close to the road and power company line. The inverter is rated to a maximum of 264 VAC - thus we should be covered. It might be that our mountain location and small town grid are causing the voltage rise.