Aurora inverter: "waiting for sun" msg

[carlos16196]

Hi all,

This is the first on-grid system I design and install. I live in Amman-Jordan but here we follow same UK standards so basically we have the same G83 applied (with of course different orientation and inclination for panels).

The configuration I designed is one string of 8 x 250W panels (Philadelphia Solar PS-M60H), and a Power One inverter: Aurora UNO-2.0-I-OUTD-S.

The system has been working like a charm for 14 days, using around 70% of production and exporting the rest to the grid during the day, and then consuming from the grid at night.

Today I went to check on the production of this amazing inverter, and to my surprise the inverter wasn’t displaying anything (blank screen, just like it does when I check it at night). So I pressed the “enter” button, screen started, inverter did the grid check, and then a message displayed “Waiting for Sun”. (just to eliminate a lot, panels are clean with not even a spot of shadow on them)

So as anyone else would do, I turned off inverter’s DC switch, and external grid’s AC switch. I got my multimeter and tested the string’s Voc, which was around 270V (maybe less or more but certainly in that range). So I reconnected them back and still same result “Waiting for Sun”.

Later on, I checked each panel individually for Voc, and they all gave me the expected average value of 35V. I didn’t do Current Isc check as I’m afraid of short circuiting the panels and don’t want to damage cables with arc. Also, I checked the Vstart value, which has always been 200V. I don’t want to change that value as it has been working before and Im pretty sure I am getting more than 200V.

The tricky thing that is getting me more confused, is that on the display of the inverter, it shows instant values of current and voltage for both PV (on the left) and grid (on the right), what is strange is that for the PV side it shows current but no voltage, but as I said earlier, when I disconnect string’s cables and use my multimeter I got around 270V.

Also, if there was something wrong or damaged in the inverter, shouldn’t it display an error message?

Can anyone around here please help me troubleshoot this issue?

Any kind of help will be much appreciated.

 

[SolarCity]

Are you leaving the inverter for a while to see if it sorts itself out? Sounds like a stupid suggestion, but if you're not leaving it long enough to go through its initial start up then that may be why you're getting the problem.

 

[carlos16196]

hi solarcity, thx for your suggestion.. well yes today i had several 1 hour intervals where i wouldnt know what else to do, so i suppose those intervals would be enough. and also, i didnt mention that before but its been 4 days since i last checked, and from my total production calculations it seems this has been going on for 2 days now.

what else can i do to determine if problem is from the inverter or from the panels, or even from the cabling?

 

[Gavin A]

test varistors, check fuse (if there is one), check you're getting voltage on the inverter side of the incoming MC4 connectors, then either ring power-one to arrange a replacement varistor, or replacement invertor depending what you find.

 

[carlos16196]

hello Gavin A, and thx for reply. i will test varistors first thing in the morning, but that raises 2 questions:
1) wouldnt a damaged varistor result in a warning msg or error code on the display?
2) and according to my knowledge i will need to desolder those varistors to test resistance, wouldnt that cause a warranty issue?

also, there is no fuse as u expected, and i will try to find the first contact point inside the inverter to test voltage coming from string's mc4.

im just asking a lot of questions to understand what im doing and stay on the safe side. thank you

 

[Gavin A]

tbh it's probably a back to the factory job, but just best to cover the bases first though.

2 erm dunno, not actually had to do this with an aurora, wasn't an issue with SMA IIRC.

 

[carlos16196]

ok, so i checked MOVs today, for this specific inverter there are two varistors for input and two for output. one of the two input varistors had very low resistance (around 2 ohms), and the other had a high one (around 8K ohms).


I also tested output varistors with same result one has low resistance and other is ok.


I am surprised no error was displayed on the screen regarding a bad varistor.. anyway, i will be taking this inverter to official distributor of power-one inverters in my country, and ofcourse get back to you guys on wether they confirm this is the issue or not.


and btw, for future readers and regarding the desoldering i asked about in previous posts, varistors in this inverter arent soldered, they are mounted using a three holes clip, just press on three little buttons at the same time and pull out the varistor.

 

[Gavin A]

and btw, for future readers and regarding the desoldering i asked about in previous posts, varistors in this inverter arent soldered, they are mounted using a three holes clip, just press on three little buttons at the same time and pull out the varistor.

ah, thought that was the case, but wasn't confident enough to dispute what you were saying as I assumed you were looking at soldered varistors at the time.