Sunny Boy TL Series Arc Fault

dgrilley

My solar was installed 4 years ago and has worked perfectly up until this past Sunday when I got the dreaded Arc Fault Check DC Power Generator 4301 alarm.   I have the TL 5000 SMA inverter.   My system was under a 10 year warranty and was designed and warrantied by a company that has since went out of business.   The electrical contractor that installed the system is still in business but so far getting in contact with them has been like pulling teeth.  I have emailed, sent a web site inquiry, and called what appears to be a service that answers phones for them but so far have been unable to talk to anyone in 3 days.   I'm going to assume that I have no recourse as far as the warranty goes and while I'm willing to pay to have it permanently fixed I have a lot of concern based on things I've read that the issue may keep returning.   As far as basic troubleshooting I've so far look up on the roof and found a pigeons nest underneath the panels although it doesn't look as if there is any wiring or obvious issue near the nest.   On the ground side I opened the box below the inverted and tried to connect individually my A and B array of panels, but I think maybe I would need to reset the fault for that test to have been valid?   Everything inside this box looks clean.   I've also opened the AC manual disconnect box and in here I actually do see some contacts that are somewhat black.  My question is is it possible for an arc in the AC disconnect box to trip the inverter and give a DC Arc Fault?   If anyone has any suggestions on how I might be able to troubleshoot this further I'd appreciate it.  I'm willing to do anything from the utility panel up until the solar panels, but I don't want to have to lift and move around solar panels.   Any suggestions also on what to look for if I hire someone outside the installer to come look at this as so far I can't get in contact with them?   

Dave Angelini

What does SMA say? Have you told them what you wrote here? 

I doubt the AC side could do this but why don't you just jump the contacts that look bad. There should be a breaker upstream that you can shut down for this test.

I have made a small fortune replacing arc fault PCBs and so this can be pretty common. Especially ABB types. Yes you need to reset the AFCI for each test.

SMA has had me replace a few for people who are out of business as there are few who want to travel up into the rurals where I live.
They pay about $300 and expenses so I think you can convince them to get someone. First you have to diagnose and prove it to them.

Your test idea is a good one on separating arrays. Do it again. That should prove it is not the wiring out to the array. Good Luck

billybob9

It looks like were in the same boat with a SMA 5.0 inverter on 2 strings. If you read my post here "2 or 3 strings" you'll see I've MAXED out the SMA inverter with solar wattage. If you add up the wattage on both your strings and it is over 4800W then this might be the problem. I think what may be happening is when most home systems used 250W panels, 16 panels on a string was standard. Now 300W and 320W have taken over and 16 of these panels is over the size of a 20A breaker at the box. On low Voltage months this would not be a problem but peak months might get you to that breaker tripping point.

billybob9

Sorry, that is 16 panels on 2 strings

dgrilley

I know this thread is old, but the issue has come up again.   A year ago when I wrote this I figured out how to reset the alarm and once done it went away.   Fast forward to now and the issue has happened again.  This time resetting the alarm just causes it to come back immediately.   I forgot about my idea to test the A & B separately so I will try that tomorrow once I have sun resetting the alarm this time between each reset.  The AC side still looks a little bit burned so I also may try to bypass that by connected the wires together and you are correct about another disconnect upstream in my electrical panel.  Billybob if the problem were watts though it would reset and work once the wattage was low enough?   Even in the late evening at this point the fault comes back immediately once i reset it.   

Dave when you said you replacing arc fault pcbs you are talking about the little device on the circuit board inside the inverter?   How would I prove to them the PCB is the issue?

BB.

What looks "a little burned"? The PCB board, or the wiring entering the wire connectors? (wire too small, moisture causing corrosion, need to clean/re-torque wire screws--Less common issues such as aluminum wiring or very fine wires--such as welding cable vs solid or course stranded wiring?)

-Bill

dgrilley

The only thing that looks a little burned at all is the AC disconnect.  I don't think that can shut down the inverter?  The message from the inverter itself says check DC power generator so I'm thinking the AC disconnect isn't the issue.  Everything else I can visually see the DC disconnect, the DC inverter, and the junction box on the roof all look good.   I also don't see any evidence in the panels themselves of animal tampering or any obvious signs of wire issues there.  I'm going to test the A/B sides individually tomorrow and report back, but if both sides show arc fault I'm  highly suspicious that the inverter is faulty.   In the manual it seems to indicate that there is a way to bypass the AFCI through software, but I'm not sure I have a way to connect to this thing even if I did want to bypass this important safety feature...

BB.

If the AC disconnect was ever switched under load, you could see the results of an arc... Should not be a big deal.

If you see arcing/pitting on the major faces of the contacts--That could be an indication of poor/dirty AC connections and you could be getting an arc and arc fault from that...

Although, it does sound like the DC side is getting the arc fault (problem with electronics or real--hard to tell). But as Dave says--He has replaced more than a few ArcFault boards because of factory issues.

-Bill

Dave Angelini

Not sure what the problem is without a good peek. You do have to have a valid warranty! 

 I have made a small fortune changing AFD's up here in the mountains. I get hired because few companies will send repair folks to the places I frequent. It is a good deal for me as even if changing the AFD does not fix the problem, I get paid in advance. The company then pays me to change the inverter.

The companies that sell solar on the radio, often come up here, install it and forget it.   AFD is always the weak link. Always!
 I will not use it for my offgrid clients unless it is easily bypassed.