SMA Tripower Core1 Arc Faults

S

solarken

NABCEP PVIP
Location
Hudson, OH, USA
Occupation
Solar Design and Installation Professional
I have several commercial customers where I installed SMA Tripower Core1 62.5 inverters, most with multiple inverters at the site. Besides an issue in 2021 where i had to replace the ARTX boards under warranty due to a manufacturing defect, they have been generally reliable. Lately, however, I am seeing Arc fault errors in multiple inverters. I inspected an array a few weeks ago that experienced the error, and found no wiring issues with any accessible wiring, although I did not disassemble the array to get at all the string cabling. I moved a few strings from one string group to another (to help identify which string if it recurs), reset the error, and it has been operating fine since. Last night, one inverter at a different site is reporting the errors, Event ID 4301-Serial El Arc detected in string ABC, followed by Event ID 8206-Electric arc detected. This site is 3.5 hrs away. Is anyone else experiencing these errors with customer systems? I am trying to understand if there is another widespread circuit board issue or false positive, or if it is indeed a real arc fault. Thank you for any help.
 
We are getting these are several projects and exactly as you describe. It only happens on projects with RSD devices. We still haven't been able to resolve them. It moves from string to string so the string group troubleshooting tool really doesnt help.
 
cbunas said:
We are getting these are several projects and exactly as you describe. It only happens on projects with RSD devices. We still haven't been able to resolve them. It moves from string to string so the string group troubleshooting tool really doesnt help.
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Yeah, we had a lot of problems with projects with multiple SMA Tripower inverters with RSDs as well. The problem we had was that the keepalive signal on the DC conductors can couple capacitively between conductors supplying different inverters, and the signals are not in phase, so the RSDs get confused. Remediating that sort of thing is a major pain.
 
ggunn said:
Yeah, we had a lot of problems with projects with multiple SMA Tripower inverters with RSDs as well. The problem we had was that the keepalive signal on the DC conductors can couple capacitively between conductors supplying different inverters, and the signals are not in phase, so the RSDs get confused. Remediating that sort of thing is a major pain.
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That sounds like the crosstalk issue that Tigo decided not to tell anyone about before selling a hundred thousand units. I have 2 sites that the inverters are on separate roofs and still having the issue so that is not it. I guess they fix it by installing a separate Tigo radio unit but you have to run a power supply.
I'm chasing a phantom Arc fault on a APSmart RSD system right now and those conductors are not run together either. Any thoughts?
Stay away from any RSD designs at all cost and use certified racking systems and designs.
 
Also you have to be connected to the Core1 to execute the Reset Operating Inhibition so this is a giant PITA. It will run for 1-2 months and they error again.
 
cbunas said:
That sounds like the crosstalk issue that Tigo decided not to tell anyone about before selling a hundred thousand units. I have 2 sites that the inverters are on separate roofs and still having the issue so that is not it. I guess they fix it by installing a separate Tigo radio unit but you have to run a power supply.
I'm chasing a phantom Arc fault on a APSmart RSD system right now and those conductors are not run together either. Any thoughts?
Stay away from any RSD designs at all cost and use certified racking systems and designs.
Click to expand...
We (the company I retired from about a year ago) switched from SMA to SolarEdge for three phase inverters where rapid shutdown was required because of the issues we were having. We still had issues from time to time, but not nearly as often.
 
ggunn said:
Yeah, we had a lot of problems with projects with multiple SMA Tripower inverters with RSDs as well. The problem we had was that the keepalive signal on the DC conductors can couple capacitively between conductors supplying different inverters, and the signals are not in phase, so the RSDs get confused. Remediating that sort of thing is a major pain.
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I have heard about the cross talk issue that can occur with different inverters, but this is not occurring at the sites we have installed because the array sections that feed different inverters have PV conductors physically separated. And I would think RSD crosstalk would not result in an Arc Fault detected error, but assuming you did not imply that.
 
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cbunas said:
Also you have to be connected to the Core1 to execute the Reset Operating Inhibition so this is a giant PITA. It will run for 1-2 months and they error again.
Click to expand...
You can reset it remotely through the EnnexOS Sunny Portal. You don't have to be onsite. See screenshot.
1727480976629.png
 
cbunas said:
That sounds like the crosstalk issue that Tigo decided not to tell anyone about before selling a hundred thousand units. I have 2 sites that the inverters are on separate roofs and still having the issue so that is not it. I guess they fix it by installing a separate Tigo radio unit but you have to run a power supply.
I'm chasing a phantom Arc fault on a APSmart RSD system right now and those conductors are not run together either. Any thoughts?
Stay away from any RSD designs at all cost and use certified racking systems and designs.
Click to expand...
Are there any UL3741 certified systems for sloped roof, metal roof, non-ballasted applications?
 
Tigo is having MAJOR problems with the TS4-A-F burning up, as are other RSS manufacturers. Have seen multiple commercial sites in multiple states coast to coast with the same issues - burned up RSS modules. Ironically these "fire safety" devices and all the associated additional connections are in fact causing a lot (if not most) of the solar fires and increasing the risk to firefighters. NFPA really screwed the pooch on that one.
 
solarken said:
I have heard about the cross talk issue that can occur with different inverters, but this is not occurring at the sites we have installed because the array sections that feed different inverters have PV conductors physically separated. And I would think RSD crosstalk would not result in an Arc Fault detected error, but assuming you did not imply that.
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Yes. I exactly implied that crosstalk on Core1 inverters using internal radio creates a false arc fault warning. It requires a site visit to reset the inverters if the software setting for arc faults remain the factory setting of "Arc Fault with Startup Inhibition". Of course if you have the inverters connected to Sunny Portal you can reset remotely but most site do not use Sunny Portal and some with 3rd party monitoring cannot.

In addition to crosstalk (which happens when 2 or more separate inverter's DC homeruns are routed together or near each other), SMA core1 inverter use Shadefix. Shadefix sends a radio signal through the DC homeruns that also can create a false arc fault reading and shut down the inverter. Both of these issues are caused by the fact that the radios are all on the same channels. There are now white papers on SMA technical portal that you can search for, but I had to figure this out the hard way.

1) Turn off Shadefix
2) Change the arc fault settings to Arc Falt Without Startup Inhibition
3) Ensure your firmware is up to date
 
slik056 said:
Tigo is having MAJOR problems with the TS4-A-F burning up, as are other RSS manufacturers. Have seen multiple commercial sites in multiple states coast to coast with the same issues - burned up RSS modules. Ironically these "fire safety" devices and all the associated additional connections are in fact causing a lot (if not most) of the solar fires and increasing the risk to firefighters. NFPA really screwed the pooch on that one.
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Yes they did. We get about 10% defects on APSmart / APSystems and way more on Tigo. Luckily on APSmart they just crack the case and ooz black goo all over which is probably why there are no fires. Tigo is close to filing for BK last I heard. We do everything we can to not use and RSD unit.
 
Also, not all SunSpec inverters are compatible with all Tigo and Tigo type rapid shutdown devices.
 
cbunas said:
Not every system can be configured to use Sunny Portal. Most of the hundred or so Sunpower projects we installed cannot due to how the PVS5/6x works with the cell comm and no ethernet.
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I'm not following you. The SMA EnnexOS Sunny portal is for SMA inverters. And the SMA Tripower Core1 can be reset after Arc fault, remotely thru the portal just like I showed in the screenshot.
 
cbunas said:
Yes. I exactly implied that crosstalk on Core1 inverters using internal radio creates a false arc fault warning. It requires a site visit to reset the inverters if the software setting for arc faults remain the factory setting of "Arc Fault with Startup Inhibition". Of course if you have the inverters connected to Sunny Portal you can reset remotely but most site do not use Sunny Portal and some with 3rd party monitoring cannot.

In addition to crosstalk (which happens when 2 or more separate inverter's DC homeruns are routed together or near each other), SMA core1 inverter use Shadefix. Shadefix sends a radio signal through the DC homeruns that also can create a false arc fault reading and shut down the inverter. Both of these issues are caused by the fact that the radios are all on the same channels. There are now white papers on SMA technical portal that you can search for, but I had to figure this out the hard way.

1) Turn off Shadefix
2) Change the arc fault settings to Arc Falt Without Startup Inhibition
3) Ensure your firmware is up to date
Click to expand...
I don't believe SMA Shadefix sends any radio signal through the DC lines. Where did you hear that? Shadefix looks to just be a fancy way of describing a more sophisticated MPPT algorithm that can detect multiple peak power points and choose the highest one. There is nothing for the inverter to communicate to over the PV runs, it is internal to the inverter operation as it varies the current and voltage operating points.
And I think your suggestion to change the arc fault setting from the default to defeat the startup inhibition is not generally a good one, and could be dangerous. You want to know if an arc fault has occurred, and you should do some level of verification about whether it is an actual arc fault or looks to be a false alarm. Since you can reset the arc fault either onsite or thru EnnexOS portal, then experience and judgement can guide the appropriate course of action, and how much verification should be done before resetting. If the setting is changed to auto reset like you suggest, you could have a recurring arc fault situation that is real, but not addressed because it just keeps getting reset and ignored until a fire starts.
 
cbunas said:
That sounds like the crosstalk issue that Tigo decided not to tell anyone about before selling a hundred thousand units. I have 2 sites that the inverters are on separate roofs and still having the issue so that is not it. I guess they fix it by installing a separate Tigo radio unit but you have to run a power supply.
I'm chasing a phantom Arc fault on a APSmart RSD system right now and those conductors are not run together either. Any thoughts?
Stay away from any RSD designs at all cost and use certified racking systems and designs.
Click to expand...
Crosstalk and nuisance arc fault tripping are unrelated problems. Arc fault and RSD system interactions have been known to cause nuisance arc fault tripping in systems where the MPPT and inverter are from different manufacturers. Manufacturers don't talk about this and there has been some push to get testing for interaction added to the relevant UL Standards but I don't know if they ever were. Of course there is also a very good possibility that after a few years systems develop intermittent arc faults that are real. Since arc faults are dangerous it's not good to just blow them off as equipment errors and they can be very hard to troubleshoot.
Crosstalk is not an equipment failure, it's a misuse of equipment problem. The only time people will run into crosstalk issues is if they think they can use RSD to shutdown only some inverters and arrays on a roof to do maintenance. With the other inverters in operation crosstalk can occur. But RSD was never intended or designed to be used like this. It's designed to be activated for all inverters and arrays on a roof at once when the building is on fire. No crosstalk issue when used like that.
 
solarken said:
I'm not following you. The SMA EnnexOS Sunny portal is for SMA inverters. And the SMA Tripower Core1 can be reset after Arc fault, remotely thru the portal just like I showed in the screenshot.
Click to expand...
It's like I said; not every SunSpec equipped inverter is compatible with every RS device. Before pairing an inverter with an RSD it is imperative that you consult the inverter manufacturer to see which RSD will work with their equipment.
 
pv_n00b said:
The only time people will run into crosstalk issues is if they think they can use RSD to shutdown only some inverters and arrays on a roof to do maintenance. With the other inverters in operation crosstalk can occur. But RSD was never intended or designed to be used like this. It's designed to be activated for all inverters and arrays on a roof at once when the building is on fire. No crosstalk issue when used like that.
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A couple of things...

One is that what you speak of is not the only possible effect of crosstalk. In one system we installed with two SMA inverters, when we started one inverter it came up and worked fine, but when we turned on the second inverter, about half of the strings on the first inverter went into shutdown. We had run some of the DC conductors for both inverters in the same cable tray and the keep alive signals from the inverters were not in sync, so some cancellation occurred and some of the RS boxes lost the signal.

The other is that (as in what you said) one inspector failed an inspection of ours because when he turned off the breaker to one of the ten SMA inverters, not all of its strings went into shutdown because of crosstalk from the others. I pointed out to him that the code only requires a singe RS initiator (in this case the PV disco on the whole system), but he was having none of it. In order for us to satisfy him we had to not only separate the DC conductors to the array to each inverter from the others, but we also had to air gap the racking for each inverter's modules and ground them separately. It was a laborious and expensive PITA.
 
ggunn said:
It's like I said; not every SunSpec equipped inverter is compatible with every RS device. Before pairing an inverter with an RSD it is imperative that you consult the inverter manufacturer to see which RSD will work with their equipment.
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How is this relevant to what you quoted from my response? 🤔
 
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