GFDI problem with SMA 2500 inverter
spurlocktools
Registered Users Posts: 11 ✭✭
I have a grid tied PV system with two Sunny Boy 2500UW4E inverters, each connected to its own 15 panel array. It has been working fine for six years, but just now one inverter gives me a ground fault error, while the other still operates correctly. Both the red and yellow LEDs are on, and the display reads, "Earth Cur". According to the manual, this should mean a ground fault in the PV array. However, when I swapped wiring so each inverter was connected to the opposite array, the fault stayed with the same inverter. The GFDI fuse is good, I swapped fuses between inverters just to make sure.
This seems to me to prove a fault in the inverter, not the array, otherwise the fault would have moved to the other inverter, correct? Has anyone else encountered a problem with a GFDI becoming too sensitive with age?
Other tests I have done: After turning off the DC disconnect and disconnecting the ground lead from PV modules & rack, the voltage across pos and neg PV leads was 380V, the same for each array. Also an ohmmeter test between each PV lead and the module ground wire shows no short. I also temporarily disconnected the module & rack ground lead and turned the system back on, and the problem remained. After each test I have followed the "commissioning" procedure in the manual but the LEDs still indicate a PV ground fault.
I'll be calling the SMA help line tomorrow, but would appreciate hearing any other thoughts or tests I might try.
This seems to me to prove a fault in the inverter, not the array, otherwise the fault would have moved to the other inverter, correct? Has anyone else encountered a problem with a GFDI becoming too sensitive with age?
Other tests I have done: After turning off the DC disconnect and disconnecting the ground lead from PV modules & rack, the voltage across pos and neg PV leads was 380V, the same for each array. Also an ohmmeter test between each PV lead and the module ground wire shows no short. I also temporarily disconnected the module & rack ground lead and turned the system back on, and the problem remained. After each test I have followed the "commissioning" procedure in the manual but the LEDs still indicate a PV ground fault.
I'll be calling the SMA help line tomorrow, but would appreciate hearing any other thoughts or tests I might try.
Comments
I believe the "Ground Fault Detection" circuit functions by measuring the voltage drop across the GF Fuse. You can try measuring both the AC and DC voltage across the fuse and if you see more than a few volts--you may have some current leakage somewhere.
If there is little to no voltage across the fuse--It sounds like an inverter problem (that, and all of the other testing you have done).
By the way, do you get the GF LED when the sun is up or at night too? (I don't know if the GF LED latches or needs to be reset if the fuse blows).
-Bill
Thanks for your reply. I don't get any voltage readings at the GFDI fuse, once the system signals a fault it requires going through the "commissioning" procedure to reset. Steps are:
Disconnect AC and DC disconnects
Remove GDFI fuse
Switch on AC disconnect
Switch on DC disconnect
If after 20 sec. the red led is on, there is no PV fault and you can disconnect DC again and insert the fuse.
If both red and yellow LEDs are on then there is (supposedly) a PV fault.
There is no display at all after dark.
Just to clarify further, there is no voltage at the GDFI fuse until the supposed fault is corrected and the system reset, but it will not reset since it thinks there is a ground fault.
I have no experience with GFCI as regards inverters. But with GFCI receptacles and breakers - yes I have seen them become more sensitive with age and require replacement. I have seen this many times in fact.
Just wanted to report my problem is resolved. Monday morning I called SMA tech support and he agreed that since I had swapped wiring between my two PV arrays and inverters and the problem stayed with the same inverter, that the inverter was likely the problem. So I went with their $360 inverter swap, where they send out a refurbed inverter immediately along with a call tag to return the original. Got the replacement the next day, installed it in 10 minutes and it worked fine, no more ground fault error display.
I'm very pleased with SMA's service in this case. The phone tech was local (not in India), and very attentive and knowledgeable. If it were not for the weekend, I would have only missed a day or two of power production. It's always nice to find a company that does what you would expect them to do, but that so many do not.
This inverter failure has also prompted me to install a small solar powered cooling fan to make life easier for my inverters in the long run. So all in all a positive experience.
Nice to hear a customer service story with a happy ending.
-Bill
Just had the same problem with on of my 2500s. Switched out the GFDI board and that solved the problem. I'll find out on Monday what a replacement will cost from SMA.
I am having the SAME issue with my SMA2500U !!! I guess I need to call SMA again...
Spm
Quick question - Which board is the GFDI board, and how much did SMA charge to replace it?
Spm
Had another GFDI board go bad. I wonder if this is a problem when the sunnyboys get older. As usual SMA wants to do the 360.00 swap instead of just selling me a new board that takes 5 minutes to install. I'm trying to track down the sensor to replace it on the board to see if that will fix the problem.
Just repaired 2 of the GFDI boards in my 2500s. Replaced the CMS2005 sensor on both and they are running fine now. I had to order 10 CMS2005 from Germany(minimum order and 156.00 in shipping). Now I have a few extras, so if anyone one has this problem with their 2500U and they need the part I have a few spares now. e mail me abaknonATaol.com
Sold all my extra CMS2005s. If you need them, contact the company in Germany. If someone else ends up buying a bunch, hopefully they will post there extras here.
I had read this a while ago, then couldn't find the posting again until today. Darn - think I might need the CMS2005s. Do you know if it's the same chip in the 1800 (circa 2004)?
"contact the company in Germany" SMA? or ?
If it's the right chip, I'll probably buy the minimum. I suspect we'll continue to see this problem.
I think I have found the item: http://www.sensitec.com/deutsch/produkte/strom/cms2005.html
and available through a reseller in qty 1: http://de.rs-online.com/web/p/stromschleifen-ics/7639790/
Price is just under 20 Euros, plus VAT, plus freight. Perhaps VAT doesn't apply for export, but not sure if they ship to US yet. If not, I've a contact in Holland who can probably buy and ship to me.
RS also has a UK site, but there the minimum qty seems to be 10.
Looks like I have the same problem with my 1800U and SMA tells me they don't do the exchange anymore for the 1800U.
Did you end up ordering from Germany? What was shipping and how long did it take?
Anyone have an extra they want to sell?
I also just ended up ordering 10 CMS2005 sensors. Going to replace the one in my 1800U. I'll have some extras if anyone needs to buy one.
Frank
I'd be very interested to hear if your fix worked. I'm having the same problem with a 1800U. I'd be interested in buying one of your sensors if that took care of the problem.
Bill
So why did you not just buy the extended 10 year warranty at purchase? Was it not offered at the time of your purchase? Isn't it only $100 for the extended warranty?
I have several good GFI boards for the sunny boy inverters.
http://www.greensolarelectric.com/Inverterrepair.html
Is there any form of reset process? Any temporary way to definitively check the GFI board besides floating the array ground?
Also wondering if this board is primarily and only for the DC side of things? Thanks.