Xantrex Grid Tie Inverters Work Intermittently

CoinMLS
CoinMLS Registered Users Posts: 10 ✭✭
in Advanced Solar Electric Technical Forum #1
I have an 8.5 year old 8kW system with 2 Xantrex GT 3.8 Inverters (3.8kw). One inverter was replaced after about 6 months of use but has been fine since. The installer is no longer in business. I am very handy and have an Electrical Engineering degree but I don't have much experience in this area. The whole array is on the same surface with the same sun exposure in Phoenix, AZ.
Lately I have had noticed that the system is working intermittently. Sometimes one inverter is online producing 2500-2800W (fairly normal value) and the other is "Inverter Offline." Then sometimes the other system works and the other is offline. Sometimes they are both working. Today it was sunny all day, they were both off until around 2pm when one of them started working. The other never did.
Here is what I have determined so far:
1. There are no faults displayed by the unit
2. Both units show ~300Vdc coming in from the solar array on my DVM whether the inverter is online or not. I think this rules out array or wiring issues to the array.
3. Fuses in both units are fine.
4. I have not yet removed the cooling fins to inspect behind those components.
5. I have tried switching them on and off

Any ideas? I find this to be really a peculiar failure mode, and I'm really surprised that it affects both units.

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  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    #2
    Try using the multimeter to measure your household AC line voltage.  With a lot of solar in neighborhoods, or sometimes with insufficient feeder wire gauge, the Line voltage can rise ABOVE spec and the system shuts down.
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

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  • CoinMLS
    CoinMLS Registered Users Posts: 10 ✭✭
    edited December 2018 #3
    Thanks for the reply. I don't think either of those are the problem, after all, the system has worked for over 8 years. The wire appears to be 10 or 12 AWG which should be fine. L-L voltage was 241V, each leg was 120Vac. Voltages similar on both units. And again today, one was working, the other was not at one time. Today, 1 unit ran for 2 hours, the other for about 4, and they should have run all day, it was not cloudy at all. It seems to be consistently that they run late in the day.

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  • littleharbor2
    littleharbor2 Solar Expert Posts: 2,101 ✭✭✭✭✭
    edited December 2018 #4
    Maybe unrelated but thought I'd mention. These inverters had a problem (I honestly don't know what the problem was) that was fixed by xantrex. The indicator, as I understand it is the addition of the small label at the very bottom right of the data label on these inverters. The ECO-7779 label on the upper photo is the one I'm referring to.  Not sure if this repair was required on the 3.8 Kw models.

     

    2.1 Kw Suntech 175 mono, Classic 200, Trace SW 4024 ( 15 years old  but brand new out of sealed factory box Jan. 2015), Bogart Tri-metric,  460 Ah. 24 volt LiFePo4 battery bank. Plenty of Baja Sea of Cortez sunshine.

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  • CoinMLS
    CoinMLS Registered Users Posts: 10 ✭✭
    #5
    I was just looking at that last night. I did submit a recall claim 2 years ago and they sent me some kits that I never got around to installing. Looks like it is to replace 2 capacitors near where the solar voltage comes in. The problem was that these capacitors were exploding. Mine look fine. I'm going to take the fins off and visually inspect the rest of the caps today. I'm thinking it's got to be capacitor related as maybe it takes several hours of generation to get it to work with some degraded/damaged capacitors.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #6
    There was an issue with input capacitors on some of Xantrex's product line. There were something like 4 capacitors that failed... Two or three they could read the lot code (all from one lot). And another that they could not... So, being conservative, they decided to replace all the capacitors.

    As I recall, these were polyester capacitors--And if they fail (overheat/arc?) they release acetylene gas as they decompose (possible flammable/explosive issues).

    This was from a hand full of years ago. I don't have any other information.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • CoinMLS
    CoinMLS Registered Users Posts: 10 ✭✭
    #7
    I can't seem to figure out how to "get the fins off." The units are still hanging on the wall and connected, I'm trying to avoid disconnecting and taking them down if I can avoid it. I'm wondering if there's something I need to pry or persuade a little bit but I don't want to damage or bend anything. I removed screws on the top and on one side. Any help or ideas are appreciated.

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  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    #8
    You don't take the fins off. That's about 10lbs of extruded heat sink with lots of circuitry built on the backside (that's the FETs and drivers)    The whole works (box) is on a hanger and you take it off the wall, and the dealer gives you a replacement.    Unless you made pry marks and dents trying to open a box with no consumer replaceable parts.  
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

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  • CoinMLS
    CoinMLS Registered Users Posts: 10 ✭✭
    #9
    Thanks for the info. Not sure I'll get a replacement unless I buy one, it's out of warranty. Nice thought that someone would just give me one though. I wanted to check the condition of the capacitors, if there are any more behind the fins. I haven't caused any damage. Is there anything else to look for then?
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  • mcgivor
    mcgivor Solar Expert Posts: 3,854 ✭✭✭✭✭✭
    edited December 2018 #10
    This link has info regarding the capacitors.
    https://solarindustrymag.com/schneider-recalls-xantrex-solar-inverters-due-to-injury-hazard/
    1500W, 6× Schutten 250W Poly panels , Schneider MPPT 60 150 CC, Schneider SW 2524 inverter, 400Ah LFP 24V nominal battery with Battery Bodyguard BMS 
    Second system 1890W  3 × 300W No name brand poly, 3×330 Sunsolar Poly panels, Morningstar TS 60 PWM controller, no name 2000W inverter 400Ah LFP 24V nominal battery with Daly BMS, used for water pumping and day time air conditioning.  
    5Kw Yanmar clone single cylinder air cooled diesel generator for rare emergency charging and welding.
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  • CoinMLS
    CoinMLS Registered Users Posts: 10 ✭✭
    #11
    I did install the new capacitors, no improvement (I didn't expect any). I guess I will call the inverter repair people.
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