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Yesterday, my Tesla app showed a complete loss of power generated from about noon on. It's working fine now. When I called Tesla tech support, they suggested the problem is probably in my Sunny Boy SB6000US inverter. I'm not aware of this happening in the past. Is there a way to diagnose potential issues with my inverter?
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Now it looks like I'm losing energy generation for 2-3 hours a day. There are no messages. What could be the problem, and how do I fix it?
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I believe I've found the problem. I hung shade cloth in front of the inverter, and it didn't cut out. I also noticed I'm not hearing the fans running. I understand the fans can be replaced, but I can't find a part number or source for the SB6000US. Can anyone help with this? Also, please share the voltage and whether it is AC or DC, so I can test the fans.Last edited by Actonite; 10-02-2026, 05:52 PM.Comment
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I found the 2 fans on the bottom of the inverter, but I can't figure out how to remove them. I have the 2 fans from my deceased SB6000 that I might be able to jury rig into my SB6000US.Comment
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OK, I removed and tested the fans. They are in perfect shape. They're just not getting power from the inverter. Anyone know how to problem shoot this issue?
Could there be a bad sensor that needs to be replaced? If so, how do I access and replace it?Last edited by Actonite; 10-02-2026, 09:38 PM.Comment
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Hi There,
I think the fans only come on when the unit starts to get hot, I have only ever noticed my fans on a few times over many years. Might be nothing wrong at allComment
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I agree, but the unit is shutting down rather than running the fans. It's only an issue when the sun beats down on it. The shade cloth is helping, but I'd like to fix the problem.Comment
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you may have a problem with the temperature sensor not detecting the high temp.Comment
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I agree with scrambler. it could be the fan thermostat is bad. Sorry i do not own that type of inverter. Maybe ask the mfg for some helpComment
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Unfortunately, SMA hasn't responded.Comment
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reading the AI searches above, do you get any error message, LED status blinking etc that you can map with the error guide in the installation manual?
Any diagnosis you can run from the SW monitoring side?
Have you opened it and cleaned everything from dust accumulations, obstructions etc...
"SMA’s installation/maintenance docs describe a fan test procedure using internal jumpers and observing fan spin when the inverter is powered."Last edited by scrambler; 10-06-2026, 09:49 AM.Comment
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Everything is clean, and I don't get any error messages.Comment
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The two to three hour dropouts that start at midday and clear themselves are the classic thermal derate, so the shade cloth test was the right call and it pretty much convicts the fans. Before you rig the old ones, check the label on the dead set for the voltage, because the SB6000 fans are DC, usually 24 volt, fed from a small internal supply rather than the array side, so they are safe to bench test on a power supply. The part that will bite you is the connector and the mounting clips, not the fan itself. Once you have the voltage and the size in millimetres, a same size fan from any electronics supplier will work as long as the airflow direction matches the arrow on the housing. Keep in mind SMA de-rates instead of faulting, which is why you see no messages.
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The pattern you described is the giveaway. Losing generation for two to three hours in the middle of the day, and the shade cloth stopping it, points at heat and the fans rather than the array. What I would check next is why the fans are quiet when they test fine on the bench. The SB6000US fans are usually 24 volt DC fed from a small supply inside the inverter, and many have a third wire for the tachometer so the board knows they are turning.
Meter the fan header right after the unit starts up. No voltage there means the controller or the temperature sensor is the problem, not the fans. Voltage but no spin can be a lazy thermistor.
Do not chase the part number too hard. Hole spacing, thickness and voltage are what matter, and a same size fan will fit.
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