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Can a Sun Gold, model LFPV10KW, solar inverter be damaged if one or both of these things are done:

  • the inverter's terminals are shorted together while attaching the 220amp battery to the inverter. With one of the battery cable connected to the inverter, the pliers used to connect the second battery cable to the inverter touched, during tightening, both positive and negative post. The individual luckily only received minor burn the hand.
  • the inverter's output is connected to the sub panel, through a 60A breakers. Three of the circuit breakers in the sub panel was then connected to three circuit breakers (under terminals screws) in main panel. When the utility power was cut off, the inverter took over. But when the utility power was restored the inverter did not transferred back. While under utility power, both inverter and utility are feeding power into the panels.

Back story: My electrician, in order to test the transfer switch inside the inverter, decided to run wires from the circuit breakers in the sub-panel to circuit breakers in the main panel. When the power in the main panel was shut off, the invertor kicked on. However, when the utility power was cut back on, it created a back feed, and the 200amp main breaker sparked, meanwhile the inverter did not shutdown.

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  • I condensed the question, hopefully to get it answerable. I was unable to interpret how the main breaker "ack"ed, so I figured that meant "tripped. If I'm wrong, please feel free to edit again what the main breaker did. I also took out the "what will the breaker do" question, as that depends on the type of inverter and is really a subject for a different question. Nov 25, 2023 at 12:11
  • Also, please edit into this question the model number of your inverter, it may help the answerers. Nov 25, 2023 at 12:12
  • Welcome to the site Trench. Please merge your accounts so you have access to edit, comment, and accept answers on your own question.
    – BMitch
    Nov 26, 2023 at 16:25

2 Answers 2

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The battery short will probably have not caused damage, at least not to the inverter assuming it was powered off at the time. (I suspect the battery would have short-detection built into its BMS. You could check yourself by reading its data sheet.) Lucky escape for your installer with only minor burns, though.

Regarding the output non-transfer, I would guess the inverter configuration may be to use battery power in preference to grid power. Review the configuration, and perhaps ask some gentle probing tech support questions to find out if it is behaving correctly. (Or just allow the battery to run down, then see what happens.)

Openly disclosing the installation issue to your inverter vendor risks your warranty. And, depending on your contract with your installer, it might also risk your ability to seek recourse through his (/her) insurance. Perhaps not by the word of contract, but it will make steering away from assumptions of damage more difficult.

If you do find the inverter is behaving incorrectly once you have reviewed configuration, then have your installer make a careful read of its data sheet. If the short is clearly outside of tolerance, then you may have to concede defeat.

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TL;DR The inverter may be damaged.

I agree with @dentarthurdent's answer that shorting out the battery input terminals on the inverter while connecting the battery would be quite unlikely to damage the inverter.

Also, Sungold's LF-PV inverters come with an instruction manual, which does report that the inverter has short circuit and backfeed protection. So theoretically if the electrician wired utility power to the inverter's output through the subpanel breakers, the inverter may have caught this and saved itself.

On the other hand, it may not have saved itself...

The "test" procedure that you've described taken by your electrician is a worry:

Three of the circuit breakers in the sub panel was then connected to three circuit breakers (under terminals screws) in main panel.

As described, your electrician wired three extra power channels through breakers between the main and subpanels to "test" the inverter's transfer switching function. This sounds quite strange. Although I have not read the whole inverter manual, it does not appear that this is a stated test procedure.

The inverter has two power delivery functions, according to the manual:

  • AC-passthrough or Line Priority: The utility power is passed through until it fails, then the inverter output turns on.
  • inverter-preferred UPS: the inverter provides power while its batteries or other sources can feed the load, then when the battery/sources cannot provide any more, utility power is connected in. When the batteries/sources return to acceptable levels, the inverter takes back over.

From this:

When the utility power was cut off, the inverter took over. But when the utility power was restored the inverter did not transferred back.

It sounds like your inverter may have been in UPS mode, so wasn't acting like you'd expect it to act, as it would in AC-passthrough mode.

That oddball wiring test does not appear to be in the manual that I've seen. The correct test would have been to check that the desired inverter operation mode was set, turn off the utility power, and see if the inverter kicks in and drives the subpanel loads.

Even if the inverter still works now, there may be some damage that may only show under heavy load or show further in time, and that may be diagnosable by Sungold as not-under-warranty activity.

If the electrician's test procedure is not in the manual (you'll have to read the whole thing), the electrician owes you a new inverter.

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