Solar system, 2 SW5548 inverters wired for 220v. Have worked fine for 10 years til last week. Now only one will regulate to my 118v line. The other goes to 84-90 volts and just sits there. Any ideas?

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I assume both inverters connect to the same battery bank so any problem with batteries would effect both inverters the same way. You say one inverter "regulates" to the AC input and the other "goes to 84-90 volts and just sits there" I'm not sure what you're describing but If you mean the defective inverter only puts out 84 to 90 volts, I would suspect a defective MOSFET (power transistor) Use an oscilloscope to look at the output waveform and see if there are missing steps to the staircase waveform.

How are the batteries for that inverter? Have you got a dead battery in the loop?

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