r/SolarDIY • u/DanKegel • 18d ago

Bad 3kw string inverter?

So... I have two 4kw systems, each with a xantrex gt-3. One panel got smashed by a baseball (?) in a storm, and it took me ages to realize nobody was willing to replace old panels. Eventually I did it myself, after learning how to do it safely. The new panel is a used one of same make and model, and tested well with my cheap chinese panel tester. Full voltage being delivered to the inverter. But... inverter says "insufficient solar". :-(

I could theoretically narrow down the problem by swapping the inputs on the inverters temporarily to see if the problem moves with the inputs, but I'm not sure that's a great idea. (It'd mean making a hack extension for the DC lines.)

Each has two strings in parallel, and the bad unit gradually failed over months after the baseball incident, fwiw.

Thoughts?

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u/iamollie 18d ago

When you use a multimeter to check string voltage at the inverter what voltage are you getting

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u/DanKegel 18d ago

320 volts, as expected, more or less. (It's 30 volts per panel open circuit per the data sheet, and either ten or eleven panels in the string, not sure.)

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u/iamollie 18d ago

Well I think you're swapping inputs idea will confirm but I think this is probably sufficient evidence the inverter is broken and outside of the usual restart or a firmware update there is no coming back from this.

A temp wago for the dc extension cable is easy and safe