SolarEdge - Crispy AC Lines, Blown Disconnect Fuses

[EOppie]

Thursday, I noticed that our solar production started to drop in the afternoon, but I didn't think anything of it since it had started to rain.







Output Log Showing when things seem to go kaput




Yesterday, woke up to no production out of the unit, and no display on the SolarEdge Inverter. Did my normal turn it off and back on again from the AC Disconnect to the Inverter Switch, nada. Opened the Disconnect switch, confirmed power on the line side, no power on the Inverter Side. Checked the fuses, both were open. Called the Installer, they said they had to call SolarEdge to have them "Check the logs" after 3 hours and no response from them after calling back, I contacted SolarEdge, they said they have no errors recorded from the unit.







Disconnect Switch




All looked normal in the disconnect, opened up the bottom DC Safety switch box on the inverter....and found crispy AC wires and the faint smell of magic electrical smoke. Nothing else seemed damaged.







Inverter AC Wires







Inverter Disconnect Box

Frustrating to be down for the weekend while I wait for the installer to open on Monday. Has anyone ever experienced something similar to this on the output AC side?


No issues with the grid power, we have two surge protectors, one at the panel, and one on a subpanel, both are fine. One has a counter on it and doesn't show any additional surges.

[jflorey2]

Looks like a loose/high resistance connection on the L2 line. Possibilities:

-Undertorque
-Got a bit of insulation between the plate and the wire
-Wire/lug incompatibility? But the wire looks like copper, so probably not.

[EOppie]

Thanks for the insight. To me, it looks like they should replace the connectors for both L1 and L2. Should I also request the pull new AC lines to the disconnect? Doesn't look like they will have much of a service loop to play with to cut back the crispy section.

[peakbagger]

It looks to me like the connections were not torqued appropriately and it caused a high resistance connection. If there is enough slack in the cables that they can be cut back to the point where the insulation is not degraded and re-terminated on new DIN rail connectors.

[solarix]

Poor terminal connections doesn't explain why the fuses blew. A failed inverter could cause a short between the conductors, cause them to get crispy and blow the fuses. Its also possible the connections got hot and became bad enough that the inverter's output could not handle it causing it to fail. I think you have a blown up inverter.
Another failure related to SolarEdge plasticy design issues.

[bcroe]

With a new installation the original torque on wiring connections may not be enough. I would
go back and re torque all the current carrying terminals several times in the first couple years.
Seems like, the daily cycle of running hard all day and then cooling off at night can work
things loose, I burned out an AC and a DC connection. good luck, Bruce Roe

[SunEagle]

Poor terminal connections doesn't explain why the fuses blew. A failed inverter could cause a short between the conductors, cause them to get crispy and blow the fuses. Its also possible the connections got hot and became bad enough that the inverter's output could not handle it causing it to fail. I think you have a blown up inverter.
Another failure related to SolarEdge plasticy design issues.

Well fuses have a thermal element that will melt and open the circuit. High amps can do that but also heat on a bad termination will move up the wire and can affect a fuse.

You just have to look at all the reasons that cause the crispy insulation and "blown" fuses in a circuit.

If possible I would use a thermal image camera to see where the hot spot is and where it is going.

[EOppie]

So they came out and replaced the L1 L2 and Neutral DIN Connectors. They also pulled new wire to the safety disconnect for L1 L2 Neutral and Ground. AWG 6. The tech stated it looks like the connectors were loose. We have been generating power for the past two days now, and I do have access to a thermal camera, likely will try to take a shot or two in the coming days to see if everything is happier.