Random spikes and dips in array voltage

[Goin'Solar]

Anyone know what might cause random spikes and drops in array voltage? I wired up my second array today and got everything done just as the sun was going down. Actually sun was pretty much all the way down and just had that evening glow. I tested the voltage at the wires and was getting about 430 volts steady from the array. I connected the wires to the disconnect, then from there to the inverter and flipped on the disconnect. The inverter was reading 395, 180, 220, 170, 310, etc. in random fashion from the array. Disconnect was switched off and left until I can get back out to do more diagnostics.

Inverter is EG4 18kpv with 1 array already connected and working fine with no random voltage. I have connected the working array to all 3 PV inputs and they all worked properly.

The array I was connecting today is 13 panels, in series and was repurposed from an old SolarEdge system. It had optimizers attached that I removed, but now I'm wondering if I missed one or if there may be a hidden controller of some sort. Or if maybe there is a dead panel causing the issue. Panel specs are below.

 

[Samsonite801]

My guess is the inverter was doing MPPT sweeps on the circuit, and due to weak setting Sun, the voltage was lazy, so the sweeps were fluctuating the voltage a lot, as it couldn't get anywhere near to finding Imp at that time.

Try more testing when the Sun is strong, and the voltage should have more backing behind it...

 

[Goin'Solar]

My guess is the inverter was doing MPPT sweeps on the circuit, and due to weak setting Sun, the voltage was lazy, so the sweeps were fluctuating the voltage a lot, as it couldn't get anywhere near to finding Imp at that time.

Try more testing when the Sun is strong, and the voltage should have more backing behind it...

Thank you. This was the answer.

Turned it back on and holding a nice steady voltage of about 356 right now.