Can failed wind turbine load bank damage solar controllers

It has been a decade or two since I did printed circuit board design... But, if I recall correctly, very roughly, the flash over voltage is roughly 50 volts per 0.001 inch across a clean circuit board  and around 500 volts per 0.001" through the board (no voids).

Otherwise, carbon tracks can form from dirt/salt/etc. on the surface of the board. Inside the board (and possibly on the surface) copper whiskers can grow and cause shorts.

How high of voltage did your battery bank voltage go? Very roughly, it is possible for a wind turbine to output several times its rated load voltage if driven at rated RPM... For example, in the olden days, one could buy a kit that would allow a car alternator to output around 120 VDC on a 12 volt alternator.

For a DC battery bank--Say 48 volts--A "working" bank can run as high as 62 VDC or so and Xantrex/Schneider has an error log entry if the battery bank exceeds 72 VDC (has happened on at least one member's system here).

My guess, for a 48 VDC battery bank, if you see over 72 VDC for any length of time--That is an "out of control" charging event and runs the risk of battery bank and connected electronics/devices damage.

To get arc tracks on a clean board, I would suspect that your system would have to see 5x or more on a (well design) 48 VDC system (charge controller).

Battery banks seem to be relatively rugged against surge current from lightning. The lead acid battery has both (relatively large) capacitance (between + and - connections). And a typical design would have the Negative Terminal tied to earth ground (metal water pipe in ground, ground rods, ground plates). Plus, lead acid batteries will take "excess voltage and current" and gas (hydrogen and oxygen generation)--So lead acid batteries do have a method to "manage" excess energy to a degree (other battery chemistries like many Lithium Ion types do not).

Our retired forum founder has said, from his experience, that lightning strikes were far more likely to take out the AC output of an AC inverter than the DC input.

I would suspect that the carbon tracks are more likely from dirt/dust/humidity accumulation (always the issue between forced air cooling with little dust control vs the more expensive sealed unit design) or the possible "real bug" that got in the controller and shorted out some leads with their body?????

-Bill