IMO,
load over current might represent batteries that are too low, and trying to draw more than your controller can put out
load short circuit could mean a short in the wires going to the
battery, or a
battery that has failed
external wiring error-??? did you change anything when you set it up for the winter?
I would disconnect from everything and check battery voltage, if low manual charge, if ok, reconnect
solar and see if error goes away check all wiring for loose,burnt connections