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