I installed a Waytek CB Switch on the controller output. Protects against a short and can manually turned off. Because of the high voltage of serial panels I installed a A/C disconnect switch on the panel input, no fuse.
Some controllers like my Morningstar suggest disconnected the panels before the battery and the opposite when connecting.
More than 2 parallel panels should have a fuse for each panel probably located in the combiner box. If a panel were to short then the other panels could w/o fuses cause it to overheat and even catch on fire.