BTW MPPT controllers usually switch to PWM mode (uses Isc - I short circuit) for lower charge rates which is another reason for a larger fuse, might even reach full amps under the right conditions, probably for a limited time.
I have a switch, no fuses on my 3x serial panels. And a 60A switchable CB, Blue Seas I think - but independent unit that isn't installed in a breaker box. No need for a breaker box. PLUS DC switching under load is much more intense on contact arcing than AC. DC breaker boxes and CBs are expensive and not found in hardware stores.