fuses are rated for interupt current, interupt time, and arc interuption voltage. that is how much current before it trips, how long an overcurrent takes before it blows, and how high the voltage can be and still interupt the current and not sustain an arc thus not interupting the current flow.
AFAIK for solar panels, since most are used in houses and many are interconnected to the house power feed and power line there are spec's for the fuses to be used.
Now, when used with a trailer, likely another story. no line connection, no feed to the power grid.
Now I am by no means an expert on this application, but if it was me using a 15A auto blade type fuse and fuseholder I would feel comfortable.
BTW 14Ga wire is rated for 15A, 10Ga wire is rated for 30A in romex, higher in individual strands. The 10Ga gives lower voltage drop.