Breakers may not be correctly marked for capacity. I had that very problem with a 30 amp, which would trip at 23.3 amps.
For 500 watts of panels I would not use either a breaker or a fuse between the panels and the controller. I would use a DC rated switch.
Look up cloud lensing effect.
The old school was to over size the charge controller by 25%.
If the panels are brand new they may do 125% of their rated output in the first month. Add lensing effect and output may be a lot higher that expected.
My choice would be a larger capacity controller. Tristar 60 MPPT would be an excellent choice.
