With a pulse width modulated pwn charge controller the worst case amps flowing to and from the controller are the same so the fuse and wire size can match.
Fuse between solar panel and charge controller.
There are three different locations that we recommend installing fuses or breakers.
With 10a fuse you could deliver 120w before it breaks.
Maxi fuses provide circuit protection typically between a charge controller or small inverter and a battery bank.
10a car fuses are fine for that.
The load terminal of the solar controller can be connected with a dc power device which is the same working voltage as the rated voltage of the battery and the controller supplies power to the load with the battery voltage connect the positive and negative poles of the load to the load terminals of the controller there may be voltage on the load side please be careful to avoid a short circuit when connecting the load a fuse should be connected to the positive or negative cord of the load.
Jst ensure you use appropriate wire gauge.
First between the charge controller and battery bank second between the charge controller and solar panels and third would be between the battery bank and inverter to determine the fuse size needed between the charge controller and battery bank you simply match the amperage rating on the charge controller.
As an example blue sky recommends a 60 amp fuse breaker for their solar.
Class t fuses are used as circuit protection between a battery bank and an inverter.
Mppt charge controllers on the other hand are able to both lower the voltage and increase the current flowing between the controller and the battery bank so the exact size wire and fuse size must be recalculated or obtained from the charge controller manual.