The main function of a solar charge controller: adjust the power (amps) going into the battery to a correct value, normally the maximum the battery will accept, without overcharging, but charging it in the shortest possible time.
This is an essential part of the solar system, and should be carefully elected.
Different brands and types can be acquired, with different charge states, adjustable and non adjustable bulk, absortion and float voltages, with/and/or without automatic equalization modes, displays, temperature compensated models or Mppt controllers.
We do just about all of them and we will happily advise you on which one would suit you most