EL-MU400SP Waterproof MPPT Solar Charge Controller.
I couldn't test this one because everyone both units Amazon sent me were broken, but lots of other YouTuber's recommend it. You can't control the current, but if your solar panel is 200W or less, that shouldn't be an issue. It can take an input voltage of 24-85V; voltage 24-85V; output power 400W.
Purchase on Amazon.open_in_new