No DC to DC converter is needed, thats what the mppt charge controller does
connect to the battery first, when the controller sees it is on a 12v system
it will use thee correct 14v charging, some older controllers need you manually select the settings via switches,
a 12v battery is not 12v, it is over 13v at full charge and 12v is 50%
that is the improvement of 100+ years of battery technology
you don't charge a battery at 12v, it takes 14+v to do it right
thats 280w output, input must be greater
335w is about perfect for a 20amp controller
you will need different controllers for the different panels
the different operating voltage of panels is too great
the output side of the the separate controllers/panel systems
can go to the same battery bank
the panels will ever 'see' each other, never be connected together
the controllers need to have the same voltage settings for best operation
same charge voltage same float voltage
