Solar Connectors 8 AWG and 10 AWG MC4 connectors

Look for a inline wire reducer that you can use to transition the MC4 connector wire to the 8AWG cable right at the solar panel.

Did your pre-wire package include a roof mounted combiner box? If the run from the panels to the roof combiner box is short, you may be able to get away with using the MC4 cabling to the box and then the 8AWG from the combiner box to your solar controller & batteries without a significant voltage drop.