Solar cables, extending to the basement, which type?

I’ve 10 solar panels on the roof, connected in two series of 5 panels, connected to my Goodwe inverter. I want to change the setup, put a MPTT instead of the Goodwe, the MPTT will be installed in the basement, together with the batteries. For this I need to extend the cables for about 12 meters extra. Apart from the thickness of the cables (which can be calculated using the Victron tool) what is the best way to extend these cables? Suggestions on how to address this?

Mc4s connections and proper solar cable.

You basically make an extension lead or buy one if you don’t want to spring for the proper crimpers too.

As an example.