In our store we have 10AWG PV extension wires in lengths from 3ft to 100ft, these have MC4 connectors already crimped on to make life easy! On one end is a male MC4 connector and on the other end is a female MC4 connector.
The trick is if you have a wire run of say 30ft from your solar panel to your MPPT controller then you would order a 60ft length of PV extension wire. By cutting it in half you then have 2x30ft lengths with MC4 connectors to go at the panel end and bare wire to run into the MPPT controller. One of the 30ft lengths will be for your positive wire and the other will be your negative wire.
The alternative would be to buy a length of plain PV extension wire, a pack of MC4 connectors, the MC4 crimping tool and crimp on your own connectors. Not an impossible task but something that can be avoided.
The wiring sketch below helps show how the PV extension wire and other key components come together.
