The default for players when using their Force Powers will be as Dark Side users as that is the way the Sith train their students. This means that to use Light side pips on a roll they need to flip a Destiny point and then suffer strain equal to the amount of Light pips they wish to use. This will generate conflict equal to the amount of strain suffered.
If a character can reach 30 Morality or lower they will use the Light side for powering the Force.
Morality is reversed for Sith users.