I'm a little confused... I never needed to load the generator onto the Rover before... but after the latest loop, now I suddenly can't leave Talos without loading a generator onto it? Now it requires power? Where did that come from? Nothing in the logs explain why that wasn't a thing but now it is?
There is a log explaining it. You see it while you're exploring Laurion and your character realises that you need some way to generate power. You don't need to load it into the rover though. It's purely optional. Your rover actually always has power, and always uses power, but it doesn't show you until you need to know about power. Since the rover has more than enough power to reach Laurion, you don't need to know until you find other uses for power (or somewhere further away to go).