[jillesvangurp]

Rtgs are quite common already indeed and will likely be a part of the solution. But it's a stretch to call nuclear the only contender. Cables are a perfectly valid way to move power around from areas that do get solar exposure. And there are plenty of ways to create batteries or store energy. It might even be possible to use resources on the moon to build those (e.g. a heat battery would be doable).

The key limitation is going to be transporting stuff from earth. Solar panels have a key advantage here: they are pretty light and easy to deploy. There's no wind or weather that will dust them over. And per launch, you can move some significant amount of power generation.