I will be traveling over there in February and was curious as to whether I would be able to charge my phone via the train system or if I would need to bring a solar/ external battery for this purpose?
Don't expect Japanese trains to have power outlets. On Shinkansen, only trains called "N700" have power outlets. But they are not used in every train on Shinkansen line. So you have to know which one is using N700. It's difficult for a visitor.
Other trains do not have any outlet.