Solar and batteries will be extremely expensive if you have no other backup but you could probably get to 80% quite cheaply with solar and around 12h of storage.
Geography absolutely matters since seasonal dips in solar generation is basically impossible to fix cost effectively with storage at more northerly latitudes as storage only makes financial sense when you can cycle it daily rather than yearly.
The contiguous US is much further south than Northern Europe so it has an easier time of it. But you ideally want wind too since it is anti-correlated with solar.
Geography absolutely matters since seasonal dips in solar generation is basically impossible to fix cost effectively with storage at more northerly latitudes as storage only makes financial sense when you can cycle it daily rather than yearly.
The contiguous US is much further south than Northern Europe so it has an easier time of it. But you ideally want wind too since it is anti-correlated with solar.