You realize this is like the US saying "lets give money to Mexico to build all of our solar power there (it is closer to the equator and thus would provide more even output throughout the year and would make more econimical sense) and just rely on them selling it to us forever at a nice price as they are a friendly country at this very moment". Or even better would be the countries further south and build a sea cable on international waters so anyone with a sub can go and cut it to fuck with you,
From a national security perspective relying on such a vital resource as electricity on someone else is just plain stupid. I realize most countries are in such a relationship with oil/gas countries at the very moment but I think the goal should be to lessen this kind of relationships not increase them.
So basically one would need a lot of overcapacity to be able to produce and store enough power during the summer to last over the winter. But in places like California sure go full solar as it actually works all year around.