Solar by itself can’t replace power generation needs no matter how cheap panels get without batteries. They can only offset some demand (same for wind). And we just don’t have the capacity to do grid scale batteries - we barely have enough for electric cars and we’re ramping that up as fast as we can.
The best time to have built a nuclear power plant was 20 years ago. The second best time is now. There just simply isn’t an alternative right now to drastically increasing fission capacity. China is doing it too. We have no excuse in the West aside from protecting oil interests.
The expense and time to build are not intractable issues - we just don’t do it enough to have economies of scale at play. Same goes for waste - without a double sided market nuclear is more expensive than it needs to be and legislation is blocking the second side of the market for spent fuel, which unlike fossil fuel emissions isn’t waste and can be reused for lots of applications instead of being buried in the ground (+ can be reused in breeder reactors)