A study was undertaken for the Australian grid.
https://reneweconomy.com.au/a-near-100pct-renewable-grid-for...
It basically found that you can get close to 100% relatively easily with minimal storage (5 hours average demand).
The issue with getting over the mid-90s and to handle 100% is that you need to cater for the edge-cases (conditions that may occur 1-2 times per year max).
Either way from memory, LCOE (in $/MWH) for grid-scale solar is around 50-60, adding storage brings costs up to 80-120. Nuclear is in the range of 200-300+, so even with storage the economics of renewables are better with costs trending downward. Especially when you can build them and scale them up quickly (compared to 10-15 years of nuclear builds).