[DanielHB]

Even if fusion was widely available and affordable you will still want other sources of power for peak demand. Like fission nuclear reactors, they will be good for base power-load. Fusion reactors won't be able to spin up and down based on demand willy nilly.

Given most demand is during the day and early evening solar is a good complement, but the more mixed renewals you have in your grid the better it will tolerate shocks in supply and demand.