> All is missing is the political will, not technology.
I hate this phrase and it is something both the "only renewables" and "only nuclear" camps make. Neither technology is developed enough to effectively take over the grid (plus one source is terrible for energy security, but renewables is a bit diversified, though you're arguing purely solar).
The technical problem here is that we do not yet have the battery technology to sustain the grid. These are not the same batteries that we have in our cellphones. You cannot quick discharge common lipo batteries without starting a fire. But including batteries completely changes the cost structure and environmental impact which is why many suggest baseload technologies like hydro (nuclear would fit in here as well but yes, it is costly). This also creates a drastically different cost function for places like the American Southwest vs the American Northeast.
There is missing political will, but there is also missing technology (and missing political will to fund the development of that technology).