"lack constant and predictable" We can solve this with batteries, which we have so far not been able to succeed in to do at large scales. There has been some small scale success with liquid batteries, using cheapish elements.
Which in theory is feasible to scale up.
Technically yes, economically difficult for most nations, if it's approached at this level.
Germany has had an interesting approach to solar, where they subsidized solar panels for homeowners. I think it is the smarter approach because you incentives individuals to go green, rather than trying to implement a top down solution.
And even so, we will need to keep power plants on call for redundancy and high load purposes.
