I'm a huge fan of solar, but until we have things like flow batteries, it's only a partial solution. (A flow battery would allow stockpiling charge during the summer to use in the winter.)
A: Nobody is proposing making the grid 100% solar all the time.
B: there is no need for new magical technologies to make energy storage feasible. There are dozens of different battery technologies that scale well, including iron-air and zinc-hybrid, and grid-scale pumped hydroelectric storage has existed for over 100 years but has never been prioritized because emissions have historically been an unaccounted externality of generation.