The problem of fluctuating Earth bound solar energy collection and supply due to night/ day/ weather cycles and fluctuations only exists whilst the geographic area used is relatively small.

If all solar power is pooled in a worldwide grid, then the average power generated becomes a constant. As one area goes into shade, another comes out of it, so fluctuations are ironed out.

Then, ensuring adequate supply to meet demand involves just making sure that at any time, there is more than needed to maintain the energy needed by consumers at any single point in the grid.

If not enough, just add more panels, anywhere in the grid.

Batteries are no longer needed after that point, solving the often quoted environmental issues of having batteries in the system.