Imagine that we've improved the level quality, affordability, and ease of use of photo-voltaic solar, and it's use is widely distributed in the USA. We've improved the grid for power distribution, we increase wind, hydro, geothermal sources for 24-hour generation and create a storage network to the point where fossil fuel generation is only needed for, say, 20% of our energy needs, and peak/backup needs.
Everyone is happy, bliss abounds.
Would such a system be vulnerable to a natural disaster? If there was another Krakatoa event, with an equivalent amount of ash thrown into the atmosphere, how much, percentage-wise, of a reduction in solar intensity would we see, and for how long?