This article does a poor job of explaining why there is going to be a problem and relaying the point of the study.

To model the grid and power infrastructure into the future, assumptions must be made about where the power is derived.

The article fails to provide the basic factors contributing to the problem, even though the study itself does a fine job.

So California wants to legislate electric cars. That means higher demand in a shorter period of time. Meanwhile Calofornia wants to legislate 'clean' or 'green' energy production. If that's a design limitation then the outcome is a shift away from what is the normal situation we face with energy use today.

Energy use at night with a highly solar derived power system requires significant storage and efficiency loss. Charging all of California's electric cars in 2035 will be a demand that far surpasses anything seen today. These things that we see causing rolling black outs and brown outs, like AC use spikes in summer will be a blip compared to the consistent vehicle charging demand.

Interesting, though, the electric vehicle adoption basically negates the storage problem if a parallel infrastructure of charge back from homes at night is implemented. Charge your car at work in the sun and use it to power your home at night.