The pithy answer is “That’s why people build them in deserts.” However, electric grids need excess capacity spread across large areas for when demand spikes and stuff breaks. Luckily peak demand doesn’t line up with wide scale rain as AC demand falls.

Also, PV unlike concentrated solar does produce power during storms it’s just significantly less than normal.

Reminder that other "low value energy demand" is easy bufferable - one can easy heat water in a isolated ground tank with excess solar and use that storage in winter.