A new study published in the journal Renewable Energy uses data from the state of California to demonstrate that no blackouts occurred when wind-water-solar electricity supply exceeded 100% of demand on the state's main grid for a record 98 of 116 days from late winter to early summer.
Yes — solar panels work on cloudy days. They produce 10–70 % of their rated output depending on cloud thickness, because they use diffuse (scattered) light, not just direct sunbeams.