At times of the year when there are blizzards, I seriously doubt the rest of solar installations in the US are going to be running anywhere near capacity.
First: So? PV is so cheap overcapacity isn’t unreasonable.
Second: My first visit to the USA, I saw people surfing in Asilomar on Christmas Day/Boxing Day and it remained warm and sunny throughout my stay in California, yet a few days into that trip New York was suffering a blizzard that Trump was trying to argue disproved global warming: https://en.wikipedia.org/wiki/Early_2014_North_American_cold...
At times of the year when there are blizzards, I seriously doubt the rest of solar installations in the US are going to be running anywhere near capacity.