I don’t think we get even 100 days of sunshine here.
Clouds don’t completely block sunlight. The “solar insolation” figure is based on actual readings averaged over several years time, including cloudy days, rain, angle of the sun in each season, etc. There are many solar projects in Michigan. At the present retail price of $5/watt of panel, they would never pay for themselves, but they DO produce electricity year-round. At $0.30/watt they would pay for themselves in less than ten years.