Where I live, the number of sunshine hours in December varies between 6 and 49 (years 1981-2010), average is 26 hours. That means a bit under one hour per day on average, but sometimes there's a week when the sun doesn't show up at all.
Not really a great place to use solar when you need most electricity, although on the average we get more sunlight hours than Central Europe. We just get them when there is less need for electricity.
