Solar is more effective in low temperatures than in high temperatures. Also northwest US is max around 49 degrees north, which is around Paris in Europe and it is normal to have solar much farther north in Europe
Solar panels are extremely popular in Stockholm, 59 degrees North and less than 1,000 km from the Artic Circle. During winter, they produce very little electricity, admitedly... but they work well in all the other seasons so they still significantly reduce electricity consumption.
