At 60-70 degrees latitude? Maybe for a week in June.

Even if such a thing were feasible on buildings, the ferries navigate so the cells cannot be simply tilted south.

Well no, not inside the arctic circle, not as much for most of the year.

Also, the steep mountain sides occlude the sun for large parts of the day - especially during winter[1].

[1]: http://www.tinderangel.no/wp-content/uploads/2017/07/IMG_018...