Solar energy in Finland is used primarily for water heating and by the use of photovoltaics to generate electricity. As a northern country, summer days are long and winter days are short. Above the Arctic Circle, the sun does not rise some days in winter, and does not set some days in the summer. Due to the low sun angle, it is more common to place solar panels on the south side of buildings instead of on the roof. Mounting them vertically reduces the average output by 22% from mounting at a 60° angle.