Rjukan does not get any direct sunlight between September and March. The mountains on both sides of the valley are too high and too close. For the factory workers who lived here from the early 1900s, winter meant months of shadow.
The idea of using mirrors to reflect sunlight into the valley was first proposed in 1913, the same year the town was being built. Sam Eyde, the founder of Norsk Hydro, thought it was impractical and built the Krossobanen cable car instead, so workers could at least get up to the sunlight.
A hundred years later, in 2013, the mirrors finally became reality. Three computer-controlled heliostats were installed on the mountain wall at 742 metres elevation, about 450 metres above the town square. Together they cover 51 square metres and readjust their angle every ten seconds to track the sun. The reflected beam creates a spotlight of sunlight on the town square below, covering about 600 square metres. A semi-circle of wooden benches marks the illuminated area.
It works best in winter, which is the whole point. In summer the mirrors still operate at reduced power, but the town gets direct sunlight by then anyway. The effect in the dark months is surreal: a patch of warmth and light in a valley that should have neither.
The idea of using mirrors to reflect sunlight into the valley was first proposed in 1913, the same year the town was being built. Sam Eyde, the founder of Norsk Hydro, thought it was impractical and built the Krossobanen cable car instead, so workers could at least get up to the sunlight.
A hundred years later, in 2013, the mirrors finally became reality. Three computer-controlled heliostats were installed on the mountain wall at 742 metres elevation, about 450 metres above the town square. Together they cover 51 square metres and readjust their angle every ten seconds to track the sun. The reflected beam creates a spotlight of sunlight on the town square below, covering about 600 square metres. A semi-circle of wooden benches marks the illuminated area.
It works best in winter, which is the whole point. In summer the mirrors still operate at reduced power, but the town gets direct sunlight by then anyway. The effect in the dark months is surreal: a patch of warmth and light in a valley that should have neither.