Solar Array Will Light A Long Norwegian Winter

Gaustatoppen, which occludes the sun in Rjukan valley five months of the year.
Gaustatoppen, which occludes the sun in Rjukan valley five months of the year.

It’s pretty dim in Rjukan, Norway, for five months of the year. Between the capital of Oslo to the east and the famous Norwegian fjords on the west coast, the town of about 3000 lies in a narrow valley at the foot of Gaustatoppen, the highest mountain massif in Telemark County. Winter sports attract many seasonal tourists, and the area is Northern Europe’s top spot for ice climbing, having 190 frozen waterfalls.

But the mile-high peaks and Rjukan’s northern location mean that the sun, which is visible at night in the summer months, starts disappearing behind the mountains in September and doesn’t fully return to the village until sometime in March. Seasonal affective disorder there may even outrank frostbite as the most serious health complaint….

This winter, things are going to look a little different in downtown Rjukan, thanks to a plan first proposed by famed Norwegian industrialist Sam Eyde around a hundred years ago. Eyde conceived of lighting the town during the shadowy months with mirrors on the mountains, but he lacked the technology to do it. He built a cable car instead to allow the townspeople a glimpse of the sun in the dark period of the year.

With the invention of helicopters, computers, and solar panels, Eyde’s initial dream is becoming reality this year. The heliostat installation is designed and has been funded for less than $1 million, mostly (80%) with private money.

A construction crew has felled trees to provide an uninterrupted line of sight from sun to mirror and from mirror to town. After laying a concrete foundation on the slope a quarter-mile above the village, they started installing three huge mirror panels flown in from Germany by helicopter several weeks ago.

The completed mirror assembly will measure about 540 square feet and will redirect the winter sun into the town center. It will illuminate an elliptical area over 2150 feet square. Solar power will allow a computer in the town hall to track the movement of the sun with sensors on the installation, calculate the best angle for the mirror to focus the spotlight, and adjust the array accordingly. Solar will also power the occasionally necessary mirror-washing.

Will the installation do its job? We won’t know until September, but despite the vaunted mischief of Norway’s imaginary trolls, the prognosis is good. The centuries-old Italian alpine valley of Viganella has had a similar reflected light arrangement since 2006.

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