Stories tagged heliostats


A mirror in the sky: Courtesy gualtiero

Here in Minnesota the days are finally getting longer and we’re getting more daylight each day. Residents in the Austrian town of Rattenberg are also grateful for the return of spring’s longer days. You see, Rattenberg gets no sunlight at all from late fall to mid-winter. The town was founded some 700 years ago and was uniquely situated between the Inn River and the Rat Mountains for protection from bandits. However, the same mountains that protected the town from bandits also leave it in shadows from November to mid-February as the sun never rises far enough on the horizon to shine directly onto it.

People in Minnesota sometimes get a little discomforted during the shorter days, some even suffer from Seasonal Affective Disorder (SAD), which is a mood disorder associated with depression episodes related to seasonal variations of light. I can’t imagine what it would like to live in a shadow for over three months of the year – knowing that there is sun, but that it is blocked by a nearby mountain. Residents of Rattenberg have been leaving the town for sunnier locations and the town’s population is declining.

To help its residents get some light during the winter the town is working with Bartenbach Light Laboratory to install 15 heliostats (giant mirrors that track the movement of the sun) about a quarter of a mile outside the town – and beyond the reach of the mountain’s shadow. The heliostats will reflect the sunlight to a giant mirror covered tower in the city, which in turn will reflect the light to small mirrors on buildings throughout the town, which then transfers the light to the streets. The heliostats and mirrors will be installed this August at a cost of around $2 million. The hope is that tourists, who frequent the town in the summer to purchase blown glass artwork the town is famous for, will now visit year-round, and that residents will no longer look to leave for sunnier locations to live.