The placement of solar panels on snow-covered mountains can boost the production of electricity when it is most needed — in the cold, dark winter.

Solar-power systems have long been﻿ hampered by a seasonal problem: the panels produce more energy in summer than in winter, at least in the mid-latitudes, where much of the planet’s population lives. To meet the goal of drawing 100% of energy from renewable sources, planners need to find ways to increase winter output.

Seeking to do so, a team led by Annelen Kahl at the Swiss Federal Institute of Technology in Lausanne analysed how the location and orientation of solar panels in Switzerland affected the panels’ energy production. The group found that output rose when the panels were sited at high elevations, where fewer clouds block the Sun, and in snowy areas where the snow reflects radiation onto the panels. Installing the panels vertically — which allows snow to slide off — enhanced their output even more.

In the depths of winter, panels placed at an optimal orientation on snow-covered mountains produced up to 150% more power than panels in urban locations, the authors found.