A snaking wall of solar panels has been attached to Switzerland's longest dam. The solar dam is helping the landlocked nation maximise its green energy production in the winter months. The Lake Muttsee dam, in the central Swiss canton of Glarus, is over 7,800 feet (2,400 metres) above sea level and is surrounded by snow-capped peaks - something that the team behind the AlpinSolar project says is a key benefit.