SSE is celebrating 75 years of operation at Sloy Power Station, one of Scotland’s most iconic hydro schemes and the UK’s largest conventional hydroelectric facility.
Officially opened on 18 October 1950 by Her Majesty Queen Elizabeth, the 152.5MW station generates around 130,000MWh each year, enough to power approximately 48,000 homes.
Sloy can reach full output in under five minutes, providing crucial flexibility to the national grid.
Built between 1945 and 1950 under the Hydro Electric Development (Scotland) Act 1943, the project was considered a remarkable post-war engineering achievement.
Water from Loch Sloy travels through a 3km tunnel under Ben Vorlich before descending four high-pressure steel pipelines to the generating hall at Inveruglas Bay on Loch Lomond.
Recognised by Historic Scotland for its bold modernist design, Sloy forms part of SSE’s 1.5GW hydro fleet, which produces over 3TWh annually, enough to power more than one million homes.
SSE Renewables director of hydro Robert Bryce said: “Sloy Power Station is a remarkable achievement of Scottish engineering, reflecting the skill, dedication, and determination of the people who built and then operated it over the past 75 years. Beyond its impressive scale and design, Sloy has consistently delivered fast, flexible, and reliable renewable power to the grid, helping to meet peak demand and support communities across Scotland.
“The station remains a vital part of SSE’s hydro fleet and will continue to play an essential role in enabling the UK’s transition to a net zero energy system, providing dependable, low-carbon electricity for generations to come.”
SSE head of heritage Gillian O’Reilly said: “For 75 years, Sloy has been at the heart of Scotland’s hydro heritage, built and maintained by generations of dedicated engineers and operators. As we celebrate this milestone, we honour the people whose skill and commitment have kept the station running and delivering clean, reliable energy. Their work ensures Sloy continues to make a real difference, supporting communities and helping the UK transition to a net zero future.”
Construction of Sloy began in 1945 and was completed in 1950, with workers facing extreme Highland weather – only 21 dry days were recorded in four years.
Its 357-metre-long, 56-metre-high buttress dam raised Loch Sloy by 155 feet, creating capacity for 36 million tonnes of water.
The build involved over 1,700 blasting operations and 180,000 tons of rock excavation.