Sloy/Awe hydro power scheme

The 152.5MW Sloy Power Station and Dam is the largest conventional hydro power station in SSE’s existing hydro power fleet. Construction on the scheme began in 1949 and was completed in 1951, becoming the first hydro scheme to be developed under the North of Scotland Hydro-Electric Board. The scheme celebrated its 70th anniversary in 2021.

The existing power station is fed from Loch Sloy, just four kilometres away but, crucially, over 277 metres higher than the power station. An adapted pumped storage scheme would take excess energy from the grid and use it to pump water from Loch Lomond to the upper Loch Sloy where it would be stored before being released to power the grid when wind output is low and customer demand is high.

If progressed for development, the proposed pumped hydro storage project at Sloy would become SSE’s second such flexible electricity storage scheme in development, alongside the company’s plans for its proposed £1.5 billion Coire Glas scheme between Fort William and Inverness in the Scottish Highlands.

Power stations

Power stations	Capacity (MW)	Gross head (metres)	Average annual output (million units)	Year started
Sloy	152.5	277	130	1950
Sron Mor	5	46	7	1957
Clachan	40	294	82	1955
Allt-na-Lairige	6	249	19	1956
Cruachan*	440	365	c700	1965
Nant	15	172	36	1963
Inverawe	25	36	106	1963
Kilmelford	2	111	12	1956
Loch Gair	6	109	19	1961
Striven	8	123	22	1951
Lussa	2.4	116	9	1952

*No longer owned by SSE Renewables

Major dams

Major dams	Type	Length	Height	Completed
Sloy	Massive buttress	357	55	1951
Allt-na-Lairige	Pre-stressed gravity	425	24	1956
Shira (main)	Round headed buttress	725	45	1959
Shira (lower)	Concrete gravity and earth fill with concrete core	305	18	1956

If you're interested in our hydro heritage, visit Pitlochry Dam Visitor Centre, located beside our Pitlochry Power Station in Perthshire, Scotland.

The visitor centre showcases the rich history of hydro electricity in the north of Scotland and how it transformed all our lives. On display are a number of fascinating artefacts that show how generations of homes have been transformed by electrical appliances.

Visitors will meet the visionaries, such as Tom Johnston, who saw the untapped potential of hydro power in Scotland as well as hear the stories of the Hydro Boys and Tunnel Tigers who lived – and sadly in some cases died – building the schemes.

Pitlochry’s ‘fish ladder’ was integral to the design for the hydro electricity scheme in the early 1950’s. Thousands visit the Dam to see the salmon swim to their breeding grounds up river and now everyone can learn the secrets of that incredible journey.