Located on the northeastern shore of Loch Lomond at Inveruglas (Argyll & Bute), the Sloy Power Station is the largest conventional hydro-power station in Britain, generating 152.5 MW of electricity. Opened in 1950 by Queen Elizabeth, the Queen Mother (1900 - 2002), the station forms part of the Sloy-Awe Hydro-Electric Power Scheme. Water descends through tunnels and pipes from Loch Sloy, 2½ miles (3.5 km) to the west northwest, passing through the southern slopes of Ben Vorlich. Four 2-m (6.5-foot) diameter high-pressure steel pipes drop down to the station each supplying a separate generator set. The head is 277m (909 feet).
Sarah Boyack, Environment Minister in the Scottish Government, re-opened the power station in 1999 following a £113-million refurbishment which involved renewing the generation plant, new cabling and pipework, and internal decoration. This extended the life of the station but also increased capacity through the use of modern turbine and generator technologies. Three of the original four 32.5 MW generators were upgraded to 40 MW. The station is responsive to the demand for power; it can be operating at full load within five minutes of starting. At full load, nearly 4.54 million litres (1 million gallons) of water pass through the turbines every minute. Electricity is exported to the national grid via 132kV overhead lines from the nearby Sloy substation.
In 2010, permission was granted to develop a 60 MW pumped storage scheme to run in conjunction with the existing station. This will involve pumping water back from Loch Lomond to Loch Sloy during offpeak periods as a means of storing excess energy. Pumped storage had been proposed in the 1940s as part of the original scheme at Sloy, but never built.
The station is operated by Scottish and Southern Energy.