Its Scottish Water Horizons Ltd subsidiary received 45 expressions of interest in the contract and 17 companies submitted their bids in the battle for full tender.
It was eventually awarded to four contractors – Absolute Solar & Wind Ltd, FES Ltd, Saliis Ltd, and Styles & Wood Ltd, who will now develop, design and install solar panels – also known as photovoltaic (PV) cells – at Scottish Water works across the country.
In an effort to take advantage of falling technology costs, and to provide some security from the insecurity of the PV market, the framework will run for an initial period of one year with two further one year extensions.
Scottish Water has reduced its base electricity consumption by more than 5% since 2010.
Total carbon emissions have fallen by 18% since 2006-07 and renewable energy generation has doubled since 2013 to over 50GWh – the same as powering 50 million washing machines.
Scottish Water now has 26 sites with hydro turbines that harness the natural flow of water through pipes to produce electricity.
It also generates renewable power through 18 wind-powered sites, 24 solar farms and two biomass plants.
And a food waste recycling plant near Cumbernauld, owned by the subsidiary, generates enough bio-gas to power 2,000 homes.
Andrew Macdonald, Head of Scottish Water Horizons Ltd, said: “This investment further demonstrates our commitment to reducing energy costs and ultimately keeping bills as low as possible for customers.
“Through use of technologies such as solar panels, several of our water works can now generate at least all – and in some cases more – of the energy they need to operate.
“Not only does this benefit Scottish Water but it contributes to national renewable energy targets.
“We’re pleased to be working with experts in the sector to improve our provision of renewable energy and help maintain Scottish Water’s place as one of the best value providers of water in the UK.”