The 12,000 solar panels floating on Portugal's Alqueva reservoir are the size of four soccer pitches. The panels can produce 7.5 gigawatt/hours of electricity a year, equivalent to supplying 1,500 families or about one third of the power needs of nearby Moura and Portel. Built by EDP, the country's main utility, Europe's largest floating solar park is part of Portugal's plan to cut reliance on imported fossil fuels. In 2017, when EDP installed a pilot floating solar project on the Alto Rabagan hydro dam, it became the first in Europe to test how hydro and solar power could be complementary. "It's the way the world, and Europe in particular, has to go to reduce the dependency of carbon fuels, of course, reduce the strategic dependency and of course reducing the prices of the pool markets," says Miguel Patena of EDP. Not only do they produce cheaper power, but floating panels on dams free up valuable real estate and can hook up to existing links to the power grid. Excess power generated on sunny days can be stored for use on cloudy days or at night.