Link is to a 2 day old youtube clip:

     This week, Imogen put this to the test and visited the Alqueva Reservoir in Portugal to see EDP's remarkable 5MW floating solar farm. Working in combination with its Hydroelectric Dam neighbour, this project shows the enormous potential and scalability of floating photovoltaics. 

For some context, a number of countries have floating solar panels arrays across reservoirs, eg:

    Floating Solar UK is a subsidiary of Ciel et Terre International.

    Sheeplands farm is the first site in the UK to Install Hydrelio floating Solar PV in 2014.

https://www.floatingsolarpanels.co.uk/

It's a double benefit (done well) solar power and reduced evaporation.