Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain
the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in
Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles
and JavaScript.
Covering canals with solar panels helps the panels to operate more efficiently — and the shade helps to keep the canals’ water from being lost to evaporation.