Solar panels on water canals seem like a no-brainer. So why aren't they widespread?

Back in 2015, California's dry earth was crunching under a fourth year of drought. 

Then-Governor Jerry Brown ordered an unprecedented 25 per cent reduction in home water use. Farmers, who use the most water, volunteered too to avoid deeper, mandatory cuts.

Brown also set a goal for the state to get half its energy from renewable sources, with climate change bearing down.

Yet when entrepreneurs Jordan Harris and Robin Raj went knocking on doors with an idea that addresses both water loss and climate pollution - installing solar panels over irrigation canals - they couldn't get anyone to commit.

Fast forward eight years. With devastating heat, record-breaking wildfire, looming crisis on the Colorado River, a growing commitment to fighting climate change, and a little bit of movement-building, their company Solar AquaGrid is preparing to break ground on the first solar-covered canal project in the United States.

“All of these coming together at this moment," Harris said. “Is there a more pressing issue that we could apply our time to?"

The idea is simple: install solar panels over canals in sunny, water-scarce regions where they reduce evaporation and make electricity.

A study by the University of California, Merced gives a boost to the idea, estimating that 63 billion gallons of water could be saved by covering California's 6,437 kilometres of canals with solar panels that could also generate 13 gigawatts of power. That's enough for the entire city of Los Angeles from January through early October.

But that's an estimate - neither it, nor other potential benefits have been tested scientifically. That's about to change with Project Nexus in California's Central Valley.

Solar on canals has long been discussed as a two-for-one