If panels are 20% efficient at turning solar energy into power (as has been the case in lab tests), then we could feasibly cover a land area about the size of Spain and power the entire Earth renewably in 2030. Just taking a corner of Utah and Nevada could power the entire United States with solar power, Tesla CEO Elon Musk pointed out during his talk at the Université de Paris Panthéon Sorbonne.

And yet solar only provided .39% of energy in the US in 2015.

But Lyndon Rive, the CEO of SolarCity, said solar is going to start gaining real traction in the next few years.

"The way we build power plants today won't happen in five years time," he said. "I'm absolutely sure thats the case."