"Yes, we will build a wall," he told a crowd in Cedar Rapids, Iowa. "We have to stop the drugs from flowing in."
"I will give you an idea that nobody has heard about yet," he said. "The southern border. Lots of sun, lots of heat. We are thinking about building a wall as a solar wall. So it creates energy. And pays for itself."
"And this way, Mexico will have to pay much less money. And that's good. Right?" quipped the president, whose initial pledge to make Mexico pay for the wall has met with stiff resistance from America's southern neighbor.
"Pretty good imagination, right? My idea!"
The US administration put out a call for proposals several months ago for the construction of the border wall, one of which -- submitted by a Las Vegas businessman named Tom Gleason -- involved using solar panels.
Under pressure from Democrats, the US Congress has so far refused to commit funding to the project, agreeing only to finance maintenance on existing parts of the border fence.
The real funding battle will play out starting in October, when 2018 budget negotiations begin in earnest.
(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)