Trump proposes solar wall along Mexican border

US President Donald Trump has suggested that his proposed wall along the Mexico border could be covered with solar panels. 

At a rally in Iowa, Trump said the panels would not only offer cheap energy but would also help to pay for the wall.

According to him, the proposal is his own, saying: "Pretty good imagination, right? Good? My idea."

However, covering the wall with solar panels has been included in designs submitted by companies.

During his election campaign, Trump pledged to construct a wall along the Mexican border to keep out illegal immigrants as well as drug trafficking. 

"Pretty good imagination, right? Good? My idea."

Trumps: "We're thinking of something that's unique, we're talking about the southern border, lots of sun, lots of heat. We're thinking about building the 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?" 

He added: "Solar wall, panels, beautiful. I mean actually think of it, the higher it goes the more valuable it is."

More than 200 companies are reported to have expressed an interest in response to an invitation from the Department of Homeland Security (DHS) for the proposed wall. 

The DHS told BBC that 20 firms have been shortlisted.

Trump has insisted that Mexico will have to pay for the bill, but Mexican President Enrique Peña Nieto has dismissed the idea.