President Donald Trump, during his meeting with Congress on Tuesday, floated the idea of having his Southern border wall covered with solar panels.

Trump suggested that he could build a wall “40 to 50 feet high and covered with solar panels,” according to a report from Axios.

The energy generated from the solar panels could be used to pay for the cost of building the wall, Trump intimated, according to three sources in the story.

It is unclear how serious the president was about the proposal, but he appeared eager to discuss progress for the project.

“The wall will be a great help, and it will happen; believe me,” Trump said to reporters after the meeting.