Trump’s solar wall plans need a clean view

US president Donald Trump’s suggestion to add solar panels to a wall he wants built along the border with Mexico may require some unexpected cooperation from America’s southern neighbour to make it a reality – Mexico will have to agree to help keep it clean.

Mr Trump said on Wednesday in Iowa that the structure, to combat illegal immigrants as well as drug traffickers, was already being planned. “We’re thinking of something unique talking about the southern border [with] lots of sun and heat,” he said. “We’re thinking about a solar wall so that it creates energy and pays for itself.”

The president said that this would ease the financial burden of payment, which he wants Mexico to bear, something Mr Trump promised during his election campaign. He said: “We’re working it out so let’s see. Actually to think of it, the higher it goes, the more valuable it is.”

The Mexicans have repeatedly said that they have no intention of financing the scheme. Mr Trump says that Mexico will pay for it eventually. However, he may now also have to work out how to persuade them to clean it too.

According to Frank Wouters, a UAE-based renewable energy strategist and consultant, if the wall is built with solar panels on top, the mirrors will need to be positioned to receive the most amount of sunlight during the day – which for northern hemisphere countries, including the US, means facing them to the south. Regular cleaning is needed to ensure that the efficiency of the panels do not decline.

“Please consider that with a south-facing wall, the cleaning will have to be done from the Mexican side,” said Mr Wouters, who has also helped lead solar power projects in the UAE.

Another consideration – which is a point that developers in the UAE know all too well – is that power produced by solar photovoltaic (PV) technology has become cheap.

Mr Trump’s vision is, in contrast, expensive – with panels mounted on top of heavy infrastructure. Selling the power generated by the solar wall may not produce enough revenue to make it viable.

The cost of electricity generated from solar PV is now almost a quarter of what it was in 2009 and is set to drop another 66 per cent by 2040, according to Bloomberg New Energy Finance. “By then a dollar will buy 2.3 times as much solar energy than it does today,” it said in a new report. In addition, solar is already as cheap as coal in the US.

“Solar panels are very cheap now so I’m not convinced the revenue that is generated would come close to what is needed to pay for a wall,” Mr Wouters said.

“It looks like the proposed wall includes a great deal of materials and adding cheap solar on top of an expensive support structure means that solar is only going to be a marginal contribution.”

But Mr Trump insists: “History is written by the dreamers and not the doubters.”