Egypt’s self-cleaning solar panels shed desert dust

[CAIRO, SciDev.Net] Egyptian scientists have developed two nature-inspired technologies that use motion to keep solar panels free of desert dust, preserving their efficiency and cutting the costs of manual cleaning.

Drawing from the way tree leaves naturally shed dust and dirt, researchers at the German University in Cairo designed a self-cleaning system for lamppost-mounted solar panels, to tackle one of solar energy’s biggest challenges in arid environments — dust buildup.

When dust accumulates on panels, it forms an insulating layer that blocks sunlight and significantly reduces efficiency. Studies in the Middle East and North Africa have shown steep performance losses — from 17 per cent in six days in Kuwait to up to 66 per cent over six months in Egypt.

“About a month ago, the company developing the new design installed its first vibration-based self-cleaning panels in a residential complex in Cairo’s Fifth Settlement,” says Mohamed Salama Abd-Elhady, professor at the German University’s Faculty of Engineering and Materials Science.

“The early results are very promising and confirm our earlier research findings.”

The system uses a mechanical vibration mechanism that shakes off dust twice daily — once at noon and again at 3am, for about one minute each time.

In trials, conventional panels lost around 33 per cent of their efficiency after six weeks without cleaning, while panels fitted with the vibration system and an antistatic nano-coating lost only 12.9 per cent.

According to Hossam Mohamed, the engineer who founded the company commercialising the system, the key is the deliberate imbalance in the components.

A small electric motor with an unbalanced metal weight generates continuous vibrations, controlled by an electronic unit that sets the operating times. The system can run on power from the panel itself or a small independent battery.

“Residential complexes often pay companies to clean their panels regularly, which is a significant cost,” Mohamed explains.

“Our technology reduces the need for manual cleaning to once every two to four months, depending on local conditions and exposure to dust.”

Essam Tawfik El Shenawy, head of the solar energy department at Egypt’s National Research Centre, praises the innovation but questions the panels’ ability to withstand continuous vibration and the overall economic feasibility compared to manual cleaning.

Mohamed insists the system has been rigorously tested and calibrated to ensure the vibrations don’t damage the panels. Abd-Elhady adds that the savings could be substantial: cleaning a single lamppost-mounted panel can cost up to 200 Egyptian pounds (US$4) per month, meaning a complex with 200 lampposts might spend 40,000 pounds (US$800) monthly — a cost that could be significantly reduced with the new technology.

Wind power

The research team has also developed another version of the technology that eliminates the need for electric motors by mimicking how tree branches sway in the wind. This wind-driven self-cleaning system uses a flexible mounting structure that allows the panel to vibrate naturally as air passes over it. A rear spring returns it to its original position.

In a six-week field trial, panels with the flexible mounting lost only 5 per cent efficiency due to dust, compared to a loss of about 25 per cent in traditional fixed panels.

Abd-Elhady acknowledges that a big challenge with this system is that its performance varies with the seasons, with the wind-based system likely to be more efficient in winter when winds are constant.

But he adds: “Its performance will still be much better than relying on manual cleaning, both in efficiency and sustainability.”

According to Mohamed, the company is now expanding production of the system to meet growing customer demand.

He says the first product was well-received in a residential complex where it was installed and is now being supplied to another residential community in Egypt’s Giza governorate.

This article was produced by SciDev.Net’s Middle East and North Africa regional desk.