Less Dirt, More Sun: PV Cleaning Solutions For Spotless Efficiency

With the sun generating more energy than humans will ever need, solar panels are a crucial source of green energy and play a pivotal role in the decarbonization of our economies.

But they, too, have vulnerabilities: among them, the fact that they must be positioned outdoors in warm, often dusty parts of the world. And when dust, pollution, bird droppings and the like settle down on panels, they can reduce the efficiency of the panels greatly, causing substantial losses of energy. A recent study found that up to 5 grams of dust and pollution can pile on solar panels in dusty regions in just two weeks. If panels are cleaned every other month, the dust can cause energy losses of up to 35%.

The problem often requires owners of solar panels to clean them regularly, in what can be a delicate, time-consuming chore. But some innovations are also trying to find technological solutions for the problem. From self-cleaning surfaces to drones to ventilation, here’s the lowdown on the most brilliant solutions in the pipeline.

A group of British researchers from the University of Warwick, for example, have proposed using compressed air to kill two birds with one stone: cleaning solar panels while also cooling them.

• After using a mathematical model to study how dust sticks to the surface of solar panels and how air could remove it, their proposed solution entails installing a tank of air regulated by a valve and a compressor powered by the solar panels to pump the air through a series of nozzles at regular intervals.
• The flow of air from the nozzles attached at the edge of panels was found to cool the panel and carry away the dust, improving their power output between 30% and 36% depending on the airflow intervals.
• In their study, researchers outlined that it would be feasible to produce a constant airflow over the panels because the costs for producing it would be higher than any efficiency gains.
• Researchers say that the solution is affordable because all components are low-cost products.

In the U.S., a group of scientists at the University of Washington, meanwhile, have developed a self-cleaning surface for solar panels.

• Their solution is to place the solar panel onto a vibration stage and equip it with patterns of Anisotropic Ratchet Conveyors (hydrophilic curved rungs on a hydrophobic background, also known as ARC).
• In an experiment, the scientists applied water droplets to a dirty solar panel through a pipette. Vibration transported the droplets through the module, making them reach the contaminated areas. Researchers claim that droplets could even defy gravity to climb uphill, provided that the solar panel was tilted at an angle smaller than 15 degrees.
• The tension force of the panel surface, together with the water hydrodynamic shear force, caused the droplets to remove the dust particles as the droplets slid over the module.

Another idea is to resort to electro-dynamics to prevent the dust particles from landing on the solar panels in the first place. This is the approach taken by Superclean Glass, a company founded by Alexander Orlov, a Professor of Materials Science and Chemical Engineering in the College of Engineering and Applied Science at Stony Brook University in New York.

• Superclean Glass developed a patent-pending electro-dynamic shield that repels dust from solar panels. Through electrodes, this technology creates electric fields that sweep away dust and particles from solar panels.
• The company claims the solution could save to 95 percent of the energy that gets lost on panels placed outdoors in dusty regions, leading to energy savings worth millions of dollars
• Superclean Glass says its system could also save billions of liters of water typically used to clean the modules.

ENGIE EYE

ENGIE’s CleanRight innovation can help design the most appropriate cleaning strategy for the power plant.

• Using a mix of soiling sensors and cutting-edge algorithms, CleanRight can monitor soiling losses, their evolution and their distribution within the plant.
• With those insights, CleanRight produces recommendations about which part of the plant to clean and when. It assesses the cost – both in financial and ecological terms – of each leak and cleaning operation, weighing them against each other to minimize costs. It also produces suggestions about how to clean each part to further drive down cleaning costs.
• ENGIE has calculated that utility-scale power plants can save up to 200,000 dollars per year via improvements in their cleaning systems designed through intelligent business decisions enhanced by CleanRight.

But cleaning inefficiencies can waste money, time and water beyond the energy sector, and improved strategies can benefit a wide range of other systems, too. That’s why ENGIE Lab CRIGEN Drones & Robots Lab has also developed an innovative solution to clean urban lighting through drones.

• The introduction of LEDs in urban lighting has greatly reduced the number of cleaning operations required by urban lighting, lamps still require a great deal of cleaning to comply with regulations and to maintain lighting quality. And, of course, street lights remain hard to reach and prone to cumbersome manual cleaning operations.
• The Drones & Robots Lab has proposed a more efficient, cheaper way of doing this through an autonomous mobile robotic platform with a telescopic mast equipped with a motorized cleaning brush. Through hardware and software solutions developed by the Lab, the innovation can identify and reach street lamps autonomously and clean urban lighting with flat, horizontal or tilted optics.

In Chile,  ENGIE has have invested in the  company Inti-Tech and accompanied them in their process of continuous improvement and market positioning. Inti-Tech now offers worldwide a solid solution for the cleaning of solar panels in both centralized and decentralized plants. Its "as a service" solution is composed of robots, automated, without the use of water, managed via Internet, and with a zero emissions operation. Considering the number of solar plants today and in the near future, it is easy to see the strategic importance of this solution for the energy sector.