It is assumed that solar power may attain 10 percent of global power generation by the year 2030, and possibly most of that will be situated in desert areas, where there is ample sunlight. However, the mushrooming of dust on solar panels or mirrors is already a major challenge for the people occupied in solar panel cleaning services in California. It minimizes the yield of photovoltaic panels by as much as 30 percent within a single month. So, frequent cleaning is necessary for such installations.
However, presently solar panel cleaning is expected to consume nearly 10 billion gallons of water every year. It’s sufficient to supply drinking water for almost 2 million people. Endeavors at waterless cleaning happen to be labor-intensive and may lead to irreparable scratching of the surfaces, which also minimizes efficiency. Recently, a team of researchers at MIT has designed a method of automatically cleaning solar panels, or the mirrors of solar thermal plants, in a waterless, no-contact system that could drastically minimize the dust problem, as they claim.
The novel system utilizes electrostatic repulsion to lead to the detachment of dust particles and effectively leap off the panel’s surface, without the necessity for water or brushes. To trigger the system, an electrode simply passes just above the solar panel’s surface, transmitting an electrical charge to the dust particles, which are then repulsed by a charge used on the panel only. The system can be automatically utilized with the help of a simple electric motor and guide rails along the side of the panel.
Although concerted efforts globally to devise ever more efficient solar panels, a tedious challenge such as dust can put a serious dent in the whole thing. Lab tests have confirmed that the drop-off of energy output from the panels occurs steeply at the very outset of the process of dust accumulation and can conveniently reach a 30 percent decrease only after a month without solar power cleaning in Chino or other locations. Even a 1 percent drop in power, for a 150-megawatt solar installation, may lead to a $200,000 loss in annual revenue. The researchers say that worldwide, a 3 to 4 percent depletion in power output from solar plants may incur a loss of between $3.3 billion and $5.5 billion.
Many of the largest solar power installations in the world are located in desert regions. Some are in the U.S too. The water applied to clean these solar panels with pressurized water jets must be trucked in from a distance, and it has to be extremely pure to prevent the leaving behind of deposits on the surfaces. Dry scrubbing is often used. However, it is less fruitful to clean the surfaces and may lead to permanent scratching that minimizes light transmission as well.
Water cleaning consumes nearly 10 percent of the operating costs of solar installations. The new system could minimize these expenses while enhancing the overall power output by providing more regular automated cleanings.
Other groups have attempted to develop electrostatic-based solutions. However, these have depended on a layer called an electrodynamic screen, using interdigitated electrodes. These screens may have major flaws that let moisture in and compel them to fail. Though they might be effective on a planet like Mars, where moisture is not a major challenge, even in desert environments on Earth this may pose a serious problem.
The newly developed system only necessitates an electrode, which can be a simple metal bar, to pass over the panel, assembling an electric field that conveys a charge to the dust particles as it goes. An opposite charge utilized on a transparent conductive layer only a few nanometers thick accumulated on the glass covering of the solar panel then repulses the particles, and by computing the accurate voltage to apply, the researchers could find a voltage range enough to overcome the pull of gravity and adhesion forces and force the dust to lift away.
Applying categorically prepared laboratory samples of dust with various particle sizes, experiments established that the process effectively works on a laboratory-scale test installation. The tests revealed that humidity in the air offered a thin coating of water on the particles, which proved extremely crucial to making the effect work. Experiments were performed at differing levels of humidity from 5 percent to 95 percent. As long as the surrounding humidity is more than 30 percent, you can remove nearly all the particles from the surface. However, as humidity reduces, it becomes difficult while cleaning solar panels in California.
Conclusion
Once you get to 30 percent humidity, maximum deserts will fall in this regime. Even those that are usually drier than that have higher humidity during the early morning hours, causing dew formation, so the cleaning could be accordingly timed.
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