One of the biggest challenges facing the PV panel industry is performance. Companies are testing combinations of silicon and perovskite, microscopic algae, flexible materials, and other innovative technologies to make panels more efficient. They're also pushing extreme quantum efficiency to produce more electricity. The other challenge is cleaning the outermost layer of these panels.
There are apparent enemies, like snow. Logically, if snow covers a solar panel, it won’t work. But while snow isn’t a problem in many parts of the world, dust is. Cleaning the panels is challenging, but one company may have found the solution: an electrodynamic layer that removes dust from solar panels.
Cleaning Solar Panels Without Water
It may seem strange, but dust is one of the biggest enemies of solar panels. Several studies show that a dirty panel performs much worse than a well-maintained one. In 2016, experts published a study that compared the performance of a panel full of dust with another that the team cleaned daily for five months. The first was 29.76% less efficient than the second one.
The researchers claimed that dust accumulates in certain areas and causes permanent defects. Other studies have looked at average incident solar radiation and found losses of 1%, translating into an 8% to 15% reduction in yield. In this analysis, other elements, such as feces, were found in addition to dust. The team also discovered that solar power plants suffer an annual efficiency loss of 40%.
Cleaning solar panels with water is one solution. However, the problem is when the water only reaches specific areas. For example, sometimes the panels are on the roof of a house. As such, some companies have developed robots to solve this problem, and others clean the panels with a tractor equipped with a water tank and a roller. Still, experts may have found a more straightforward and optimal solution given that tens of millions of gallons of water are needed to clean the panels each year, creating a black water hole.
Boston University startup Sol Clarity has been experimenting with a panel cleaning system consisting of an electrodynamic add-on film. It doesn’t look complicated to apply to panels since it’s a thin, transparent layer that works with a small electrical charge.
The Electrodynamic Screen (EDS) system charges dust particles with static electricity. Once it's captured the particles, EDS “sweeps” them up using an electromagnetic wave.
Depending on the requirements, EDS consists of two or four screens and the power supply layer. The standard assembly consists of a transparent adhesive applied directly to the solar panel and a dielectric layer of ultra-thin flexible glass with transparent electrodes printed with silver nanowire ink.
Sol Clarity has experimented with other materials, such as aluminum-doped zinc oxide, as a transparent conductive ink. Still, the stability of the electrodes was poor compared to the silver nanowire ink. The company aims to achieve high reflectivity, which it got with the chosen material. These electrodes are inside the EDS, so they don’t reflect the sunlight that reaches them but bounce the light reflected from the panel’s surface.
The video below shows how EDS works:
The company notes that 1 Wh of energy is enough to clean 10.7 square feet of fan panels, equivalent to 500 photovoltaic modules per day using 1 kWh of electrical power. The system takes one minute to perform the cleaning process, and in various tests, it has shown that it can recover more than 95% of the energy capture losses due to dirt.
Because of its characteristics, companies can use EDS in flexible modules. One of Sol Clarity’s goals is to make its system cost-effective, so the company is looking to place these layers in large power plants and produce them by screen printing, an industrial process.
The next step is to further test the system. Sol Clarity has installed EDS in plants in the Atacama Desert in Chile and near a beach to test its durability in a salty environment. Of course, the goal is to get funding.
This article was written by Alejandro Alcocea and originally published in Spanish on Xataka.
Images | Cambridge, Sol Clarity
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