How dust accumulates on solar panels, and how LONGi Hi-Mo 5 Anti-Dust modules prevent it

Solar PV system underperformance is a constant concern. The best operations and maintenance (O&M) strategies deploy a combination of monitoring and on-the-roof personnel, but solar panels are out in the elements. Even the most robust O&M plans can’t keep pace with everything Mother Nature – and human beings – throw at them.

The NABCEP CE Conference in Raleigh, N.C., showcased a great example – not in any presentation, but the yellow film covering my car leaving the conference.

Pollen! In one day’s time, it covered everything within miles. This reminded me of a video I saw at RE+ 2023: a demo of LONGi’s Hi-Mo 5 Anti-Dust solar panels. Watch how quickly the snow melts off of it.

Valuable PV production is gained that typically would have been lost under a blanket of snow. But what does that have to do with the solar panel’s anti-dust properties? A lot, according to LONGi’s research.

Anti-dust R&D

Anti-dust modules and anti-soiling solar panel coatings are not new, but LONGi’s research and testing indicated that more could be done. The “2022 LONGi Global Customer Satisfaction Survey Report” shows that 80.13% of residential and C&I scenarios are troubled by module dust accumulation. Anti-dust innovation for solar panels would not only boost base-line PV system performance, but also reduce the frequency of module cleaning, saving on O&M costs.

The power generation gain of the Hi-Mo 5 Anti-Dust solar module will vary by region and month due to factors like dust accumulation and rainfall, but LONGi’s long-term outdoor testing (seen in video above) showed a max power generation gain of 6.08% in a single month, and a monthly average of 2.4%. LONGi also estimates the Hi-Mo 5 Anti-Dust design saves about at least 1 cleaning per year.

How does it work? Why does that snow sliding off explain everything? Much of it actually comes down to the frame.

Here is more than you’ll ever want to know about dust, its impact on solar panels, and how LONGi’s new anti-dust modules are built to mitigate it.

Dust accumulation explained             

The accumulation of dust is mainly caused by atmospheric dust precipitation, which is either environmental (weather and climate influences, such as dust and haze) or man-made causes (emissions, traffic dust, etc.).  The shape of dust sedimentation — horizontal or sloping dust sedimentation — also factors in, as the loss of power increases with the height of the dust sedimentation.

Dust accumulation on modules leads to three major effects:

  • Sheltering effect: Dust accumulation can block the incident light, resulting in weaken photoelectric effect and power loss of PV modules;
  • Corrosion effect: The acids and alkaline substances in the gust accumulation are easy to corrode the coating and glass, forming “rainbow patterns”, reducing the incident light, and power loss of PV modules;
  • Temperature effect: Dust accumulation causes the operating temperature of the module to rise, forming hot spots, resulting in reduced cell life and sheltering effect.

Dust impact on PV performance

  • In LONGi laboratory conditions, 90 mm dust sedimentation is able to cause 23.39% power loss.
  • U.S. Renewable Energy Laboratory data show that dust accumulation can lead to a loss of efficiency of 7%, even up to 50% in areas of high ash accumulation, and a loss of 20% for household use.
  • Testing also showed a relationship between bottom cell shading ratio and power loss: When the bottom cell shading ratio is 90% the module power degradation is 44.7%.

Key dust accumulation scenarios

  • Small roof slopes: The roof slope of general residential and C&I (logistics, manufacturing and processing industries) scenarios is small, so the dust, pollen and snow accumulation does not easily slip off.
  • C&I sites with more particulate matter. High-emission enterprises such as the chemical industry, nonferrous metal industry, and paper industry have more suspended particulate matter in the production environment, so the dust accumulation of modules is large;
  • Low cleaning frequency: Any site, such as colleges and universities, that need to reduce contact with the outside world due to protection and safety requirements, and often prefer low cleaning frequency.
  • High difficulty in cleaning: Functional buildings such as sunlight houses, photovoltaic car sheds, and household roofs often have weak roofs or no roofs at all, making manual cleaning difficult.

Designing Hi-MO 5 Anti-Dust product

longi anti-dust Module frame example

Hi-MO 5 Anti-Dust product is specially designed for dust accumulation scenarios in residential and C&I customers.

The frame design is crucial because it allows dust sedimentation to naturally slide off with rain. Compared to the conventional frame design, the anti-dust accumulation frame design has a short edge border that is as high as the glass surface. As shown in the Figure 3,allowing the dust accumulation on the module to slide off naturally under the influence of gravity and rainfall, and avoids the formation of the dust sedimentation at the bottom of the module which blocks the incident light and affects the power generation performance of the module.

anti dust frame

This design not only effectively reduces the power generation lose caused by dust accumulation obstruction, corrosion, and hot spots, but also reduces the frequency of module cleaning, saving operation and maintenance costs.

The short frame not only ensures reliable loading through the patented frame structure and material selection standards, but also ensures reliable encapsulation through the new gluing process and encapsulation technology, providing all-around protection for anti-dust modules.

At present, the anti-dust design product is only available in 54 version, the product referred to as Hi-MO5 54HPBF, with a maximum power of 420W, a maximum conversion efficiency of 21.5%, a module size of 1722mm x 1134mm, and a module weight of 20.8kg.

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