Do Solar Panels Need Cleaning After A Rainstorm?

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Solar energy is rapidly becoming a cornerstone of our efforts to combat climate change and transition to sustainable energy sources. As solar panel installations adorn rooftops and fields around the world, a common question arises: Do solar panels need cleaning after a rainstorm?

Rain is often considered nature’s way of cleansing, but does it truly render solar panels spotless and efficient? In this blog, we’ll explore the science behind solar panel cleanliness after rainfall and decipher whether regular cleaning is necessary to ensure optimal energy production.

The Rainfall Effect on Solar Panels

Rainwater, in theory, should clean solar panels by washing away dust, dirt, and debris that accumulate over time. The reality, however, is a little more difficult. When raindrops hit solar panels, they can dislodge some surface dirt, but they may not remove stubborn grime or bird droppings effectively.

Additionally, rainwater isn’t pure; it contains minerals and pollutants from the atmosphere, which can leave residues on the panels after the water evaporates. Over time, these residues can form a layer that obstructs sunlight and reduces the efficiency of the panels.

Factors Influencing Cleaning Needs

Several factors determine whether solar panels need cleaning after a rainstorm:

Location: Areas with high pollution levels or surrounded by trees are more prone to dirty rainwater and, consequently, dirtier panels.

Type of Module: Different types of solar panel modules have distinct cleaning requirements. Monocrystalline modules are more sensitive to dust and dirt accumulation, necessitating more frequent cleaning compared to polycrystalline ones. However, it’s essential to periodically inspect polycrystalline modules for signs of dirt buildup.

In areas prone to dust storms or frequent storms, establishing a regular cleaning routine is crucial due to significant dirt accumulation. Additionally, if trees or large objects cast shadows on the modules, reducing efficiency, regular trimming is necessary to prevent dirt buildup.

Angle and Tilt: Solar panels installed at an angle or with a tilt are less likely to accumulate debris, as rainwater can easily slide off the surface. Flat panels are more susceptible to residue buildup.

Frequency of Rainfall: Regions with frequent rain may experience a more consistent cleaning effect compared to arid areas where rain is scarce.

Type of Dirt: The nature of the accumulated dirt matters. While loose dust might wash away, sticky substances like bird droppings often require manual cleaning.

Age of Panels: The cleaning requirements of solar panels are influenced by their age. Older panels are more prone to dirt and debris buildup due to wear on their protective coating. Regular cleaning is essential for all types of solar panels to ensure efficient performance and longevity.

Energy Efficiency Goals: If you aim for maximum energy efficiency, regular cleaning might be essential to ensure optimal performance.

The Efficiency Debate

Studies and experiments have been conducted to determine the impact of dirt and debris on solar panel efficiency. Research suggests that even a thin layer of dust can reduce energy output significantly.

A study by the University of California, San Diego, found that panels in their experiment that hadn’t been cleaned for 145 days lost about 7.4% of their efficiency. While this loss might not seem drastic, it can accumulate over time, leading to substantial energy wastage.

The Economic Aspect

Apart from efficiency, the economic considerations also play a role. Cleaning solar panels can be labor-intensive, especially for large-scale installations. However, the cost of cleaning should be weighed against the potential increase in energy production. In many cases, the additional energy generated by clean panels can offset the cleaning costs, making it a financially viable investment.

Research For Solving Problem Of PV “Soiling”

Researchers examining the panel and trying to fix a dusty issue. Research on PV “soiling” is still underway at the National Renewable Energy Laboratory (NREL), with the goal of developing patentable technologies to tackle the issue and mapping out the areas where soiling causes the most problems.

How Often Should Solar Panels Be Cleaned?

There are numerous factors that influence how frequently solar panels should be cleaned, but in Las Vegas, homeowners should clean their solar panels twice or three times a year. This should eliminate dust that has accumulated throughout the year, as well as pollen, which can be abundant in the spring.

They should also clean their solar panels after a dust storm or if bird droppings or other debris are found on them. Homeowners may want to clean more frequently depending on their circumstances, especially if they reside in new developments on the outskirts, near active construction, or large motorways.

The traditional belief had been that rainstorms were sufficient to clear all solar panels of dust, but a 2009 Google study seemed to upend this when they discovered a 30% boost in solar panel efficiency from cleaning.

However, further research, including one conducted in adjacent Tucson, revealed that dust had only a minor impact on solar panel efficiency, with cleaning resulting in a 1% improvement in efficiency.

Overall, it appears that rain may readily clean slanted solar panels, however flat panels require particular attention because the water simply evaporates and leaves build-up behind. Keep a watch on your utility bills, and if you detect a drop in production, it may be time to clean.

While rainwater does contribute to cleaning solar panels to some extent, it may not be enough to maintain peak efficiency, especially in areas prone to pollution or infrequent rainfall. Regular cleaning, tailored to specific environmental factors and the type of dirt involved, is essential to ensure the longevity and optimal performance of solar panel installations.

In the grand pursuit of a sustainable future, where every bit of energy production matters, keeping our solar panels clean and efficient is not just a matter of choice; it’s a necessity. Whether you choose to clean your solar panels yourself or hire professionals, the effort is a vital contribution to maximizing our renewable energy potential and, consequently, reducing our carbon footprint on the planet. So, after the next rainstorm, while nature does its part, a little human intervention might just be what we need to harness the sun’s power to its fullest.