The how and why of solar panel cleaning

More and more industrial units are installing rooftop solar panels to be more self-sufficient for their energy needs, and meet their renewable energy goals. Edward Dsouza, President, ServiceMASTER India and subject matter expert Prem Prakash dissect the maintenance of solar panels for optimum efficiency.

Why solar panels need regular cleaning

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Flying dust/dirt, tree leaves and debris, and bird droppings can soil solar panels. The consequences of not cleaning them regularly are poor radiation due to surface sheathing (7% annually), lower power generation (by 15-20%), compromised return on investment and reduced panel life. On the other hand, regular cleaning increases radiation and power generation, enhances solar efficiency and improves the life of the module.

A cleaned module will have approx. 0.5% lower energy production every year due to aging, whereas an uncleaned module will cause a 7% reduction in energy production. Panels should be cleaned at least twice a year.

Seasonal variations

Summer:

• Risk of fire due to hotness of the panel and dry atmosphere.
• To reduce the risk of fire due to dry leaves/grass/papers, panels to be cleaned frequently or SOS basis.
• Dry cleaning/low pressure blower cleaning to save water.

Winter:

• Snow and ice is a winter threat. Cleaning of snow and ice from panels sometimes needs a filament heating process.
• Conventional cleaning processes sometimes damage/scratch the panel surface.

Monsoons:

• Rain is followed by high-speed winds which can cause panel damage due to tree branches flying and falling on the panels.
• Dry leaves accumulation on the panel is another challenge.
• Average power output gets reduced during monsoons due to reduced sunlight. The losses can be minimized by keeping the panel clean.

Spring:

• Pollen gets accumulated and forms a thin layer on the panel
• This absorbs most of the photons, making the surface less radiating.
• Pollen is sticky in nature and becomes thick soon.
• Pollen cleaning to be done more frequently than normal cleaning.

How to curtail risks of rooftop panel cleaning

• Trained and medically fit staff, tested negative for fear of heights.
• Adequate PPE/safety gears and supervision.
• Presence of a safety officer/first aid/primary health care representative/paramedic.
• Cleaning equipment stationed firmly on the rooftop.
• No high-pressure air/water cleaning.
• Zero possibility of human walk on panels.
• Avoidance of manual cleaning.
• We prefer to use a camera to monitor the level/quality of cleaning.

Equipment for solar panel cleaning

• Robots: Module cleaning, Driving, AI-enabled
• 7.2 metre telescopic wet panel cleaner using soft brush and adjustable suction pressure.
• Adjustable pressure dry cleaner
• We prefer not to use a lot of water, and go chemical-free/use soft chemicals to avoid damaging panels.
• Sometimes due to hard stains, non-abrasive mild soap/detergent/diluted Isopropyl alcohol can be used on a minimal requirement basis. Otherwise, water is sufficient if the panel cleaning is done periodically.

Reducing water usage

• Use of robotic dry cleaning with adjustable pressure suction, which requires less water.
• Use of anti-soiling coating to reduce 50% of water usage.
• Self-cleaning panels, which are still under test.
• Keeping surroundings clean of vegetation and soil.
• Adhering to wind direction protocols while installing panels.