Solar Panel Cleaning: Why It’s Important & How to Do It Right

Dirty solar panels can result in up to a 25 percent decrease in energy production.

Where every kilowatt-hour (kWh) of energy makes a difference in your home's production and use, a 25% loss is significant.

When you purchase solar panels, the estimated output of your system accounts for "unavoidable losses due to soiling." To compensate for this, many solar owners add more panels later—when regular cleaning could help maintain efficiency.

We’ll walk you through the "why" and "how" of solar panel cleaning so you can maximize efficiency and protect your investment.

Do I Need to Clean My Panels?

Your location, terrain, and weather conditions determine how often you should clean your panels. If you live in a desert, a wooded area, or a highly polluted area, you’ll need to be more proactive.

Before taking action, check with your solar provider to see if your contract includes cleaning or maintenance services. If you lease your panels, the solar company that owns them should handle cleaning and maintenance at no cost to you.

What Is Making My Solar Panels Dirty?

Solar panels accumulate various types of debris, including:

• Bird droppings
• Pollution grime
• Dirt
• Dust
• Ash from wildfires 
• Pollen
• Fallen leaves
• Ocean salt 

When these materials cover your panels, they block sunlight and prevent the solar cells from operating at peak efficiency.

If you clean your panels only once or twice a year, you may want to consider more frequent maintenance.

Will Rain Keep My Panels Clean?

A common misconception is that occasional rain is enough to clean solar panels.

Heavy rainfall can help clear off debris, especially if it happens regularly. However, light rain can be worse than no rain at all—it can harden dust and dirt onto panels instead of washing them away. Rain can also introduce pollen, further reducing efficiency.

Which Cleaning Method Is Best?

Choose a cleaning method that increases panel productivity without costing more than the energy savings it provides. Be mindful of how your approach may affect your panels and their warranty.

DIY (Do-It-Yourself) Cleaning

Before attempting DIY cleaning, review your solar contract, warranty, and manufacturer’s instructions. The last thing you want is to void your warranty while trying to save money.

Keep these tips in mind:

• Power off: Solar panels should not be cleaned while active, so check your manufacturer's specifications for turning off the electrical currents produced by the panels and going into your home. 
• Scaling your roof: Climbing up onto your house can be dangerous depending on the height and angle of your roof, so use the appropriate ladder size and gear and exercise caution if you proceed.
• Water: Cleaning solar panels the correct way requires using soft water to avoid lime-scale buildup that can damage the panels. You can treat your hose water with a water softener if it's hard water. Deionized or distilled water works best as you treat your panels with a mild and non-abrasive detergent, vinegar, or solar-panel-specific cleaning solution. 
• Scrubbing: Using hard brushes can damage your panels, so use a soft scrubber or dishcloth instead. 
• Temperature: If you rinse panels with cold water on a hot day, the glass of the panels may crack as the water dries, so cooler days are better to minimize this risk. 

Professional Cleaning Services

Hiring a professional can eliminate the risks associated with DIY cleaning, such as falling from your roof or using improper cleaning methods.

The downside is cost. Depending on the frequency of service, you might spend more on cleaning than the energy savings it provides.

You can check Thumbtack's average cost calculator to find solar panel cleaning costs nationwide. On average, professional cleaning costs between $100 to $200 per session, though prices vary based on your panel array size and location.

Automated Cleaning Systems

Installing an automated cleaning system is a good choice if you're looking for a permanent solution to solar panel cleaning and you can afford yet another investment in your solar system. 

Benefits include:

• Reduced risk of panel damage.
• No need to turn off your system for manual cleaning.
• Lower chance of injury from climbing your roof.

Additionally, if purchased as part of a new solar system, an automated cleaning system may qualify for the 30% federal tax credit. Consult a tax professional to determine eligibility.

Products and systems vary by brand, but automated solar panel cleaning systems generally include a nozzle permanently affixed to the roof or panels. The connected housing system is located on the ground and includes the soap, water, and anything else necessary to operate the system. 

Automated cleaning systems typically include roof-mounted nozzles connected to a ground-level unit containing soap, water, and necessary components.

One such system, RST CleanTech Solutions, keeps panels clean using minimal water and no soap. With only a yearly filter change required, the system can be controlled via an app.

Control What You Can

Over time, solar panel efficiency naturally decreases. That’s why most manufacturer warranties last 25 years.

While long-term efficiency loss is inevitable, keeping your panels clean ensures they produce as much power as possible throughout their lifespan.