Is Solar Panel Cleaning Necessary?

If you have a solar energy system or solar photovoltaics (PV) array at your facility, you know how much money solar panels can save you on your electricity bill if they’re working the way they should be. What you may not realize is if your solar panels are dirty their performance levels will drop. Dust and dirt buildup can affect the energy output of the solar panels.


Do solar panels need cleaning? 

Yes, your solar panels need to be clean in order to operate at optimal performance, but as we will discuss later, depending on your location, relying on rain for cleaning solar panels may be enough. 

In a study published in Renewable and Sustainable Energy Reviews, researchers found accumulated dust on solar panels affects the amount of energy delivered from the array on a daily, monthly, seasonal, and annual basis. 

After a three-month test on solar panels located in an industrial area near a railroad in Boston, Massachusetts, scientists found an average of 1% of power loss from dust accumulation, with the highest degradation at 4.7%. 

In another study done in California that looked at about 200 solar panel arrays, annual losses due to dirty solar panels ranged from 1.5% to 6.2%.


How to clean solar panels?

You have three options when it comes to cleaning solar panels. You can do it yourself, hire professional cleaners, or install a self cleaning system.

Doing it yourself can be a tedious undertaking depending on where the panels are located and how difficult it is to get to them.

A self cleaning system is one of the best ways to ensure your solar installation is working the way it should be. A self cleaning system takes care of the cleaning for you, can clean more often so your panels are always free from dust and debris, uses less abrasive materials and methods as traditional cleaning methods, and can increase your energy production by up to 30%. Learn more solar panel cleaning tips here.


Should I hire someone to clean my solar panels?

In some cases, you may need to hire a professional solar panel cleaning service to clean your solar installation. This might be the safer and easier option. 

Professionals have insurance and more than likely can guarantee their cleaning services, unlike your maintenance staff. Your solar panels may be in a hard-to-reach spot or on a roof that is too high, steep, or otherwise dangerous for your staff to tackle. A self cleaning system provides a more economical option when you start to add up the costs of hiring professional cleaners, which means a quicker ROI for you. 


How do you clean solar panels yourself?

Your maintenance staff or cleaning crew will need a hose, a bucket of soapy water with a mild soap like dishwashing detergent, a soft scrubber or sponge, and a squeegee. Do not use pressure washers, harsh chemicals, or abrasive scrubbers, which can damage your solar panels and solar photovoltaic cells. 

  1. Fill your bucket with water and a little soap (don’t put in too much).
  2. Gently hose off your panels.
  3. Soak your soft scrubber or sponge with the soapy solution and use it to clean off the panels.
  4. Hose off the panels again, making sure to get rid of any soap residue.
  5. Repeat until the panels are clean.
  6. Squeegee the panels try, trying your best to not leave any streaks.


Does self cleaning solar panel technology really work?

Something else to consider is an automated solar panel cleaning system. Instead of periodically cleaning your panels, you can fully eliminate soiling losses by investing in an automated system that can clean your panels weekly. 

Keeping your array clean often can increase your energy production by up to 30%! Sometimes a cleaning crew can cause damage to your panels through their use of abrasive cleaners or hard water, which can void your warranty on the installation. 

We’ve discovered a fully automated cleaning system that has a patented feature of purifying the water used to clean your panels from limescale. The water from the system is applied through drip irrigation technology at a low pressure and at night, avoiding potential cracking of the solar panel glass if cold water is applied during warmer temperatures. 

On top of that, the system has an app that allows you to remotely clean your array and notifies you of faults.


Does rain clean solar panels?

It depends on the area and environmental factors of where the solar panels are located. In the above-mentioned study of California solar installations, after a slight rain, the efficiency of some of the solar panels declined sharply, while the performance of some of the panels improved. 

According to the researchers of the study, a rainfall of at least 20mm is needed to adequately clean solar panels and ensure optimal solar output.

The National Renewable Energy Laboratory’s (NREL) Best Practices for Operation and Maintenance of Photovoltaic and Energy Storage Systems report finds heavy rains can completely clean solar panels, while light rains can have the opposite effect or make soiling and dirt buildup even worse.

NREL suggests solar arrays in areas where there are frequent heavy rains don’t need to invest in a cleaning regimen, but special conditions require a cleaning schedule. According to NREL, sources of soiling that may indicate the need for frequent solar panel cleaning include:

  • Construction dust
  • Pollen
  • Bird populations
  • Diesel soot (i.e., bus depots)
  • Industrial sources (i.e., cooking or manufacturing)


How important is it to keep your solar panels clean?

Having clean panels ensures your solar array is working at maximum efficiency and maintains its life. 

Taking a few steps to ensure your solar panel system is in top shape allows you to reap the benefits of solar power for years to come! 

Have questions about a solar PV system installation or want some guidance on the best self-cleaning solar panel technology? Please reach out to one of our experts so we can help.

Vanessa Peng

Vanessa Peng

Vanessa Peng is the Marketing Coordinator at WattLogic. As a former television news reporter, Vanessa enjoys creating written and video content for WattLogic and has an interest in environmental issues.