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Why Do Solar Panels Need Cleaning?



No matter where you live in the U.S., the solar panel industry is booming, and government plans for promoting renewable, cleaner energy sources only indicate that it's going to expand even more. 

According to studies by the Solar Energy Industrial Association (SEIA), the solar panel industry has experienced an average annual growth rate of 49% each year over the past decade. While California still leads the way as having the largest market share, solar is now a market in all 50 states, with Texas and Florida leading in the most rapid growth. 

On January 1, 2020, California passed a solar mandate that requires solar panels on all new single-family residences and multi-family residences up to three stories high. Solar energy advocacy groups are pushing for similar legislation in additional states -- particularly Nevada, Colorado, New Mexico, Texas, Minnesota, Michigan, North Carolina, Maryland, Pennsylvania, and Massachusetts -- by 2022. Whether solar panels are big in your area yet or not, they likely soon will be. 

As window cleaners and pressure washing/soft washing contractors, there is a huge, growing market for solar panel cleaning that is still largely untapped. It's a natural add-on service using equipment you likely already have.  

How Do Solar Panels Work?

Solar Panels are made up of numerous, small units called “photovoltaic” cells. (“Photovolaic” is the term for converting sunlight to electricity.) The simplified explanation of how they work is to allow the particles of light (i.e., photons) to knock electrons free from atoms, which in turn generates electricity.

For a solar panel to work correctly, it has to let in sunlight. That’s the reason that most industrial solar panel fields are located in sunny locations, primarily in the Southwest and along the Southeast coast, where the weather is consistently sunny. While solar panels don’t work as well on cloudy days, they also don’t work as well if they are dirty.

Another important fact is that solar panels have individual cells that are wired in a series. The same principle applies to solar panels as the old-fashioned Christmas lights – i.e., if one is not working efficiently, it affects the whole strand and cuts the efficiency.

You can also think of the cells like pieces of a pipe, and solar power is the water flowing through the pipe. Depending on the type of technology used in the solar panel, even if one cell is dirty (or in the shade), it can work like a blockage in the flow. The output of that particular string of cells may be significantly reduced.

Solar panel owners can actually monitor and measure how much efficiency is being lost due to dirty panels. However, unless they are properly educated on the need for cleaning solar panels, they may not recognize why their efficiency is going down. It’s up to the professional cleaning industry to inform and educate customers about the need for solar panel cleaning.


Why Do Solar Panels Need Cleaning?

Solar panel manufacturers generally argue that rainfall is enough to keep solar panels clean. But that’s basically like saying rain is enough to keep your car clean. 

  1. Solar panels are often located in areas that don’t get a lot of rain, so even if the rain would actually clean the panels, they aren’t getting rained on. 
  2. Just like with windows, rain and tap water can leave spots and stains that reduce the panel’s ability to absorb sunlight.
  3. Beyond rain and tap water, there are other issues. Yes, dust is a big contributor to dirty solar panels, but it’s not the only one. For one, there’s the problem of bird droppings. Another issue may be exhaust debris, especially if the panels are near an airport or even a busy intersection. If the panels are near a food processing plant, they may get an oily residue. Lots of trees around? Expect tree sap.
  4. Some solar panels are placed at a slight, gradual slope. Depending on the panel's frames, rainwater may run downward on the panel, then build into a stagnant pool because the water is trapped by the frame. As the water evaporates, the dirt and dust residue is left behind, blocking the sun and reducing the 
  5. One thing to watch for is solar panels that are placed at a gradual slope. Depending on the module frames, rainwater may run downward then build into a stagnant pool at the bottom of the frame. When the water evaporates, dust residue is left behind, which acts like shade and reduces the solar cells' energy production. , 

Again, all of this is good news for you as a professional cleaning contractor, but you must educate customers on the need for proper cleaning.




Who Needs Their Solar Panels Cleaned?

Residential Solar Panels

These are a potentially an easy sell – especially if you’re already there cleaning windows or washing their home, deck, roof, driveway, or patio. Residential clients are likely to pay more per panel, but the amount of work will be less than with commercial or industrial clients. You will most likely need to educate residential customers about the need for cleaning to produce better energy results.


Commercial Solar Panels

Commercial clients such as grocery stores, shopping centers, schools, etc., are installing carports with solar panels, as well as some commercial clients adding to their buildings. The nice thing about about the carports is they are generally easy to access, and again, can either be a nice add-on service or a good way to get your foot in the door for other cleaning opportunities. These customers most likely monitor their efficiency more closely than homeowners and will notice when their panels are not working properly and need to be cleaned.



Industrial Solar Panels

Solar Panel Farms are comprised of large, industrial power-producing fields of solar panels. These groups typically have a set budget for cleaning and contract with a maintenance company. This is generally the most difficult market to get into. 



How Should Solar Panels Be Cleaned?

This is the great news for window cleaners! 

Solar panel cleaning uses a water-fed pole and purified water, just like you use for window cleaning, again making it a natural add-on service.

We also offer specialized rotating brushes that make solar panel cleaning faster and easier.