PWGB Update: Opportunities in Residential Solar Panel Cleaning

Written by Terri Perrin | Published August 2024

Regardless of where you operate your pressure washing business in North America, there is one thing we all have in common—the sun shines on all of us. True, it shines more brightly in some regions than others, but we are all blessed with the beauty of the sun. Whether that sunshine translates into opportunities to add solar panel cleaning to your service offerings is another story. In most cases the market niche for cleaning service providers is residential or small commercial solar panel installations. Those big solar field installations that you drive by aren’t really on our radar.

Solar panels are typically an attractive investment for homeowners (and some businesses) who are tired of paying high electricity prices, have roofs with decent sun exposure, and want to reduce their environmental impact. However, industry experts advise that the amount of sunshine is not an automatic qualifier for solar energy acceptance. States must actively invest in developing a solar industry and promote interest in solar energy with funding and incentives for residents to get on board the solar bandwagon.

According to the National Renewable Energy Laboratory, the U.S. had about 3.9 million photovoltaic solar power systems installed at residences at the end of 2022. That number has grown by an average of 37 percent annually since Congress passed a federal tax credit for solar power in 2005.

Another report, published online by Statista.com in December 2023, explained that “solar is becoming an increasingly important energy resource in the United States, accounting for 45 percent of new electricity-generating capacity additions. Of the total solar capacity installed in the USA in 2022, over 20 percent corresponds to residential installations.”

So, recognizing that pressure washing service contractors in many regions will start seeing an ever-increasing number of both free-standing and rooftop-installed solar panels when called to wash a home, it’s time to focus on how to properly clean them.

For some “boots on the ground”—or should we say “boots on the ladder”—advice, we spoke to Josh Tillman, owner of Squirt’s Pro Wash in Glennville, GA. Tillman is relatively new to the pressure washing industry, having started his company in 2021. However, he has a penchant for doing thorough research and is a firm believer that it’s best to arm yourself with information rather than make mistakes or lose business. As a result of doing his due diligence before expanding services, and the fact that he is based in a small town with limited house washing opportunities, the scope of his service offerings grew rapidly to include cleaning solar panels, oxidation removal, paint prep, industrial jobs, and more.

“Generic house washing is still the meat and potatoes of my business, but I soon found myself taking on jobs that other service providers didn’t want to do,” explains Tillman. “In addition to doing my research, I also work closely with my local LANDA distributor, L&H Industrial Supply in Savannah, GA. They offer amazing guidance and support. I now clean solar panels, and so much more, with complete confidence. I’ve worked hard to establish a reputation as an exterior cleaning service, not just a power washing company.”

 

 

 

 

 

 

 

Geographical Considerations

Challenges (and opportunities) will vary with accessibility to the rooftops due to the lay of the land, roof pitch, and the type of roofing materials used in different regions of the continent. Although the southern and southwestern parts of the United States provide more opportunities than northern-tier states, solar panels are everywhere. Tillman explains that the grime buildup you’ll encounter will vary significantly by region and includes everything from moss, mold, and mildew to residue from vehicular traffic, industrial plants, and more. The first step is to learn what grime issues you may face in your geographic region.

Today’s Homeowner Television conducted a survey about residential solar power use. They learned that solar friendliness is a complex topic, as many factors impact a state’s solar industry. Their study revealed that California, Massachusetts, Arizona, Hawaii, and Nevada ranked among the highest for residential solar installations. North Dakota, South Dakota, Alaska, West Virginia, and Nebraska ranked among the lowest.

Typical Job

“The most important thing to recognize is that while solar panels may take a beating from the sun, they are quite delicate,” warns Tillman. “This is no time for high PSI pressure washing or use of harsh chemicals. I like to compare roof washing and solar panel cleaning to washing a ‘regular’ car versus washing a Porsche Carrera. Be gentle!

“Also be aware that you are not trying to achieve a 100 percent spot free clean as you would for windows,” adds Tillman. “Your job is to improve the efficacy of the solar panel by removing residual buildup and to protect the integrity of the solar panels as well as the aluminum housing/ trim. Both the panels and the trim are reactive to the application of sodium hypochlorite (bleach). And remember that solar panels also have electrical wiring that you need to be aware of.”

Before you start any solar panel cleaning project, Tillman stresses that you need to ask the following three materials science questions:

• What are the solar panels made of? If you thought glass, think again! The U.S. Department of Energy reports that crystallinesilicon (c-SI) accounts for 84 percent of solar panels in the USA. Other materials include cadmium telluride, copper indium gallium (di)selenide panels, and thin-film amorphous silicon. The surface of each solar panel is covered in a protective coating. The use of chemicals will likely result in this coating being stripped off, compromising the silicon panel.

• Why do they need cleaning? Learn what type of contaminants or residue you are dealing with.

• What product will be most effective? Ask the homeowner if he or she knows what their solar panels are made of and research what is safe to use on that material. Never use harsh chemicals or bleach. (More info on chemicals and application is below.)

Reaching For The Rooftops

Regardless of the type of installed roofing materials, homeowners in general are wary of having contractors walk on their roofs. This is due to the fear of damaging the shingles or shakes as well as a fear of lawsuits in the event that a contractor falls off the roof. They are even more wary when they have potentially tens of thousands of dollars’ worth of solar panels installed up there. So don’t walk on the roof unless you absolutely have to. Instead, always use a quality ladder equipped with stabilizers (bullhorns) and an extension wand to reach high areas.

There may be times when you are asked to soft wash a roof and clean the solar panels at a residence. Understand that you can’t apply a single solution and/or method to both. They can be done on the same day but are separate applications. So, put your soft wash or power washing gun down for now!

Equipment And Supplies

Cleaning solar panels requires (at least) 150 feet of hose, a water-fed extension pole (15-ft to 20-ft length), an applicator (18-in. to 30-in. size), water bucket, solar panel cleaning solution, tap or deionized water tanks, a soft bristle boar’s-head brush, and a couple of long extension ladders with

WHAT ARE THE DIFFERENCES…

…between regular tap water, reverse osmosis (RO) water, and deionized (DI) water? It’s all about the level of purity. Reverse osmosis water is cleaned for drinking but still saturated with salts and oxygen. Deionized water removes those salts and oxygen but not the dissolved solids found in water. (And, apparently, it doesn’t taste very good.)

Water can be deionized following the application of reverse osmosis (RO), where it is passed through a semipermeable membrane to remove water impurities. This includes ions, organic compounds, and particulates. Water processed using RO has attained the highest level of purity.

stabilizers. Truck-mounted water tanks for your water source are a must because you want to ensure a clean water source, not well water, which may have debris or mineral particulates. While the deionized water that you would use for window cleaning can also be used for solar panels, it is not absolutely necessary because your goal is not a spot-free shine.

Considering you are not going to be using strong chemicals, you shouldn’t need much in the way of personal protective equipment; however, good quality anti-slip footwear is a must. You don’t want to be slipping off a ladder because you’re wearing sandals.

Rather than chemicals, use tap water and a mild car-wash soap. To enable you to reach higher areas, apply with a water-fed extender pole for the initial rinse. Depending on the residue buildup, you may need to attach a soft bristle boar-head brush—the type you might use on a car or boat— and apply some good old-fashioned “elbow grease.” (Yes, you may have to do some gentle scrubbing.)

Tillman highly recommends Maguire’s Wash and Wax ™ as an example of an inexpensive, effective, and safe product for cleaning solar panels. It provides enough power to clean and leaves a light wax.

Avoid the use of Dawn™ dish detergent. While it may be effective and safe to use to clean oil off of ducklings, Dawn contains a degreaser that can strip the surface of the solar panel.

Again, never use sodium hypochlorite.

Considering that you are using mild products, you generally do not need to cover vegetation, patio furniture, etc. However, as with all pressure washing, be mindful of doors, windows, trim, etc.

Techniques That Work Best

If you have been asked to clean a roof and solar panels, do the roof first. Dry sweep any roof areas with loose organic debris, being careful not to drop anything on the solar panels or sweep debris across or under them. Protect the solar panels with tarps, if you are safely able to do so. Otherwise, clean around them while protecting them with clear running water, being careful not to splash any chemicals onto the panels. Have a neutralizer handy to apply and rinse in the event you accidentally overspray chemicals onto the panels. Proceed with the roof washing as you normally would. Once complete, attend to the solar panels.

Cleaning Solar Panels

Inspect panels for cracks, exposed wires, or anything that may look out of the ordinary. Record damage by taking photographs and writing it down, then immediately report it to the homeowner. (This can also be done when you visit the site to quote the job.)

Ensure there are safe places to position your ladder, avoiding damaging landscaping/vegetation and also being mindful of safety. Move furniture, etc. out of the way. (Better yet, ask the homeowner to move furniture in advance.)

If the panels have been cleaned in the past three to six months, skip the application of soap and simply rinse with deionized water using a soft wash gun with a 12-volt pump.

If the panels have not been cleaned in the recent past, soap them up with a strip washer on a long extension pole. Dwell time will vary according to the amount of residue buildup. The important thing is to be sure not to let the soapy water dry. If it does dry, you’ll have to scrub again to rinse off.

Rinse with less than 150 PSI with clear tap or deionized water through a water-fed pole.

Work in small sections to eliminate streaking. Applying from the bottom up with the cleaner and top down for the rinse.

What To Watch For

It should come as no surprise that solar panels get hot and can crack if washed during the hottest part of the day, so schedule solar panel cleaning for early morning. For example, if the temperature is 100°, then the solar panels could be 180°. Once the panels reach 140–150°, the risk of cracking is much greater. Use a basic temperature gun to check the surface temperature before cleaning.

How To Bill

While some contractors charge “per panel,” Tillman finds that that can be restrictive. And it doesn’t take several important “cost of doing business” factors into consideration.

“Pricing really is subjective,” believes Tillman. “Remember, you are operating a business, and you need to make a certain amount of money per hour to pay for equipment costs, labor, insurance, etc. I charge $125 to $150 per man hour on the job and then estimate and add the chemical cost, multiplied by two. I feel this makes more sense than charging per panel because there are so many variables such as access to site, size and scope of the project, extent of grime, distance traveled, and more. If you have more than one employee on the job, the price per hour goes up, but of course the time it takes to complete the job goes down, so it works out in the end.”

Ancillaries

As with any pressure cleaning contract, visiting the site to provide a quote gives you an opportunity to offer valueadded services. Aside from offering to do their laundry, any surface you would normally clean is a good possibility for tie-ins with cleaning solar panels.

Problem Areas To Avoid

Cracked panels and structurally faulty roofs must be identified before any work begins. Talk with the client to develop a workable plan, such as cleaning after repairs are made or cleaning only panels that are intact.

How To Fix Mistakes

Oops! You missed a spot. Get your equipment back up and do it again, and thoroughly rinse it all the way to the ground, including the windows, etc. if there is overspray.

Contributor Bio

Josh Tillman is owner of Squirt’s Pro Wash in Glennville, Georgia. Tillman and his team specialize in power washing pretty much everything residential-related as well as RVs, boats, and more. They take pride in the fact that they spend hours researching the proper products and techniques to clean exterior services. They have been cleaning solar panels for about three years CT