How to Clean Solar Panels: 9 Simple Steps to Maximize Solar Energy Production

Learning how to clean solar panels can improve the efficiency of solar energy systems and reduce home energy costs. Here are some easy steps for cleaning solar panels.

By Jacqueline Medina and Evelyn Auer | Updated Oct 30, 2023 6:14 AM

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A hand cleans solar panels with a yellow rag against a bright blue sky.

Photo: istockphoto.com

Solar panels have become increasingly popular as a source of renewable energy. By absorbing sunlight, they create a current that’s converted to usable electricity. There are many advantages of solar energy, including reduced energy bills, a smaller carbon footprint, and increased home value. Solar is also becoming increasingly attainable, especially with the help of one of the best solar panel loans. However, solar panels are worth it only if they generate enough energy to reduce the need for electricity from the grid. The amount generated depends on the absorption of sunlight, so if solar panels are dirty, they’re not as efficient as they can be, especially considering the fact that the cost to install solar panels can be quite high.

In general, the best solar panels require little cleaning and maintenance in areas that receive regular precipitation. Rain can wash away much of the dirt and debris that might block a home’s solar panels from absorbing the maximum amount of sunlight. However, grime can still build up over time. Especially in dry climates or near construction or industrial sites, relying on rain to keep panels clean may not be enough. Learning to clean solar panels can help homeowners save money on solar panel maintenance costs.

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Even if they were installed by one of the best solar companies (like SunPower or ADT Solar), solar panels need regular maintenance to remain at peak performance. With a few easy-to-find tools, homeowners can learn how to clean solar panels on a roof or ground array safely to boost their efficiency, as well as determine when it might be best to hire professional help for solar panel cleaning.

Why do solar panels need to be cleaned?

A tool with yellow brushes is uses to clean solar panels.

Photo: istockphoto.com

Many homeowners understand that solar panel systems need direct sunlight in order to function. Because solar panels are located on a home’s roof, they are bound to accumulate dust, dirt, leaves, bird droppings, and other kinds of debris. Over time, the buildup of these substances can begin to limit the amount of sunlight that the panels are exposed to, resulting in a significant drop in solar panel efficiency. This process occurs even more quickly for panels that are completely horizontal as this does not allow rain to wash away the dirt. Cleaning solar panels can keep them operating at maximum efficiency, as well as prolonging the solar panels’ lifespan. Failure to clean the panels regularly may even cause homeowners to void their solar panel warranty.

How often do solar panels need to be cleaned?

Homeowners may not be sure how often to clean solar panels. In most cases, once or twice a year is typically sufficient. However, the exact frequency that is necessary can depend on a few factors. For example, in regions that receive relatively low amounts of rainfall, panels may need to be cleaned more often. Homes whose roofs have little to no slope may also need more frequent cleaning. In the event that a neighbor is having construction done to their home, a cleaning may be necessary after the project is completed in order to remove any dust that has settled on the panels. Timing is also a factor in solar panel cleaning. The panels will need to be relatively cool so that water does not evaporate during the cleaning process. Applying cold water to hot panels can also cause them to crack. For this reason, the best times to clean solar panels are in the morning or evening, on cloudy days, or in the spring and fall months when the weather is mild.

Time required: 1 to 2 hours
Difficulty: Beginner
Estimated cost: $50 to $100 (when supplies are first needed)

Tools & Materials
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Before You Begin…

Not all solar panels have the same maintenance suggestions, so it’s important for a homeowner to check manufacturer instructions before doing any DIY cleaning work. It’s also worth noting that, despite the higher initial cost of solar shingles, this type of solar roof may not require cleaning at all. Unless a homeowner is cleaning the best portable solar panels, their system is likely located on the roof. In this case, homeowners will also want to judge their ability to work safely when learning how to clean solar panels that are high up. Suppose the solar panels are too high to reach comfortably with tools or are set in a steep or slippery location. In that case, it’s a good idea to hire professional assistance to avoid potentially serious injuries.

Tips for Cleaning Solar Panels

  • Cooler days are better for completing a solar panel cleaning project because they minimize the risk of cracking glass as the water dries.
  • Abrasive, heavy-duty detergent is not recommended for cleaning solar panels. A small amount of gentle, nonabrasive soap mixed with one part vinegar and eight parts water is an excellent homemade solution for cleaning the glass on solar panels.

Safety Considerations

  • Solar panels must be turned off before cleaning, and the underside should never be touched.
  • It’s safest to clean solar panels from the ground with extension tools while wearing gloves. However, homes with second or third stories may require climbing up to the roof.
  • Homeowners who are unsure of their ability to clean their solar panels safely will want to consider calling a local solar power professional to complete the job for them.
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STEP 1: Gather tools, materials, and safety equipment.

In most cases, the tools that will be necessary for solar panel washing can be purchased at a local hardware store. Solar panels can be treated similarly to windows or other glass surfaces. Homeowners can combine water with a mild soap to create a cleaning solution. For scrubbing, a soft sponge or brush that will not scratch the surface of the panels will be sufficient. A lint-free cloth or squeegee can be used to remove excess water. While standard hardware supplies can be used for a solar panel cleaning project, safety considerations are critical. A hard hat, ladder support, and harness are recommended for any homeowner who plans to work on a roof instead of from the ground.

STEP 2: Turn off the solar panel system by following the manufacturer instructions.

If DIY solar panel cleaning is feasible, the first step is shutting them off. Solar panels are electrical equipment and cannot be cleaned while active due to the risk of electric shock. A solar panel manufacturer’s specifications will explain how to make sure electrical currents—both produced by the panel and going into the home—are turned off.

Solar panels are being cleaned with water being ejected from a small green hose.

Photo: istockphoto.com

STEP 3: Dislodge any dust, dirt, or leaves with a soft brush.

Leaves, bird droppings, and dust accumulate on solar panels. Even though rain clears away some of this, it doesn’t get everything and can create dirty residue when puddles evaporate. Debris can be removed with gentle brushing from a soft-bristled tool to start the cleaning process.

This can be done from the ground if the soft brush is attached to a telescopic extension pole with a threaded tip or hook. Some poles can extend to 24 feet. Without a long enough extension pole, reaching solar panels to brush will require an extension ladder. If it is necessary for the homeowner to climb onto the roof, it’s wise for them to take safety precautions, like wearing a hard hat and harness.

Starting with a gentle brushing is the best way to clean solar panels because if a lot of material is sitting on solar panels, immediately mixing the debris with water might cause spread and smear. Brushing breaks down and removes some material, making the next steps in the cleaning process more effective. It’s a good idea to wear work gloves to keep hands clean and safe.

It’s also a good idea for the homeowner to see if the panels have drainage holes, and if so, ensure that they are clear. These holes will be located along the sides of the panels and can be cleaned by inserting a toothpick inside.

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STEP 4: Use a garden hose to spray the panels clean.

Water is a major player in solar panel cleaning. After dry debris is removed by brushing, a garden hose can remove most remaining dirt on solar panels.

It may be tempting for a homeowner to hit solar panels with as much water as possible to get the job done quickly, but high-pressure cleaning is likely to create fine cracks on their surfaces. This will ruin the efficiency of the solar system and cause future problems. It may also void existing warranties due to noncompliance with manufacturer specifications for solar panel maintenance. If a hose has a high-pressure attachment, it will need to be removed before solar panel cleaning.

The key to this step is careful, deliberate spraying along each solar panel. If a garden hose doesn’t allow for enough spraying control, a telescopic hose wand may help. This will have a more supportive grip than a hose on its own.

STEP 5: Scrub any problem areas with a soft brush and water.

After spraying away most of the mess, problem areas can be given extra attention with a sponge, squeegee, or soft cloth dunked into a bucket of clean water. Gentle, focused cleaning in a repetitive motion—with some patience—is best since aggressive scrubbing can scratch the panels.

Even cleaning products deemed “safe” for use on solar panels can be abrasive. Water is the best solar panel cleaner, especially if it’s deionized or distilled. This water attracts other chemicals, so it’s more efficient for cleaning. If deionized or distilled water isn’t available, treating hose water with a water softener can help improve its cleansing power.

Four rows of solar panels are pictured against a sunset.

Photo: istockphoto.com

STEP 6: Apply a cleaning solution for heavily soiled areas, making sure to wipe and rinse the solution thoroughly.

If there are stubborn spots that water can’t handle, a squirt of mild, gentle dish soap mixed with one part vinegar to eight parts water can boost cleaning power. Strong chemicals are not recommended as they can damage the surface of the panels. Any soap will need to be used sparingly and with caution. When soap is rinsed, it can leave a residue that dirt clings onto in the future, leading to streaky solar panels. Not only is this less aesthetically pleasing, but it can also compromise some of the panels’ functionality. Glass cleaners can also be used instead of soap as they are typically designed not to leave unsightly streaks.

STEP 7: Use a squeegee or soft cloth to thoroughly dry the panels once clean.

To avoid hard water marks and streaks, each panel will need to be dried thoroughly. If the homeowner is using a squeegee, it’s best to begin at the top of the panel and work in downward strokes until the entire panel is dry. Additional drops can be wiped up with a cloth. It’s important for a homeowner to be selective about the kind of cloth used to dry the panels since even a seemingly soft towel has the potential to leave scratches on the panels’ surface.

STEP 8: Restart the system and monitor your home’s solar output to measure the cleaning’s impact. 

Because solar panels create usable energy by capturing sunlight, giving them more sunlight will increase their solar output, or how much power they produce. This is why solar panels are most often set up in sunnier locations. Based on the specifics of the solar system, its location, and environmental factors, solar panels are rated for a solar output within a specific range of watts.

Normal operating conditions cause fluctuation within the predicted range. When solar panels are dirty, however, they produce energy at the low end of the range. With a lower solar output, homeowners rely on power from an additional energy provider, driving up energy bills and time in the solar payback period.

To determine how much impact cleaning solar panels has, homeowners can review their energy bills before and after the cleaning. Clean solar panels will have lower energy costs because they allow maximum exposure and higher solar output.

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STEP 9: Contact a solar panel professional for complex cleaning and maintenance needs. 

Depending on how many solar panels are needed to power the home, as well as how accessible they are from the ground, solar panel cleaning can be a challenging and lengthy process. If cleaning solar panels seems more dangerous than beneficial, homeowners can contact one of the best solar panel cleaning services (such as Window Gang) as a practical solution to improving solar output. Even though solar panels don’t need constant cleaning, removal of buildup is part of their maintenance. Finding a solar panel cleaning professional is best for conditions that are too complex to tackle with a garden hose and sponge. In some cases, the solar panel installation company that installed the system in the first place may offer this service, but there are also companies that clean solar panels exclusively.

Solar panels cannot be used while they are being cleaned. If a homeowner hires professional services, they can work to turn off the electricity and do the cleaning, putting homeowners at ease and giving them confidence that their system will not be impaired through electrical error.

To get the most out of a professional solar panel cleaning service, homeowners can begin a mock version of the cleaning process. They can clear leaves or large debris to get a good idea of specific cleaning problems that need to be addressed.

Since solar panels are often set on roofs or high areas, cleaning solar panels requires careful attention to safety. Only solar panels that are easy and safe to access should be cleaned without professional services.

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