When dirt and debris blocks sunlight from reaching your home solar panels, cleaning them can boost their production. You can clean solar panels on your own or with some help, either from a professional service or Mother Nature herself.
In this article, we answer all the questions that we commonly hear from our customers regarding solar panel cleaning, including how to do it yourself, when to tag a professional, and how often you should clean solar panels to optimize system performance.
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Tips for Cleaning Solar Panels
If you’ve decided to clean your panels yourself, there is one crucial point: Be gentle and do not use any abrasive materials or tools. Avoid scratching or damaging the glass at all costs.
While you should check the manufacturer’s recommendations for your solar panels, you can follow these steps to clean most systems.
- Use a garden hose to initially wash away dust and other debris from your panels.
- Fill a bucket with clean, warm water and dish soap, as if you were going to wash your personal vehicle.
- Wipe away all soiling on your panels with a sponge or soft brush, but never touch any of the wiring or step on your panels.
- Use a squeegee to wipe away any dirty water.
For the best results, follow these tips from the solar experts at Palmetto.
- Solar panels can become very hot during the day, so it's best to clean panels in the morning or early evening.
- Avoid splashing cold water on a hot glass surface. It can lead to cracks.
- Never use strong cleaning fluids or harsh chemicals like laundry detergents, ammonia, or acids.
Remember that you can always call in the professionals to get the job done safely and efficiently. While not every solar company offers maintenance or cleaning, some, like Palmetto, do.
What are the Causes of Dirty Solar Panels?
You need to oil, maintain, and clean your car so it runs more efficiently. Likewise, you may want your house windows to be crystal-clear and grime-free so you can enjoy the view of their property. For many of the same reasons, your solar panels need to be cleaned, as accumulated leaves, bird droppings, and other debris can block the sun’s rays and reduce your system's efficiency.
Bird droppings
If branches hang over your solar panel array, you should be prepared to do some extra cleaning from bird droppings and related debris. Even a small spot on a panel can significantly lower its efficiency, but technologies like power optimizers and microinverters can mitigate energy losses from dirt, like bird droppings.
Pollen and leaves
As pollen is a sticky material that doesn't dissolve in water, it can be harder to clean off your panels than many other materials. If you live near pine trees or other pollen-rich plants, springtime windy weather can coat your panels in pollen. In the fall, you may also need to deal with leaves falling on your panels. While dry leaves just blow away in the wind, wet leaves typically stick.
Dust, dirt, and other debris
Dust and dirt are common enemies of solar power systems. Your solar panels may need special attention and frequent cleanings if located near main roads, factories, an airport, or another industrial facility, which can produce more than the normal windswept dirt and dust.
Water
Now, you may be thinking, “Wait. You told that customer to use water to clean their panels. Why is it on the list?” Fair question! The issue has to do with the pooling of cleaning or rainwater on horizontal solar arrays. Apart from simply reducing your solar energy generation, water can leave a muddy residue after it evaporates, requiring even more cleaning.
Do Solar Panels Need Cleaning?
Like anything that stays outside every day and night, solar panels will eventually accumulate dirt, dust, and other materials. How frequently you may have to wash your panels depends on several factors.
- System design: The exact location and spacing of your solar installation will affect how and when panels need to be cleaned.
- Installation angle: Steeper panel angles can reduce dust and debris build-up, while low-angle installations are more susceptible to soiling.
- Size/number of panels: Cleaning larger systems, with a greater surface area, will require more work.
- Location: Your location will help determine how often your panels need cleaning, with local pollution, pollen, and dust levels varying around the country.
- Types of build-up: The frequency and urgency for cleaning dirty solar panels depends on the severity of the build-up and how much light is being blocked.
- Weather: Dry locales without much rain or snow can necessitate greater cleaning frequencies, while rainier areas might get more frequent natural cleaning from the rain.
So, do solar panels need cleaning? Our definitive answer comes in three parts:
Answer #1: Yes, and You Can Do It Yourself
Bird droppings and other dirt agents can affect your solar panel's performance, especially if your panels lie truly horizontal on the roof. That's where washing the panels becomes important, though it doesn't have to be a thorough or routine cleaning in many cases.
Cleaning your solar panels is usually a relatively easy task. All you need to do is to spray the panels with average-pressure water from a well-angled garden hose while standing on the ground.
If you want extra cleaning power, a long-handled squeegee or soft brush plus a medium-pressure hose nozzle can work wonders. With the nozzle, directing the spray will become easier. You'll then wipe off the water using the squeegee for maximum electricity production. This approach provides even more cleaning power, but it does depend on the angle of your roof, roof height, and panel placement, because not everyone will be able to reach their roof, even with a long handle.
Answer #2: Yes, but You Don't Need to Do Anything
Maintaining your panels is essential, but you don't need to clean them as often as most people think. You may need to remove the occasional buildup of leaves, bird droppings, and other debris to maximize the amount of sunlight exposure your panels receive. Any regular wind and rain will typically sweep off most of the dirt, so it's better to let nature take its course and only do one thorough cleaning every year to maximize energy production.
When it comes to doing any thorough cleaning and maintenance, it’s best to hire a professional with the knowledge and tools to get the job done safely and correctly the first time.
Answer #3: No, Unless Something Really Bad Happens
Researchers at the University of California left solar panels on a roof for 145 days without cleaning. Their findings? The panels' energy generation efficiency dropped by 7.4%.
It may surprise you that the efficiency of your solar panels can remain intact over a long period, considering all that exposure to debris, dust, heat, and rainwater. But you can trust your panels to withstand the regular wear and tear of the elements.
Solar companies employ only the leading technologies and engineering skills when manufacturing their products. Their design processes usually account for the effects of dirt, water, and pollen from everyday use.
You still need to be on the lookout for any obvious structural issues with the panels, supports, and roofing.
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Can Cleaning Solar Panels Improve the Performance of PV Systems?
As we've seen so far, the short answer is, "The impact of dirty solar panels on solar power production depends on various factors." But we're interested in the long answer, right? Let’s dig into the science and math a bit.
An experiment involving solar panels on a low-slope roof sought out the difference in energy output before and after a thorough cleaning.
The researchers found an average 3.5% boost in energy production (the amount of power produced over time) after cleaning the panels using a soft rag and water. The implication here is that the energy yield increase was low, despite the high amount of dirt accumulation.
Things became interesting when heavy rain did the cleaning job. The average performance increased by only 1.9% after rainwater pounded on the dirty panels. What does that mean? A good shower from the skies can take care of some cleanup, but it’s not as effective as the proper equipment and some elbow grease.
You may want to check how much your dirty solar panels are costing you in terms of energy generation. Here's a simple formula for determining the value of solar panel cleaning:
Yearly Energy Production (kWh) × Production Loss From Dirty Panels × Electricity Cost per kWh
For example, if your residential solar energy system can produce 10,000 kWh of electricity per year, and you assume a 5% loss of production due to panels being dirty, and you pay $.20 cents per kWh for electricity from your utility, your yearly cost of electricity loss from dirty panels is as follows:
10,000 × .05 × .20 = $100
A 5% electricity production loss might not sound like a lot, but it can definitely add up, and suddenly you’re paying way more to your utility company on your electricity bill than you need to be.
The Science of Cleaning Your Solar Panels
Yes, rain helps wash solar panels and keep dirt at bay, but it comes with several downsides, which can lead to noticeable performance problems on panels set at low angles.
- Rainwater comes laden with pollen and dirt
- It can pool on the surface of your panels, especially if the glass surface sits lower than the frame
- Once the rainwater evaporates, it can leave behind a muddy residue
So, should we rule out the need for cleaning solar panels? Not yet. Researchers at Google's solar farm have a different story.
In one set of their experiments, they studied 1.6MW of horizontal solar panels on flat carports in Mountain View, California. These panels operated untouched for 15 months.
After cleaning them, they realized that the energy production from their carport solar panels had doubled overnight! Eight months later, they cleaned those same solar panels and learned that the output had gone up by 36%.
So, what's our conclusion? All solar panels still need frequent cleaning, especially if they're horizontal or almost horizontal on your roof. If yours are tilted appropriately, a reasonable amount of rainfall will get them mostly clean, but a scheduled annual visit from cleaning professionals may further help your overall renewable energy output.
How Often Should I Clean My Solar Panels?
In most cases, you only need to clean your solar panels once or twice per year. We recommend scheduling your annual cleaning routine during the spring. That avoids the heat of summer and harsh elements of winter.
However, your solar panels might need extra attention in some locations. For example, the southwestern US experiences more significant dirt accumulation because of limited rainfall. Also, panels in homes near airports, factories, freeways, and other sources of pollution will need more frequent cleaning.
Winter and autumn are other special cases. Removing leaves and heavy snowfall can boost your solar performance significantly.
Do I Need to Clean Off Snow From Solar Panels?
Heavy snowfall can make anyone nervous about their system not generating enough energy. However, snow on your solar power panels usually melts away quickly, thanks to the heat created by the solar panels, and their slick surface. Snow on a panel melts faster than on an empty roof due to the high difference in heat between the two surfaces.
But if the snow is taking longer to melt and your battery storage is running low, you don’t have to wait. You can brush the snow off your panels to get them back to producing power right away.
Make sure you use the right equipment to avoid damaging your panels and compromising their warranty. Shovels, standard brooms, and other non-specialized tools should not come anywhere near your panels. A suitable snow roof rake created for the task will come in handy here. They typically cost around $30 to $150.
Can I Use a Pressure Washer When Cleaning My Solar Panels?
No. Not at all. High-pressure water is among the biggest enemies of your solar equipment.
First, high-speed water can quickly force its way through the seals around the frames and you don't want water inside you solar panels. That water can promote corrosion of the fine wires, which leads to the failure of the solar panel and its photovoltaic cells.
Also, the glass surface can break under high water pressure. We hear you asking, "Why then don't we see damage resulting from continuous rainfall pounding on the glass?" That’s because panels are designed to resist hours of heavy rain falling across a wide surface area. But washing the panels with high pressure directs a focused beam of water in a highly concentrated spot, which creates an increased chance of stressed areas that can crack.
What is Localized Soiling?
Localized soiling of solar panels is when material like bird poop, leaves, and any other heavy blockages get stuck on your panels, but only cover part of the panel. Compare that to general soiling, where material like dirt and dust covers the entire panel surface.
When rain and wind fail to remove localized soiling, this sort of debris may block some parts of the equipment, leading to hot spots.
Your panel is made of several individual cells (60 in most cases). When localized soiling blocks sunlight from reaching one of the cells, its energy production drops. However, full current flowing from the adjacent cells may pass through the affected one. The result is overheating at that cell, a phenomenon that can cause damage to the panel.
Yes, modern solar panels come with multiple built-in bypass diodes to keep hot spots at bay. But those extra-dirty areas can still lead to damage over time that can increase your solar panel maintenance cost.
Key Takeaways
- It's understandable to want to clean solar panels to maximize their performance.
- It's good to pay attention to the condition of your solar panels.
- Be careful with how you clean them.
- Proper cleaning in the right context can improve the performance of your solar panels.
- Deep solar panel cleaning is best left to professionals like Palmetto that have the knowledge, experience, and equipment to get the job done safely the first time.
Frequently Asked Questions
How often do you need to clean solar panels?
The recommended frequency for cleaning solar panels depends primarily on local conditions, including the amount of annual precipitation and the levels of dust, pollen, pollution, and other airborne materials. In general, most solar panels need to be cleaned only once or twice a year or whenever system performance has noticeably dropped due to dirty surfaces.
Can I clean my solar panels myself?
Yes, you can clean solar panels yourself or you can hire a professional. If your solar panels are on your roof or in a hard to reach area, hiring a professional is recommended for your personal safety. With this in mind, a garden hose can sometimes do the trick between professional cleanings.
I live in a snowy area. Will solar panels work for me?
Yes, solar panels work in snowy areas. Although solar panels cannot produce electricity while covered in snow, snowfall can help clean solar panels by wiping away dust and debris. Further, light reflecting off of snow can also be absorbed by solar panels, leading to increased energy production in snowy conditions known as the albedo effect.
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Cory O'BrienSenior Director - Growth MarketingCory brings over 8 years of solar expertise to Palmetto, and enjoys sharing that knowledge with others looking to improve their carbon footprint. A dog lover residing in Asheville, NC with his wife, Cory graduated from UCSB. If you run into him, ask him about the company he founded to rate and review beer!
