How to clean your solar panels
While a solar energy system is generally a “set it and forget it” system that allows you to passively produce renewable energy for your home, you may need to freshen up your panels occasionally. While it’s not absolutely necessary to clean solar panels, you may be losing out on value and efficiency by not doing so. In this article, we’ll provide answers to some common questions solar panel system owners have about solar panel maintenance and how to perform it safely.
Do I have to clean my solar panels?
Your solar panels need to be exposed to sunlight in order to produce power. However, unless you live somewhere with high amounts of smog, dust, dirt, grime or sand blowing around, solar panel cleaning is generally not necessary. In most cases, occasional rain will be enough to naturally and safely keep your solar panels clean and free of debris that could lower production. But a good clean every once in a while can help to maximize your panel’s photovoltaic (PV) production. So if you need or want to clean your solar panels, we’re here to help you determine the best way to do it!
Can I clean my solar panels myself?
Just like washing your car, you can definitely DIY solar panel upkeep, but there are also professional solar panel cleaners to make it easier. In fact, for a small fee, your solar installer may even do it for you! If you have a rooftop system, it might be a good idea to enlist a cleaning service, if only for safety precautions. A professional solar panel cleaning company may not do a significantly different or better job than you can do yourself, but they are better equipped to safely clean and maintain rooftop units. For ground mount units, it may not be worth the service fee when you can safely and effectively clean your own panels with a water hose, some dish soap, and a soft rag.
Types of of professional cleaning
There are many different types of professional cleaning companies that can help you. Robotics companies use semi-autonomous machines to clean without as much direct personal work involved. Some maintenance companies also use soapless brushes and sponges to clean panels to avoid potentially harmful residues. Other high-tech cleaning options are in development including waterless vibration and nanoparticle coatings.
Does your solar lease cover panel maintenance?
If your panels are leased, solar lease agreements will often include a maintenance clause of some sort. Some companies will perform regular maintenance on their panels, including washing services, while others will just repair damages the customer reports. It’s important to remember that solar panels generally require little maintenance, and simply spraying your panels down with a hose occasionally can do the trick.
How to clean solar panels
Here’s a step-by-step guide on how to clean your solar panels:
- Shut off your solar panel system – this will help ensure your safety and that equipment is not damaged.
- Use a soft brush to clean the surface of your dirty solar panels to remove any debris like dirt and dust.
- When cleaning your panels with water, be sure to use a standard garden hose and soapy water. There’s no special cleaning solution you need to purchase to clean your panels, just regular dish soap will work perfectly. You should avoid using a high-pressure hose that you might use to do things like power washing your house, as they have the ability to create cracks or otherwise damage your system.
- After you have finished the cleaning process, monitor energy output to see the difference in efficiency that cleaning has made!
What should you use to clean your solar panels?
When cleaning your solar panels, the most important consideration to keep in mind is that scratching or damaging the glass in any way will reduce a panel’s energy production. It’s best to approach panel cleaning the same way you might clean your car. Dish soap and clean water applied with a soft sponge or cloth is the safest and easiest cleaning method. It may also be helpful to use a squeegee to remove dirty water. Remember – avoid damaging or scratching the glass at all costs!
On rare occasions, oily stains can appear on your panels. You might find these if you live near a common truck route or an airport, and they can be tackled with a little isopropyl alcohol and a rag. It’s essential that you avoid using strong cleaning detergents, as these can streak and damage the glass and impact panel efficiency.
How often should you clean solar panels?
The frequency of solar panel cleaning depends primarily on where you live:
- In desert climates including the U.S. southwest, more regular cleaning is needed due to the large amount of dust and sand that could affect a solar energy system’s output.
- Solar panels in polluted areas near highways, factories and airports should also be cleaned more frequently to avoid residue buildup from pollutants that could result from heavy machinery nearby.
- In heavily wooded areas, solar panels should be frequently cleaned to prevent obstructions as a result of overgrown vegetation and bird droppings.
Should you remove snow from your solar panels?
In the winter, snow on solar panels generally doesn’t need to be removed – it will typically slide off on its own. Most panel installations are tilted at an angle, and snow will naturally slide off as it melts. If snow persists on your panels, you can also invest in tools like a solar panel snow rake, which makes it easy for homeowners to safely remove snow covering on solar panels. It’s important that you don’t use a standard broom, shovel, or another non-specialized tool to remove snow from panels, as they can scratch the panel glass and lower your solar power production.
Frequently asked questions about solar panel cleaning
Dish soap and a soft sponge or rag are the best thing to clean solar panels with.
Yes, you can clean solar panels yourself by filling a bucket with water and using dish soap and a low pressure hose.
Keeping your solar panels clean will not automatically void your warranty, but be sure to avoid using harsh chemicals and pressure washers or other water fed poles that could potentially crack or otherwise damage your panels. Improper cleaning practices do have the potential to void your warranty, so be sure to read the details before you jump into cleaning yourself.
Windex is a cheap and widely available cleaner that is excellent for cleaning glass surfaces such as those on a solar panel to make sure they are running at maximum efficiency.
While they may be good for cleaning other parts of your home, a pressure washer should never be used on solar panels to avoid damaging them and creating cracks.
A professional cleaner may charge between 150 and 300 to clean solar panels. This varies widely on the type of panel, the degree of cleanliness and how many panels you have. Costs range from 15-30 per panel.
While debris being cleaned off naturally by rain will help, making a concerted effort to clean your panels will lead to increased solar panel performance.
It is recommended that you clean your solar panels every six months to a year in order to maximize the efficiency of your solar panels.
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About Jacob Marsh
Jacob is an EnergySage writer with expertise in solar, electrification, and renewable energy. With over five years of experience researching and writing about the home energy industry (plus a degree in Geological Sciences from Tufts University), he brings a unique scientific approach to writing and investigating all things energy.
Solar Panel Cleaning Systems and their Pros and Cons
The following post is dedicated to solar panel cleaning systems for the commercial, industrial and utility-scale solar panel cleaning segment. While productivity rates are a very important KPI to define your solar panel cleaning system, we recommend considering other variables as well. Below you will find our framework for defining the best solar panel cleaning system for your portfolio of assets that need cleaning.
Compatibility (Machine to solar installation)
Solar installations are very diverse and that is their nature. It is fundamental that you choose solar panel cleaning machinery/robotics that is compatible with the solar installations you have to clean. For example, you cannot use a tractor/brush system on an agrivoltaic installation that has crops on the ground. To make a good decision, it is important to understand the solar installation types and the machinery available. If you would like to learn more, you can enroll in our Solar panel PV Surface cleaning school.
The Economic Value of Solar Panel Cleaning and the Opportunity
Solar panel cleaning is done primarily for economic reasons. Solar farms lose power output and hence revenue. What are the challenges we face in the Solar OM Industry?
- Quantifying the revenue loss due to soiling
- Quantifying the ideal cleaning frequency and schedule
- Quantify the value add from solar panel cleaning
- Defining the solar panel cleaning equipment that allows for maximum efficiency for the existing PV design
- Altering the PV design to allow for
- Efficiency
- Operator Safety
Case Study = 50 MW at 45/MWh
Cleaning frequency if ofter determined by visual inspection but to accomplish an economic impact, it is necessary to work with solutions like our PV soiling monitor and software.
The Opportunity
If managed properly, solar panel cleaning does bring significant economic value. However solar panel cleaning goes hand in hand with the opportunity to apply PV anti-reflective coatings. For more information, please feel free to schedule a meeting here. https://calendly.com/soilar-tech/ In general, PV anti-reflective coatings increase performance 2-4% however knowing when this should be done is the key to accomplishing this economic opportunity. Below you can see that just 2 applications of PV anti-reflective coatings on a 50 MW site create 1,431,820 gains throughout the solar assets lifetime or an ROI of 294% in 7 years or approximately 42% per year. Since these coatings should be applied immediately after cleaning, it is a service offering that can and should be provided by a solar panel cleaning company. If you are interested in learning more about adding solar maintenance service, please contact us at Soilar Technologies. Below you can see the added value of both services on a 50 MW installation.
Solar Panel Cleaning Systems
There are many ways to clean solar panels but the general dos and don’ts include
- Don’t use a pressure washer
- Don’t use lots of water (it is expensive and the property owner will not forgive you)
- Do consider automation as it lowers the cost of cleaning significantly and increases your productivity and quality
- Understand that there are 2 main segments. 1) Commercial Industrial Solar Panel Cleaning Systems 2) Utility-Scale Solar Panel Cleaning Systems.
Commercial Industrial Solar panel cleaning systems
Commercial and Industrial Solar panel cleaning systems are challenging because they rarely have water and energy sources next to the solar panels. They can be dangerous to clean since they may be on rooftops, carports, or off the ground. Each installation is very unique since solar panel installers do not consider cleaning when they design the layout. Soilar Technologies offers this support to PV developers and designers.
Semi-Automation
Within semi-automation, you have solar panel cleaning systems
- Solar Panel Cleaning Robot – The robot is driven by an operator via remote control. The robot travels in xy-axis coordinates and is very similar to driving a remote control toy car. This system requires a high upfront cost but productivity levels improve by 4x. There are several xy semi-automated robots on the market but not all brands are the same and the quality of the manufacturer and post-sale service is important.
- Pros – Productivity rates improve by 4x, Less exposure to employee lawsuits, it safer than cleaning manually, less water consumption, Facilitates scaling of your business. Payback happens within the first month.
- Cons – Requires an investment of USD 20,000 – USD 50,000, Operators must be trained, the robots can be heavy and may require 2 to 3 operators. Inclination levels may be an issue.
- Lift and Shift Solar panel cleaning machine that is moved and allocated by an operator. This system also works nicely but usually requires “Custom-made solar panel cleaning robots”.
- Pros – If inclination levels are high this robot will work, easy to use, and Payback happens within the 6 months
- Cons – Time to delivery, since these robots are custom, you will have to wait 3 months to get them.
Manual Solar Panel Cleaning Systems
- Cleaning manually with a water-fed pole. While this system “works” for just about any installation, it is expensive in terms of labor rates and liabilities associated.
- Pros – cheap labor can be used, easy to start a business with this method
- Cons – Lots of people means lots of liability. Accident levels will be higher with this cleaning system. Water consumption rates are much higher with this system.
Utility Scale Solar Panel Cleaning Systems
- Tractor Brush System – This solution requires a higher upfront cost since you need a tractor, hydraulic arm, and Smart rotating brush with proximity sensors however it is the most productive solution on the market.
- Pros – The cheapest way to clean a utility-scale installation, Great payback, and ROI
- Cons – Cannot be used on all installations, may not be ideal for very desertic areas such as the Sahara or Atacama desert
- Powered Lift and Shift – This solar panel cleaning system is great for utility-scale installations where a tractor cannot be used or the ground is pure sand like in the Sahara or Atacama desert. With this solution, the operators fix the robot to several arrays and simultaneously move them down the array. The robots can do dry and wet cleaning and are extremely productive.
- Pros – This system works on just about every utility-scale installation, Payback compared to manually cleaning is extremely high, CAPEX values are reasonable any ROI usually happens with the first cleaning
- Cons – expensive than the Lift and Shift system, requires more operators than the Tractor Brush system
Fixed Slider with Docking Station – 100% Dry cleaning
Dry Solar Panel Cleaning Robotics
- – – This system is abuzz these days and conceptually it is very simple. We have one robot per row/array that is fixed and solar-powered. The robot moves back and forth daily and no human intervention is needed. While this system is being implemented the CAPEX values are extremely high and the performance loss due to soiling “the cost of being dirty” on the solar panels has yet to prove that the ROI is ideal.
- Pros – Human intervention is only required for technical repair. Performance loss due to solar panel soiling is virtually zero. Great for areas that are VERY remote and with extremely high soiling levels.
- Cons – CAPEX values are VERY high and performance loss due to soiling has to average over 3% for this system to be justified. The financials still do not prove that this system is economically beneficial. These solutions only work in extremely arid regions such as the Atacama and Sahara desert where humidity levels are virtually non-existent since they only do dry cleaning. These solutions do not work well where there is humidity.
Solar Panel Cleaning Automation is a very young industry. When choosing your system we recommend you work with consultants to find the best solution for your company or installation. Key takeaways
- Study the system cost not just the cost of the machinery.
- Calculate your CAPEX OPEX for each system to determine the best solution from a financial perspective.
- Water is expensive, consider it in your analysis. Different robots have different consumption levels.
- Robots have different productivity levels, consider this in your analysis.
- Wear and Tear are extremely important – There are lots of cheap robots on the market that high very high wear and tear costs. Consider this factor in your analysis.
- Inclination levels are a factor you must know. Not all robots have great inclination levels.
- PV Soiling Levels are key. You have to compare the cost of being dirty to the cost of each solar panel cleaning system to see with the system is ideal. Invest in soiling monitoring such as the solutions.
- Work with solar panel cleaning engineers to find the best solution.
The quest to find the most productive machine
Most OM directors or solar panel cleaners begin their quest for finding the ideal machinery by looking for the most productive machine in the marketplace. This is a very valid beginning however solar panel cleaning has many complexities and setup time and distance between installations is one of the biggest challenges when trying to do the job.
Common Mistakes
Asking the manufacturer of the machinery “How many panels per day can the machine do”? Productivity is ideally measured by square footage or similar. This is a direct relationship between brush width and array width.
Assuming the answer the manufacturer gives you is truthful.
Assuming you can be performing impeccably 24 x 7. The distance between sites often conditions your crew to clean one site per day in the case of CI installations.
Assuming that machinery productivity impacts the project more than logistical efficiency. Experience has shown that logistics are a dominating factor in the success of a project.
Distance to project sites is a bigger factor than machine productivity
Setup and Logistics are a bigger factor in many situations (not all) than machine productivity
Assuming water filtration is done flawlessly and without delays.
Assuming your crew is 100% productive
Understanding that weather may impact your productivity more than machine productivity. If it is raining, you cannot clean.
Assuming that the logistical part of the business is easy
Learn more about our Solar Panel Cleaning Certified Partners here.
Copyright © 2019 Carla Dawson. All rights reserved. All documents are protected within the meaning of copyright law. Carla Dawson reserves all rights to exercise intellectual property rights. Copying of this content is not permitted without express written authority. Violations are an offense and are liable for damages.
Carla Dawson
Carla Dawson founded Soilar Technologies, a NextGen PV Soiling Mitigation Technology Company in 2019. NextGen PV soiling mitigation can be defined as:
“Mitigating photovoltaic soiling by using 21st-century technologies throughout the solar plant lifecycle with the objective of increasing performance, reliability, asset life, and warranty compliance. NextGen PV Soiling mitigation is typically a data-enriched Smart system that combines technologies such as solar panel cleaning robotics, PV anti-soiling coatings, PV abrasion testing, bird deterrent solutions, PV soil monitoring, electrodynamic shields (EDS), condensation prevention, tracker/stowage position, and cleaning schedule optimization, solar panel cleaning software, analytics and other technologies.”
NextGen PV soiling mitigation is a phrase that was coined by Carla Dawson and Klemens Ilse in 2022. Soilar Technologies is dedicated to helping solar panel cleaners, EPC, solar installation companies, and entrepreneurs solve their PV soiling problems from design to the operations and maintenance stage.
Fighting Dirty: Manual Washing vs. Automatic Cleaning of Solar Modules
If only a solar project was truly finished once you hooked it up to the grid. We now know better than to expect an array to function at peak production for 20 years without a little upkeep. OM has grown into a huge business, and module washing is an important segment that shouldn’t be forgotten. Just as quickly as system owners have recognized a need for panel cleaning, new technologies have entered the market. No-touch robots offer an alternative to manual washing, and now some techniques avoid water altogether. Both sides say they’re better than the other—manual washing may be more precise and of a higher quality while automatic/robotic cleaning might be quicker and can be scheduled more frequently. What method works best for your system?
Manual Washing Elite Module Washing, based out of Longmont, Colo., is a manual panel washing team that mobilizes to nearly any location in the United States and abroad. Rather than have Elite affiliates in various cities, CEO Bryan Dirkes said having one team allows him to make sure everyone is qualified and properly trained.
“We hire everyone locally here out of Colorado, and we travel to the sites with our set crews,” he said. “Everybody knows their job, everybody knows what they’re doing. There isn’t any training each day or worrying about if so-and-so can do this.”
Elite works mostly on utility-scale sites and usually won’t take on a new customer unless it’s at least 40,000 panels. Contracts are based on how dirty the geographic region is—arid and agricultural areas tend to be dirtier than others and require more frequent cleanings. Often, the beginning of summer is Elite’s busiest time because a lot of customers want panels cleaned at the height of the solar season to get maximum output.
Elite only uses water and a soft bristled brush to clean panels. Through local water hookups, the crew filters the water to make sure it’s at 0 TDS (total dissolved solids). Dirkes said that even though there are biodegradable soaps, the amount you would need to clean a large utility site with 1 million panels is too much to be comfortable with soaking into the ground. Water does a great job alone.
“Glass is already porous by nature. It has little divots you can’t see with your naked eye,” he said. “If you use any sort of soap or a squeegee for that matter, it’s going to end up filling those pores and you’ll get dirt, soap particles, anything stuck. Your glass is eventually going to haze over time.”
Elite prefers brushes over squeegees because they also help to clear gunk around the frame.
“Our brushes get in between the frames a bit. A lot of companies that use squeegees don’t have that capability,” he said. “They pull that squeegee down and it crams that dirt into that bottom rail. If it happens to flip to the other side on a single-axis tracker and it rains, then all that mud and grime is just going to be coming down the top of that panel. It totally defeated the purpose of cleaning. The brushes help push that stuff out of there and a rinse knocks it off completely.”
While Elite is contacted after owners notice production has slipped, Dirkes said most business comes during initial budget proposals before projects are even built. The company is currently bidding on projects that won’t begin construction for another year or two. This proves that everyone is taking panel washing more seriously.
“We’re always improving on our equipment and our procedures. By doing that, it can only make us better and faster,” Dirkes said. “We’re continuing to strive toward anything we can do to speed up the process or lower the price on something as vital as module washing.”
Automatic Cleaning Heliotex has been manufacturing automatic cleaning systems since 2008 and has installations worldwide but focuses on California and Arizona. There are no moving parts or robotic elements; the Heliotex system looks like a sprinkler, with nozzles positioned every few panels. The system runs a wash (with soap) cycle and a rinse cycle, with adjustable frequency. No tools are used, and panels are cleaned just by gravity.
While the company suggests a one-minute wash and rinse cycle once a week, some installation areas may need more. Take a rooftop solar system next to a cement manufacturer. That constant Cloud of dust should be cleaned weekly (if not daily). Heliotex owner Gene Hunt’s motto is to “clean it before it gets dirty.”
“Every day that you’re not cleaning the panels, it’s going to get dirtier,” he said. “There are two things with cleaning: You must use clean water, and don’t allow the panels to get dirty. Once they’re dirty, it’s harder to get clean.” That’s why Heliotex persuades customers away from manual cleaning once or twice a year. With the Heliotex system, a quick and automatic spray on a weekly basis boosts production.
“Our system affords the opportunity to keep your panels clean every day, not just two to four days a year,” Hunt said. The system operates in the overnight hours to 1) not interfere with the electricity-producing daytime, 2) prevent damage to the panels (you don’t want to spray water on hot glass at high noon) and 3) avoid soap and water drying prematurely. Heliotex has its own soap concentrate for use during the wash cycle that Hunt said complies with all EPA conditions and is biodegradable even over time and continual use.
Wash and rinse cycles do not always have to be run in succession. Hunt said that while washing doesn’t have to be done every week, rinsing more frequently does help keep panels clean without having to use the soap.
“The panels might not be too dirty so they’ll clean once a month but run just water cycles in between,” he said. “It ensures that you don’t get an accumulation of particulates on the panels.”
Frequent rinses takes away the concern of bird droppings and other debris baking on and really needing some elbow grease to remove.
Heliotex its systems by square-feet not kilowatts. The biggest requirement is access to water and water pressure. Heliotex will install various pipes and pumps if necessary to make sure the spray on the panels cleans them effectively. Rather than being an annual OM cost, the Heliotex system can be looked at as a complementary installation to the solar array and take advantage of various tax rebates. SPW
WATER-FREE CONTENDERS
Drought-stricken regions are usually the ones with the most solar installations. So why not use a waterless cleaning system? Here are two robots fresh to the market.
Ecoppia’s E4 The E4 water-free, robotic solution from Ecoppia cleans panels every day with a soft microfiber and gentle air flow. Floating over a frame that travels alongside each row of panels, Ecoppia claims the E4 removes 99% of dust during its daily cleanings. Each E4 robot has its own solar panel, so no power is taken from the solar row it’s cleaning. Headquartered in Israel, Ecoppia has cleaned more than 5.1 million panels since forming in 2013, mostly in the dusty, desert regions of the Middle East.
Ecovacs Robotics’ RAYBOT Household robotic innovator Ecovacs Robotics just recently introduced the RAYBOT, a waterless solar panel cleaning robot. The small robot suctions to panels tilted up to 55° and sweeps, blows and vacuums dust and dirt. A detachable battery is easily replaced when power runs out. Ecovacs is currently conducting final tests for the solar robot in China and California and expects RAYBOT to launch later this year.
About The Author
Kelly Pickerel
Kelly Pickerel has over a decade of experience reporting on the U.S. solar industry and is currently editor in chief of Solar Power World.
Комментарии и мнения владельцев
It is recommended to clean the panel during the night time to make sure there is no loss of energy due to this activity when water cleaned at high module temperature may lead to loss of module efficiency.
Hello; I have a question about solar panels cleaning. does the solar panels power need to be turn off before they get cleaned or the power can stay on during the cleaning service? Thank you for your assistance
with a small attachment called “mud killer”, no dust could accumulate close the low-lever aluminum frame. This is especially good for low-angle installation of roof top solar application. You can contact tech#testpv.com for details.
Automatic system for cleaning and washing PV solar panels using special unique dedicated sprinkles. With soft water and Motorola controller. No mechanic movement parts, No maintenance, fast R.O.I Website – http://www.ruth-agri.com A video clip here: https://www.YouTube.com/watch?v=WVTkM8vOrmIt=40s E-mail: yanivwaldman@gmail.com
Interesting article but lacks important details like how many gallons per panel are used and the cost per panel in the different scenarios. My research and testing led us to untreated water and squeegees as the most cost and water effective. The idea that the panel glass suffers from the squeegee process is nonsense in our experience and I doubt any panel manufacturer would agree with that notion.
What Homeowners Should Know About Solar Panel Cleaning
The appearance of any unknown substance on your solar panels can be a cause for concern. One of our customers recently contacted us about a dusting of white powder they saw on their panels. Our examination revealed that the culprit was pollen that had accumulated on the solar panels, so there was no reason to panic, as the panels were still producing energy, they just needed a good cleaning.
We suggested that they could start by spraying the pollen off using a water hose to clean the panels. Then we recommended that they sign up for a thorough panel cleaning service at least once per year. It would prevent build-up in the future and ensure maximum efficiency and savings from their solar power system.
This homeowner’s concerns got us thinking about the sort of solar panel cleaning questions that most homeowners have:
- Do solar panels need cleaning?
- What solar power cleaning tasks can you do on your own?
- When should you hire a professional cleaning company to clean your solar panels?
- Will cleaning your solar panels improve their performance?
This article will answer all your concerns regarding these and other questions.
What are the Causes of Dirty Solar Panels?
You need to oil, maintain, and clean your car so it runs more efficiently. Others want their house Windows to be crystal-clear and grime-free so they can enjoy the view of their property. For many of the same reasons, your solar panels also need cleaning. Accumulated leaves, bird droppings, and other debris can block a significant amount of the sun’s rays, reducing your system’s efficiency.
Bird Droppings
We all love trees, as they beautify and freshen up our property. But birds also love them for nesting or chilling spots. If branches hang over your solar panel array, you should be prepared to do some extra cleaning.
Bird droppings tend to be more notorious than dust, leaves, and pollen, especially if they harden and stick on the panels. The accumulated debris from birds can block significant light from the sun, and it’s more difficult to remove just by spraying your panels with water.
Thankfully, products and services exist that can indicate if bird droppings affect the current flow in your solar energy system. Microinverters help with this, as the technology allows you to see when a single panel is generating less electricity because of blockage or debris.
Pollen and Leaves
Pollen has evolved into a sticky material that doesn’t dissolve in water. As a result, it can be harder to clean since it doesn’t just blow away in the wind. If you live near farmlands or areas with a lot of vegitation, expect pollination agents like wind, insects, and birds carrying pollen to pass over your panels and drop some of it on them. In fact, windy weather is more likely to blow pollen onto your panels in the first place instead of blowing it away.
You may also need to deal with leaves falling on your panels, especially if your trees are deciduous, meaning they lose their leaves each year in the fall. While dry leaves just blow away in the wind, wet leaves typically stick to panels as heavy rain can act like glue.
Dust and Dirt
Dust and dirt is a common enemy of solar power systems, and its effects go beyond the accumulation of grime. It’s true that sun rays may still pass through a thin layer of dust, and wind or rainwater can quickly sweep most of it off. But if your PV array is located near dustier areas such as farmlands, main roads, cement factories, and quarries, the story changes. Your solar panels will need special attention and frequent cleaning as they have to contend with far more dust and dirt.
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, the water layer can leave a muddy residue after evaporation, necessitating more frequent cleaning.
Do Solar Panels Need Cleaning?
Like anything that stays outside every day and night, solar panels will eventually accumulate dirt. But how frequently you may have to wash your panels depends on several factors, including:
- System design
- Installation angle(s)
- Size/number of panels
- Location
- Types of dirt
- Weather
- Duration between thorough cleanings
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.
As we suggested to the customer with the white powder on their panels, 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.
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:
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 Can I Clean My Solar Panels?
Cleaning your solar panels doesn’t have to be extensive or risky work. If you’ve decided to clean your panels yourself, what matters is that you follow these cleaning tips to keep both you and the solar system safe.
When in doubt, just remember that you can always call in the professionals to get the job done safely and efficiently. Because some solar installers are only focused on new installations, they don’t all offer services like solar panel cleaning. If that’s the case, rest assured that Palmetto can still provide any of your solar service and maintenance needs.
Tips for Cleaning My Solar Panels
Before setting out to clean your panels, you must keep in mind one crucial point: Avoid scratching or damaging the glass at all costs. You don’t want your energy production to plummet.
When cleaning solar panels, you will always be gentle with them by using these solar panel cleaning tips and tricks:
- Solar panel models are not all created the same. It’s prudent to check with your product’s manufacturer to see if they have specific instructions for cleaning.
- Consider using a garden hose first. But if grime and dirt have built up on your equipment, it’s time for a thorough cleaning.
- Most likely, the only equipment you need is a bucket with clean, warm water, a soft cloth, dish soap, and a soft brush or squeegee.
- Pick an evening, a morning, or a cool day to do the cleaning. You don’t want to get burned by hot panels on a sunny day. If it’s too sunny, the soapy water can evaporate before you get time to wipe it away, which can leave a smear or residue that can reduce your panels’ efficiency.
- Avoid splashing cold water on a hot glass surface. It can lead to cracks due to sudden contraction.
- Apply the warm water and dish soap on the panels’ surfaces using a soft cloth or sponge. Do NOT clean the wiring underneath.
- Use a squeegee to get rid of dirty water.
- Never step on your panels, as this can damage them and cause premature failure.
- Avoid brushes with sharp bristles that can scratch your solar glass surface.
If you live near an airport or a route frequented by trucks, expect to find a few oily stains on your panels. In this case, you can use a rag and a little isopropyl alcohol to remove them.
Pro Tip: Strong cleaning fluids should not touch your expensive investment at all. Harsh chemicals and liquids like laundry detergents, ammonia, and acids can react with or streak the glass surface, leading to damages and a loss of energy production.
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 Southwest 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 heavier-than-average snowfall and leaves can boost your solar performance significantly.
Do I Clean Off Snow?
We get it. heavy snowfall days 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 investment and compromising its warranty. Thus, 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 moisture can quickly force its way through the seals around the frames and get into vulnerable technology. These water leakages 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.