How traditional solar panel cleaning leaves value on the table, or rather, on the panels.
If you are a solar energy system owner, cleaning your solar panels regularly is a no-brainer. Dirt, air pollution, even bird droppings can settle on your panels, preventing the panels from producing energy at maximum capacity. Simply put, panels dirt = lower energy production. And lower energy production directly translates to lower energy revenue (or savings) for you, whether you consume the electricity directly or provide it to another entity. So, it’s important to keep your panels as clean as possible. Easily solved, right? Not quite.
Did you know that even if you clean your panels regularly, you’re still likely leaving tens of thousands of dollars on the table every year?
The reason is that dirt lands on your solar panels every day, keeping the sun from reaching the panels. The amount of production lost over time due to this dirt is called the “soiling rate”. If this rate is high enough, manual cleaning doesn’t have a large impact on improving production and project owners pay the price.
Traditional cleaning = Lost revenue
Traditional manual solar cleaning techniques drag down solar owners’ long-term revenue. How? Every day, dirt and other particles settle on the surface of your solar panels, which keeps the sun’s rays from reaching the panels. The production lost as a result is known as the soiling rate. And if the soiling rate is high enough, even regular manual cleanings don’t stand a chance to significantly improve production. and solar owners pay the price.
Not only do cleaning fees add up over time, but you also lose money from the reduced production of soiled panels between each cleaning. While you may be able to tolerate lower production due to soiling losses for a year or two, the reality is that you are missing out on this added revenue every single year for the entire lifetime of the system. That’s 20 years or more with lost profits. Below, we take a look at an example to understand just how much money solar owners are leaving on the table. or rather, on their panels.
Lost revenue grows exponentially as soiling increases
In California’s Central Valley, average daily soiling loss ranges from 0.5% in the winter months up to 1.5% in the fall months. This translates to an average of nearly 1% production loss added per day. Each additional day means even more losses from soiling.
Average Daily Soiling Losses per Month in the Central Valley
By this estimate, you’ll reach 7% cumulative panel soiling over the course of a week, amounting to almost 150 in lost revenue (or value) for a 1 megawatt (MW) system. Your lost revenue continues to increase exponentially as more time goes by and your soiling levels accumulate on your panels.
Revenue Loss by Number of Days After Manual Cleaning in the Central Valley
Cleaning fees are an added long-term cost
On top of this, cleaning fees create additional annual costs. Regular manual panel cleaning services can range from roughly 5,000 to upwards of 75,000 per year, depending on cleaning frequency. When combined with production losses due to soiling, a 1 MW system cleaned weekly at 50 cents per panel can cost you about 84,000 every year… for 20 years or more. Ouch!
Switching from weekly to monthly or even quarterly cleanings can lower your annual spend on cleaning fees, but keep in mind that your production losses also increase as your cleaning frequency decreases.
This means that no matter how you shake it, traditional solar panel cleaning will continue to drag down your long-term solar profits.
Revenue Loss with Manual Solar Cleaning by Cleaning Frequency
It’s time to come clean
You may be asking yourself, why isn’t this lost revenue commonly discussed amongst solar developers and landowners? Until recently, manual panel cleaning was the only option, so solar owners had to make their peace with the long-term costs and production losses that come with cleaning their systems, not to mention the occasional manual cleaning that gets lost by heavy wind the next day. What a loss to pay for a cleaning only to see your panels dirty again.
The great news is that there’s no need to settle anymore: Automated panel cleaning systems like RST Nightwash™ allows you to clean every day, minimizing losses and maximizing production. Plus, you can avoid manual cleaning costs for good. By switching to an automated cleaning system that can be paid off in just a couple of years, you can finally stop paying for regular cleanings and maximize production. and therefore profit. from your solar panels, for good.
Simply put, keep your panels clean all the time to maximize production and value for your system.
Want to learn more about how to come clean and escape long-term solar panel cleaning costs? Reach out to RST CleanTech for a complimentary assessment.
Solar Panel Cleaning.Boost efficiency by keeping your solar panels free of dirt and debris.
You can lose up to 33% of your solar efficiency from dirt on your solar panel. Keeping panels free of dirt and debris will allow your solar panels to absorb the maximum sunlight available and mantain the highest performance.
Lower Bill
Keep your electricity bill low. Dirty panels are another type of shaded solar panels, and shaded solar panels produce less power. By cleaning your panels regularly you keep them running at maximum output.
Catch Electrical Issues
Getting your solar panels cleaned properly will ensure their long term health production. Our solar technicians are trained to catch any issues with your system help you fix them; we recommend adding a solar inspection during your cleaning.
Why our clients trust us:
We had solar installed in 2016 and due to a reoccurring leak over our patio and our original installer needing 8 months to get to our house, we had
We had solar installed in 2016 and due to a reoccurring leak over our patio and our original installer needing 8 months to get to our house, we had NYSM complete the removal and reinstallation for us. The crew arrived early, worked very quickly without taking a break, and seemed to be really honest and nice. They left the roof and property in clean condition and I wouldn’t hesitate to hire them again if I’m in need of a solar service provider near me.
Matt and his team were very professional and affordable. The crew showed up to our house in Westchester in masks and put back up the system they had taken
Matt and his team were very professional and affordable. The crew showed up to our house in Westchester in masks and put back up the system they had taken down three weeks ago. They had us wait until our new roof had two heavy rains on it to be sure it didn’t leak before they reinstalled it which I think is very wise. If you’re looking for solar service provider, I would definitely recommend them.
Great solar service help. The guys worked quickly and efficiently. It took them the full day to remove our 55 panel system and they finished right before it started raining. When.
Great solar service help. The guys worked quickly and efficiently. It took them the full day to remove our 55 panel system and they finished right before it started raining. When they came back to complete the reinstallation, which took two days, they put the array back right where it was and even blew the leaves out of our gutters. Good price and good communications for a solar service provider.
Great solar service help. The guys worked quickly and efficiently. It took them the full day to remove our 55 panel system and they finished right before it started raining. When.
Great solar service help. The guys worked quickly and efficiently. It took them the full day to remove our 55 panel system and they finished right before it started raining. When they came back to complete the reinstallation, which took two days, they put the array back right where it was and even blew the leaves out of our gutters. Good price and good communications for a solar service provider.
Matt from NY Solar Maintenance and Repair was lovely to deal with in every way. He was recommended by the company that acquired the firm that installed our solar
Matt from NY Solar Maintenance and Repair was lovely to deal with in every way. He was recommended by the company that acquired the firm that installed our solar array a number of years ago. In the past year pigeons took roost under the array creating a mess on our property, and a nuisance to our neighbors. Matt was great to communicate with during our estimate process; his was the 6th we received for installation of a critter guard and removal of the pigeons. From his depth of experience he was able to give us great information advice, then the best price, and ultimately a beautiful job professionally promptly executed. This was a project that we would much preferred to avoid, but Matt made it better than we could have expected. I recommend Matt wholeheartedly and would contact him again if we ever had need of service related to our solar array.
The Economics of Cleaning Solar Panels
Soiling loss is the term given to all energy production loss in a solar system that is attributed to the panels being dirty. This panel soiling can come from:
- Atmospheric dust
- Bird Droppings
- Ash from wildfires
- Pollen from adjacent trees
- and other factors
We know that the economics of cleaning residential solar systems are not great. If a residential owner experiences 7% soiling loss annually on a 5-kW solar system in California, they will see about 65 lost over the course of the year. We are forced to ask ourselves if the cost to wash our panels justifies the savings, as this is generally how we view the economics of solar.
While the figure above wouldn’t motivate most people to climb up on the roof and clean their solar panels as often as they might clean the family car, it is not the full picture of what soiling does to our systems.
Economics are, of course, important but other factors must also be taken into consideration. To bring it back to the family car, it will probably not affect daily gas mileage when one decides between regular and synthetic oil, but the latter will likely ensure that the car lasts long enough to be handed down to that lucky first child when they come of age.
The same can be said for solar panels. Two important negative effects of soiling that do not necessarily impact daily energy production relate to two jargon terms: PID and Riso. Don’t worry, these terms are explained below.
Economics of Cleaning Solar Panels
We have seen above that a 7% average annual loss on an average sized system does not justify the effort of cleaning. Well, what if a system does not fall on the average? What if the annual loss is greater than the 7% average? In their study, Zorilla and Casanova found that daily soiling rates can reach up to 25% during the dry summer months. These rates are mitigated by a significant rain event, but during the extended dry periods of the summer, these levels can be sustained throughout times when we generate the most solar energy all year.
For Example
This leads to an annual average of 10% on a system that is above average at 10 kW we see the soiling loss value rise to nearly 190. If this can be recovered by simply hosing down the solar panels a couple of times a year at nearly zero cost, it becomes a lot more attractive to do so. The key to knowing if we should be addressing soiling losses at home is through determining daily soiling losses and daily soiling accumulation.
Local solar soiling losses can be determined using soiling measurements with devices located adjacent to the array or by taking measurements on the panels themselves before and after cleaning.
Once a daily soiling accumulation rate has been determined we can calculate the rate at which soiling losses build on a daily basis. This value will lead to the optimal time to clean from a financial perspective.
One aspect that needs to be taken into consideration if attempting to hose down a PV system is water hardness. It is true that water spots will negatively impact the production so this author recommends testing water hardness before attempting to clean panels with a quick spritz.
If the intrepid panel washing homeowner needs additional motivation for testing water, just ask the plants in the yard, they can also benefit from a little added knowledge of what is coming out of that hose. As with those plants in the yard, a solar array should be hosed down in the morning or early evening. This will prevent large temperature swings that could affect the panels as well as allowing for the water to run off without as much water-spot depositing evaporation. This should be done at domestic water pressure and never with a pressure washer.
Cleaning Modules
- If cleaning is required beyond a simple rinse, a soft (read: non-abrasive) means can be employed to remove more stubborn dirt. First, we use only pure water and a soft sponge, non-abrasive brush, microfiber cloth or anything you would take to your car’s finish to wipe the area while maintaining a wet surface. After wiping down, rinse the system again and let dry.
- Although rare, there are instances where the above steps do not fully clean the array. In such cases, it is ok to use a very mild biodegradable cleaning agent. Repeat the steps above employing the cleaning agent and rinse very well when complete.
It is important to note, that when working around solar panels, we should never step on any surface of the panel. Also, in many cases, using an abrasive cleaning method can void a manufacturer’s warranty so take exceptional care when cleaning your system.
Potential Induced Degradation (PID)
PID is a type of degradation that can build up in solar panels (and therefore arrays) over time. This loss can render a PV system useless. Without getting too far into the weeds, PID is caused by electrical fields in and around the solar panel itself. These electric fields are generally harmless but can be worsened when the surface of the panel is covered in an electrically conductive layer of dirt. I apologize for bringing up High School chemistry but dirty water allows electricity to flow and pure water does not.
What does this mean for solar panels? When the surface of the panel is dirty, it allows for interaction between these internal and external fields of the system. This interaction is the breeding ground for PID. Though, some manufacturers have mitigated this effect as of recently, avoiding PID via keeping an array clean is a cheap and effective way to prevent it for the previous generation of solar panels.
Isolation / Insulation Resistance (RISO)
Riso is a term given to a test that inverters perform before initiating system start. This test is designed to determine if the electrical connections are ok before starting up the system. If this test fails, the inverter will not turn on. This is an excellent feature for the safe operation of a PV system. The effects of soiling on this issue come into play in the same way as we saw with PID above.
If the system and its electrical connections become coated in dirt, this test could result in an unnecessary failure during early morning dewy situations. This will generally present itself as an error on the inverter (Riso Low) and can substantially impact the annual production of a system if the system must wait first for sunrise and then for everything to dry out before turning on.
These are a few of the important characteristics to consider when thinking about the issue of soiling on a solar system and whether or not to clean. All too often we think only about the immediate economics of our solar installations, but as time goes on, and we become savvier to all this technology that now pervades our lives, we learn more and more about how to use it to the utmost potential.
For high-tech and reliable soiling monitoring equipment, Fracsun has developed a state-of-the-art product. You can inquire about their technologies here. To request a product quote, you can visit here.
Guest Blogger Bio:
Catlin is the co-founder of Fracsun which has built a patented device that allows system owners and operators to locally measure soiling rates and determine financially optimal cleaning schedules.
Catlin has nine years of engineering experience in commercial and utility project development, module product management, new product development, sales engineering, estimating, system design, installation and project optimization. He has worked in project development in the Philippines, Thailand, Singapore, Vietnam, India, Nepal and Indonesia. In several of these markets, he has led training workshops, teaching engineers and installers of local companies industry best practices for design, installation, and maintenance of solar assets.
The Ultimate Solar Panel Maintenance Guide To Keep Your Panels Working As Efficiently As Possible
Samantha covers all topics home-related including home improvement and repair. She previously edited home repair and design content at The Spruce and HomeAdvisor. She also has hosted videos on DIY home tips and solutions and launched multiple home improvement review boards staffed with licensed pros.
We earn a commission from partner links on Forbes Home. Commissions do not affect our editors’ opinions or evaluations.
Table of Contents
Solar panels typically don’t require much maintenance other than periodic cleaning and keeping them free from obstacles that can cast shadows over the panels. Solar panels need an unobstructed path to the sun to operate optimally.
Solar panels are designed to withstand extreme weather events like hail, snow, ice and wind to provide lasting performance. Solar panels typically have a lifespan of 25 to 30 years with regular maintenance, but should you start to see a dip in their output, it might signal it’s time to clean them.
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How to Maintain Solar Panels
Dirt, debris, dust and other items can dirty solar panels and if the accumulation grows too much, it can start to impact the amount of energy that the solar panels produce. Be sure to turn your solar power system off prior to cleaning. Cleaning solar panels by spraying them down with lukewarm water from a hose usually does the trick. Do not use cleaning agents or soap to clean solar panels because they can leave streaks and damage the panels.
For solar panels with heavier deposits, spraying them down with a lukewarm water from a garden hose and wiping them down with a non-abrasive, microfiber cloth can get them clean. If you clean them while on a roof, remember to do so safely by using a safety harness to prevent falls. If cleaning from a ladder, use caution to prevent falls. Best yet, a telescopic pole with a microfiber cloth attached to it can help you safely clean solar panels from the ground.
TIP: Do not clean your solar panels on a sunny day because it can leave smudges since the water can evaporate quickly.
Cleaning Solar Panels in Winter
Sometimes snow and ice can accumulate on solar panels but since they’re angled, it usually melts and slides off. Should snow or ice persist, spraying panels with lukewarm water can help remove it.
Avoid using hot water to clean snow and ice from solar panels because the temperature discrepancy can cause the panels to crack. You can also brush the panels off with something non-abrasive to prevent scratches.
How Often Should Your Solar Panels Be Maintained?
Solar panels only need maintenance two to four times a year, but check your solar companies manual for panel specific maintenance care. Fall and spring serve as good times to perform maintenance work because panels can need cleaning following winter where dust and debris can accumulate. Fall is also a good time because of the falling leaves and other droppings. Beware of other issues like sap from trees and bird droppings.
Checking your solar panels four times a year can help you track the performance of your panels better. You can notice issues sooner and address them faster. You should also inspect wires and connections to ensure they’re in working condition. Sometimes critters can gnaw on them without you noticing.
You can also hire a professional to perform an annual inspection if you’d rather have a pro do the job.
How to Know When Your Solar Panels Need Maintenance
It’s important to track the energy output of your solar panels closely. Typically a prolonged drop in production signals a maintenance need. Solar panels tend to decrease in performance as they age but early in their lifespan, any drop is more likely to come from dirty or obstructed panels.
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Solar Panel Maintenance Cost
Solar panel warranties can cover some of the maintenance costs with performance guarantees, but to have a pro service your panels, it can cost between 140 to 180 annually. An annual inspection can cost about 150 and cleanings can cost 150.
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How Does Severe Weather Affect Solar Panels?
The best solar panels stand up well in severe weather with most built to withstand wind speeds up to 140 mph. Solar panels can also sustain hail storms. In 2017, a hail storm in Denver saw just one of 3,000 panels damaged at the National Renewable Energy Laboratory.
THIS IS AN ADVERTISEMENT AND NOT EDITORIAL CONTENT. Please note that we do receive compensation for any products you buy or sign up to via this advertisement, and that compensation impacts the ranking and placement of any offers listed herein. We do not present information about every offer available. The information and savings numbers depicted above are for demonstration purposes only, and your results may vary.
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What to Do With Unusable Solar Panels
Most solar panel components can be recycled, like the frames and glass. Of course, it’s best to check with your local recycling center to see what they’ll accept. Occasionally, solar panels can have small amounts of toxic metals like lead and cadmium, which must be taken to hazardous waste facilities.
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THIS IS AN ADVERTISEMENT AND NOT EDITORIAL CONTENT. Please note that we do receive compensation for any products you buy or sign up to via this advertisement, and that compensation impacts the ranking and placement of any offers listed herein. We do not present information about every offer available. The information and savings numbers depicted above are for demonstration purposes only, and your results may vary.
Frequently Asked Questions (FAQs)
Are solar panels easy to maintain?
Solar panels remain relatively easy to maintain because they sit at an angle, which makes it easy for debris, snow and ice to slide off. Spraying them with a garden hose makes it an easy task, but do not attempt to spray solar panels with a pressure washer because the force can damage the panels.
Can you monitor the health of your solar panels?
You can monitor the output of your solar panels. Some installers have monitoring software included with their installation packages, but it’s usually not real-time monitoring. Installers typically have a web portal with day-after data. You can purchase a solar monitor or find a solar panel monitoring app.
Do solar panels really need to be cleaned?
In some climates, rainfall will suffice to clean solar panels, but in drier climates, solar panels will need cleaning because too much dust and dirt can accumulate. That accumulation can shade the panels and reduce their output.
Will rain clean solar panels?
Rain will clear solar panels in many cases but it won’t completely clean solar panels. After a rain, soil can accumulate at the bottom edge of the solar frame, which can obstruct the cells from producing energy.
Is it okay to hose off solar panels?
Yes, you can use a garden hose to spray down your solar panels to clean them. Hosing them off might not completely clean your panels because dirt can still accumulate at the frame. Also, beware that any damage that occurs as a result of your cleaning the panels might void your warranty.
How do you clean ground-mounted solar panels?
You can clean ground-mounted solar panels in the same manner as rooftop solar panels. Be sure to avoid any soap or cleaning agents, pressure washers and abrasive clothes or rags to clean them. Also, shut down your solar power system before cleaning.
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