How to Clean Solar Panels

How to Clean Solar Panels

Many people purchase and install solar panels without ever considering a key aspect of solar panel ownership, that is, solar panel cleaning. While this may not be the most interesting topic when talking about solar panels, it’s certainly one of the most important if you own one. Solar panels require obstruction free sunlight, which means all that dust and debris slowly accumulating on the surface of the panels will reduce your solar panels efficiency.

As easy as they are to use, solar panels aren’t miracle products. They’ll require regular maintenance like other outdoor equipment. So, how exactly do you clean a solar panel? What sort of solar panel maintenance is regularly required? We’ll answer these questions and more below. You want your solar panels to work at peak efficiency, and as an added bonus regular cleaning will make them look their best.

What NOT to do

To begin we’re going to cover some common mistakes people make when cleaning their solar panels. First, let’s examine some of the cleaning products you should not use.


Don’t use anything made of metal as it can damage the glass and leave scratches which then cast shadows. Any shadows will decrease the amount of sunlight your panels receive and lower its efficiency. Also, be sure to stay away from any detergents, and soaps with any grit to them as they can also scratch your glass.

Hard Water

If your property has hard water, which is water with a lot of minerals, then you may want to take extra care when doing any solar panel cleaning. Hard water can leave mineral deposits behind which may cloud or obstruct the glass making shadows, and thus, less sunlight reaches your solar panels.


Certain detergents and cheaper window cleaners can leave cloudy streaks on the glass after cleaning. Make sure to check if your cleaning product leaves streaks before using it on your solar panel.

Finally, we have some things not to do when dealing with your solar panel maintenance. These deal more with safety and damage rather than cleaning products.

Roof Safety

If you have roof mounted solar panels, be sure you’re physically fit enough to get onto your roof safely and then clean the solar panels. If not, consider calling a professional service or even asking a friend or family member for help. Don’t try to clean your solar panels if you aren’t sure you can get to your roof.

Time of Day

Don’t try to clean your solar panels during the hottest part of the day, as its both harder work for you, and it makes the water you’re cleaning with evaporate leaving streaks and grime behind rather than being wiped away.

Most Common Cleaning and Maintenance Methods

Most Common Cleaning and Maintenance Methods

Now you know what not to do when dealing with solar panel cleaning, so lets cover some of the more common methods of cleaning that you should do instead.

Sponge and a Hose

An old classic. This is the most tried as true method for cleaning most outdoor equipment and your solar panels are no different. Often times you don’t even require soap, just be sure if you do use any soap its grit free and has no extra bits in it that may scratch the glass. Be aware though that if you have to get on your roof to clean your solar panels you’ll have to get your hose up there too which may be difficult for some people.

Another thing to consider is the type of sponge. It should be soft and non-abrasive and absolutely no metal or hard plastic scrubbers. Also be aware of anything like sap or bird droppings as wiping these across your solar panels glass can damage it as well, leading to more solar panel maintenance. This is especially true for flexible solar panels, which are especially fragile.

And finally, when using a hose and a sponge take note of the time of day. Generally you’ll want to do this in the early morning or dusk as the sun isn’t beating down on your solar panels. The midday sun heats them up causing the water you’re cleaning with to rapidly evaporate and leave behind smudges.

Nano-Hydrophobic solutions

Now, that word “Nanohydrophic” may seem confusing, but it just means it repels water at a molecular level. You can buy these Nano-Hydrophobic solutions online or in some stores that carry solar panels. They work in all climates and are effective against things like dust, pollen and dirt.

What it does is it coats your solar panels glass in a very thin film, 8 nanometers in fact, that actively resists water forcing it to gather like a ball. Combined with a sloped solar panel this prevents almost any water from gathering and evaporating on the panels themselves, and the evaporation of water is the number one cause of dust and smudges on your solar panels.

These solutions can be expensive however, if your property has a lot of solar panels for instance. Also, it’s only truly useful if you have sloped solar panels, or at the very least solar tracking solar panels. But, for someone with a small amount of panels and a bit of time to spare every few months these are a great investment.

While you’re at it, you may wish to clean your other components, like your solar charge controller and solar inverter.

Solar Panel Cleaning Robots

This one may seem strange but many businesses that have a large volume of solar panels have started to use these robots to clean their panels. They work diligently regardless of inclement temperatures and require no breaks, and even better they’re relatively small and sleek. Most come with several different brushes so you can be sure you’ll have a brush for every panel type or level of soiling. They automatically switch between connected and touching solar panels, and are extremely lightweight which means they can easily be transported manually to other slopes. The obvious draw in the money saving potential which is huge, as the robots themselves work autonomously for the most part. If its charged, all it requires is a connection to water, like a hose. Unfortunately, they’re pretty expensive, so unless you have a massive amount of solar panels or are wealthy you might want to consider another option. Also, if you have an automatic solar angle calculator and repositioning system, you may wish to forego this option.

How Often Should I Clean my Solar Panels

This is a hard one to answer exactly. There are a lot of environmental factors that go into determining how often you should clean your solar panels, such as the amount of pollen in the air, the air quality of your area, any leaves on your property, snow, rain, even living near the ocean. All of these things may affect the length of time you can spend between solar panel cleaning. The short answer is every year. However if you live in a place where one of the above mentioned things happen fairly often you might want to consider cleaning them more often than that.

Recent studies have shown that your solar panels efficiency could drop by as much as 5% each year its left unclean, and in some cases it could lose up to 3% even when cleaned once a year. If you’ve purchased and installed a solar system on your property leaving it dirty basically defeats the purpose of using solar energy at all, which is high efficiency which translates to more savings.

If you’re someone who hates the idea of cleaning and maintenance you might want to consider one of the hydrophobic self cleaning solutions or even one of the solar panel cleaning robots available on the market now. Some of these allow a one time setup which just works on its own for several months without any human interference. Just remember you will eventually have to check on your solar panels.

Things that Minimize Cleaning and Maintenance

One approach is to choose a spot on your property to install your solar panels that will be as dirt and debris free as possible. This will ensure your solar panels last as long as possible. One of the first things to consider when deciding this might be any structures that might block direct wind from hitting your solar panel without blocking any sun. This might be difficult to achieve but is very beneficial as wind generally deposits pollen and dust onto your panels glass reducing sunlight intake.

Another thing to consider is any pollen producing trees being situated directly above the panels. These trees will shower your solar panels in bright yellow pollen severely hindering its ability to take in sunlight. Besides pollen you might want to check for any trees that drip sap. Sap is very hard to remove and can lead to a lot more solar panel maintenance, so it’s best to avoid it in the first place.

If you live somewhere that gets a lot of snow or rain, then consider getting sloped solar panels installed. The slope helps keep snow and rain from pooling on the solar panels, which creates smudges. To even further aid this you can coat the solar panels in a hydrophobic solution which prevents water from pooling on the glass.

How to Tell Your Solar Panels Need Cleaning

How to Tell Your Solar Panels Need Cleaning

Now you know all about several different ways to clean your solar panels, but what about knowing when to clean them, and how often you’ll need to clean them in your specific area? There are a few ways to tell this, and we’ll go over them below. But remember, these are just general guidelines. If you think you should be cleaning your solar panel more often, go ahead, it won’t damage it as long as you follow the instructions above.

Check your bills

One way to tell if you should schedule some solar panel cleaning is checking your monthly electric bill. You may notice your bill slightly increase as your solar panels are unable to cover as much of the electrical load on your grid. This is because they are taking in less sunlight which means less energy provided. If you notice this then you should consider thoroughly cleaning your solar panels. However, if you want more constant monitoring of your solar panels output, consider the following option.

Remotely Monitor them

This method is a bit more advanced, but can give you the most constant monitoring of your solar panels. Installing a camera system near the bulk of your solar panels can help keep an eye on the surface of the glass, making sure you can clean it as soon as you notice dirt and dust gathering. It also serves as a security measure against vandals. Another way of monitoring your solar panels for energy loss caused by dirty glass is using a solar panel monitoring system which tells you exactly how much energy each panel is producing. However, if you’re not the most technically minded individual, or you just have too many solar panels for it to be feasible you may want to consider checking your bills each month instead.

Visually Inspect them

This is the most straightforward of all the techniques. You can just go take a look at them around your property. If you see layers of dirt, dust or pollen then they could probably do some solar panel cleaning. However, if you have a lot of solar panels or a limited schedule this method might not be ideal. Also, many people have roof mounted solar panels, which means you’ll need to get up on the roof to check them first, and then get up a second time to actually clean them if you discover they’re dirty. If you have access to something like a drone you can fly above them and check if they need cleaning, saving you a trip up and down from the roof.

Whatever method you choose to clean your solar panels, just be sure it gets done. Solar panel efficiency degrades over time, and degrades even further when covered in dirt and grime. Regular cleaning will also save you money by letting in more sunlight to the cells themselves. Hopefully you’ve found the right approach for cleaning, but if not, just try some out until you find a technique you like. (Looking for more information about how to install solar products? Check out our article on wiring solar panels!)

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