Solar panel cleaning: What you need to know

One of the biggest benefits of going solar is that it’s pretty much a "set it and forget it" way to power your home with renewable energy. But for solar homeowners, depending on where you live, you’ll still need to clean your solar panels once or twice a year to ensure you’re getting the maximum energy benefit from your solar investment. Cleaning your solar panels is a relatively simple process though, and you can easily do it yourself or hire a professional service to take care of it for you.  

Cleaning your solar energy system helps maximize your panels’ efficiency by allowing them to absorb the most sunlight possible. When dust or other particles cover your panels, it means they won’t be able to produce as much power -- and ultimately that means you’ll lose some of the financial benefits of going solar. That’s why it’s important to keep up your solar panel maintenance, and clean them about every six months if you live in a dry or dusty environment. 

In this article, we'll answer some of the most common questions that solar panel system owners have about solar panel maintenance and how to clean them safely.

Your solar panels need to be exposed to sunlight to produce power. If they get dirty or build up layers of grime and dust over time, those pollutants and particles will prevent your panels from absorbing as much sunlight as possible, which is known as soiling. In certain areas of the U.S., the energy lost from soiling each year is as high as 7%, according to the National Renewable Energy Laboratory (NREL). 

But there’s good news, too. Solar panel cleaning is often unnecessary unless you live somewhere with high amounts of smog, dust, dirt, grime, or sand blowing around. In most areas of the country, occasional rain is typically enough to naturally and safely keep your solar panels clean and free of debris that could lower their energy production. 

But a good clean every once in a while can always help maximize your panel's photovoltaic (PV) production no matter where you live. So if you need or want to clean your solar panels, here are the smartest and most efficient ways to get your panels washed off and producing the maximum amount of energy possible.

Just like washing your car, you can DIY solar panel upkeep, but there are also professional solar panel cleaners to make it easier. For a small fee, your original solar installer may even do it for you. If you have a rooftop system, enlisting a cleaning service might be a good idea, if only for safety precautions, as professionals will have more experience using high ladders to reach your roof, for example.   

A professional solar panel cleaning company may not necessarily do a significantly better job than you can, but they're likely better equipped to clean and maintain rooftop units safely and already have all of the necessary equipment. Plus, professional solar panel cleaning will usually only cost you around $150-$300, or $15-$30 per panel.

Professional cleaning may not be worth the cost for ground mount units, because you can safely and effectively clean your panels with a water hose, some dish soap, and a soft rag without having to climb onto your roof.

Types of professional cleaning

Various types of professional cleaning companies can help you. For example, 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 processes are currently being developed, including waterless vibration and nanoparticle coatings.

Does your solar lease cover panel maintenance?

Solar lease agreements will often include a maintenance clause, but keep in mind that it can sometimes be hard to wrangle the company to come perform any maintenance once they’ve installed your system.

If you own your solar panels, some companies will perform regular maintenance on their panels, including washing services, while others will repair damages the customer reports. You’ll need to read the print of your agreement to figure out whether cleaning services are included. It's important to remember that solar panels generally require little maintenance, and spraying them down with a hose occasionally can usually take care of most of the dust and debris.

Here's our EnergySage step-by-step guide on the best ways to clean your solar panels:

1. Shut off your solar panel system – this ensures your safety and that your equipment won’t get damaged.

2. Use a soft brush to clean the surface of your dirty solar panels to remove debris like dirt and dust. Never use a rough or coarse brush as it could damage your panels. 

3. When cleaning your panels with water, use a standard garden hose and soapy water. You don’t need to purchase any particular cleaning solution to clean your panels; regular dish soap will work perfectly. Avoid any strong cleaning agents like bleach that could damage your panels. You should also avoid using any type of high-pressure hose that you might use for things like power washing your house, as they can create cracks or otherwise damage your system.

4. Use lukewarm water when cleaning your panels as very hot or cold water could also damage your panels. 

5. After you’ve finished the cleaning process, check your panels’ energy output so you can see how much more efficient they are after cleaning.

When cleaning your solar panels, the most important consideration to remember is that scratching or damaging the glass in any way will reduce a panel's energy production - much more than any removable soot or dust build up will. The smartest way to clean your solar panels is to approach the process the same way you would 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 bit of isopropyl alcohol and a rag. You may be tempted to use strong cleaning detergents as a fix, but they can leave streaks, damage the glass and impact the efficiency of the panel, so avoid using them.

You should clean your solar panels about every six months. Of course, the frequency of solar panel cleaning depends primarily on where you live. For example, if you live somewhere where it rains a lot, you may need to clean your panels less often than if you live somewhere dry and dusty where debris builds up more quickly. 

• In desert climates, including the U.S. Southwest, more regular cleaning is needed due to the large amount of dust and sand that can affect a solar energy system's output.

• Areas near highways, factories, and airports tend to be more polluted, so solar panels should be cleaned more frequently to avoid residue buildup from pollutants that could result from heavy traffic and machinery nearby.

• Solar panels should be frequently cleaned in heavily wooded areas to prevent obstructions like overgrown vegetation and bird droppings.

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 invest in tools like a solar panel snow rake, which makes it easy for homeowners to remove snow covering on solar panels safely.

But it’s important to keep in mind that you shouldn’t use a standard broom, shovel, or any other non-specialized tool to remove snow from panels; they can scratch the panel glass which will lower your solar power production.

What is the best thing to clean solar panels with?

You can simply use dish soap and a soft sponge or rag to clean your solar panels. Don’t use harsh cleaning agents like bleach. You never want to use a rough or coarse brush to clean your solar panels, as anything that’s not a soft material could potentially damage them.

Can I clean my solar panels myself?

Yes, you can clean solar panels yourself by filling a bucket with lukewarm water and using dish soap and a low-pressure hose. If you have a particular high or steep roof, however, you may want to consider using a professional service that can do it safely.

Does cleaning my solar panels void my warranty?

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 can sometimes void your warranty, so be sure to read the details of your contract before you jump into cleaning them yourself.

Can you use Windex on solar panels?

Windex is a cheap and widely available cleaner that is excellent for cleaning glass surfaces such as those on solar panels to ensure they run efficiently.

Is it okay to pressure wash solar panels?

While they may be suitable for cleaning other parts of your home, you should never use a pressure washer on solar panels to avoid damaging them and creating cracks.

What is the cost of cleaning solar panels?

A professional cleaner may charge between $150 and $300 to clean your solar panels. This varies widely based on the type of panel, how dirty your panels are, and how many panels you have. Costs range from $15-$30 per panel.

Does cleaning your solar panels make a difference?

While rain naturally washes away dust and soot which helps keep your panels working and absorbing sunlight, making a concerted effort to clean your panels will increase solar panel performance, increasing your financial energy savings in the process.

How often should solar panels be cleaned?

We recommended that you clean your solar panels every six months to a year to maximize the efficiency of your solar panels. If you live in a geographic location where it rains a lot, you may not need to clean your solar panels as frequently.

If you’re interested in going solar, check out our EnergySage Marketplace, which connects you to local solar installers who compete for your business by providing custom solar quotes tailored to your specific needs. Over 10 million people visit EnergySage annually to learn about, shop for, and invest in solar. Sign up today to see how much you could save with solar!