Cleaning Solar Panels: Why, When, and How To Do It

When it comes to helping families save money on their energy bills, solar panel systems are a fantastic addition. However, in addition to the cost-saving and environmentally friendly advantages they provide, they may also require some maintenance. Fortunately, unlike your car, these responsibilities rarely extend beyond the occasional car wash or waxing session.

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Why clean your solar panels?

Because solar panels are typically installed on roofs or in open areas, they are exposed to a wide range of weather conditions. It is not uncommon to find bird droppings, leaves, pollen, dust and even grime on the surface of solar panels depending on the location of the panels as well as the climate and installation conditions.

You’ve probably figured out that anything that prevents light from passing through is detrimental to the efficiency of your solar panel system. Because of this, experts recommend cleaning solar panels twice a year at the very minimum.

When it comes to cleaning panels across the country, dust is by far the most common cause of failure. However, even in this case, its impact on the efficiency of a solar panel is not as severe as it might appear at first glance.

University of San Diego scientists discovered that the average dirty panel loses approximately 0.05 percent of its daily production. Over the course of three months, a 5 kW system will incur a loss of approximately $20 in electricity bills.

Another study conducted in Spain found that an average performance drop of only 4.4 percent occurred after a year’s worth of dust accumulation was observed. The majority of people will not notice this decrease unless they have a significantly larger system or unless the dust has accumulated for at least a year.

This explains why homeowners should clean their solar panels; doing so will help to ensure that your solar system operates at peak efficiency.

The decision to clean solar panels will also be influenced by the following factors:

  • How much dust will collect on your solar panels over time? As previously stated, the average dust buildup causes little harm, but it can be particularly damaging in certain circumstances.
  • How big of an impact will dust buildup have on your solar system’s energy production? If dust causes your system’s efficiency to fall below 95 percent, experts generally agree that it’s time to clean it.
  • How much rainfall does your local area receive on an annual basis, on average?

Why does rainfall matter?

Solar panels may be exposed to a wide range of dirt and debris, but they are also exposed to rainfall, which washes away the dirt and leaves the panels looking like new. According to studies, normal rainfall helps to wash away dust, allowing your solar system to operate at approximately 95% of its maximum capacity. That explains the phrase “Let me just leave it to the rain,” which is usually not a bad thing, but is not always the best course of action in certain situations.

You should still clean your solar panels because dust is not always the only culprit when it comes to solar panel corrosion. Furthermore, there may be leaves, pollen, bird droppings, and other debris that is not easily washed away by the water from the rain. And sometimes all it takes is a little rain for these contaminants to mix with the wrong kind of slurry, making the situation far worse than it needs to be.

According to the findings of the Spanish study, prolonged periods of time without rain can result in daily energy losses of up to 20 percent. Consequently, in dry climates with lots of dust and wind, the efficiency of solar energy systems drops progressively worse the longer the dry spell lasts, as shown in the chart below.

Some pointers and factors to think about when deciding whether or not to clean your solar panels are listed below to make the decision easier for you.

Face your solar panel directly towards the sun for maximum exposure

A solar panel with a sloping roof makes it easier for rain to properly clean the surface of the panel. Experts have discovered that a pitch as small as 5 degrees can be effective in achieving the desired effect. So, if you notice that your solar panels are completely flat, it is possible that rainfall is not having the desired effect, and it is likely that it is time to schedule a cleaning appointment.

Your location

If you live in an area that receives less than a reasonable amount of rain each year, it’s also a good idea to think about where your system will be installed. If it is located directly next to or downwind from an agricultural field, a busy highway, or factories, it is likely to receive more dust than the average solar panel system, according to the Environmental Protection Agency.

Aside from the amount of dust you receive, your geographic location may also have an impact on the type of dust you receive.

The Type of Dirt

Next, think about the types of dirt that your panels are most likely to encounter. However, industrial smog tends to leave behind a hazy film that is difficult to remove even after a heavy downpour of precipitation.

Tree-lined neighborhoods and rural areas attract large amounts of bird droppings, which may persist even after a few drops of rain. As a result, regularly inspect your panels before and after rain to determine how much dirt is being washed away. If not, you should consider having them cleaned before they become too clogged with debris.

If you decide to clean your panels…

You’ll come to the conclusion that it’s time to clean your solar panels. Perhaps there is too much dirt buildup, or perhaps you simply want to adhere to the one- or two-times-a-year cleaning schedule recommended by the manufacturer. Regardless of which option you choose, you will have two options: do the cleaning yourself or hire a professional solar cleaner to do it for you.

How do these two stack up against one another?

DIY vs. Hiring a Professional

As a general rule, cleaning your solar panels shouldn’t be more expensive than the savings you expect to realize from using solar energy in your home.

Residential solar cleaning projects are estimated to cost between $150 and $330 on average in the United States, according to Bluesel home solar’s estimates. The cost of a single panel can range anywhere between $15 and $35. Price varies according to factors such as your geographic location, the size of your solar panel, and how easy it is for you to access your solar energy system

If you’re more of a cost-conscious individual, how do you determine whether or not paying to have dirty panels cleaned is worthwhile? It’s a simple calculation: compare the cost of cleaning with the amount of money your dirty solar panels cost you in daily production losses.

The following formula should be of assistance:

Cost of Monthly Production Loss = (Total kWh Produced by System Each Month) x (30 days x 0.0005) x (Price per kWh)

Using a professional solar cleaner may be an option if the total sum of all monthly losses in a year (or six months) exceeds the average cost of solar cleaning services in your local area.

Depending on the household, the cost of paying more than $150 for panel cleaning is less expensive than the total cost of having dirty panels. As a result, they decide to do it themselves in the “do it yourself” style. It’s also possible that you believe cleaning your system is a simple task that you can complete in a short period of time.

In either case, there are a few things to think about before embarking on a DIY adventure. These are some examples:

How high is your roof?

Let’s start with the safest territory possible. DIY solar cleaning is simple for the average person and consists of spraying water on their solar panels from the ground. This is due to the fact that dust is relatively easy to clean, and spraying upwards with a garden hose simulates the cleaning effect of rainfall. A safety concern comes into play here as well, as you want to avoid climbing to your rooftop if at all possible.

However, if your roof is too high to spray from the ground, you’ll have to climb up on it yourself. But not necessarily by you; if you’re not comfortable with ladders and the climb is too difficult for you, it’s best to leave it to the professionals who are more than capable.

How are your panels mounted?

Some people are quite comfortable with heights and consider ladders to be nothing more than portable stairwells with nothing frightening about them. If you are one of these people, you may want to think about how you will arrange your panels before you begin climbing.

Are they positioned sufficiently away from the roof’s edges? Consider whether you have enough space between your panels if you have multiple panels. These should assist you in determining whether or not you will be able to maneuver around safely while attempting to clean solar panels.

How’s your roof?

The condition of your roof is the last of your safety concerns. Even if the ceiling is high enough for you and the space between the rafters is ideal for movement, how is the pitch and what kind of roofing materials are used? If the roof is too steep, you should reconsider your decision to attempt the climb. It’s possible that the roof is also fragile or slippery, and attempting to clean your solar panels will only put your life in danger.

What does the dirt buildup look like?

Dust can be easily washed away by rain, and a little garden hose pressure, when used correctly, can do the same. Sticky substances such as smoke, bird droppings, and (a lot of) pollen, on the other hand, are not the most DIY-friendly types of debris. While it is still possible to remove them, doing so can be a time-consuming and labor-intensive task that requires a lot of scrubbing. When in doubt about your ability to complete this task, consult with a professional solar panel cleaner in your area for assistance.

How to clean your solar panels

Cleaning your solar panels should be a simple task if you are confident in your ability to complete the task yourself. Here are a couple of helpful hints, as well as instructions on how to go about the cleaning process.

Check-in with the solar installer or refer to the user manual

This step will reveal any important information about the solar system that you should be aware of, as well as any special precautions that should be taken before cleaning, such as turning off your system.

Try hosing your solar panels off from the ground

Hoisting solar panels off the ground is the most straightforward, safest, and most cost-effective method of installing clean solar panels. It is most effective if your roof is low and dust accumulation is the primary issue with your panels.

Make sure you use enough pressure to remove dust, but not too much pressure, as this will cause dirt particles to race across the panels, scratching the surface of the panels. These scratches cause tiny shadows to be cast on the PV cells, reducing the efficiency of your solar panels in the long term.

Also, avoid spraying water on the underside of the solar panel on purpose if possible (the space between the panel and your roof). A small amount of accidental splashing will not harm your system, but a large amount of water at a high enough pressure may cause significant damage.

For heavier buildup that requires you to climb…

You’ll need a soft brush, a squeegee, mild soap, and either a water hose long enough to reach your panels or a bucket filled with water to complete this task successfully. The majority of people have access to these cleaning supplies in their homes. It’s always possible to purchase all-in-one window washing tools at a reasonable price from your local hardware store if you don’t already have them.

Clean water and a small amount of soap should be combined once you have everything ready. After that, rinse the solar panel thoroughly with clean water to remove any remaining dirt. As soon as the panel is in place, gently scrub the tampered glass with a soft scrubber dipped in soapy water to remove any remaining residue. After that, rinse the surface with clean water from the hose and squeegee the panel to remove any remaining water. Repeat the procedure on all other panels in your system until you are completely satisfied with the results.

However, even if this is something you intend to do, it is preferable to have the necessary safety equipment in place before climbing onto your roof. After all, the last thing you want is to be injured or worse yet, to die while cleaning solar panel systems.

When cleaning your panels, it is also important to choose the most appropriate time of day. During the day, the sun raises the temperature of the glass to dangerous levels. Consequently, water evaporates too quickly after it comes into contact with the glass, leaving dirty marks that are even more difficult to remove than they already are. The sudden temperature change can also cause the glass to crack, resulting in a permanent reduction in the energy output of your solar panel.

So the best times to clean are during cooler weather, such as on an overcast day, in the evenings, or ideally, first thing in the morning before the sun comes up. Typically, the dew that accumulates overnight softens stubborn dirt and grime in the morning, reducing the amount of time spent cleaning your solar panels, as well as the amount of soap and water used.

Or seek professional solar panel cleaning services

Maybe you don’t have enough free time to complete a small DIY project, or you don’t have the necessary safety equipment, or you just can’t bring yourself to trust a ladder with your weight on it. Whatever your reasons are, don’t be afraid to hire a professional solar cleaner to clean your solar panels.

Professionals are well-trained and equipped for this type of work, and they will almost certainly perform significantly better than you. Fortunately, many solar panel installers also provide professional cleaning services, which are sometimes available at a discounted rate to their current customers.