Solar Panel Cleaning - a Complete Guide

Solar panels require little maintenance after installation and are expected to last 25 to 30 years. However, solar panel cleaning is necessary to maintain an optimal generation of power.

Dust and grime on solar panels can cause energy losses of up to 7% per year in some areas of the United States and up to 50% in parts of the Middle East. So, how what’s the best way to remove harmful dirt from your solar panels?

Let's take a look at some of the ways for keeping solar panels clean, as well as some of the elements that influence solar panel maintenance and cleaning.

Why Solar Panel Cleaning Is Important

The topic of solar panel cleaning is a touchy subject among solar panel owners. Some argue that it’s absolutely important, while others will claim that rain is enough to wash away any issues the panels may have.

The answer is somewhere in the middle of the spectrum. You don't have to clean your solar panels, but if you don't, you're going to lose some efficiency. Rain will undoubtedly wash away some of the dirt that has accumulated on the panels, but it’s not as effective as a good clean with some elbow grease.

In general, when dust, dirt, pollen, and debris accumulate on solar panels, it has the potential to reduce the efficiency of a solar panel by about 5%. 

This isn't a significant difference, but it can add up depending on the size of your solar power system. Obviously, the percentage can increase if you live in a location where it rarely rains or when the air is very dusty and unclean.

Ultimately, solar panel maintenance is necessary from time to time if you want to keep everything running at its best. So, if you want your panels to last a long time and run at maximum efficiency, and avoid the common problem of pigeons nesting under your solar panels, you need to clean them. This is the best way to do it:

How to Clean Solar Panels

Cleaning your solar power system isn't difficult for the most part. The most difficult aspect is getting the tools necessary to reach the complete surface area of the panel, which will vary depending on the size of your panels.

The Hose

In most cases, rinsing rooftop solar using a hose from the ground level is the safest cleaning option. 

The water spray should fall like precipitation on the solar panels, allowing gravity to do all the heavy lifting. Be patient if bird poo proves to be a tough opponent for your man-made shower.

After the bird droppings have been softened by the water, a second or third run of the hose should remove the majority of it. Staying on the ground also reduces the chance of falling and hurting yourself if your panels are fixed to your roof.

Avoid using high-pressure jets or a pressure washer to spray the panels. This could scrape and damage the panels, lowering their performance and efficiency as well as reducing their life expectancy.

Isopropyl Alcohol

If you can safely climb to the roof for a closer cleaning, you can clear oily smudges with isopropyl alcohol without leaving a mark. When you use alcohol, the ideal technique is to spot clean only those places that need to be cleaned.

We don't recommend using detergent or soap to remove persistent stains since they create a residue on the panel glass that ultimately attracts more dirt in the future.

Under no circumstances should you stand on the solar modules. Any pressure on the solar panels could result in microcracks, which would diminish the amount of energy produced.

Scrub

If the debris on your panels is more than simply dust and dirt, and includes sticky substances like bird droppings or sticky plant resin, you should scrub them thoroughly.

You don't want to be too harsh on the panels though. Choose a gentle scrubber, squeegee, or brush to avoid scratching or damaging the panels. Also, choose a gentle soap that contains no chemicals that could hurt or degrade the panels.

After that, use these steps to clean the panels:

1. Fill a bucket halfway with warm water and a few drops of mild soap.
2. Use a hose or another low-pressure sprayer to rinse solar panels.
3. Scrub the panels lightly with soapy water and the scrubber to remove any debris or buildup.
4. Avoid placing too much pressure on the panels as you work as this could damage the cells beneath and cause more harm than good.
5. Thoroughly rinse solar panels to eliminate any soapy water.
6. Dry the panels in the sun.

And there you have it; it's a simple process that requires little more than a scrubber capable of reaching across your panels. Keep in mind that solar panels get quite hot in summer. You might want to do this first thing in the morning or last thing at night to avoid burning yourself.

It’s a good idea to disconnect your solar panels while you’re cleaning them to avoid getting water in any of the sockets and potentially shorting out the circuit.

Vinegar Solution

You can do this just as effectively by cleaning your solar panels with vinegar. Vinegar is a natural product with the ability to clean all types of crystal and metal objects. 

In a spray bottle, combine 1/4 cup vinegar, 1/2 teaspoon liquid non-abrasive soap or detergent, and 2 cups water.

Spray a little mist of water on your solar panels. After the initial hosing, thoroughly spray or spread your cleaning solution over the solar panels. Clean the modules properly to remove all dirt and grime. 

Pick up your hose and spray a gentle jet of water down the solar panels once more after you've washed off all the crud.

Hiring a Professional

Getting a professional cleaning service is another option for cleaning solar panels. Many businesses offer this service in exchange for a price. Some companies, for example, may bill you on a yearly basis, while others may bill you for a one-time service.

However, before you hire a professional cleaner, you should consider the cheapest option, which is to clean the panels yourself.

Cleaning companies arrive with fancy cleaning equipment, leading you to believe that they can clean it better than you can. As a result, paying for them may not be worthwhile if you can do it yourself. 

However, if you have stubborn rust on your solar panels, you should definitely consider hiring professionals.

How Often Should You Clean Them

Solar panels are simple to maintain. You don't need to clean them as frequently as you might believe. 

Detritus such as bird droppings and leaves can sometimes prevent the panels from gathering sunlight. If there are lots of these obstructions on your panels, you should clean them as quickly as possible.

Doing so will help them last longer, which will reduce how often your solar panels need to be replaced. 

Even if the surface has dust and debris, it won't be enough to prevent the panels from functioning properly. In general, you should clean the panels once a year in the spring, summer, and autumn. 

During the winter, though, you should clean it once a month because the amount of sunshine is at its lowest.

Various factors such as weather, location, and pollution may influence how often you clean your solar panels.

It's also a good idea to keep track of how the energy efficiency of the panels varies before and after you clean them. You should also keep an eye on how the cleaning time intervals affect the outcome.

Location

The location of solar panels has an impact on how often you should clean them and how to do so to keep them efficient. Meaning, in some cases, more regular cleaning may be beneficial.

Polluted Environments 

Solar panels in polluted places, such as near highways, factories, or airports, will be exposed to high levels of dirt in the atmosphere.

Forested Areas

Leaves are more likely to fall on the panels in installations with a lot of trees nearby, obscuring solar absorption. Birds are attracted to trees, which can lead to droppings that have accumulated and that cover the PV cells and harm the surface because of acidity, lowering efficiency.

Deserts 

Sand accumulates on solar panels in arid and sandy locations like the US Southwest and the Middle East, blocking light and scratching the surface. Wildfire ash can swiftly fall on panels in big clumps in places like California and Australia.

Furthermore, the angle at which you install the solar panel on the roof influences how often you should clean it. Rainwater runoff cleans panels set at an angle more effectively than flat-mounted panels, where water can create a pool and leave residue as it dries.

Large commercial solar installations need more frequent cleaning than residential solar systems since the larger the installation, the more power generation is inhibited by unclean panels. As a result, robotic systems are more appropriate for commercial use.

How to Know It’s Time for a Clean

The most obvious sign that solar panels need cleaning is when the system's efficiency begins to deteriorate.

Pollution is usually worse in the winter because cold air retains pollutants closer to the ground than warmer air in the summer.

As a result, the optimum time to clean solar panels is in the spring, as they become too hot to touch throughout the summer. Cleaning them in the morning or early evening, when they are colder, is usually the best time.

Final Thoughts

Now that you’ve read all about solar panel cleaning, you know bird droppings, pollution and dust can reduce their efficiency. If you live in an arid area or near a pollution source, or if your panels are positioned flat, you may need to clean them more frequently. Keeping them well maintained will reduce your payback period.

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