Do Roof Solar Panels Need to Be Cleaned? Why, How & How Often!

There are several things you can do to get more energy out of a solar panel. These include locating them away from shade, orienting them southward, and tilting them 30° from the horizontal.

All of these are done during installation and are more technical than the average homeowner is prepared to deal with. But what happens after installation? How do you maintain the maximum efficiency of your solar panels?

One of the simplest and non-technical ways to guarantee that solar panels produce as much energy as they can is to keep them clean. It might seem basic but it works.

In this article, we will show you how well it works.

We will explore when and how often you should clean your solar panels. We’ll also share with you a step-by-step guide on how to clean them to keep them running at their maximum potential.

How Often Do I Need to Clean My Solar Panels?

Solar panels should be cleaned once every six to twelve months. The frequency with which you should clean them depends on how quickly they get dirty. If you live in a windy or desert area, for example, your solar panels are likely to get dusty quicker which may necessitate more frequent cleaning.

A frequently serviced car runs better than one that is only touched when it breaks down. You want to make sure all the parts are oiled so the car runs smoothly. While a solar system does not have any moving parts it does have components that should be serviced regularly. Keeping your solar panels clean is the simplest way to do this.

How Dirty Do Solar Panels Get?

Solar panels are outdoor equipment. They are exposed to the open air outside. If you have seen what your car looks like when it has not been washed for a while then you can imagine what your solar panels on the roof must look like.

Solar panels are exposed to dust, bird droppings, and leaves. While dust is more common, bird droppings are a bigger problem. The dust washes off in the rain but bird droppings are more stubborn as they don’t easily wash off.

In some cases, the rain can mix all the dust, droppings, and other dirt to create a thick coat of grime that is much harder to wash off.

Dirt accumulating on your solar panels effectively blocks them from absorbing sunlight. The reduced absorption means they produce less energy. But just how much of an impact can dirt have on your solar panels?

Why You Should Clean Your Solar Panels

Dust or dirt will reduce the total energy your solar panels will produce. It can affect the output by between 1.5 to 6%. In drier desert areas or places with greater air pollution, the decrease in output can be as much as 50%. (Source)

The output of a solar panel is largely determined by how much sunlight it can absorb. The more sunlight it gets, the more energy it produces. A layer of dust or leaves over the solar panels reduces how much sunlight the panel is exposed to. (Source)

Not only does dirt reduce the effective absorption of sunlight, but it can also directly harm solar cells

A solar panel has between 60 to 72 solar cells. A cell that’s shaded by dirt will act as a resistance to the current produced by other cells. This can cause the other cells to heat up and fail.

How Do I Know When To Clean My Solar Panels?

Generally, you should clean your solar panels every six or twelve months. Any longer than that and you risk reducing the efficiency of the solar panels by anywhere between 5 to 20%.

While dirt can come from anything from snow to debris, dust is the most frequent problem as it accumulates quicker than anything else. The dust can come from wind, cars, or pedestrian movement and the prevalence of industrial activity close by.

A three-month study done in Boston, Massachusetts found that dust reduced the average solar irradiance or how much sunlight a solar panel received by 1%. On some days this went as high as 4.7%.

It gets worse in drier areas that experience long spells without rainfall. In these areas, every day without rainfall saw a 0.2% decrease in the efficiency of solar panels as a result of reduced sunlight caused by dust films. This can reach up to 6% losses per year depending on your location. (Source)

Cleaner solar panels are more productive solar panels. But how do you clean solar panels? Should you jet wash them or is rainwater enough to get the job done?

How Do You Clean Solar Panels on A Roof?

The simplest way to clean solar panels is to just let the rain do it. While rainwater might be simpler, especially for rooftop solar panels that are hard to reach, it is not the most effective way to clean them. You may need to use soap or a specialized liquid detergent to get dirt-like bird droppings out.

Rainwater itself also contains dust particles that may remain on the solar panels. Some areas like Southern California do not get enough rain. This would then mean you have to take matters into your own hands and wash the solar panels. But how do you wash solar panels on a roof?

One way is to hire a contractor to do it for you. This is the simpler option as it does not involve you getting up on the roof yourself. The second option is of course to do it yourself. Here’s a step-by-step guide on you would do it.

1. Make sure to do it on a cloudy day in the early morning or evening. Coldwater on hot glass can crack the glass on the solar panels.
2. Shut down your system before you start.
3. Use a soft cloth, squeegee, or brush that will not scratch the glass. Use warm water with mild soap to wash and clean water to rinse the soapy water.

We aslo highly recommend that you check out our following posts

• Can You Use Rain X On Solar Panels? Panel Washing Brief Guide!
• What Are The Best Natural Products To Clean Solar Panels With? (Brief Guide!)
• What Can You Clean Solar Panels With? Efficient & Cheap Methods!

Is It Ok to Hose Off Solar Panels? Can You Jet Wash Solar Panels?

You can hose off solar panels. A high-pressure jet wash is not recommended for solar panels as you might end up scratching or cracking the glass.