How To Clean Solar Panels on Roofs?

How To Clean Solar Panels on Roofs

As more and more homeowners are going solar, this is another one to add to the long list of chores!

You may be prompted to ask whether it is necessary at all. After all, you don’t climb up to keep your roof clean. It gets washed by rainwater whenever it rains. Isn’t that enough for solar panels as well?

Well, it depends. If you live in a place where it rains frequently, then maybe it is enough. If you are living in a dry climate, close to industrial belts or construction sites, the dust buildup is bound to be more than average. It also depends on the debris and bird droppings collecting on the panels. 

All these and more tend to settle down on solar panels, obstructing the sunlight and reducing their efficiency. If you want to get the best out of your home solar energy installation, which is what you should be aiming for, you need to keep the panel surface free of dirt, dust, debris, and stains.

You must be wondering how to keep solar panels clean. Periodical panel cleaning is the solution. How often you need to clean panels depends again on your location, how fast the dirt accumulates, and how the dirt buildup affects the panels’ performance.

There are professional solar panel cleaning services to do the job for you. If you don’t want to spend money on them and would like to do it yourself, read on.

This article will help you with the do’s and don’ts of solar panel cleaning and explain the procedure in steps.

Why do you need to clean solar panels?

It is hard to generalize when it comes to depending on rain for cleaning solar panels. If the air is clean and birds in your location are uninterested in solar panels, occasional rains like once a month or once in two months would be enough to keep the panels clean. If this is not the case, even with more frequent rains, you may have to get the panels cleaned.

Dust, dirt, smog, pollutants, and particulate matter present in the air can settle on the panels during the dry spell. When it rains, the rainwater will bring more of these and deposit them on the panels. If the rain is not heavy enough or the deposits are too much, rainwater won’t be able to wash them off the panels completely. Once the rain stops, these deposits dry out on the surface of the panels and obstruct the sunlight from penetrating the glass cover.

These deposits form layers on the surface of the panels and with each rain, more layers get added. Besides these “invisible” deposits, there are also the issues of bird droppings, leaves, and pollen. The combined effect of all these can bring down the efficiency of solar panels by as much as 20-50% if left unattended.

After driving your car in the rain, wouldn’t you want to get it cleaned? Why do we get our windows cleaned now and then? Solar panels are similar in many aspects. 

While some dirt and debris will get washed away, the rain will bring more and make a slurry of sorts. Ultimately, whatever is left behind dries up and forms a layer of deposit. For windows and cars, it is more about cleanliness and visual appeal. But for solar panels, this affects their performance as well. 

To enjoy the benefits of clean energy, you need to invest some time in keeping the panels clean.

How do you know that it is time to clean panels?

The easiest way to gauge the output of your solar panels is by including a solar power monitoring system in your installation. This will tell you how much energy the solar panels are generating. 

Again, this varies from season to season with the weather changes and the position of the sun. If you have monitored the energy output of your system for a year, you will know what to expect on any given day. If the solar power output monitor is showing lower output than you expected, the most common reason is the dirt buildup on the panels. 

Some of the points for you to get cleared are:

  • Are there tall trees close by, shedding leaves on the panels?
  • Are you positioned downwind from high-pollution sources like industries, construction sites, or highways?
  • Are your panels placed at an almost horizontal angle?
  • Does it rain very sparsely in your area?
  • Are you affected by pollen, smog, or forest fires?
  • Do birds nest under the panels? – Learn How to Get Rid of Pigeons Under Solar Panels.
  • Does it rain too much in your area?

Too much rain can also harm the panels. Coupled with high humidity, this is the perfect setting for fungus, algae, and moss growth. The more it rains, the more it accumulates. 

Solar panels placed at near-horizontal angles have more chance of retaining dirt and debris than ones kept at steeper angles. As the angle of incidence of sunlight is the guiding factor, this is not a choice for you.

So, what next?

When you notice the low output in the solar power monitor, you should physically inspect the panels and look for reasons. At times, an overhanging tree branch may be the culprit and not the dirt buildup. 

Accessing the rooftop panels may be an issue for some homeowners. Can you make it with a ladder? Another more expensive option is to rent a man-lift or scaffolding. 

Once you have inspected the roof and decided that there is indeed too much dirt and debris on the solar panels, it is time for you to plan the cleaning. 

If you are planning to clean the panels from the ground, you can consider telescopic cleaning tools like brushes and water hoses that can be operated from the ground. 

Before you get started…

If you have a flat roof and you have placed the solar panels on a sturdy mount there, it is just a matter of a half an hour or one hour job to clean panels by yourself. On the other hand, if your roof is sloping and there is no flat surface for you to perch yourself while cleaning, you should seriously consider hiring a professional for the job. 

In case you decide to go ahead with the DIY method, ask yourself whether you can handle the job safely. If the solar panels are too high or if the positioning is too steep or slippery, reconsider the DIY approach. Nothing is more important than your safety.

If you are approaching the solar panels from the ground using a ladder or something similar, make sure that you are wearing a harness and the ladder has support. A safety helmet is also a must-have for the project.

Next, you should find the right cleaning tools. Though the rules are the same for most solar panels, it is always ideal to consult the cleaning instructions provided by the manufacturer. 

cleaning solar panels

Tips for washing solar panels

1. The first step is to shut off the solar power system. You should never attempt to clean panels when the system is generating electricity. If you are unsure how to do this, refer to the user manual provided by the manufacturer or call their helpline with the query.

2. If you have the choice, choose a day when the sun is not shining bright. Rainy days are not suitable either. Choosing a cooler day has another advantage as well. On a hot sunny day, when the water dries off on the surface of the panel, there is a bigger risk of its glass top cracking. 

3. The best way to clean solar panels is to choose a day after a bout of heavy rains, as it would have cleaned most of the deposits and soaked up the rest. This would make your task easier and faster.

4. Choose a brush with soft bristles as hard ones can scratch up the glass tops of solar panels. These scratches can prevent the sunlight from being absorbed. 

5. Heavy-duty detergents are also not recommended. You may be tempted to go for one when there is lots of dirt buildup. It would help in cleaning the surface faster. But in the process, it can also damage the glass top as well as the metal frame. 

6. In fact, if you clean the panels frequently, you can do it without soap or detergent. If at all necessary, use a mild one like a dishwasher detergent. You can make your own solar panel cleaning solution by mixing a small quantity of mild soap solution with one part of vinegar and eight parts of water.

7. You may clean the upper surface of the panels, which is usually the protective glass sheet. While at it, do not attempt to wet the underside of the panels where electrical connections are made. Even if there is dirt and debris collected under the panels, it is safer not to clean it by yourself. Call in professional cleaning services for the same. Anyway, this will not affect the performance of the panel. If at all you want to clean it, use a dry, wooden brush to clear the collected dirt and debris.

8. If your home is multi-storied and the only approach to the solar panels is from the ground, better rent a man-lift or scaffolding to reach them.

If you still feel you are up to the task, go ahead with it. However, at any point, if you feel that the task is way beyond your capabilities, pause the work immediately. There is no harm in getting a professional to finish the task.

Step-by-step instructions to clean solar panels

  1. If you choose a day right after the rain, you will have it easier. The rain would have cleaned some of the deposits and soaked the rest. 
  2. As a first step, use the brush to remove the loose dirt and debris collected on the surface of the solar panel. 
  3. Sprinkle water on the panel to soak the remaining deposits. If there is too much buildup, you may have to do this a few times at intervals. 
  4. Once the water has loosened up the deposits, you can use the soft brush to dislodge them. If you feel it is still not coming off the way you want, you can again sprinkle water, let it soak, and use the brush. Continue this until you are satisfied with the results.
  5. Use a garden hose to wash down the dislodged deposits. 
  6. If there are problem areas where the deposits are refusing to come off, you may sprinkle a mild cleaning solution and clean the area with a sponge, cloth, or a soft brush. 
  7. Hose down the panel surface and wipe it down with a soft cloth. Wiping can eliminate the chance of traces of deposits forming streaks on the panel surface. Using distilled or deionized water can help eliminate chances of streaks forming on the panel surface.
  8. Once the cleaning is over, let it dry out in the sun for some time before you start up the system.

Check the solar energy output in the monitoring system. You should notice an increase in the power production, now that the panel surface is clean and absorbing all the sunlight falling on it.

Bottom line

You may clean the solar panels yourself as a part of regular maintenance. However, you may have to go for a more comprehensive cleaning occasionally and it is ideal that you call a professional for the job. Unless you are used to this kind of work, it is easier, cheaper, and safer to get even the regular upkeep of panels done by a professional solar panel cleaner.

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