Solar energy is one of the most promising power generation technologies in existence, and is the future of power generation. The development and implementation of solar panel systems will allow us to make a significant stride towards achieving a sustainable society. It is no wonder then that people and governments have openly begun to embrace this technology. This is evident from the fact that the years spanning 2000 and 2020, solar has experienced an annual average growth of 42%.

However, like most systems, solar panel systems have their own set of flaws that hold them back from achieving their full potential. One of these major flaws is the loss of efficiency of the system due to dirt and debris accumulation on the panel surface. According to research, a solar panel system can lose up to 25% inefficiency due to human pollution dirtying up the solar panels. The statistics presented above signify the importance of cleaning solar panel systems regularly. This article will take you through all you need to know about cleaning solar panels.


Cleaning Solar Panels – A Step-by-Step Guide on How to Do It


Cleaning solar panels is a multistep process. Following the steps laid in this short guide will help you ace your solar panel cleaning. So without further ado, let us begin:

Choose the Right Time

The first and foremost step in cleaning your solar panels is to decide what time of the day would be right to do it. You might be wondering what time has to do with cleaning, right? Cleaning your solar panels at the wrong time of day can potentially damage your panels over the course of time. Cleaning your system in the afternoon, when the sun is at its peak, means you are cleaning the panels when they are at their hottest during the day.

Pouring water on the hot panel glass will lead to an abrupt change in its temperature, resulting in the glass cracking. Additionally, any water you pour on the panels will quickly dry up due to the intensity of the sunlight, with would leave patches of watermarks. Moreover, cleaning your system at this time of the day would also mean that you are disrupting your solar energy supply at the time when it would be giving you the highest output during the entire day.

Bearing this in mind, it is vital to perform your cleaning at a cool time of the day, such as in the morning or in the evening. A bonus of cleaning early in the morning is that the dew that condenses on your panels overnight will soften the dirt and debris, allowing for easier cleaning.

Shut Down Your Solar Panel System

Before you actually begin the cleaning, it is essential for you to ensure that your system is completely turned off. The user’s manual you will have received when installing the system will have the shutdown procedure inscribed in it, so be sure that you follow the instructions properly. For additional guidance, you should consult the inverter manufacturer’s operating handbook.

Ensure that all DC or direct current systems are turned off completely. You can turn off the AC systems using the solar supply main switch. This is because working on live electrical components with water is never a good idea as even a tad bit of water seeping into any of the live components or circuits could lead to a massive electrical catastrophe such as fire due to short-circuiting.

Disconnect or Block Your Gutters or Rainwater Collectors

Many homes have rainwater tanks that collect the rainwater that runoffs from their roofs so that they can use it at a later time. To prevent the dirty runoff water from getting mixed with your clean water, you should temporarily disconnect or block off the channel to those tanks.

Brush Off Dirt and Grime

Before wetting your panels, it would be better to brush off as much dry grime and dirt as you can. This makes cleaning solar panels easier.

Wet the Solar Panels

Although the effectiveness of clean solar panels is substantially higher, you must clean them carefully to avoid harming the panels. Make sure the water is only directed at the top surface of the panels. During the cleaning procedure, some water may come into contact with the backs of the PV modules; however, you must avoid getting it into the gap between the panels and the roof.

Use Mild Soap and a Soft Cloth

When washing your panels, using a soft cloth and mild soap can prove to be an effective way to remove the hard-to-clean dirt and grime that has built up on the panels. In addition, you can use a windshield wiper, a high-quality soft brush, or a cloth-wrapped sponge to wipe the surface of the panels. Coupling any of the previously mentioned tools to a long extension can allow you to safely clean the panels while staying on the ground.

Rinse the panels with clear water after removing the persistent dirt and debris. Ensure that all of the soap has been entirely washed off from the panels and that the panels have been thoroughly dried. Any leftover water or soap stains can be prevented by air dying the panels.

When cleaning solar panels, you should consider doing so while staying on the ground as it is much safer. You can use a hosepipe equipped with a suitable nozzle to accurately direct water onto the panels without having to climb up on the roof. Furthermore, you can use extensions to elongate your equipment, allowing you to wipe the panels from the ground.

However, cleaning solar panels from the ground might not be a possibility for you. In that case, be sure you’re wearing the right safety gear. Having soap and water with you when climbing up can make the surfaces much more slippery, increasing the likelihood of you losing your step and falling down. Therefore, it would be much wiser for you to hire a professional for the job.

What Not to Do When Cleaning Solar Panels


Use a Pressure Washer

While pressure washers can be excellent for cleaning external elements of your house, such as the roof and gutters, they should never be used for cleaning solar panels. You may argue that their high pressure and tremendous range make cleaning wide sections of the panels quite effortless; doing so runs poses the danger of damaging your solar panels by scratching or even cracking the glass panes.

Additionally, the intense force of the high pressured water may loosen the attachments of the panels, thereby allowing the water to make its way into the panel. Therefore, avoid the use of high-pressure washers!

Hard Bristle Brushes

Dirt and grime can accumulate and latch themselves onto the surface of your panels. This dirt and grime buildup can be quite difficult, necessitating the use of mildly soapy water and a brush. However, when selecting a brush for your cleaning, always go for a high-quality soft brush to avoid damaging the panels’ surface.

Using a hard bristle brush, on the other hand, can lead to a damaged panel surface. Hard bristles brushes can scratch the surface of the panels. A large number of minute scratches will disperse much of the incident solar energy. This can result in reducing the efficiency or even preventing the panels from harnessing solar energy. Even if you want to go lightly, never use a harsh bristle brush because it will almost certainly inflict permanent damage.

Strong Cleaning Fluids

The difficult-to-remove dirt and grime might lead you to assume that stronger cleaning solvents would be an effective remedy to the problem. On the contrary, using cleaning products with powerful and abrasive chemicals in it may harm the glass panels and diminish their efficiency dramatically. Instead, use liquid soaps in mild quantities for cleaning solar panels and stay away from anything with high alcohol content.

You might be surprised to learn that even a high concentration of soap can be harmful to your panels. It can leave a thin film over the surface of the panels, which shade the solar cells within just as dirt and debris do. Additionally, it can also promote the buildup of dirt and debris, resulting in your panels requiring more frequent cleaning.

Techniques for Soapless Cleaning of Solar Panel Systems

Professional solar panel cleaning services, scientists, and R&D teams have been working for ages to develop new and more efficient ways for cleaning solar panels. Two such techniques have been discussed below:

Soapless Brushes and Sponges

Several solar energy companies in the US have adopted a cleaning method that does not require the use of soap or any other cleaning fluid other than water. This method uses deionized water along with a vehicle-mounted or electric rolling brush to wipe away the dirt and grime without leaving a dirt-attracting film that reduces the efficiency of the panels by shading them.

Waterless vibration

Scientists at Heriot-Watt University in Scotland and a NASA-funded project in the United States have devised a cleaning method that involves vibrating the solar panels in order to shake off the dirt and grime accumulated on the panel surface. This technique works by mounting a direct-current (DC) motor on the back of a panel and tuning it to produce vertical vibrations. This method is still relatively new and may take time to be adopted by professional solar panel cleaning services. Nevertheless, it’s still good to know that there are more cleaning options on the way.

Professional Solar Panel Cleaning Services – When Should You Call Them?

Whether or not you need the assistance of a professional solar panel cleaning service depends on the design and slope of your roof. If, for instance, your roof has firm graspable elements which you can use to secure yourself to the roof, then a DIY cleaning of solar panels wouldn’t be out of the question.

On the other hand, if you have a steep roof design with nothing to anchor yourself or the ladder to, cleaning solar panels yourself would be foolish. Especially more if you don’t have the proper equipment, experience, or both.

There are several other scenarios that would call for the need of professional solar panel cleaning services. Some of these include:

  • You have deciduous trees growing over your solar panels.
  • You live within a heavily polluted or coastal area which means more frequent and thorough cleaning.
  • You are elderly or simply not confident getting up on your roof.
  • You notice a particularly tough buildup of filth on your panels, such as bird droppings.

Benefits of Cleaning Solar Panels

Cleaning solar panels may sound like quite a hassle to most people, which begs the question: why should you do it? Following are some of the main advantages that will convince you why cleaning solar panels is important:

Improved Efficiency

While it may be common knowledge that cleaning solar panels increases their efficiency, the margin by which this happens may surprise you. Not cleaning solar panels can, on average, reduce the efficiency of your system by 5%. Solar panels in a heavily polluted area that haven’t been cleaned for a month can have their efficiency reduced by as much as 35%. In some cases, researchers saw a 50% increase in the efficiency of solar panels after they were cleaned.

While the cases mentioned above may be extreme situations, it is nevertheless evident that cleaning solar panels can massively improve your system’s efficiency.


Regular cleaning is a warranty condition for many solar panel companies and manufacturers. If there is no confirmation of frequent cleaning, the warranty may be voided. As a result, if you want to be safe in case there is a malfunction, you should clean your panels on a regular basis.

Increased Longevity of the System

The atmosphere is littered with soft sand grains, dust particles, and grime suspensions. When you don’t clean your solar panels on a regular basis, these will eventually build up and wear down your solar energy system. While it may not be noticeable initially, the efficiency of your panels will deteriorate over time, and you also risk diminishing the lifespan of your system.

Shorter Payback Period

Solar panels systems can be quite expensive; installing a solar energy system requires you to invest a large sum of money. Naturally, you’ll want to see a quick return on your investment, meaning a short payback period. However, lower efficiency of your system due to a lack of cleaning means that your system saves you less money on your utility bill each month, leading to a poor ROI.

Cleaning them, on the other hand, improves their efficiency by allowing more light to reach the cells, resulting in a higher return on investment. This means that you recover your installation cost sooner.

Frequently Asked Questions (FAQs)

Does Cleaning Solar Panels with Hard Water Reduce Their Output?

Hard water can lead to scaling on your solar panels, which in turn can result in a loss in electrical output, reversed polarity, or even the formation of hot spots, which can be fatal for a solar panel.

Will Cleaning Solar Panels with Vinegar Damage Them?

No! Vinegar is an excellent solution for cleaning solar panels as the acetic acid it contains is strong enough to remove persistent debris without harming your solar panels.

Final Word

While cleaning solar panels might seem bothersome, it is quite vital to ensure that solar panel systems keep operating at their optimum. Surely, the benefits of doing so will make the trouble worth it by recovering your installation cost in a shorter time, and providing you with a more reliable energy output.

The team at Firefly Solar are ready to answer your questions and give you a no-obligation price quote. Feel free to call us at 864-252-7858 or book a consultation online. And we’ll get in touch within 24 hours.