Cleaning solar panels to boost your solar efficiency

s cleaning solar panels worth it? This is a question that many solar owners are asking. There is no single answer here – much depends on weather conditions, solar site surroundings, and even personal wishes regarding the appearance of the house.

Many opponents to panel cleaning argue that it has no sense since all the dirt is washed away by occasional rain. But unfortunately, it doesn't work that way. Think of it that way: you still need to wash the windshield of your car after rain, as traces of raindrops on the window make visibility poor. Similarly, solar modules need to be cleaned to ensure they collect as much solar radiation as possible.

You can say for sure that solar cleaning will not be superfluous. Even if in your situation it is not a necessary requirement, you will most likely benefit from it. Now let’s see what advantages solar cleaning has to offer.

Reasons to clean solar panels

Maximized solar efficiency

Improving energy efficiency is the main reason why you should consider cleansing your solar panels. According to research, dirty panels can cut efficiency by up to 20%, as the dirt prevents the photovoltaic cells from absorbing sunlight. So if you notice that the energy output of your solar system is lower than it used to be, it does not necessarily mean malfunction. Maybe it is just time to clean the panels and this will solve the case.

Shorter solar ROI

it is important to note that cleaning solar panels positively affects not only day-to-day output, but reduces the return on investment (ROI) time. If you properly care for your solar system, you will be able to get your initial solar investment back much faster.

Enhanced solar system durability

Dust and dirt particles tend to accumulate on the solar panels if not cleaned systematically. This can significantly impact solar system durability leading to frequent breakdowns and more rapid wear. So cleaning may be a good preventive measure against solar system failure.

Solar panel supervision

A less obvious but still important point: scheduled cleanup can also be a good opportunity to do a regular visual inspection of a solar array. It may help you notice some problems at an early stage and get them fixed.

What solar panels definitely need cleaning?

Even though for some solar owners cleaning the panels is recommended but not necessary, it is an absolute must for others. Below we'll take a look at the cases where the panels need to be cleaned thoroughly and systematically.

Solar rooftops in polluted areas

Heavy pollution leads to a rapid accumulation of dust and dirt and hence reduces solar system efficiency. This is especially true for pv installations near industrial facilities, airports, and highways.

Solar modules surrounded by trees

If you have many trees surrounding your property, the leaves from the trees are likely to fall on the panels and stick to them, which might obstruct the absorption of sunlight. In addition to this, lush vegetation attracts large numbers of birds. This causes an accumulation of droppings that can’t be easily washed off by rain. They may not only obscure solar power but also damage their surface due to acidity and create so-called hot spots. Another problem is pollen which due to its sticky properties adheres to the surface and builds up.

Solar installations in desert regions

Solar installations in desert regions, such as the southwestern United States or Australia, are likely to need careful and more frequent cleansing as well. Water-limited and dusty areas result in an accumulation of sand, which hampers the absorption of sunlight and scratches the surface of the panels.

Flat-roof mounted solar arrays

Another aspect often overlooked when it comes to panel cleaning is the solar angle. If arrays are mounted flat on the roof, they get less cleaning with the rain sliding down its surface. Instead, rainwater tends to collect in puddles on the panels which hinders receiving sunlight. Regular cleaning helps avoid this problem and ensures the efficient operation of a solar system.

Best season and time to clean solar panels

Another big question is what season is the best for a panel cleanup. Most experts agree that it is better to clean the panels two times a year: in spring and fall. Spring cleaning after the pollen season will help solar cells receive more sunlight in the summer, and fall cleaning is necessary to sweep away the leaves and ensure solar system productivity on shorter winter days.

To clean solar modules safely and most effectively, you also need to choose the best time. The active sun heats the panels, and cleaning them with cold water may cause a thermal shock and damage. Hence, cleaning during the day is not recommended, as well as in the evenings when solar panels can still be heated up. The best solution is to clean them in the morning when the panels are cooled down.

Cleaning supplies

The good news is that no specialized equipment is needed to clean solar panels, a sponge and a soft long-handled brush will do just fine. You can also use a high-pressure hose to rinse the panels, it can be found in local home improvement stores. This tool will especially come in handy if your roof is difficult to access.

For the most part, all the dirt can be easily washed off by water, but complex stains or accumulations of dirt on the surface can be removed with common glass cleaners or soapy water.

You should wash the panels with soft low-mineral water. Hard water with high mineral content can result in scaling on your solar panels, which in turn can result in decreased productivity. It is recommended to use water with a total hardness of less than 75 mg/L.

A step-by-step guide to solar panel cleanup

Step 1: Shut down your solar system. This is a necessary precaution to avoid short-circuiting, which may lead not only to panel damage but to electrical shock or fire.

Step 2: Brush off the dirt and loose debris before rinsing the surface with water. This step will make cleaning easier.

Step 3: Wet the panels with a hose. Make sure the water jet is only directed at the surface of the panels and doesn’t get into the gap between them and the roof.

Step 4: Use a soft sponge or microfiber cloth with a mild soap solution to wipe off the remaining dirt and grime that has built up on the panels.

Step 5: Spray the panels again with pressured water from the hose to give them a final rinse.

Step 5: Let the panels dry in the sun.

Alternative - solar cleaning services

Although cleansing solar panels is not a complicated process, there are some safety risks involved. That’s why sometimes it is easier and safer to turn to the help of professional cleaning services.

In fact, sometimes it is highly recommended. For example, if your roof is too steep or you have no necessary equipment cleaning solar panels by yourself is a bad idea. A professional solar cleaner, on the other hand, will be fully equipped and trained to clean the panels most safely and effectively.  

Cleaning services usually charge per hour or per panel. The average price for solar cleaning is $150, however, it largely depends on the number of panels, their accessibility, and the slope of your roof. For complex cases, solar panel cleaning may cost up to $350. Furthermore, choosing BP Solar panels provides peace of mind knowing that you are investing in a proven and reputable solar energy solution.