The Facts About Commercial Solar Panel Cleaning

by | May 22, 2023

Brush cleaning solar panels

Regular maintenance is key to keeping any investment running smoothly. This is especially true of solar systems, where a routine inspection and cleaning keeps panels generating more energy. If ignored, dust, dirt, and grime tints panels, blocking light and reducing electricity production. Dirty environments can even slow the output of solar energy by as much as 30% in one month.

If you have a solar partner like King Energy that covers operations and maintenance, they’ll make sure your panels stay in top-notch condition. A partner handles commercial solar panel cleaning, servicing, and repairs for the life of your system. They’ve built the system on your multi-tenant building at no cost, so they’ll want in keeping it running smoothly.

If you don’t have a partner, maintenance is challenging at commercial scale. You could task an in-house team with cleaning your panels, but it’s time consuming and you’ll run the risk of accidental damage or improper servicing. You could also try contracting a third-party agency, but that’ll cut directly into your margins.

Regardless of how you approach the dust and grime on your commercial solar system, having a firm understanding of what’s required for cleaning helps you understand your options. Here are some of the most frequently asked questions about commercial solar panel cleaning:


How do you know when to clean commercial solar panels?

In most cases, you’ll know when to clean a commercial solar system because the dirt and grime is visible to the eye. But, unlike residential installations, you’ll never be able to tell from the ground. Your commercial building’s flat roof and parapet walls hide solar systems from view. So, you’ll have to inspect your panels up close to know when it’s time to clean.

Commercial roofers recommend that you check panels during your standard roof walk, which should occur about every 6 months. While you, or your roofing contractor, are scanning for pooling water or loose flashing, they also suggest that you look at each of the panels for buildup.

It should be easy to spot the dirt and grime collecting on the glass front of the panels. You’ll likely see a layer obscuring the panel’s black silicon insides, often enough to smudge with your finger. The type and consistency of the dust depends on the environment, but it can be a mix of pollen, sand, dirt, soot, and more.

Dirty solar panel swiped with dusty red ragDirt accumulates on solar systems and lowers panel efficiency.

You may also find solid debris obstructing your systems. Just like on vehicles, bird droppings are a common occurrence and create larger blockages. Wet leaves also harden into a paste after rain, clinging to the panel or siding depending on tilt.

If you have a solar partner, they can monitor the efficiency of your solar system and know precisely when to clean without coming on site. They digitally measure the solar system’s output, creating an efficiency percentage. When productivity drops below a certain level, the partner knows it’s time to clean the panels and sends a specialist to your commercial building.


How do you clean commercial solar panels?

Cleaning commercial solar panels can be fairly labor intensive at commercial scale, but there are some high tech tools to help. If you’re cleaning manually, expect to spend some time and energy cleaning the entire system.

To start, you’ll need a ready source of tap water and a bucket, as well as a little dish soap. Then, scrub each panel gently with a soft brush or rag and rinse with the solution. It’s not required, but you can also finish with glass cleaner. Repeat this process for every panel.

You’ll also want to plan cleanings in the early morning or evening, as panels can get hot during the day and dry unevenly or cause burns. It’s also recommended to plan cleanings during mid-spring and mid-fall, as winter and summer can have the most buildup of dirt.

Don’t use a high pressure hose or power washer to clean commercial solar panels. These can damage fragile hardware and crack glass, requiring expensive replacement parts down the line. You’ll also want to stay away from laundry detergent or abrasive chemicals, as they can strip coatings off glass or scratch the surface.

When cleaning, it’s also important to avoid touching any of the connections on the underside of the panels or shift the ballasted mounting racks from their position. This can loosen wiring and create electric hazards or move panels into bad positions.

This manual process isn’t very cost effective for commercial solar systems, so solar partners often use robotics to clean solar panels instead. This solar panel cleaning equipment ensures consistency, speed, and safety, keeping panels in peak condition to improve their lifespan.

Although the type used may vary by project, the robots are battery powered and operated by an O&M specialist. Once on site, the operator mounts the robot to the solar system and controls its cleaning cycle with a remote control.

The equipment allows for a variety of cleaning types. For simple systems with low buildup, the robots can run on a dry cycle and conserve water by cleaning with just brushes. For dirtier panels with more residue, the robots can also run wet, using reverse osmosis and deionized water to remove tough buildup.


Can I clean solar panels with vinegar?

Yes, some people add vinegar to their cleaning solution to break down tough dirt and reduce streaking. Mix an 1/8th cup of vinegar for every one cup of water to create a cleaning solution–no soap required.

Vinegar is natural, non-toxic, and inexpensive, making it a solid alternative to soap or other glass cleaners. Just be sure to limit contact with other plastics or metals, as it can dull or discolor materials other than glass.


How often do you clean commercial solar panels?

Most commercial solar operators clean their systems every six months to a year, although the exact timeline can vary. If your building is in a heavily polluted area or close to major roadways or industrial sites, it’s recommended to clean more often because of the quick buildup of hard-to-remove smog and grime.

Also, serious environmental events like local wildfires or wind storms can create an unnatural buildup of ash or dust on your panels. Check panels after these special circumstances, as they may require cleanings outside of your regular maintenance.

For large partners, frequency is usually determined by panel efficiency. They’ll set cleaning timelines based on energy generation and environment. For example, in drier desert climates, they may recommend regular dry cleaning with robots to remove the constant stream of sand and dust.


Do you need to turn off solar panels to clean?

In a commercial setting, you shouldn’t need to turn off your solar system to clean the panels. They function during rain and other environmental events, so there isn’t too much risk for a robot operator or manual cleaner. But, it’s likely that maintenance and repairs will happen during cleaning, so your system may require a shutdown on a case-by-case basis.

If you have a solar partner, they’ll handle every aspect of the system shutdown and know which steps to take to ensure safety.

Team working to clean solar on commercial roofSolar partners use a variety of tools and work in teams for safety.

Since your commercial building is still connected to the grid, your tenants won’t experience a blackout when cleaning requires a shut down. Tenants most likely won’t even know that the system is off, and regular utility electricity keeps flowing to units.

If you’re managing cleaning in house, you might want to turn off your solar panels to clean the system just to ensure safety. Water and electricity can be a potent mix to an untrained hand, and shutting down the system reduces the risk of accidental shocks if loose connections become damp.


How much does commercial solar panel cleaning cost?

The cost to clean solar panels at a commercial site varies widely depending on the size and location of the solar system. Estimates can range from five hundred to a few thousand dollars. Maintenance companies often bundle cleaning with other package items in the operations and maintenance category.

The cost also varies by contractor. Some charge by the square footage of the system, taking into account roof space and placement of the panels. Others charge by the panel and include additional time-on-site fees. Large-scale cleaners even charge by the megawatt size of the system for industrial systems.

If you have a roof rental solar partner, cleaning commercial solar systems is free. They’ll handle all of the operations and maintenance work for the life of the solar system.


Does rain clean solar panels?

Yes, rain can clean solar panels by washing away light residue, offering a free alternative to manual labor or robotic cleaning. Rain also cools panels to optimal temperature and briefly increases their efficiency.

But, rain has the potential to create a larger issue for unmaintained systems. Rain can turn stubborn, built-up dust into a thicker mud that acts as a major light blocker. In some cases, rain water can also dry unevenly or come mixed with environmental debris, creating a film that traps more dirt on the panels.


How do I maintain commercial solar panels with King Energy?

While it can be tempting to handle commercial solar panel cleaning in house, having a partner like King Energy is the easiest and most cost-effective way to keep operations running smoothly for your commercial property. We’ll handle the details, and you can focus on the big picture of your investment.

King Energy rents roof space at multi-tenant properties, installing and maintaining solar systems at no cost to owners. We handle the program from start to finish, managing everything from cleaning solar panels to billing tenants for their energy use. It’s a hassle-free way for property owners to access solar, increase rent roll, and boost the value of their investment. Plus, it’s an easy way to save tenants money on energy costs.

Contact our team for a personalized proposal for your commercial building.