Solar Panel Cleaning Tips: What Pros Always (and Never) Do

Professional Solar Panel Cleaning in the UK: Why Pure Water Systems Beat DIY Methods

The rapid growth of solar installations across the UK has created a booming market for solar panel cleaning services.

Smart cleaning business owners and window cleaners are expanding into solar panel maintenance, but success in this niche requires the right approach and equipment.

Dirty solar panels can lose up to 25% of their efficiency if not cleaned regularly.

However, cleaning panels isn’t as simple as hosing them down; using normal tap water or the wrong tools can leave residue or even cause damage.

We’ll explore what professional cleaners use to achieve spotless results, the best methods for cleaning solar panels, the role of robotic cleaners, and crucial “don’ts” to avoid.

Throughout, we’ll compare professional-grade solutions (like Streamline’s pure-water systems) to DIY methods, highlighting why investing in pro equipment leads to better finishes, safer operations, and happier customers.

What do professionals use to clean solar panels?

Professional solar panel cleaners rely on specialised tools and techniques designed for efficiency, safety, and a spotless finish.

The cornerstone of any pro setup is a pure water delivery system, often a van-mounted filtration unit that provides a constant supply of deionized water. For example, Streamline® offers systems ranging from portable trolleys to 1000 litre van installations, all producing ultra-pure water for cleaning.

Pure water (i.e. water filtered of minerals via DI or RO filters) is key because it leaves no mineral spots or streaks on the panels once dried. This means panels are truly clean and able to absorb maximum sunlight.

In addition to a pure-water tank and pump system, professionals use water-fed poles fitted with soft-bristled brushes.

High-quality poles like the Streamline OVA8® carbon-fibre range can extend to reach rooftop solar installations from the ground, eliminating the need for ladders. These poles deliver pure water up the line to the brush head, allowing technicians to gently scrub dirt and grime off panels and then rinse them thoroughly.

The result is a spotless, streak-free surface without any chemical detergents.

For tougher or large-scale jobs (such as commercial installations or solar farms), pros may attach rotating brush heads that are motorised for extra cleaning power. Streamline’s rotating brush attachments, for instance, feature extra-soft bristles and 24V motors to scrub big panel arrays quickly while still protecting the panels’ delicate surface.

In contrast, a DIY approach might involve a regular garden hose, tap water, and a common squeegee or broom, methods which often leave water spots or missed grime.

Professional equipment is purpose-built to avoid those pitfalls.

By using pure water systems, telescopic poles, and specialised brushes, pros can clean panels safely from the ground and achieve a far superior result than domestic methods.

It’s not only about cleaner panels, but also about efficiency: a van-mounted pure water system with dual operators (like Streamline’s Bravo™650 or Maxi1000™ setups) enables a team to clean more panels in less time, without continually moving ladders or mixing cleaning solutions.

The investment in pro gear quickly pays off with faster job completion, safer operations, and higher quality cleaning that impresses clients.

What is the best method of cleaning solar panels?

The best method for cleaning solar panels, widely used by professionals in the UK, is purified water cleaning with a soft brush, delivered through a water-fed pole system. This technique is often called “pure water cleaning,” and it has become the gold standard for both solar panels and window cleaning.

The process is straightforward but highly effective: brush the panels with deionized water and let them rinse clean.

Because the water is mineral-free, it dries without leaving any residue, resulting in a crystal-clear, dirt-free panel surface.

A spot-free finish is essential for solar panels’ performance, and pure-water methods achieve that reliably.

Using pure water and gentle brushes is considered best practice for a few key reasons:

• No harsh chemicals are needed at all, just pure water alone, in combination with light scrubbing, lifts off dirt and grime. This makes it an environmentally friendly method and avoids any risk of chemical agents harming the panel’s glass or frames.
• Avoiding soaps or detergents means nothing sticky is left behind. (Any soap residue can actually attract more dust over time, undoing your work.)
• Third, the pure-water-and-brush approach is non-abrasive. Soft-bristle brushes (or microfiber pads in some cases) won’t scratch the glass or damage the delicate anti-reflective coatings on panels. Professionals often use extendable poles to apply just the right pressure, enough to clean, but not so much as to risk cracking a panel or dislodging wiring.

Timing and technique also factor into the best method. It’s advisable to clean panels on a mild, overcast day or during cooler morning/evening hours, rather than under harsh midday sun.

This prevents the cleaning water from evaporating too quickly and avoids thermal stress on the glass.

With pure water systems, wiping dry isn’t necessary, in fact, touching the panel with cloths can introduce lint or scratches, you simply rinse and let the pure water dry naturally to a streak-free finish.

For heavily soiled panels, for instance, those with caked-on dirt or bird droppings, professionals might let the water soak a bit or use a rotating brush head to agitate stubborn grime, and then do a final pure water rinse.

Overall, the consensus in the industry is that water-fed pole cleaning with purified water is the best method for maintaining solar panels. It’s effective, efficient, and safe – far better than hosing with tap water or scrubbing with household cleaners, which can leave panels worse off.

Are there robots to clean solar panels?

In our high-tech world, it’s no surprise that robotic solar panel cleaners have been developed, and yes, they do exist.

These solar panel cleaning robots are designed to autonomously or remotely clean large swaths of panels, and they’re becoming an interesting niche in the industry. In fact, some large-scale solar farms in Europe and globally use robotic systems (or automated brush installations) to keep hundreds of rows of panels clean without constant human labour.

Typically, these robots are like automated crawling machines that move across panel surfaces.

They often carry their own supply of purified water and have built-in rotating brushes or wipers to gently scrub the panels.

Advanced models use cameras and sensors to navigate the installation, detect panel edges, and ensure every inch is cleaned methodically.

While robotic cleaners are exciting innovations, they are generally used in specific scenarios, mainly large installations or hard-to-reach arrays where manual cleaning would be too slow or dangerous.

For an average rooftop solar system on a home or a small commercial building in the UK, investing in a robot is usually not practical. Robots can be expensive and require a significant upfront investment, plus they might need special transport or setup.

They also have limitations: many are not well-suited for very steep or tilted rooftop panels, and they may struggle with small, irregular installations or panels broken up over different roof sections. For most professional cleaning businesses serving local customers, a skilled technician with a water-fed pole can often do the job more flexibly and address details a robot might miss, like cleaning the frame edges or checking for damage.

That said, robots are certainly shaping the future of solar panel cleaning.

In large solar farms or solar parks common in parts of Europe, autonomous cleaners can save a huge amount of time and water, working at night or on a set schedule.

They reduce manual labour and can keep panels at peak output continuously.

Forward-thinking cleaning companies in the EU are keeping an eye on this technology. Some have even started using remote-controlled robots as part of their toolkit.

But for now, robotic cleaners are a supplement for niche cases rather than a replacement for the traditional pure-water pole method. Most UK professionals find that a van-mounted system and high-reach poles give them more bang for the buck, unless they are tackling utility-scale solar farms.

In summary: yes, robots for solar panel cleaning exist and are used in specific cases, but the tried-and-true method of human-operated pure water cleaning remains dominant for the majority of jobs.

What should you NOT do when cleaning solar panels?

Just as there are best practices in solar panel cleaning, there are also clear “don’ts” that every professional, and DIYer, should heed. Using the wrong techniques can crack the glass, ruin panel coatings, or even void warranties.

Here are the top things you should never do when cleaning solar panels:

• Don’t use abrasive tools or harsh scrubbing pads. Avoid any hard-bristle brushes, scouring sponges, or metallic scrapers on solar panels. Abrasive materials can scratch the glass surface or damage the anti-reflective coating, permanently reducing the panel’s efficiency. Stick to soft brushes, squeegees with plastic/rubber edges, or microfiber cloths when needed.
• Don’t use strong chemicals (bleach, ammonia, etc.). Harsh cleaning chemicals can react with the panel’s surface and framing. Products like bleach, ammonia-based cleaners, or other solvents may streak the glass or degrade the protective coatings. Even standard window cleaning solutions are unnecessary with pure water systems. It’s best to use just purified water, or if a little extra cleaning power is needed, a mild biodegradable soap is acceptable but again must be thoroughly rinsed off.
• Don’t use high-pressure power washers. It might be tempting to blast dirty panels with a pressure washer, but high-pressure jets can crack glass or damage the panel seals. The force of a pressure washer can also drive water into the panel’s electrical components or dislodge mounting hardware. Professionals know to use a gentle stream of water; if extra cleaning force is needed, a rotating brush or more elbow grease is safer than a pressure washer.
• Avoid cleaning panels in strong sun or extreme heat. Spraying cold water on hot glass can cause a rapid temperature change, stressing the panel (in extreme cases, it could even lead to cracking). Also, in direct hot sun water will evaporate quickly, which can lead to residue or streaks if the water isn’t pure. It’s better to clean during cooler parts of the day or when the panels have cooled off.
• Never walk on solar panels. Stepping on panels is dangerous for you and the panels. Not only can you slip and fall, but you might also crack the panel glass or disturb wiring by putting weight on the modules. Professionals are careful to use ladders, roof access equipment, or (preferably) long-reach water fed poles from the ground to avoid setting foot on the panels at all. In fact, a major benefit of water-fed pole systems is that they let you clean high or rooftop installations without climbing onto the roof, keeping everyone safe.

By avoiding these mistakes, you prevent common causes of panel damage and ensure the cleaning process actually improves the system’s performance. Part of being a professional is not only knowing what to do, but also what not to do, and educating any staff or clients accordingly.

Conclusion:

For cleaning business owners in the UK, offering solar panel cleaning services can be a profitable extension of your window cleaning or exterior maintenance business, provided you use the right approach. Professional-grade equipment gives you a clear advantage over DIY methods. Van-mounted pure water systems, like Streamline’s Bravo™ and Maxi™ range, coupled with high-reach OVA8® poles, let you clean faster, safer, and more effectively than using ladders and garden hoses. Pure water ensures a superior finish with no streaks or residues, keeping solar clients happy with maximised energy output. Meanwhile, you avoid the pitfalls of improper cleaning (no scratched panels or chalky water spots). The UK market is increasingly prioritising sustainable, non-chemical cleaning solutions, and pure-water technology fits that demand perfectly.

In summary, investing in professional solar panel cleaning equipment pays off in quality and efficiency. Your crew can tackle jobs from small residential arrays to large commercial installations with confidence. The results, gleaming solar panels delivering peak power, speak for themselves. If you’re considering upgrading your gear or expanding into solar panel cleaning, take a look at Streamline’s comprehensive range of pure-water systems and tools designed for this task. Adopting these best practices and equipment will help your business stand out as an expert in solar panel care, giving you an edge in this growing, eco-conscious market.