How to Clean Solar Panels
Solar panels work quietly in the background, soaking up daylight and turning it into usable power for your home. Over time though, things like dust, pollen, bird droppings, road grime, and general pollution start to build up on the surface. It’s subtle at first. Then output dips. If it’s left long enough, that dip can affect what you expected from the system in the first place.
Learning how to clean solar panels properly isn’t about chasing perfection. It’s about keeping light flowing freely to the cells and avoiding the small mistakes that can shorten a system’s working life. Done right, cleaning helps protect your investment without introducing risk.
When Solar Panels Actually Need Cleaning
There’s no strict calendar rule here. Panels don’t need attention just because six months have passed. They need attention when performance or conditions suggest it.
Long dry spells are a common trigger. Without rain to wash things away, dust settles and stays put. Bird activity is another giveaway. One or two marks aren’t a problem, but repeated droppings in the same area can block light more than you’d expect.
Seasonal changes matter too. Spring brings pollen and sap. Summer adds dust and insects. Autumn drops leaves and debris. Winter is usually self cleaning thanks to rain, though snow or ice may need intervention during milder spells, if it’s safe to do so.
A Calm, Practical Approach to Cleaning
Cleaning panels doesn’t need special gear or chemicals. It does need patience and restraint. Always check the manufacturer’s guidance first, and if anything feels unsafe, stop.
Start by choosing the right moment. Early morning or evening is ideal, when panels are cool and water won’t evaporate instantly. Avoid windy days or wet conditions.
Shut the system down fully before you begin. Panels generate voltage whenever light hits them, so this step matters more than people realise.
Use a soft brush or microfibre cloth to remove loose debris. Leaves, dust, and grit should come off dry before water is involved. This reduces the chance of scratching.
For washing, lukewarm water is best. A small amount of mild soap can help with stubborn marks, but plain water often does the job. Wipe gently. No pressure. Circular motions lift dirt without stressing the glass.
Rinse thoroughly using a low pressure hose or spray bottle. Soap residue causes streaks and reduces efficiency. Let the panels air dry naturally before restarting the system.
Cleaning Portable Solar Panels
Portable panels are simpler, but they still benefit from care. Shake off loose dirt first. Wipe with a damp cloth and lukewarm water. If they’ve been used outdoors for camping or travel, a light clean after use is usually enough.
Because portable panels are folded and stored, they often stay cleaner than roof mounted systems. Still, visible grime is your cue.
How Often Cleaning Makes Sense in the UK
For most UK homes, once or twice a year is enough. Properties near trees, farmland, busy roads, or coastlines may need cleaning every six months.
Rather than guessing, keep an eye on your system’s output. A noticeable drop during similar weather conditions often points to surface buildup.
Professional cleaning every year or two can also be useful, especially if access is awkward or the roof pitch is steep.
Safety Comes First, Always
Cleaning solar panels involves electricity, height, and water. That combination deserves respect.
Always shut the system down before cleaning. Even diffuse daylight can generate voltage.
If panels are on a roof, wear non slip footwear and avoid overreaching. Don’t step on panels. Ever. If you need ladders or harnesses and don’t have them, it’s time to call a professional.
Use only soft tools. Abrasive brushes, harsh chemicals, and high pressure washers can cause micro cracks that quietly reduce output over time.
Weather matters too. Avoid frosty mornings, wet roofs, or strong winds. A calm, cool day is safest and gives the best results.
When Professional Cleaning Is the Better Call
If access is difficult, the roof is steep, or the panels sit high above ground, professional cleaning makes sense. Specialists use purified water systems that leave no mineral residue and reduce the need for chemicals.
They’re also useful when stubborn grime won’t shift or when you want a full system inspection alongside cleaning.
Common Mistakes That Cost Output
Using bleach, ammonia, or strong detergents is a big one. These can damage surface coatings and void warranties.
Cleaning during hot midday sun is another. Cold water on hot glass risks thermal stress.
High pressure washers may feel efficient, but they can force water into seals and wiring.
And skipping shutdown? That’s a safety risk, plain and simple.
Why Clean Panels Are Worth the Effort
Cleaning solar panels isn’t about squeezing out perfection. It’s about removing barriers between sunlight and the cells doing the work.
With the right timing, gentle tools, and a bit of care, panels stay efficient, predictable, and long lived. Monitor output, clean when it makes sense, and don’t take risks where help is available.
Sometimes the simplest maintenance delivers the longest return.
Frequently Asked Questions
The best way to clean solar panels is with a soft microfibre cloth or sponge and lukewarm water. Mild soap can be used sparingly for stubborn grime. Abrasive tools and harsh chemicals should be avoided.
Do not use pressure washers, wire brushes, or strong detergents. Avoid cleaning in peak sun or walking on panels. Always shut the system down first.
Yes, solar panels should be turned off before cleaning to reduce electrical risk and prevent thermal stress.
You can spray water gently using a low pressure hose. Avoid high pressure jets and extreme temperature differences.
