Solar panels are one of the smartest investments for homeowners who want to save money on energy bills and reduce reliance on traditional power sources. But like any other outdoor fixture, solar panels face dust, pollution, bird droppings, and even moss growth that gradually cut down their efficiency. Dirty panels produce less power, which means higher electricity costs and wasted potential.
This guide explains everything you need to know about how to clean solar panels on roof safely and effectively, along with why professional help can make the process smoother.
For property owners in London and Surrey, keeping panels clean is especially important because of the city’s mix of traffic pollution, rainfall, and seasonal debris. The challenge is that panels are often installed on rooftops, which raises both safety and practical concerns when cleaning them.
Why Clean Solar Panels?
Many people assume rainwater is enough to keep panels clear. While showers help rinse away some dirt, they rarely remove all debris. Over time, layers of grime build up and reduce efficiency. Research shows that dirty panels can lose 15–25% of their energy production, which directly affects your electricity savings.
Bird droppings are another major issue. Unlike dust, they don’t wash away easily with rain and can block significant portions of a panel. Moss and algae are also common in the UK’s damp climate, especially if panels are near trees. Regular cleaning isn’t just about appearances it ensures your solar system delivers the return you expect.
Safety First: Precautions Before Cleaning
Cleaning solar panels might seem like washing windows, but doing it on a roof comes with risks. Roof slopes, wet surfaces, and fragile glass panels require extra caution. Before climbing up, keep these points in mind:
- Always turn off the solar system before starting.
- Never work alone on a roof; have someone nearby in case of emergency.
- Avoid cleaning panels during the hottest part of the day, as panels can become extremely hot.
- Use a stable ladder and secure footing if you’re attempting light cleaning yourself.
If your roof is steep, slippery, or hard to access, professional help is the safest option.
When Is the Best Time to Clean Solar Panels?
Choosing the right time makes cleaning more effective and safer.
- Early morning or late evening – Panels are cooler, reducing the risk of burns and preventing streaks.
- After long dry periods – Dust and pollen are more likely to build up when it hasn’t rained.
- Seasonal checks – Spring cleaning removes pollen, autumn cleaning clears falling leaves, and winter cleaning addresses grime from damp conditions.
In London, twice-a-year cleaning is often enough, but panels in high-pollution zones or near trees may need more frequent attention.
Step-by-Step Guide: How to Clean Solar Panels on Roof
Cleaning solar panels doesn’t require fancy tools, but it does require care. Here’s a safe process to follow:
Step 1: Preparation
- Turn off the solar inverter and system controls.
- Gather supplies: soft brush, extendable pole, bucket, hose with gentle spray, and clean water.
- Avoid harsh chemicals or abrasive sponges that can scratch the glass.
Step 2: Rinse the Panels
- Use a hose to gently spray off loose dirt and dust.
- Avoid high-pressure settings, which can damage seals and wiring.
Step 3: Scrub Gently
- Dip the brush or sponge into clean water.
- Work across the panels with light pressure, removing bird droppings and stubborn dirt.
- A squeegee can be helpful for leaving a streak-free finish.
Step 4: Rinse Again
- Spray panels once more with water to wash away any residue.
- Allow panels to dry naturally.
Step 5: Final Check
- Make sure no soap or dirt spots remain.
- Inspect for cracks or damage that might affect performance.
What Not to Do
While the steps above are safe, some cleaning habits can cause more harm than good:
- Don’t use pressure washers, which may crack the glass or dislodge wiring.
- Don’t use abrasive materials like steel wool or stiff brushes.
- Don’t walk directly on panels, as they are not designed to hold weight and can be slippery.
DIY vs Professional Cleaning
Many homeowners wonder if they should attempt solar panel cleaning themselves or hire professionals. Both options have pros and cons:
DIY Cleaning
- Suitable for single-storey homes or easy-to-reach panels.
- Low cost if you already have the tools.
- Works well for light dust and pollen.
Professional Cleaning
- Necessary for multi-storey properties and steep roofs.
- Experts use equipment like extendable water-fed poles with purified water that leaves no streaks.
- Cleaning can be combined with gutter maintenance, saving time and effort.
- Reduces risk of accidents.
For many homeowners in London and Surrey, calling specialists makes sense. Not only do you avoid the hazards of roof work, but you also get a thorough cleaning that ensures long-term panel efficiency.
Maintenance Tips to Keep Panels Clean Longer
While cleaning once or twice a year is ideal, you can extend the time between cleanings with a few preventive steps:
- Inspect regularly – Look up at your panels after storms or heavy bird activity.
- Trim trees nearby – Reduces falling leaves, branches, and shade that encourages moss.
- Schedule combined services – Book gutter cleaning and solar panel checks at the same time for full roof care.
- Check after nesting season – Birds often perch on rooftops in spring; droppings can quickly affect panel output.
Costs of Solar Panel Cleaning in London
Prices for professional solar panel cleaning vary depending on roof size, height, and accessibility. On average, homeowners in London and Surrey can expect costs ranging from £4 to £15 per panel. Larger systems and difficult-to-reach roofs may cost more.
Combining panel cleaning with gutter maintenance is often more economical, as professionals are already set up with ladders and safety gear. Many local services, including City Guttering London, provide tailored quotes that cover both tasks, ensuring your entire roof system stays in top condition.
Conclusion
Clean solar panels are vital for keeping your energy bills low and ensuring you get the most out of your investment. A simple routine of rinsing and light scrubbing can restore performance, but roof safety and stubborn grime often make professional help the smarter choice.
At City Guttering London, we provide trusted roof care across London and Surrey, offering gutter cleaning, repairs, and solar panel cleaning to homeowners and businesses. With over 200 five-star reviews and a free quote available within 45 minutes, our team ensures your roof systems are working at their best.
Frequently Asked Questions
How often should I clean solar panels?
Most experts recommend at least once or twice a year, though properties near trees or busy roads may need quarterly cleaning.
Does rain clean solar panels naturally?
Rain helps rinse off some dust, but it rarely removes sticky residues like bird droppings or moss.
Is professional cleaning worth it?
Yes, especially for tall or complex roofs where safety and thoroughness matter. Professionals also use pure water systems that leave panels streak-free.
Can dirty gutters affect solar panels?
Indirectly, yes. Blocked gutters can cause water overflow and moss growth on the roof, which may spread to the panels. Regular gutter care supports clean panels.
