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Solar panels are marketed as low-maintenance, and compared to most home investments, they are. But "low maintenance" is not the same as "no maintenance". A layer of dust, a few bird droppings, or a season of pollen can quietly reduce your system's output by 5% to 25%, depending on how bad the soiling gets.
For a typical 6.6kW system generating $1,500 to $2,000 in annual savings, even a 10% drop means $150 to $200 lost each year. Over a few years of neglect, that adds up to more than the cost of regular cleaning.
This guide covers how to clean your panels safely, how often to do it, when to call a professional, and the common mistakes that damage panels rather than help them.
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Why cleaning actually matters
Solar panels work by absorbing sunlight through their glass surface. Anything sitting on that surface, whether it is dust, bird droppings, pollen, salt spray, or lichen, reduces the amount of light reaching the cells. The result is less power generated.
The impact varies depending on what is on the panels. A thin film of dust might reduce output by 3% to 5%. Bird droppings are worse because they completely block individual cells, creating "hot spots" that reduce the output of the entire string. In extreme cases, heavy soiling can cut production by 20% or more.
Australian conditions make this worse than in many countries. Large parts of the country are dry and dusty, coastal areas get salt spray, and eucalyptus trees drop sap and debris year-round. If your panels are near a busy road, construction site, or agricultural land, they will accumulate grime faster than a suburban rooftop with clear sky exposure.
How often should you clean your panels?
There is no single answer because it depends on your location, roof angle, and surroundings. Here are some general guidelines.
| Situation | Recommended frequency |
|---|---|
| Suburban rooftop, moderate tilt, no trees nearby | Once a year |
| Near coast (salt spray) | Every 6 months |
| Under or near trees (pollen, sap, bird droppings) | Every 3 to 6 months |
| Dusty or rural area | Every 3 to 6 months |
| Flat or low-tilt panels | Every 6 months |
| Near a construction site or busy road | Every 3 months until settled |
The easiest way to tell if your panels need cleaning is to check your monitoring app. If output has gradually declined and there is no obvious weather explanation, dirty panels are a likely cause. A quick visual inspection from the ground will usually confirm it.
How to clean solar panels yourself
If you can reach your panels safely from the ground, DIY cleaning is straightforward and costs almost nothing. The key word is "safely". Never climb onto your roof to clean solar panels. Falls from roofs are a leading cause of serious injury in Australia, and the savings from DIY cleaning do not justify the risk.
Check panels from the ground
Before cleaning, visually inspect your panels from ground level. Look for obvious dirt build-up, bird droppings, leaf debris, or any physical damage like cracks or discolouration.
Choose the right time
Clean early morning or late afternoon when panels are cool. Spraying cold water on hot panels can cause thermal shock and micro-cracks. Overcast days work well too.
Rinse with plain water
Use a garden hose to rinse the panels thoroughly. This alone removes most loose dirt and dust. Do not use a high-pressure washer.
Gently scrub stubborn spots
For bird droppings or stuck-on grime, use a soft brush or sponge on an extension pole with warm soapy water. Work gently to avoid scratching the surface.
Final rinse and check
Give panels a final rinse with clean water to remove any soap residue. Check your monitoring system over the following days to see if output has improved.
What not to do
Never use a high-pressure washer
The force can crack glass, break seals around the panel frame, and force water into electrical connections. This is the most common cleaning mistake.
Never use abrasive materials
Steel wool, scouring pads, and rough brushes scratch the anti-reflective coating on the glass. Once scratched, the panel permanently loses some efficiency.
Never clean panels in the middle of the day
Cold water on hot glass can cause thermal shock, leading to micro-cracks that worsen over time. Clean in early morning, late afternoon, or on overcast days.
Never use harsh chemicals
Bleach, ammonia-based cleaners, and strong solvents can damage the panel surface and void your warranty. Plain water and mild dish soap are all you need.
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When to use a professional cleaner
Professional cleaning makes sense when your panels are on a second-storey roof, steep pitch, or otherwise hard to reach safely. It also makes sense if your panels have stubborn buildup like lichen, hardened bird droppings, or mineral deposits that a garden hose will not shift.
A professional clean typically costs $150 to $350 for a standard residential system. Some companies offer annual maintenance packages that bundle cleaning with a visual inspection and performance check for $250 to $500 per year. These packages can be good value if you want peace of mind without thinking about it.
When choosing a cleaner, check that they use purified water systems (deionised water leaves no residue), soft brushes, and that they are insured for working at heights. Avoid anyone who offers to pressure wash your panels.
Cleaning and your warranty
Most panel manufacturers require "reasonable maintenance" as a condition of the product warranty. This typically means keeping panels reasonably clean and free of debris. If you make a warranty claim for reduced output and the manufacturer finds that neglect caused the issue, the claim may be denied.
On the flip side, using the wrong cleaning methods can also void your warranty. High-pressure washing, abrasive cleaning, and chemical solvents are specifically excluded by most manufacturers. Stick to the manufacturer's recommended cleaning method, which is almost always plain water and a soft cloth or brush.
If your installer has gone out of business, your workmanship warranty is effectively voided, but your panel and inverter product warranties still apply through the manufacturer. You can check whether your installer still exists using our collapsed solar companies tracker. If they have closed, a qualified repairer can handle any issues that come up.
Using monitoring to track the difference
The best way to know if cleaning helped is to compare your system's output before and after. Most modern inverters have monitoring apps that show daily and weekly generation. Check your output in the days before cleaning, clean the panels, then compare the following days (adjusting for weather differences).
If you see a noticeable jump in output after cleaning, that tells you your panels were being held back by dirt. If the output is unchanged, your panels were probably clean enough already, and you can extend the time between cleans.
For older systems without monitoring, an annual professional inspection can give you a performance snapshot and identify any issues beyond just dirt.
Frequently asked questions
How often should I clean my solar panels?
Most Australian homes should clean panels once or twice a year. Homes near the coast, under trees, or in dusty areas may need quarterly cleaning. Panels tilted at 15 degrees or more get some natural rain washing, but flat or low-tilt panels accumulate dirt faster.
Can I clean solar panels myself?
Yes, if you can safely reach them from the ground with a hose and soft brush on an extension pole. Never climb onto your roof to clean panels, as the risk of falls far outweighs the savings. For second-storey or hard-to-reach installations, use a professional.
How much does professional solar panel cleaning cost?
Professional solar panel cleaning typically costs $150 to $350 for a standard residential system. Some companies offer annual maintenance packages that include cleaning, inspection, and a performance report for $250 to $500.
Do dirty solar panels really affect output?
Yes. Research shows that dirty panels can lose 5% to 25% of their output depending on the type and severity of soiling. Bird droppings and heavy dust cause the biggest losses because they create "hot spots" where individual cells are completely blocked.
What should I never use to clean solar panels?
Never use high-pressure washers, abrasive sponges, or harsh chemical cleaners. These can scratch the anti-reflective coating, crack the glass, or damage seals. Use plain water and a soft brush or microfibre cloth. If you need a cleaning agent, use a mild dish soap diluted in water.
Is rain enough to keep solar panels clean?
Rain helps, but it is not enough on its own. Rain can wash away loose dust but leaves behind mineral deposits, pollen films, and bird droppings. Panels in areas with infrequent rain or heavy pollution will need manual cleaning regardless.
The next step
If you have any questions about the information in this guide, feel free to get in touch:
Email: andy@whysolar.com.au
Tel: +61 455 221 921
If you're considering solar panels or batteries for your home, Andy and the team can help you get quotes from trusted, pre-vetted local installers:
Written by
Andy McMasterSolar Installer Partner Relations
Connects homeowners with trusted, vetted solar installers across Australia. Andy works directly with installation companies to ensure quality standards and helps homeowners navigate the quoting process.
Learn more about Andy McMaster