The general rule for Australian homeowners is to clean solar panels every 6 months to maintain peak efficiency. However, this frequency depends heavily on your location. Homes in coastal areas (salt mist) or agricultural regions (red dust) may require cleaning every 3–4 months, while suburban homes with self-cleaning rain exposure may only need an annual service.
Investing in solar is one of the smartest financial moves an Australian homeowner can make. But there is a dangerous myth in the industry: the “set and forget” mentality.
While solar PV systems are durable, they are not maintenance-free. Living in a country with harsh environmental factors—from the red dust of the interior to the salt spray of our coastlines—means that grime builds up faster than you might expect. If you ignore it, you aren’t just losing shine; you’re losing money.
Why ‘Set and Forget’ Costs You Money
Many homeowners assume that the next heavy downpour will wash their panels clean. Unfortunately, rain often does the opposite. Just as a light shower leaves your car looking dirtier by turning dust into mud, rain can streak your panels and pool dirt at the bottom of the frame.
Industry data suggests that dirty panels can suffer an efficiency loss of up to 25%.
Think about that in dollar terms: if your 6.6kW system is designed to save you $400 a quarter, a 25% drop due to soiling could cost you $100 every bill cycle. That adds up to hundreds of dollars a year in lost savings, simply because a layer of grime is blocking the photons from hitting your solar cells.
The 4 Factors That Determine Frequency
Not all roofs are created equal. Your cleaning schedule should be dictated by your specific environment.
1. Location (Salt vs. Dust)
- Coastal Homes: If you live within 5km of the ocean, salt mist is your biggest enemy. Salt crystallises on the glass and can eventually corrode the aluminium frames and mounting gear. These panels need frequent freshwater rinses.
- Inland & Agricultural: If you are in a rural area or near new housing developments, “red dust” and construction dirt are heavy and abrasive. This layer acts like a physical blanket over your system.
2. Tilt Angle
The angle of your panels changes how “self-cleaning” they are.
- Steep Roofs (>20°): Rainwater runs off quickly, taking some loose dirt with it.
- Flat Roofs (<5°): Water tends to pool (puddling). When it evaporates, it leaves behind a concentrated ring of dirt and minerals that creates permanent shading on the bottom cells. Flat panels almost always require more frequent manual cleaning.
3. Bird Activity
Birds and bats love the warmth of solar panels. However, their droppings are highly acidic. Unlike regular dust, bird poop does not wash off easily with rain and can actually etch into the anti-reflective coating of the glass if left for too long. If you see nesting, you need an immediate clean and likely bird-proofing mesh.
4. Tree Cover
The iconic Australian Gum tree is beautiful, but a nightmare for solar. Eucalyptus trees drop oily sap and fine pollen that creates a sticky residue on panels. This residue acts like glue for dust, creating a layer that rain simply cannot shift.
The ‘Australian Seasons’ Schedule
As a general guide, we recommend syncing your cleaning with the Australian seasons to maximise output during peak sun hours.
- Late Spring (November): This is critical. You want to wash off the heavy spring pollen (especially Wattle and Jacaranda) and the sticky sap from the flowering season before the summer heat hits. This ensures you are running at 100% efficiency during the highest production months of December and January.
- Late Autumn (May): Clean off the summer dust and autumn leaves to squeeze every last kilowatt out of the shorter, weaker winter days.
Signs You Need a Clean NOW (Checklist)
You don’t always need a calendar to tell you when it’s time. Your system will often tell you itself.
- Visible Dust or Debris: If you can see a film of dust from the ground, the impact on your roof is likely double what you think.
- Bird Droppings: Any visible white spots are creating “hot spots”—localised heating that can damage the cell permanently.
- Inverter Data Drop: Check your monitoring app (e.g., Sungrow, Fronius, GoodWe). If you see a gradual decline in peak generation compared to the same time last year (and it’s a sunny day), soiling is the likely culprit.
- Pooling Water Marks: Look for dirty “lines” along the bottom edge of the panels.
DIY vs Professional Frequency
Can you grab the garden hose and do it yourself? Technically, yes, but there is a reason professional cleans last longer.
When you use a garden hose, you are spraying “hard water” full of calcium and magnesium onto hot glass. As this dries, it leaves white mineral spots (scale) that can block sunlight just as bad as the dust.
Professional cleaners use Deionised (DI) Water—water that has been filtered to remove all minerals. It dries completely spot-free and leaves no static charge, meaning it actually repels dust for longer than a hose wash.
Thinking about getting the pros in? You might be surprised at how affordable a pure water clean is. Check our guide on Solar Panel Cleaning Cost 2025 to compare standard rates across Australia.
Recommended Cleaning Schedule by Location
| Location Type | Primary Pollutant | Recommended Frequency | Best Time of Year |
| Coastal (<5km from sea) | Salt Mist & Sand | Quarterly | Start of every season |
| Suburban (Standard) | General Dust & Pollen | Bi-Annually | Late Spring / Late Autumn |
| Agricultural / Inland | Red Dust & Fertiliser | Quarterly | Post-harvest & Summer |
| High Bird Activity | Acidic Droppings | As Needed | Immediately upon sighting |
| Flat Installations | Pooling Dirty Water | Every 3-4 Months | Seasonal |
Conclusion
Ignoring your solar panels is like driving your car for years with a dirty windscreen—you can still see, but you aren’t getting the full picture. To protect your warranty and ensure you are getting the maximum ROI from your system, don’t rely on the rain.
Assess your location, check your inverter data, and establish a regular maintenance routine. A clean system is a high-performing system.
Ready to boost your energy production? Don’t risk climbing on the roof yourself. Find a verified professional near you through Clean Solar Aus today and get a free quote to restore your system to 100% efficiency
How often should solar panels be cleaned in Australia?
Generally, every 6 months. However, coastal homes (salt mist) and agricultural areas (red dust) may require cleaning every 3-4 months, while self-cleaning suburban roofs may only need annual maintenance.
Does rain clean solar panels effectively?
No. Rain often mixes with dust to create mud and cannot remove sticky contaminants like bird droppings, sap, or lichen. Mechanical cleaning is required for 100% efficiency.
What is the best month to clean solar panels?
In Australia, November (Late Spring) is ideal to remove pollen before summer, and May (Late Autumn) is best to clear dust before winter.