Do Dirty Solar Panels Lose Efficiency? (Yes, Here's How Much)
Solar panels don’t clean themselves — A layer of dust, bird droppings, or lichen could be quietly draining your system’s performance. Let’s break down just how much dirty Solar panels can cost you — and why regular cleaning is key to maximum efficiency.
Why Clean Solar Panels Matter
Solar panels work by capturing sunlight and converting it into electricity. When the surface of a panel is blocked by grime, even partially, it reduces the amount of sunlight that reaches the photovoltaic cells.
Think of it like wearing sunglasses indoors — you're still seeing, but definitely not at full clarity.
How Much Efficiency Do You Actually Lose?
Research shows that dirty solar panels can lose anywhere between 5% to 30% of their energy output, depending on how bad the build-up is.
Here’s a breakdown:
Light dust or pollen: ~5% energy loss
Heavy dust, salt spray (coastal areas): 10–15%
Bird droppings, lichen, or sticky debris: Up to 30%
Long-term neglect (1+ years): Potential for permanent damage to panel coating
A University of California study found that in dusty conditions, some panels lost over 20% of their efficiency in just a few months without cleaning.
What Contributes to Dirty Panels
In New Zealand, a few local conditions make regular solar panel cleaning even more important:
Pollens and airborne debris in Auckland’s environment forming a film over panels.
Seaside locations build up salt spray, reducing performance.
Bird activity in suburban and rural areas can lead to heavy soiling.
Moss and lichen grow faster in damp NZ climates, especially on north-facing roofs.
What’s the Best Way to Clean Solar Panels?
While a light rainfall may help, it won’t remove hardened grime, lichen, or bird droppings. The most effective method is a professional soft wash — a gentle, non-abrasive clean using purified water and specialised equipment to protect your panel coating.
Avoid DIY cleaning with harsh chemicals or scrubbing tools — this can void warranties or damage the anti-reflective layer.
How Often Should You Clean Them?
We recommend:
Every 6–12 months for general maintenance
Every 3–6 months if you live near the sea, under trees, or in high bird traffic areas
After major weather events (storms, dry dust periods, pollen seasons)
The Dirty Truth
Yes, dirty solar panels do lose efficiency — and it adds up.
If you're noticing a drop in your power production, or it’s been more than 6 months since your last clean, it’s time to schedule a professional inspection and wash.
Lux Clean Co Can Help You Maximise Your Solar Investment
At Lux Clean Co, we specialise in safe, effective solar panel cleaning using industry-approved techniques. Our team helps homeowners and businesses across Auckland and beyond keep their panels running at peak performance.
Book a solar panel clean today — and start getting the energy (and savings) you paid for.
Contact us now or get a free quote.