How to clean solar panels safely (and when it's worth it)

Solar panels are one of the few things on your house that quietly earn their keep every sunny day — but only if light can actually reach them. A layer of grime on the glass eats into your generation, and in Canberra's dusty, pollen-heavy conditions that adds up faster than most people think.

Here's when panels actually need cleaning, how to do it without damaging them, and when it's smarter to leave it to a professional.

Why dirty panels cost you output

Dust, pollen, bird droppings and lichen all sit on the glass and block sunlight from reaching the cells underneath. A light film of dust trims your output a little; heavy soiling does real damage. In dusty or bird-heavy conditions, losses can reach around 20% or more — which is a meaningful chunk of the free power you paid for.

Bird droppings and lichen are the worst offenders. Unlike an even coat of dust, they sit in concentrated patches that completely block the cells beneath them, so they're well worth removing promptly rather than waiting for the next rain to maybe shift them.

When to clean your panels

You don't need to clean solar panels on a strict schedule — clean them when they need it. That usually means:

• When they're visibly dirty from the ground.
• After a long dry, dusty spell with little rain to rinse them.
• During or after pollen season — Canberra springs are notorious for it.
• If your roof sits near trees or gets a lot of bird traffic.
• If your monitoring app shows generation slipping without an obvious weather reason.

Safety first — this is roof work

Before anything else, be honest about access. Roof work is a genuine fall risk, and no amount of extra output is worth a trip to hospital. A low, ground-mounted array or a single-storey system you can safely reach is one thing; a steep two-storey roof is a job for a professional with a proper harness and equipment.

A few rules that apply no matter who does the cleaning:

• Never walk on the panels. Your weight can cause micro-cracks in the cells that quietly reduce output for years.
• Mind the electrical side. Keep clear of cabling, junction boxes and any damaged wiring.
• Clean when panels are cool. Do it early morning or in the evening. Splashing cold water onto hot glass in the middle of the day risks thermal shock and cracking, so avoid the heat of the day entirely.
• Wait for the frost to thaw. In a Canberra winter, hold off until morning frost has cleared before you put water anywhere near the roof.

How to clean solar panels the right way

The good news is that the correct method is also the gentle, cheap one. You don't need special gear or products.

1. Pick a cool part of the day and give the panels a gentle rinse with a garden hose to lift loose dust.
2. Work over the glass with a soft brush, microfibre pad or a squeegee on a pole — enough to shift grime, never abrasive.
3. Rinse again and let them dry. If you can reach them safely from the ground with an extendable pole, even better — there's no need to climb.

For a truly spot-free finish, use deionised or purified water. Because it carries no dissolved minerals, it dries without leaving the chalky spots that hard tap water can leave behind on the glass.

What not to do

• Don't use a pressure washer. High pressure can force water past the seals and damage the panel or frame. A hose and soft brush is plenty.
• Don't use detergents, abrasive pads or harsh chemicals. They can strip the anti-reflective coating and leave a residue that actually attracts more dirt.
• Don't clean in the heat of the day, and don't climb onto a roof you can't safely work on.

How often should you do it?

For most Canberra homes, once or twice a year is plenty. Bump that up if your panels are near trees, in a dusty spot, under regular bird traffic, or coping with a heavy spring pollen load. Ground-mount arrays are easy enough to keep on top of yourself; roof-mount systems are where the safety maths usually tips people toward a pro.

When it's worth calling a professional

If your panels are on a steep or two-storey roof, or you'd simply rather not risk it, that's exactly the sort of job we handle. A professional professional solar panel cleaning service typically works from the ground using deionised water and extendable poles, so your panels get a spot-free clean and nobody has to balance on the tiles. You can grab an instant estimate in a minute to see what it costs for your setup.

FAQs

Can you pressure wash solar panels?

No. Use a garden hose and a soft brush instead. High pressure can force water past the panel seals and damage the frame or the panel itself, so a gentle rinse is all you should ever use.

Do you need special products to clean solar panels?

No. Plain water and a soft brush do the job, and deionised or purified water gives the most spot-free finish because it leaves no mineral residue. Avoid detergents, abrasive pads and harsh chemicals, which can damage the anti-reflective coating and leave a film that attracts more dirt.

How often should solar panels be cleaned?

Once or twice a year suits most Canberra homes. Clean more often if your panels are near trees or birds, sit in a dusty spot, or during heavy spring pollen.

Is it worth cleaning solar panels?

Yes, if they are visibly dirty or your monitoring shows output has dropped. Bird droppings and lichen matter most because they fully block cells, so removing them promptly is well worth it.