Cleaning solar panels: why, when and how you should do it

cleaning-of-solar-panelsClean panels are efficient panels.

Cleaning solar panels: why, when and how you should do it

How often do you clean solar panels?

How often do you clean solar panels?

Clean panels are efficient panels.

We like to keep our windows clean so why should solar panels cleaning be any exception? The question is really when you need to offer a bit of solar panel care and how. Solar panel maintenance is a question that baffles many panel owners.

To help clear up some of the confusion, this Energy Matters article examines how to clean solar panels without injuring yourself or damaging the panels in the process.

We look at panel requirements: what you clean them with and how. We also look at the main sources of dirt, and when you need to call in the professionals.

Dust, leaves and water – common solar blockers.

Can dust cause regular problems or just the build-up of grime over the years? It all depends on where you live for a start and what is causing it.

A bit of dust might not have an effect, according to tests done by Ontario Solar Installers, because light can still get through. They recommend that you let nature take its course and the rain will accomplish most of the task of solar panels cleaning.

A test done by one company found the amount the efficiency is lowered is minute – maybe 5 per cent or less. And, with a typical 5 kW system, this might equate to about $20 of loss in your energy bill. Another company found that a thorough clean made the panels 3.5 per cent more efficient.

And if this isn’t enough evidence for you, clean technology website – CleanTechnica – reported an analysis by the US National Renewable Energy Laboratory (NREL) that showed a potential 30 per cent energy yield loss per year, if panels are not cleaned monthly

Beyond this, though, leaves also block light. In an experiment carried out by company Mountain View, cleaning flat panels “doubled their energy overnight” after 15 months of operation. However, the tests confirmed that rain on rooftop panels also tends to do the job.

Special attention should be given to PV arrays situated in dustier areas if they are near farmland or next to a main road. These panels have far more dust and dirt to contend with and will require a more frequent clean.

Bird droppings: Solar Enemy No. 1

Bird droppings on your panels are more detrimental than a film of dust. Do your solar panels have a string inverter or micro-inverters? This is important because systems with micro-inverters, with an inverter attached to each separate panel, can show where one panel has been covered with droppings because that inverter will stop showing current flow.

If you have a lot of trees nearby, especially deciduous ones, they will not only drop leaves on your panels. They will also attract birds.

One thing to consider is the angle of your panels. Flat panels will need more upkeep as water can pool up and leave a muddy residue when it evaporates. Angled panels take advantage of rain running across them to keep them clean.

Solar panels cleaning: Is it worth getting professionals in? 

Australia now has more than two million rooftop installations. According to the Clean Energy Council, 2018 also saw a 45 per cent growth in commercial solar power systems.

Many homeowners opt to clean their own solar panels. This is safer from the ground, where possible – read our cleaning  solar panels guide for more tips.

But tidying up these systems isn’t always as straightforward as it seems. 

A new ‘Solar Panel Soiling’ whitepaper by solar measurement company Kipp & Zonen explores the issue of dirty panels in terms of economic, geographic and technical factors.

For instance, panel dirt is worst in desert areas like the American Southwest where the air is dry and dusty. Flat-tilt array designs also trap more dust.

Meanwhile, air pollution is also a culprit. Build-up happens on arrays close to local factories or composting facilities, the whitepaper informs.

So when is it worth enlisting expert help to sort these challenges out?

Calling the professionals may not be worth it for a bit of dust building up over time. But doing it yourself could be costly and certainly dangerous if you fall off the roof.

One idea would be to upgrade your system so you make increased savings that way. But if you play it safe there are other advantages of maintenance. You can see if cricket balls or debris from storms have cracked the panels. Also, check for wasps, possums and even birds nests.

How do I go about cleaning solar panels?

What is the best way to clean solar panels? For the DIY-minded you should find the materials at home. Because you don’t want to scratch the panels in any way, it’s best to use just water and a non-abrasive sponge to apply soapy water.

Avoid sub-standard solar panels with CEC accredited installer.

Get the most from your solar installation by choosing CEC-accredited products and installers.

Clean solar panels with a mild detergent if necessary.

And if you’re asking yourself if you can use a pressure washer to clean your solar panels, we encourage you to only use a normal hose. Using anything with high pressure may cause damage. Use a sponge if the birds have made a mess and nothing stronger than the detergent you would use with your dishes. You don’t want any strong chemicals marking the panels.

Solar power maintenance – safety first!

The best way to clean the panels is from the ground, with a long-handled implement. But if that’s not possible and you choose to go on the roof, you must take precautions.

If he falls, the rope attached to this man’s safety harness will prevent him falling to the ground.

No one should be on a roof without a hard hat and a safety harness. It is a potentially fatal environment. Check out this advice about working on roofs before you start. The task of solar panels cleaning is not worth your life!

New research to keep solar panels clean and efficient

While there are still DIY services and professional solutions to eliminate any soiling on your panels, industry innovations are also paving the way for easier upkeep.

These include:

  • Special coatings for panel glass to repel dust and reduce soiling.
  • Robotic cleaners to remove dirt at night without using water – they use soft brushes and air blowers.
  • Kipp & Zonen’s commercial tool designed to measure dirt levels.

Kipp & Zonen’s DustIQ monitor – for example – uses LED and a photodiode to monitor the amount of dirt on panels. Solar farm operators can then choose when and how often to clean their installations for maximum performance.


Do you even need to clean your solar panels? 

The average bit of dust will be cleaned away by the rain and it won’t be worth getting the professional cleaners in. If you are in a heavily polluted area, or there could be some extra dirt or obscuring objects up there, break out the garden hose and clean the panels down, keeping your feet on the ground.

If something is not budging or you need to clean a whole lot of grime and bird poop off the panels, then follow the safety precautions and get up there when it’s a cool day and you have a safety harness and hard hat.

Use a sponge with washing-up liquid to clean the panels gently. Ultimately, you may decide to leave cleaning to the professionals and just make spot checks to see how badly they need some upkeep.

One solution to prevent you having to climb up on a ladder to inspect the panels could be to have a professional company install a CCTV camera pointed at the panels so you can see for yourself when they need cleaning.