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

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

Updated 22nd July 2020

How often do you clean solar panels?

How often do you clean solar panels?

A car that’s well-oiled and serviced runs better, so there’s no surprise that solar panels do their job more efficiently when they’re given the same level of attention.

Beyond the set of wheels in our garages, we like to keep our windows crystal-clear and free of grime, too. So why should cleaning our solar panels be any exception? The question should more be focused on when you need to put in the hard yards, and how frequently.

So in this post, we’re covering all of your biggest questions around how to adopt a productive solar panel maintenance routine. We’ll look at all the requirements across what you need to clean them with and how, as well as the main sources of dirt, and when you need to call in the professionals.

Dust, leaves and water – common solar blockers.

Dust causes regular problems beyond the build-up of grime over the years. But your exact location also plays a big role in how much this can affect your system, and what triggers 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, as 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 they are not cleaned monthly

Beyond this, though, it’s important to remember that leaves also block light. In an experiment carried out by company Mountain View, cleaning flat designs “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 arrays have far more dust and dirt to contend with and will require a more frequent clean.

Bird droppings: Enemy No. 1

Bird droppings on your solar power panels are more detrimental than a film of dust. Does your array include a string inverter or micro-inverters? This is important because systems with microinverters (with an inverter attached to each separate panel) can show where one part has been covered with droppings. During these instances, the 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 rooftop, they will also attract birds. Both of these cause build-up and debris over time, making it more important to regularly employ solar panel cleaning services or efforts.

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

The best way to clean solar panels is through professional help

As of May 31, 2020, Australia now has more than 2.43 million solar power systems installed across rooftops. 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. If you choose this approach, remember that it is safer to do so on the ground, where possible. To help you, we recommend you read our cleaning solar panels guide for more tips.

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

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

For instance, dirt is worse 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?

Adopting professional solar panel cleaning services may not be worth it for a bit of dust building up over time. However, it’s highly effective when the job becomes too much of a hazard (or task) to do yourself. When the going gets tough and suddenly there’s a significant risk involved, we recommend using experts to ensure your system is tidied up to the best possible standards. 

How to clean solar panels on your roof

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 your system 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.

Use a mild detergent, if you feel like you need some extra help.

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 equipment and maintenance – safety first!

The best way to get the job done is on 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.

For example, a rope should be attached to a safety harness to prevent falling to the ground – a method often used by professionals. 

Additionally, 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 at these heights 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 array, industry innovations are also paving the way for easier upkeep.

These include:

  • Special coatings for 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 building up on the array. Solar farm operators can then choose when and how often to clean their installations for maximum performance.

In addition to this, expert facilities management companies – like industry leader Royal Flush – recommends cleaning your system at least twice a year. Doing so keeps your investment in tip-top shape to ensure better efficiency and cost-savings for the future. 

But if this isn’t enough to tip you over the edge and get your system in best working order, the Royal Flush team has also shed light on just how much energy you could be losing by avoiding a productive maintenance routine for your array. And where you’re losing energy, you’re also losing money.

For example, you could be losing up to the following percentages per quarter, if cleaning isn’t on your agenda:

  • Year 1 Q1: 5% Energy Loss
  • Year 1 Q2: 10% Energy Loss
  • Year 1 Q3: 15% Energy Loss
  • Year 1 Q4: 20% Energy Loss
  • Year 2 Q1: 25% Energy Loss
  • Year 2 Q2: 30% Energy Loss
  • Year 2 Q3: 35% Energy Loss
  • Year 2 Q4: 35% Energy Loss

Safe tips for DIYers

In between getting a professional team like Royal Flush in, there are a few simple ways you can help your system out.

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 array, 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 area 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 system 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.