Does cleaning your solar panels make a difference? Read this to save you time and money

Are you okay with losing 3.7% of your solar panels power? Do you love pouring hard-earned money down the drain? Because that’s what you could be losing if you are not cleaning your solar panels. Cleaning solar panels is a particularly contentious area within the solar community. Let’s cut through the jargon and provide you with the information to save you the most money.

In this article, we'll answer the following questions for you:

1. Do your solar panels need cleaning?

2. How do solar panels get dirty?

3. What is the best way to clean solar panels?

4. Can you pressure wash solar panels?

5. How often should solar panels be cleaned?

6. What is the best time of day to clean solar panels?

7. And finally, should you call the professionals?

Do your solar panels need cleaning?

Yes, your panels need cleaning but breathe a sigh of relief; it’s not as energy-intensive as you imagine it to be. What’s wrong with dirty panels? I hear no one asking? Dirty panels create a layer between the sunlight and the solar cells; this is bad. The less light reaching the cells, the less electricity generated, the less electricity generated, the less we can use and the less we can sell, which means higher power bills, this is bad. Fear not, good solar citizen because cleaning your panels is far easier than washing your car; this is good.

How do solar panels get dirty?

Sun Tzu said the first rule of warfare is to know thy enemy, so who are the mischievous culprits waging an unholy war on your panels. Let’s meet these offenders:

• Birds - I have no ill-will towards our feathery friends; however, you get a flock of those suckers perched above your brand spanking new solar system voiding their bowels, you are going to have trouble. Bird poo, in particular, is a shit time for your panels because, as you may have learned from our guide to solar system components, in Australia, more often than not, the panels are arranged in strings. So if a magpie fires up the fecal power plant on one of your beautiful panels blocking some solar cells, expect all the panels on that string to also be down. Cureall Pest Control have some great advice on how to bird proof your roof, and stop birds from nesting amongst your solar.

• Dust - For the most part, dust is a non-issue if you live in the city; the little dust that would land on your panels both doesn’t have a significant impact (~1-2%) on system efficiency, and also typical pitch of your roof, and our friend the rain usually takes care of this one. However, if you own flat panels, this is going to be a more serious conversation (as google found out in their groundbreaking field test that showed manual cleaning of their flat panels doubled the efficiency overnight!). So city slickers, you can turn off your brain for this one. But you country folk, our who are surrounded by our iconic red dirt, dust can really impact on the overall performance of your system.

• Grime - no, I’m not suggesting the British hip-hop community is having an impact on solar panel arrays. Grime, I’m talking about oils, industrial air pollutants, discharge from car braking systems, pollution, that kind of thing. Kipp & Zonen recently published a whitepaper that explores this grimy issue in geographic, economic and technical factors. The whitepaper shows that the build up of grime happens on arrays close to local factories, so city folk beware if you are close to high traffic areas or industrial areas, grime can and will build upon your system. Typically this is slightly more difficult to clean, but don’t worry, you are in safe hands; you don’t need to be a rocket scientist to resolve this dilemma; we will break it down for you below.

What is the best way to clean solar panels?

Listen, DON’T climb your roof to clean your panels. Unless you are a rock climbing fanatic who knows their way around a carabiner, follow the new safe work at heights advice, and safely harness and hook yourself to the roof. Otherwise, don’t bother, it’s just not worth it; it’s too dangerous. Did you know the number one cause of death at home is falling? Save climbing on the roof for the professionals.

If you're like most of us, and don't have access to a solar panel cleaning robot, the best solution is always the simplest and safest. If birds are your enemies, then the hose is your friend, the hose, and the rain. You’d be surprised how much standard tap water can dissolve and wash away dirt particles and bird poo. You can do this from the safety of the ground level. Simply, aim and fire. In no time, that dirt will be cleared, and you’ll have shining, clean solar panels.

In fact, most solar brands recommend purely waiting for the rain, and in most circumstances, this is sufficient enough to clear any debris, leaf or dirt.

Can you pressure wash solar panels?

If you are going clean your solar panels yourself, avoid pressure washers, harsh cleaning chemicals and abrasive scrubers - as these might damage your solar panels. Instead, use water, a gentle soap like dishwashing detergent and a soft brush to get the buildup out of the corners.

Apart from the hose and tap water, diluting some standard detergent is your next safest option. Don’t go overboard; you don’t want to leave any residue which may actually be harmful for the lifetime of the system. A little bit goes a long way. If you can add it into a spray bottle that attaches to your hose, you’ve got it made in the shade. Don’t forget to rinse.

For troublesome poos or stains, the first thing to do is hose (if access is restricted try a hose extender pole from Bunnings) for 10 minutes and let the water soak in, softening up the debris. Come back a little later, rinse and repeat. If you have a particularly stubborn little fellow who overstays his welcome, consider using a no scratch foam brush on a long pole, perform the above steps, then get that sponge on it, lightly circling.

There are a number of solar panel cleaning kits available online. When doing your research, please ensure those bristles are soft. These products should be stand alone cleaners for your system and you should refrain from using them to clean anything else. It’s also worth while to keep your cleaning brush head off the floor so that dirty and granules don’t find their way onto your brush and end up scratching your panels.

How to care for your panels

Be careful to brushes with soft bristles and always ensure that your sponge is free from dirt when you start - because dirty sponges are the easiest way to scratch your panels! Scratched panels will behave like dirty panels, preventing optimal sunlighting landing on the cells, but this time you won’t be able to clean them to fix them.

How often should solar panels be cleaned?

Solar panels are not your teeth; you don’t need to worry about daily cleaning. Ask yourself the question, do my panels look dirty? If the answer is no, then don’t worry. Only clean your panels when they are visibly dirty, or when you see a noticeable downward trend in your solar system's energy production (usually via the digital display on your solar inverter or monitoring device). A decline in production can also indicate other issues, but cleaning your panels is potentially the cheapest, lowest hanging fruit to try before booking in solar system maintenance.

What is the best time of day to clean solar panels?

The early bird gets the worm, and the morning is also your friend when cleaning solar panels. Firstly, it’s not going to be a million degrees, you won’t break a sweat or get sunspots. Plus, another issue can arise if you are using cold water to wash your panels in the middle of an Aussie summer! Those solar panels will be cooking! We all know what happens if you pour boiling water onto cold glass, you are going to crack that glass; the same principle can technically apply to your panels. Most likely, they won’t crack or show any visible signs of damage; however, with rapid expansion or contraction caused by temperature changes, there is a possibility that internally, small damages are building up, impairing the performance of your solar system.

Should you call the professionals?

If you have a roof that is hard to access, or there is some significant bird droppings or bat poo stuck on your panels, and you’ve tried the above measures to no avail, then yes, that’s the recommendation of Electrical Safety QLD. There are plenty of solar panel cleaning companies who will hand wash your prized panels to a professional standard.

Neglecting to clean your solar panels is like throwing money out of the window. If you don’t want to clean the panels yourself, solar panel cleaning services are available for those out there that are willing to spend the extra buck.

These cleaners do come at a cost, and you expect to pay between $7-10 per panel. So for a 6.6kW system with 20 panels, that’s roughly 200 big ones. While that seems like a lot, it’s a lot cheaper than missing time off work because you fell off a ladder. Save your pride and your back pocket.

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