How to clean solar panels | Do you need to clean solar panels?

Today we’ll take a look on how to clean solar panels. It’s easy to DIY and can potentially have a large impact in the efficiency of your system! It can also be a big waste of time, so read this article before you get the ladder out!

Do you need to clean solar panels?

Solar panels are quite hardy and rainfall can help keep them fairly clean. With that said, there are a few things which can affect your solar system’s output – especially if you have a very small tilt (or none) on them or live in a particularly dry or dusty area. Any form of debris on top of the solar panels will effectively reduce the amount of electricity that panel can produce. And without getting too technical, depending on the quality of your solar panels, an obstructed panel can have a impact on end result, especially if they have little/no tilt or you’re using string inverters.

Some of the common issues are:

  • Dust
  • Animal droppings
  • Grime
  • Leaves
  • Sea Salt Residue (if you live by the ocean)

According to a study done by Google called ‘Should you spring clean your solar panels?‘, dirt alone is probably not worth worrying about, so cleaning tilted panels is not a massive issue for most people:

“Our data indicates that rain does a sufficient job of cleaning the tilted solar panels. Some dirt does accumulate in the corners, but the resulting reduction in energy output is fairly small — and cleaning tilted panels does not significantly increase their energy production. So for now, we’ll let Mother Nature take care of cleaning our rooftop panels.”

With that said, it’s a good idea to use some sort of solar monitoring tool to see if the output of your system is in line with the natural degradation you’d expect (check the product sheet of your panels to see what their efficiency warranty is like). If you have microinverters or DC optimisers you’ll be able to track panel performance on an individual level and can utilise that information to see if you need to bother cleaning the panels, and, if you do, which ones you need to clean. Google did experience an increase in output of 36% after cleaning some carport solar panels which lay flat in a sandy area. 

Those with string inverters will also see a bigger result from cleaning dirty solar panels as every panel on a discrete string will be affected by an underperforming panel. 

It’s generally not worth paying a professional mob to clean your solar panels, but if you think they have more than just a bit of dirt on them you can have a crack at it yourself – read on if you want to learn how to clean solar panels:

How to clean solar panels

Follow the steps below if you want to know how to clean solar panels. It’s easy! 

Step 1: Materials – You’ll need a hose (tap water is fine, you don’t need distilled/demineralised water although it’ll minimise streaking), (heavily diluted) mild detergent, and a soft brush/broom.

Don’t use harsh chemicals, abrasive scrubbers or a pressure washer. These could damage the solar panels and reduce output further. 

Don’t clean your solar panels when they’re hot – do it first thing in the morning, when it’s overcast

Don’t fall off the roof (shocking, right?) Be careful and exercise fall prevention techniques.

Step 2: Try with the hose!  (Recommended pressure less than 690kPa) Use your garden hose to clean off the panels and see if that does the trick. You may not need to even get up on the roof. 

Step 3: Use a soft brush or broom. If there are any stubborn stains you can dampen a cloth and leave it on there to break it down.

Step 4: Rinse. Especially if you used detergent as it can leave behind a residue. 

In conclusion, wash your solar panels if you can see they’re dirty or you have data proving their efficacy is being compromised. Don’t just do it for the sake of it and feel free to wait for the next shower and see if that sorts things out! If you can, try to trim any trees anywhere near the panels. Any questions? Please ask in the comments section. 

We’ve also attached a vdieo from ‘DIY Dad’ on YouTube which has some good ideas about cleaning your solar panels using Windex Outdoor Glass and Patio Cleaner:

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