Do solar panels need cleaning?

Solar panels typically don’t need cleaning, rainfall is enough to free the surface of the panels of dirt and grime. The exception is for solar panels that are installed at a tilt of 10° or less, in this situation, it is recommended you clean your panels as rainfall is less effective at cleaning them.

Infographic that answers the question, do solar panels need cleaning; the answer is typically not, if the panels are installed at an angle, the benefits do not outweigh the cost. If the panels are installed flat, they will likely benefit from regular cleaning.

Does cleaning your panels improve efficiency?

It is true that the cleaner your panels are, the more efficient they are and the more electricity they will produce. The improvement in efficiency is the cause of some debate, typically though the improvements in efficiency are negligible, especially when factoring the time and cost to perform the solar panel cleaning.

Does cleaning solar panels make a difference?

The effect cleaning solar panels has on output varies depending on site-specific conditions and how dirty your panels are! For our solar power calculations, we conservatively estimate the effect of dirt and grime on panels to account for a 5% loss in output. The 5% de-rating is deemed an acceptable figure to use according to the Clean Energy Council.

Excerpt from the Clean Energy Council design guidelines for accredited installers that says to allow for a 5% reduction in output for panels that are not cleaned regularly.

Study finds that impact of cleaning is minimal

In Australia, a study conducted in Wollongong concluded that the impact of uncleaned panels on solar output was in the order of 1%, and therefore negligible.

You should clean your panels if they have no tilt

If your panels are installed at an angle below 10°, you should consider regular cleaning. A google study found that output improved by 100% after cleaning their panels for the first time in 15 months – these panels were installed flat with no tilt. A second clean eight months later improved output by 36%. Interestingly, the same study concluded that the improvement in output from cleaning the rooftop panels installed on an angle was negligible.

The Wollongong and Google studies both conclude that, cleaning solar panels installed on an angle has very little impact on their efficiency and output.

What is the cost of cleaning solar panels?

To have your panels professionally cleaned, expect to pay around $150. If access to the roof is more difficult, or you have a large system, expect to pay a little more.

If you decide to clean the panels yourself, there are only incidental costs for soap and a suitable brush. However, you should consider the cost of your time to perform the clean.

Cost vs benefit of cleaning your panels

The issue with cleaning your panels is the cost vs benefit. If you pay a professional, is the improvement in output going to pay for the $150 cost to clean? Most likely not. If your solar system makes savings of $1,500 per year, a 5% improvement in output due to cleaning, only amounts to a $75 saving.

If you clean the panels yourself, is the time and effort and risk to your safety worth the potential savings?

How to tell if your panels need a clean

There are two ways that you can tell if your panels need to be cleaned:

  • 1. Physical inspection
  • 2. Monitoring your system’s output

The best way to tell if you should clean your panels is to inspect them. If dirt and grime is highly visible, or if you can see leaf litter and animal droppings, then more than likely they need a clean.

If you have a smart monitor, you can monitor your system’s solar output to determine if your panels may benefit from cleaning. Below is a list of items that may impact on the output of your solar panels:

  • Dust
  • Leaf litter
  • Pollen
  • Bird / animal droppings
  • Traffic film
  • Salt
  • Lichen

Do-it-yourself cleaning

If you want to clean your solar panels yourself, you need to do so with caution. You need to ensure your system is switched off, and you can safely access your panels. Be careful not to scratch the surface of the panels and avoid cleaning when the sun is shining brightly.

If your panels are installed on a decent tilt, it’s likely you’ll get little benefit from the clean, so please, weigh up the safety risks beforehand.

Solar panel cleaning preventative measures

If you can install your panels at a tilt greater than 10° and position them where they are free of shading from trees, you will prevent the likelihood that you will need to regularly clean your solar panels.

Not only will the solar shading from trees reduce the output of your panels, but leaf litter and animal droppings are more likely to be an issue from an overhanging tree.

Solar panel cleaning FAQs

Do I need to clean my solar panels?

You do not need to clean your solar panels unless they are installed flat. Cleaning improves output only marginally and cost to clean them outweighs the benefits.

Does cleaning solar panels make a difference?

Cleaning solar panels typically only results in a very small improvement in efficiency. However, if your panels are installed flat, cleaning them can make a significant different to output.

How often do solar panels need cleaning?

If your panels are installed on an angle greater than 10°, they will clean themselves and you don’t need to bother. If panels are installed flat, or you are fastidious about maximising efficiency, it is recommended to clean them every 6 months.

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