Why Rain Does Not Clean Solar Panels?

Updated: Mar 28

Well, first things first...

What is rainwater made up of?

The literature explains that rainwater generally has a low pH (5.5) due to its dissolved gas content. This makes rainwater head towards the acidic end of the scale.

Then, add to this the atmospheric contaminants that rainwater absorbs during rainfall and the fact that:

  • Rainwater composition is directly related to atmospheric elements e.g. pollution

  • Seaspray can add to rainwater in coastal areas

...and this is all before


even touches

your home's surfaces!

Check out this pH scale to see how rainwater compares to regular household

items that fall into the acidic category, including urine, black coffee, and tomato juice.

Case studies have further found that rainwater with pH < 6.5 is corrosive to structures.

Dreamstime Royalty Free Stock Image - Rusted Water Pipes and Frame

So, how resistant are solar panels to the elements?

When I researched this, LG state that with premium craftmanship and materials, 25-30 years is the expected life span of a solar panel. Reliability researchers from Sandia National Laboratories (USA) who study corrosion and its effects on photovoltaic (PV) system performance explain that materials in tropical coastal regions where temperatures and humidity are higher generally corrode faster.

Like LG, bloggers agree that solar panels are designed to handle weather extremes. However, they point out one limiting consequence - that rainwater can solidify existing dust/dirt on the solar panel's surface and exacerbate its accumulation which leads to less power generation. Clean Solar Solutions (UK) provide the best comparative analogy to that of a car windscreen left unclean for 6 months... remembering...

What if your rooftop is frequented by our local high flyers?

Video - Flinders Street Townsville

That's more

to add to

the existing mess


your solar panel's


surface area

So... What next?

Mike from RPS Solar Pumps (USA) demonstrates the return of a Solar Panel's ability to absorb solar power after being cleaned in the 5 min YouTube clip below.

It is recommended that solar panels be cleaned with WATER ONLY, not chemicals

Softwash North Queensland

has invested in specialised equipment for the gentle, spot-free cleaning of your solar panels

Image - Solar Panel Clean (Kelso)

Using a water-fed pole, PURE WATER (pH 7) is applied to gently remove debris and leave a clear finish that maximises your solar panel's advertised and intended efficiency.

Image - Solar Panel Clean (Kelso)

Image - Solar Panel Clean (Kelso)

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