The cleaning conversation

We know that for many companies that install rooftop solar panels, keeping them well-maintained is a subject that many installers don’t concern themselves with.  Some solar installation companies do instruct their customers on maintenance but in our conversations with installers and rooftop solar owners, this conversation is brief. 

What happens to solar panels when they get dirty?

There is no shortage of natural factors that will cause accumulation on solar panels: 

• Dust
• Pollen
• Bird droppings
• Tree sap
• Soot
• Sand (especially in areas close to agricultural areas). 

All of these particles sink in the air around us and come to rest on your solar panels. And that’s not all: moisture accumulates at night, eventually condensing into droplets, and the more flat, even and smooth the surface is – the more the moisture just sits there.

This accumulated moisture combines with all those particles we mentioned before and creates a heavy mud, just like dough or cement, which wind or rain cannot remove. Night after night, the moisture in the air makes the paste stickier, attracting more dust, pollen and sand, encouraging the layer to settle in a thick layer on the surface of the panel. 

In short, this dirt is here to stay, unless you take care to clean it!

Tip

Isn’t rain enough to clean my solar panels?

One of the myths (that should be debunked!) is that the rain will do its work, and the panels will be cleaned from season to season.  

We know this isn’t actually true, and this 2023 study on Clean Technica has also debunked the myth that rain will keep panels clean.  So, why doesn’t rain clean solar panels?

First of all, in the sunniest parts of the US such as in the states of Arizona, New Mexico, Nevada, California, or Texas, the rain is insufficient to clean the panels thoroughly or frequently enough. In addition, rain can only reduce fine dust – but not coarse dust, sand, pollen, triple ions and dirt that crystallizes during dry periods on the panels.  Also, the relatively flat angle at which the panels are installed in most home systems only adds to the accumulation of dirt.

So, while rain can remove loose dirt, it’s not a substitute for a proper cleaning method to get rid of persistent pollutants like pollen. 

How do you clean your own solar panels?

Facts are facts: 13 billion paper towels are used annually in just the United States, adding to an already unmanageable amount of waste in landfills, oceans, rivers and lakes.

As a conscientious consumer invested in solar energy, you don’t make a decision just for your personal well-being; it’s a commitment to the health of our environment and the sustainability of our communities.

Instead of adding to the problem of excess waste, when you clean your solar panels, use a method that is 100% reusable with zero waste per use.

The problem with tap water, a squeegee, and soap

There is no doubt that as fellow DIYers, we always look for the quick solution.  Why not just go up to the roof with a rag and a hose?  But in reality, washing without proper knowledge and equipment can cause heavy damage to the system. (Remember that warranty?) These damages may not be visible at first, but over time affect the efficiency and the panels dramatically.

This is where using the right tools and techniques come in. View our comparison chart of some common methods used to clean panels.

Protecting your solar panel warranty is crucial to ensuring the long-term performance and reliability of your investment.

The most important factor in keeping your warranty intact is regular maintenance, and safe, routine cleaning is number one on the list of maintenance checks. However, accidental damage like scratches or degradation of the anti-reflective coating caused by using unapproved cleaning methods will most likely void your warranty, leaving you financially exposed if a repair is needed.

The dangers of dirty solar panels

How does dirt damage a solar panel?  

A little dirt can become a lot of dirt fairly quickly, and the efficiency of solar panels depends on how much they are exposed to the sun: dirt literally gets in the way of efficient energy production. 

But this is not the only problem. 

There is a much more serious problem: long-standing or permanent dirt creates hot spots on the panels – and these cause the system to overheat. How does that happen? 

As soon as dirt accumulates on one part of the solar panel, sunlight does not reach the photovoltaic cell below it – compromising its function.  Consequently, the load on the other PV cells connected to it increases – and the entire system heats up as a result. The reduced capacity of the blocked cell causes it to resist the passage of current through it, which causes accelerated wear and tear of not only the cell but also the materials around it.  

Eventually, it will stop working.

The efficiency of a system that is not regularly maintained can drop by about 30%, and produce electricity inconsistently and inefficiently.

Not only does the efficiency of the system decrease as soon as it heats up, consistent overheating over time can cause the entire system to stop working, as well as causing other damages that are not covered by the manufacturer’s warranty.