Solar panels do not have any moving parts, which is why there isn’t a whole lot of maintenance to take care of. However, cleaning is one aspect of solar panel maintenance that should not be taken lightly. In this article you will learn how to clean solar panels the right way.

How to clean solar panels

• The first thing you want to do is to check with your solar panel manufacturer. They might have specific recommendations for cleaning.
• Solar panels can become incredibly hot in sunshine. Either clean your solar panels in the morning/afternoon, or pick a relatively cool day.
• Try using a garden hose first; that alone might handle the job. However, if a lot of dust and dirt has accumulated, you might need to give them a more thorough clean.
• Fill a bucket or spray bottle with warm water and soap – no other special equipment is needed.
• Clean the surface of the solar panel with a soft cloth or sponge. You do not have to clean the wiring underneath.
• Show extra caution if cleaning your solar panels requires you to climb up on the roof. Consider getting professional solar panel cleaners to do the job if you’re not sure you can perform the task safely. 

A garden hose is often all you need to effectively clean your solar panels. Image source: Palomar Solar

Why should I clean my solar panels?

We know that dust, dirt, pollen, bird droppings, and other debris can negatively affect solar panel efficiency.

Google conducted a groundbreaking experiment at their 1.6 MW solar farm in Mountain View, California. They found that cleaning the solar panels was “the number one way to maximize the energy they produce.” Cleaning solar panels that had been in operation for 15 months doubled their output of electricity.

Google concluded that for flat solar panels, relying on rain alone is not an adequate way of cleaning solar panels. 

Will neglecting solar panel cleaning cost me money?

It is reasonable to assume that solar panels can lose 15-25% of their efficiency if not cleaned properly. 

This literally means that they will generate 15-25% less electricity, which you now will have to source from the utility company at their price rates. This easily adds a couple of years extra to the payback time.

How often should I clean my solar panels?

In most places, there's more pollution in the winter, which is why the spring is a good time to do an annual cleaning. Solar panels that are cleaned once and twice a year produce 3.5% and 5.1% more electricity respectively than those that are left uncleaned. 

While cleaning once or twice a year is usually enough, in some places panels require extra attention. A prime example of this is the southwest region of the U.S., where rainfall is limited for several months at a time. There, the accumulation of dirt is far greater. 

Another example is when solar panels are installed near sources of pollution such as freeways, factories and airports. Here, too, they’ll need to be cleaned more often. 

Other special cases to consider include autumn and winter, where the removal of leaves and snow is important for optimal performance.

Also take into account whether or not your panels are installed at an angle. Rainwater has an easier time cleaning solar panels that are tilted, so if your solar panels are mounted flat, you might need to clean them more often. 

Finally, here's the best piece of advice when it comes to frequency: Monitor changes in the power output of your solar panels before and after cleaning. Experiment with different time intervals. Take note and evaluate what works.

Cleaning solar panels is worth the effort

Cleaning solar panels is not really that much different than cleaning a typical window. It is not very time-consuming either. In return, you could see a big boost in your system performance, and big cash savings on your electric bills. 

In other words, 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.

Key takeaways:

• Bird droppings, dust, and pollution can all reduce solar panel efficiency.
• Leaving your panels dirty will reduce solar output and thus increase your solar payback period.
• You might need to clean more often if you are located in an arid region or near a pollution source, or if your panels are mounted flat.
• Monitor solar output before and after a cleaning to measure its impact; adjust the cleaning frequency accordingly.