Few topics have the power to polarize solar energy enthusiasts like the subject of how to clean solar panels.

When should I clean them? What should I use to clean them? Are there companies that can do this for me? Should I even be cleaning them at all?

These kind of questions are completely understandable. When you’ve invested a significant sum of money into generating your own energy and being as green as possible, you want to squeeze every last drop of energy that you possibly can out of your panels.

That’s why we’ve created this definitive guide to solar panel cleaning. Here you’ll find the answer to almost any solar panel cleaning-related question that you can think of. From what makes your panels dirty in the first place and the reasons to clean them, to a rundown of equipment available and some top tips to make sure you get the best results, we’ve got all of the answers you need.

Ready? Then let’s get to it.


How do solar panels get dirty?
Before we get into whether or not we need to clean our solar panels, first let’s look at how they get dirty in the first place. Typically, solar panels get dirty because of two factors: animals and the environment.

When we mean animals, we are mainly talking about birds. The upward angle of most rooftop panels makes them ripe for collecting bird droppings. This will affect almost every solar panel anywhere in the world, but you may find this more common if you live in a coastal area. Unfortunately, there’s very little you can do to stop the little buggers from relieving themselves over your panels. Sh*t happens, as they say.

The Environment:
It’s something of an irony that the vast majority of dirt covering your solar panels will come from the environment itself. Dust is the main culprit here, especially if you live in a particularly dry climate, but pollen and leaves can also cover your panels in a sun-blocking layer of muck.


Won’t rainwater clean panels naturally?
You’d think so, wouldn’t you? Unfortunately, in much the same way that rainwater doesn’t clean your car’s windscreen, it also doesn’t clean your solar panels. Unless you regularly receive torrential downpours, it’s likely that any dirt that’s been collected on the panels will remain – especially if the heat of the sun has dried it in.

The only way to ensure your panels are spotless is to hire a professional or clean them yourself.

But that brings us on to our next question: is a bit of dirt even an issue in the first place?


Do you need to clean your solar panels?

In short, yes.

But let’s go into more detail…

Increasing energy output:
Because the cells in your panels generate energy by using light to make electrons move, anything that blocks light transmission to the cells has the potential to diminish performance and, in turn, the revenue that you generate.

What’s more it doesn’t need to cover the entire panel to have a noticeable effect. If dirt and grime obscure just one of the cells on your panel, output for the entire module will decrease.

To confirm this theory, Google did an experiment on their own solar panel farm at their headquarters in Mountain View, CA. The results? Google found that the number one way to maximize energy output from solar panels was through cleaning them. In fact, they found that after cleaning, the energy output of panels almost doubled overnight.

Protecting your warranty:
Some manufacturers make regular cleaning a condition of your warranty. It is worth cleaning your panels purely for the sake of protecting your warranty, but by cleaning them you may also notice cracks, scratches or other instances of damage that will need to be repaired.


Even if you intend to keep your solar panels clean, it can be tricky knowing when’s the right time to get them done. This is especially true if, like most people, your panels are located on your roof.

If you do plan on completing a physical inspection, it will be obvious even to the untrained eye if your panels are dirty or not. You are looking for a layer of dust (you’ll be able to tell just by running your finger along the surface of the panel), any dirt trapped in the corner, and chips and cracks on the surface.

It’s very important that you keep in mind proper safety procedures before climbing on to your roof. Here’s what John Anderson, of Severe Weather Roofing and Restoration in Denver, CO recommends:

1. Walk carefully, never bounce or jump on you roof.

2. Wear a toolbelt and raise and lower power tools with a rope.

3. Wear shoes with plenty of traction. Work boots work the best, because of their well-defined heels.

This old house also has some great safety tips here.

For those who prefer to put their feet up rather than clamber about on roofs, the vast majority of monitoring tools that will keep you updated on how your panels are performing. If you notice a considerable dip in power compared to normal performance over a sustained period of time (several days or more) it is likely dirt or damage is the cause.

Alternatively, a simple solution is to create an annual schedule so that your panels get cleaned regularly twice or three times a year. That way you don’t have to worry about climbing up onto your roof every month to check on them or investing into equipment that can run into thousands of dollars.


How do you clean solar panels?

So your panels are dirty? Well you’ve got two options: clean them yourself, or hire a specialist firm to do it for you.

Whichever route you choose, the first step will always be the same – review the manufacturer’s instructions. Although they may not seem like it, solar panels can vary substantially between brands – and this includes how they should be cleaned.

If you’re determined to clean your panels yourselves, there is a multitude of DIY solar panel cleaning kits available. That being said, and regardless of what equipment you use, it isn’t a straightforward job. Not only are they usually fairly inaccessible (as you will have found out if you completed a physical inspection of your panels) but they also carry a risk of electrocution, especially if the glass has broken and water has entered.

We highly recommend that you use a professional cleaning company that not only have all of the necessary safety equipment and training, but also have the right tools and cleaning products to do an effective job.

If you are adamant that you are going to do the job yourself, however, here are the steps you need to take:

• Having first checked to see if your panels need cleaning (either via a physical inspection or by using a monitoring tool as mentioned previously) choose a day to clean them. Bear in mind that on your first attempt, this could take several hours, so ensure you are able to set enough time aside.

• Next, read your panels’ instruction manual to see if there is a procedure already outlined. In the vast majority of cases, this will start with turning off your panels.

• Because the panels become incredibly hot in sunlight, you’re going to want to clean them in the morning, as early as possible, or when they have been in the shade for a number of hours.

• Start by spraying the panels with your garden hose. In a lot of cases where there is only a thin layer of dirt on the panels, this alone will get your panels almost completely clean.

• For a solution, soapy water will suffice, although professional cleaning companies will use a more powerful chemical solution. Don’t use any metal or abrasive sponges or squeegees, however, as this will cause irreversible damage to the surface of your solar panels.

• Wipe clean as best you can to avoid smears, but don’t worry too much about drying – let Mother Nature complete the job for you.

If you follow these steps, you should be able to do a pretty good job cleaning the panels by yourself. Remember to consult your monitoring software to analyze the impact of your work. Power levels should increase significantly if you have done a decent job.


How often do you need to clean solar panels?

Now you’ve got a taste for it, you may wish to clean your panels frequently. But don’t go running to fetch your ladder and bucket just yet. The amount of time to leave between cleans is really dependent on where you live. If you live in a particularly dusty area of the country or a costal region where you may be more likely to suffer from bird droppings, you may want to clean your panels once every month or so. For the vast majority of the country however, three or four times a year should suffice.

If in doubt, install a monitoring system if you haven’t already and look for sustained periods of poor performance. This will be the biggest indicator that your panels are due for another clean.

Mopping up

So there you have it.

Having read this far you should have an understanding of:
• Why your solar panels may need cleaning
• What makes solar panels dirty
• How to check if your panels need cleaning
• How to clean your panels and the options open to you
• How often to clean your panels.

With all that knowledge in your toolbox, along with a bucket, hose and sponge, you have everything you need to maximize your solar panels’ energy output. But remember, there’s nothing wrong with phoning the experts for a helping hand. We’ll be more than happy to help.