How Often to Clean Solar Panels

How Often to Clean Solar Panels

So you are making money and helping the environment with your amazing solar system, but now you’re wondering how often to clean solar panels. Well, good news! We are here to help.

Lots of bloggers and cleaning companies will claim some pretty wild numbers on how much cleaning impacts your solar system… “as much as 65% losses!”, or “50% decreases in production.” But the real truth of it…

It depends on where you live! If you are in an area of relatively frequent hard rains or snow… you might never need to clean your solar panels. If you are in an area with a couple of good seasonal rains, you might only need to clean your panels once a year. 

And if you are in a dusty area with very infrequent rains, you might want to give them a couple of good yearly cleans and maybe a rinse here or there.

So… let’s figure out which one you are and get you a good answer for “how often you should clean your solar panels.”

How Often to Clean Solar Panels

First off, let’s start with the most important part of cleaning your solar panels… Do not hurt yourself or your panels!

The goal of cleaning your solar panels is likely to get a better bang for your buck. But remember! You aren’t going to care about that bang for your buck if you hurt yourself or you damage your panels.

There are two real times I recommend cleaning your panels:

  1. You physically see something on them
  2. You live in a place that doesn’t get much rain or snow

What's on Your Panels?

4 signs your panels need a cleaning

If your solar panels have any of the following four things on them then consider giving them a clean (in order of largest impact on efficiency):

  1. Bird poop
  2. Leaves
  3. Dirt, dust, or pollen
  4. Water residue

Here’s the thing though. These scenarios require different types of cleaning.

If it’s bird poop, just clean that one spot. If it’s leaves, just give them a gentle sweep. If it’s dirt, dust, or pollen, then give them a rinse and see how they look. If it’s water residue, maybe you don’t need to worry about it or use deionized water.

How dirty are your panels really?

Some companies claim 65% losses from solar panels and you know what… they might be right. Two scientific papers (Paper #1 and Paper #2) studied decreased power output from dirt and found a 55% and 50% decrease in production.

But, the key thing to know… these studies took place in the desert. If you aren’t in the desert, then you might pay more for cleaning your panels than you get in return from increased efficiency. Also, you risk harming them and voiding your warranty.

Using a monitoring app

If you want to be really accurate about when to clean your panels consider getting a monitoring app. 

I personally use mySolarEdge because you get an individual panel-by-panel layout through the app. Why that’s useful, is you can wipe off one of your panels, and compare its power output to an adjacent panel.

This way, you know approximately how much your panels would benefit from a cleaning, by comparing the dirty panel to the clean power!

What's your Climate?

First off, let’s figure out your climate. This handy-dandy climate map from the Commission for Environmental Cooperation shows areas of general climate patterns throughout the USA, Canada, and Mexico.

You can use this map to figure out if you are generally in an area of wet, moderate, or dry weather.

Climate Map
(Click the image above if you are having trouble getting to the specific map that looks like this)

If you want more specifics on the amount of precipitation you get, then you can navigate to that using some of the other handy information from these maps.

(Click the image above if you are having trouble getting to the specific map that looks like this)

1. You Live In a Dry area

Great! You now know you live in a dry area. I’ve got good news and bad news!

The good news! You are going to get lots of sun meaning you are going to get lots of power. You also will get sun when you likely need that power for air conditioning!

The bad news… you are likely going to have to clean your panels more often and you might be a little short on water.

If you live in a dry area I would recommend cleaning your panels twice a year or when you see a build-up of thick dust. 

I would recommend using a monitoring app like mySolarEdge more in drier climates because you will likely get dirtier often and lose more money from that dirt.

2. You Get Occasional Rains (moderate)

If you live in an area with occasional rains, consider cleaning your panels once a yearI would wait until the peak of the driest part of your summer and save the cleaning for then. That way, you get the best bang for your buck for time.

3. You Get Regular Rain or Snow (Wet)

If you live in an area with regular hard rains or a good snow pack I would just monitor my panels. Regular cleaning is likely not necessary as nature is doing it for you.

However, if you do see a time when things look really dusty, dirty, or… bird-poopy… think of giving them a rinse or a scrub.

I personally live in one of these areas, and I have only cleaned my solar panels of snow one time during a wild fluctuation from 2 ft of snow to 20 degrees Celsius weather one March.

When to get your panels professionally cleaned

This is dependent on you, but I would consider professional cleaning in three situations:

  1. There is a particularly dirty spot on your panels
  2.  You have a scary dangerous roof with very little room to work
  3. You don’t want to do it and have money to burn (this isn’t me… congratulations if it’s you!)
Typically, solar panel cleaning costs between $150 to $350 depending on the amount of panels you have.

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