Pollen, dust, sea salt, or pollution - if it’s in the air, it’ll eventually end up on your panels. And as a solar owner or solar care-taker, you know that what stands in the sun’s way of your panels stands in the way of your electricity savings.

Whether you’re a weekend warrior looking to maximize the payback of your system or you’re playing it safe by hiring a professional, you want to make sure your panels are properly taken care of.

But when it comes to cleaning your solar panels, you’re probably better off saving your time and money.

Should I Clean my Solar Panels?

While dust and dirt settling on your panels is unavoidable, thankfully, so is rain. Even just a mild and short rain shower will do a sufficient job of cleaning the grime off your panels and will have them performing at their full potential with no effort or money spent.

This is backed by a University of San Diego study where researchers looked at how much energy production was lost due to dust and grime each month during the summer drought. They found that in nearly every situation, hiring a professional to clean your panels is not worth the cost. There are, however, a few exceptions to this.

The Panels’ Pitch

In order for the rain to properly clean your system, the panels need to be pitched. The good news is, the study showed a pitch as slight as 5 degrees did the trick. So as long as your solar panels don’t sit completely flat, rain will be enough to get your panels clean.

The Type of Dirt

Another consideration is the dirt itself - what is making the panels dirty and how often does it accumulate? While normal air-bourne particles such as pollen, dirt, and dust will wash off in the rain with ease, there are some items that could be a bit trickier, like bird droppings. Keep an eye on your panels before and after it rains to see if they’re coming clean. If some stubborn dirt is still hanging around, it may be worth looking into having them cleaned.

The System’s Location

Another item that could factor into whether or not you should clean your solar panels is the system’s location. If your panels are located right by factories, busy highways, or fields, and the wind often blows the dust at them, you could have more dust coverage than the average solar system. If this is you, cleaning your panels may make financial sense - especially if you live in an area of the country with infrequent rainfall.

How Much Production Are You Losing with Dirty Panels?

Anything that comes between your solar panels and the sun will have an impact on how much electricity the system produces. But whether or not you should do something about it depends on how much electricity you’re losing out on. After all, professional cleaning services cost money.

In the case of typical dirt build up on solar panels, the reduction in production is so small that it’s hardly ever worth taking action.

The same University of San Diego study found that less than 0.05% of your panels’ production was lost due to dirt each day - and that’s in an area of the country infamous for infrequent rains. For a 5 kW system during California’s driest season, summer, washing the panels half-way through would lead to just a $20 gain in electricity production for the entire three months.

If you have a much larger solar system at your business or farm, you’re probably thinking “but I produce much more electricity, so I’m losing out on more savings!” That’s certainly true. If you have a larger system, you’re probably losing out on a lot more than $20, but is it still enough to pay for professional cleaning services or risk damage to yourself or your system?

To get an idea of how much your dirty solar panels are costing you, you can calculate how much a daily production loss of .05% will cost in 30 days by using the following formula. Just keep in mind this number can vary based on your own situation.

Cost of Monthly Production Loss Due to Dirt = (Total kWh Produced by System Each Month) x (30 days x 0.0005) x (Price per kWh)

Now that you have the amount of money lost due to dirt accumulation, you can compare that to the cost of cleaning services. According to Thumbtack, the national average for a residential cleaning project is $133.

This will vary with location, the number of panels you have, and the ease of access (is your system a ground mount or are they on the second story of a building with a pitched roof?) You’ll want to make sure that the price you’re paying for cleaning services will be made up through a reduction on your electric bill.

But remember, the next time it rains the precipitation will likely take care of the dirt and dust for free, literally washing away that production loss. But if you have more stubborn dirt, like bird droppings, cleaning might be the right way to go.

Cleaning Solar Panels Yourself vs. Hiring a Professional

While cleaning them yourself may seem like a great way to save money, in most cases, it’s not only a risk to your solar system and the panels’ warranty, but it’s a risk to your own safety. No amount of energy savings is worth that. You’re also risking causing damage to your system that far exceeds any gains cleaning dirt off would ever give you.

We don’t recommend you clean your solar panels, but if you’re really set on it, stick to these basic tips to limit damage to your system.

First off, check in with the solar installer to see if there is anything you should know relating to the system or special precautions you should take before cleaning. Then, make sure all the necessary safety gear is in place and being used properly.

Only use a soft stream of water from your garden hose (just like rain). Using any type of high-pressure attachment or a power washer will likely cause damage to your solar panels which could greatly (and permanently) reduce your production and void your warranty.

It’s also essential to never clean your panels with anything waxy, abrasive, or corrosive, as it could damage the coating on the panels. In fact, one of our solar panel manufacturers recommends never using any chemicals to clean your panels - just water.

Another important thing to note is that solar panels can get very hot when the sun is out. Opt for an overcast day to do the cleaning, if you’re absolutely determined to do so.

The much safer bet is to hire a professional. They’ll be using the proper equipment and materials to make sure no damage is done to your system.

If you’re seeing big drops in your system’s production, chances are it isn’t because of dirt. Though solar panels have no moving parts and solar systems typically require very little maintenance, things do happen.

While we do not offer cleaning services, our team of NABCEP-certified maintenance technicians is here to help if your production loss seems too great to be caused by soiling. Learn more about our maintenance services or fill out the form below to request an evaluation or ask us a question!