If you have a residential solar energy system installed, your solar panels are generally flat, tilted, and on your rooftop. How often do you clean your roof? Probably not very often, most likely never. Why’s that? I hear you saying “Isn’t that what rain is for?” That’s kind of the same logic for solar panels too.
In most cases, you won’t need to clean your solar panels often, if at all. After all, anything that accumulates dirt on them (for example, dust or pollen), will get washed off the next time it rains. There are some times it might make sense to clean your solar panels though. If you’ve got a lot of bird droppings on your panels, rain might not wash these off very readily, so it’s a good idea to clean them off. Also, if you live in a state that’s prone to droughts – or, if it rains, it’s only a very light, misty rain, you might need to clean them every now and then.
Do dirt and debris have an impact on the effectiveness of your solar panels? And if so, how much? Well, yes and no. And, not much. Yes, dirt and debris can affect how much sunlight gets through to convert the light to energy. But, the amount the efficiency is lowered is minute – maybe 5% or less. And, with a typical 5kW solar system, this might equate to about $20 of loss in your energy bill. Not monthly – overall. And generally, even if we are talking about areas with drought, eventually when it does rain, a couple months down the line, everything will be washed away and it might not even be worth it to deal with the hassle of cleaning it in the first place.
If you do decide your solar panels need to be cleaned, there are two main ways of doing it: hire a professional or do it yourself. A lot of solar companies will offer this type of service to you, for a fee of course. They might offer it as part of an annual maintenance service, or suggest you get it done every so often when they come to install the product. The truth is, what you get back cost-wise in your energy bill does not exceed the amount you need to shell out to these companies to perform the work. Solar companies often charge a steep amount to do this cleaning, for not much return on your energy bill.
On the other hand, if you were interested in doing it yourself, you’ll generally have all you need to do it at home. In most instances, it will involve nothing more than a hose, maybe some soap, and you’re good to go. This might be helpful in drought-prone areas as well, because essentially what you’re doing with the hose is the same thing the rain would do if you got more of it in your area.
There are ways to determine if your solar panels need cleaning to begin with. One is physical inspection of the panels for debris, dirt, bird droppings, etc. The other way is the use of a monitoring system that alerts you to how well your solar panels are functioning and performing. This can alert you to any maintenance needs for your system, whether that’s mechanical, electrical, or cleanliness.
If you are interested in cleaning your residential solar panels on your own, there are a variety of products you can use to clean them. But first things first. Check with your solar installers and providers to determine if there is any information about solar panel cleaning, recommendations, and dos or don’ts when it comes to cleaning your system.
The most effective way to clean your solar panels is with a hose and a bucket of soapy water. Essentially, in the same manner you would wash your car at home. Because you don’t want to scratch the panels in any way, it’s best to use just water and a non-abrasive sponge to apply soapy water. Keep in mind that you shouldn’t use any type of high-pressure water sprayer when washing off your solar panels. A high-pressure attachment can damage the solar panels themselves.
If you do use something other than just water – especially to get rid of pesky bird droppings, just make sure what you’re using is soft and hard bristle-free. Sponges are great products to clean solar panels with because they won’t scratch. If deciding to use a little bit of soap on your sponge, use something that you might clean your dishes with. Laundry detergents and other stronger chemicals might interact with your solar panels in a negative way. Remember that plain water works the best in 99% of cases.
Keep in mind that solar panels can be extremely hot when the sun is beating down on them. It’s best to pick a cool, overcast day to clean the panels. Not only to protect yourself from burns, but if you’re attempting to clean the solar panels when it’s extremely hot out, the soapy water you are putting on the panels will evaporate quickly and may leave a residue or smear to the panels which can affect their effectiveness.
Based on the research, experts are leaning toward “no.” And especially if you want to hire a professional company to clean them over the DIY method. The return on investment is just not there to justify the trouble. Let’s take a look at some numbers. On average, when your solar panels get dirty, expect a 5% or less change in output. And that’s just when they’re dirty. In most climates, if there is dust or debris on the panels and their energy output is registered 5% less than other times, the next rain will wash away the debris and the solar panels will return to their optimal efficiency. Even if you live in a drought-prone area – it will rain again.
In addition, most solar panels are tilted to a high enough degree that most buildup will run right off the panel instead of sticking to the top of it. Even with tilted panels, you might have some slight buildup on the lowest panel (because the runoff collects at the bottom) – but the decrease in output based on this alone is so minuscule, it’s not something worth worrying about.
Lastly, it’s a pretty small tradeoff, energy-wise and cost-wise, to climb up on a ladder, get on your roof, and clean your solar panels yourselves. When you think about getting out there and dragging a hose up to the roof to clean them, this point might really start to hit home.
So, in general, let the rain take care of your solar panel cleaning. Monitor your system’s functionality by paying attention to your energy bills and usage month-to-month. If you start to notice changes in your electric bill, maybe it’s time to think about cleaning or some other type of maintenance. If you think fluctuations in your energy bill could be because you need solar panel cleaning, see if the efficiency returns to normal after a good rain. If so, that’s probably the end of it. If you find the functionality is still acting wonky, it might be something electrical that needs fixing instead of just cleaning.
When it comes down to solar panel cleaning though, a visual inspection, a rainwater bath, and you staying on the ground (instead of climbing up a ladder), may be all the solar doctor needs to order.