Best Way to Clean Solar Panels

Solar panels does not have any moving parts, which is why there`s not 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

How to Clean Solar Panels

  1. The first thing you want to do is to check with your solar panel manufacturer. They might have specific recommendations for cleaning.
  2. Solar panels can become incredible hot in sunshine. Either clean your solar panels in the morning/afternoon, or pick a relatively cool day.
  3. First try if your garden hose alone does the job. If a lot of dust and dirt has accumulated you might need to clean more thoroughly.
  4. Fill a bucket or spray bottle with warm water and soap – no other special equipment is needed.
  5. 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.

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 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.

The same study also found that rain is not a satisfying way of cleaning solar panels. Solar panels that were cleaned professionally had a 12% higher output of electricity compared to those cleaned by rain.

How much money would it cost me to neglect solar panel cleaning? It is reasonable to assume that solar panels can loose 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 on 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.[3] However, some places do require extra attention:

In the southwest region of the U.S., where rainfall is limited for several months at a time, the accumulation of dirt is far greater. Solar panels that are installed near sources of pollution such as freeways, factories and airports 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.

Another thing to note is that rainwater has an easier time cleaning solar panels that are tilted (as opposed to flat mounted solar panels).

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 not really that much different than cleaning a typical window. It is not very time-consuming either. Neglecting to clean your solar panels is not much different than throwing money out of the window.Self-cleaning solar systems are available for those lazy folks out there that are willing to spend the extra buck.

Comments - 5

Dale Creasey

I have a 12 panel solar system, 8 120 watt and 4 75 watt. They are mounted on a rack on my roof at about 60% to horizontal. Taking the cost of the system, at 4% interest, means that I would be continually going in the hole.

I hose them off with directed stream when they appear to be dirty.

I use a small solar pANEL [1 amp] DRIVING A COMPUTER POWER SUPPLY FAN to cool my inverter, as the original fan quit.

Maximum power observed 900 watts with cloud edge effect. Normal power is about 600 watts with good angle. Because the system is mounted on a north south ridgeline roof, the paNELS FACE SOME A BIT EAST AND SOME A BIT WEST.

Total annual generation is some less than 1000 KWH. Maximum daily about 5 KWH.

If you would like more info ask


November 20, 2013 11:03 pm Reply

Giselaq Connelly

Thanks for your explanation about cleaning the solar panels. I have 18 panels distributed over a 2 story house.It was installed in January and since then I have not paid any electric bill yet. When the system was installed, nobody told me about the periodic cleaning of the solar panels. Neither did any installer tell my friends who installed the solar panels. My research on the Internet showed that they should be cleaned about every 2 months. It was said that just hosing them off would be the worst thing to do because if you have hard water, the droplet residue after drying would have a worse effect than the dust. Professional cleaning is about 200 Dollars each time. How often should these panels be cleaned? I would appreciate if we could share experiences. I have a couple of friends who are also interested in this subject. Thank you very much. Gisela Connelly

May 26, 2014 6:32 pm Reply

Kevin Ashley

I have had excellent results on my windows using Windex Outdoor Glass Cleaner which comes in a bottle that connects directly onto a garden hose. Just spray the window with water to get off the accumulated dust, then switch to the “cleaner” setting and spray from top down with the suds. Then wait a few minutes and come back with the rinse water. This product does not streak and does not leave spots; no wiping required.

Has anybody tried using this on solar panels? One advantage is that if you can reach the panels with a garden hose flow from the ground there is no need to climb on the roof.

August 27, 2014 1:29 am Reply

Fernando Vargas

I would thing that a two gallon sprayer filled with distilled water would do the job; the next best thing to rainwater. I agree on your comment that hard water would just make it worse. I would also recommend investing in some micro-cloths for gentle scrubbing and drying. Also, if using soap, one would need to make sure that all the soap is removed, from your roof as well to avoid buildup. Otherwise, soap residue might work as a magnet to attract more contaminants. Sort of the same principle as rug cleaning rugs and carpets with very hot water and not using those carpet shampoos; you can never truly remove all the shampoo out.

April 20, 2015 8:53 pm Reply

Dan Grahovac

Very helpful as I’ve been in the market for solar panels and have been doing my homework. Particularly on what it’s going to take to maintain them. I thought maybe there was more too it but from the article and from what others have said it looks like my maintenance cost, in terms of cleaning, will be relatively low. Thanks for a good read!

May 21, 2015 8:13 pm Reply

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