How To Clean Your Solar Panels

Is it necessary or simply for aesthetics? 

foothills solar cleaning panel cleaning grass valley

Why would you clean your solar panels?

  1. You want them to look clean (aesthetics).
  2. You believe it will affect performance. 

For example: Flat, non tilted solar panels near a dusty road, may need cleaning to maximize production, where tilted panels in cleaner conditions may not.  The only way to really tell if soiling is affecting the performance of your solar panels is to test and monitor system performance before and after they are clean. We will go deeper into this in future articles.

How do I clean my solar panels?
Although it is always a good idea to check online to see what your specific solar panel brand recommends, there are some general suggestions on how to clean most solar panels and they are listed below.
Here are some general rules to cleaning solar panels in our area of California:
  1. Cold water on a hot panel is not a good idea. Rinse and clean when solar panels are cool, like in the early morning. If the panels are hot, damage can occur when being sprayed by water.
  2.  With a hose, simulate rain on top of your panel. This can sometimes be all you need to do.
  3.   The pros used de-ionized water when cleaning. 
    1. Why de-ionized water? De-ionized water is water that has had the mineral ions and salts removed. If de-ionized water is not available, rainwater, tap water or diluted alcohol may be used as a secondary solution.
  4. Whatever you use, don’t scratch the surface and don’t pressure wash.
    1. High water pressure can do damage to the panels and get water where you don’t want it. 

Raining water on the panel may be all you need to do.

If you feel you need to do more and you can safety reach the panels here are some guidelines and ideas:

  1. Use a soft sponge, microfiber cloth or a soft and nonabrasive brush and lightly wipe over face of the solar panel. This may be mounted on an extension pole for an extended reach. Rinse before doing this.
  2. If rinsing with water and a sponge does not fully clean the panel and you need something extra, a mild biological and biodegradable dish washing liquid may be used on the panels with your sponge.
  3. Or if you need to go even further, Isopropyl Alcohol with a concentration of less than 10% may be be used as well. This mixture was suggested by a panel manufacturer, and may not be correct for your particular panel, again check with the manufacturer’s handbook online before trying any added soap or solution. 
  4. If using a cleaning mixture, the panel must be immediately rinsed with plenty of water afterwards.  Rinsing from the top, down.

Some last bits of advice:

  • Do not, scratch the panels!
  • Do not, clean when panels are hot. 
  • Do not, clean with Acid or Alkali detergent.
  • Do not spray under the panels as you could damage electronics and connections underneath.

Be SAFE if you are choosing to clean your own panels. Ladders and roofs can be dangerous. 

For fun… Check your solar production before you clean your panels, then check them after.  With some calculations you can determine if the effort given to cleaning the panels equals the amount of money you saved by having cleaner panels.  Over time you may see positive effects and results varied depending on soiling and tilt. 

Does this sound like too much work?

If all of this sounds like too much, we recommend you call a professional solar panel cleaner like Mathew Pavlich from Foothills Solar Cleaning. The beauty of using a pro like Foothills is that they are licensed, insured, and have over a decade of on-the-roof experience.  They use an eco-safe, 4 stage pure water system which gently removes soiling from solar panels. Call Matthew at (530) 955-0909 and let him know Harry from SEG sent you.

Stay tuned for another article on solar panel cleaning, where we will show before and after pictures of the dirty then cleaned panels as well as how effective each cleaning was in terms of gained solar production.