How to Clean Solar Panels

Investing in solar panels is an increasingly popular way homeowners are reducing their dependence on the utility grid while likely increasing their home’s value. Once installed, solar panels should work in the background, sending power to the home (and a backup battery if included in the system) without much involvement from the homeowner.

But solar panels aren’t completely maintenance-free. They’ll need periodic cleaning to continue operating at peak levels.

Why You Should Clean Your Solar Panels

... and How Often You Should Clean Your Solar Panels

Solar panels convert sunlight into energy. If debris on the panels block the sun, the panels don’t do their job as well as designed. Though estimates vary, the US Department of Energy reports that solar panels could lose 10% of their efficiency when dirty.

A good rain likely will do most of the cleaning for you. But stuck-on sap that can attract dirt could become a problem if there are pine trees nearby. And if your solar panels are in the flight path of migrating birds, well, you can imagine what your solar panels might look like after an extended period without rain.

You may only have to clean your solar panels a few times a year. Give your solar panels a visual inspection periodically. Consider cleaning them if they don’t have a glassy sheen.

"If they look like they have a frosted coating, then that definitely means it’s time for a good bath,” says Kyle Crump, owner and president of Bulldog Electrical & Solar Contractors in Smyrna, Georgia.

Also, check the power output from your panels, which is easy to do as there's usually an app for that. Consider cleaning your panels if they aren’t producing the usual amount of power.

You may have to clean your solar panels more often if your home is surrounded by trees or vegetation. The same holds true for areas that don’t get much rain or areas suffering from an extended drought.

Also, since rainfall is a good natural cleaner, solar panels mounted on steep roofs may need to be cleaned less frequently than panels mounted to roofs with only a slight slope.

How to Clean Solar Panels Safely

You'll need:

• Mild detergent
• Soft-bristled brush or sponge
• Hose with spray nozzle
• Vinyl gloves
• Telescoping water-fed brush with soap dispenser when cleaning tall roofs
• Extension ladder if cleaning roof-mounted panels
• A spotter watching when you're on the ladder

First, if you have roof-mounted panels, consider whether you feel comfortable reaching the panels with a ladder and using a safety harness. Contact a professional if you feel at all uneasy with the job. If you choose to clean solar panels yourself and use a ladder, make sure to have a spotter watching the ladder and assisting you.

Also, check with the solar panel manufacturer or the panel installer regarding whether there are any special considerations in cleaning your panels.

Here are the basic steps for regular solar panel cleaning:

1. Set up your extension ladder (and harness if needed for a steep roof) if cleaning a roof-mounted solar system.
   
   
2. Turn off the power to the solar panels following the instructions provided by the manufacturer or the solar panel installer.
   
   
3. Remove any debris trapped under the solar panels.
   
   
4. Gently spray the solar panels. Never spray directly under the panels or any equipment that may be attached to the solar array.
   
   
5. Apply the mild detergent. Yes, you can buy cleaner marketed specifically for cleaning solar panels, but dishwashing detergent works fine. Use a telescoping brush with a soap dispenser to reach roof-mounted solar panels and apply the detergent so you won’t have to use a ladder or climb as high.
   
   
6. Use the soft-bristled brush or sponge to gently clean the panels.
   
   
7. Rinse the panels with a gentle spray of water.
   
   
8. Let the panels air dry; you do not need to hand dry them.

Cleaning Tips:

• Make sure there’s no storms in the forecast, but a few clouds in the sky will make it a bit less steamy when cleaning roof-mounted solar panels.
  
  
• Never use a pressure washer or high-pressure hose nozzle. Always clean solar panels gently "like washing a baby,” says Crump.
  
  
• Use a lay-flat hose, which are lighter than a regular garden hose if you need to climb a ladder or raise the hose while cleaning.

Also: If you can do so safely, do a visual inspection for critter damage. Squirrels, for example, like to eat the plastic used in the wiring.

Cost of Hiring a Pro to Clean Your Solar Panels

The cost of having a professional clean your panels will vary based on such variables as distance traveled to your house. Expect prices to start at about $500. If hiring a pro, use that as an opportunity to have your panels inspected for such things any critter damage as well.