How Often Should You Clean Solar Panels in the Central Valley?

If you have solar in Fresno or Clovis, your panels are working in one of the dustiest environments in the country. Between farm dust, spring pollen, ag spray and a dry season that runs for months, a film builds up on the glass that quietly blocks sunlight — and your production drops with it.

So how often should you actually clean them? Here’s the short version, then the details that change your number.

The short answer: every 3 to 6 months

For most Central Valley homes, cleaning solar panels two to four times a year keeps output close to peak. That’s more often than the national average, and it’s entirely because of where we live. Soiled panels can lose 15 to 25% of their output, and out here that loss adds up month after month through the dry stretch.

What changes your number

• Near orchards or open fields? Expect more dust and ag film — lean toward every 3 months.
• Low-tilt or flat panels? They hold dirt instead of shedding it, so they need cleaning more often.
• Birds nesting nearby? Droppings are corrosive and block cells — clean sooner, and consider bird proofing.
• Heavy pollen season? A spring clean after the pollen drops makes a real difference.

How to tell it’s time

You don’t need an app to know. Look for a hazy, dull film on the glass, visible dust or droppings, or a dip in your production numbers compared to the same month last year. After a big dust event or a windstorm is another good trigger.

Why a quick hose-down isn’t enough

Spraying panels with your garden hose uses hard Valley water, which dries into mineral spots that can make things worse and are tough to remove. A proper cleaning uses purified, deionized water and soft brushes so the glass dries spot-free, with no scratching and no harsh chemicals.

Frequently asked