Maintenance Schedule: How Often to Clean Solar Panels

Updated: Oct 01, 2026
13 min

Julia ZaraevaAuthor

Maintenance Schedule: How Often to Clean Solar Panels

Technical review:

Vic started his career in solar back in 2001. He had worked for some of the largest solar companies in Florida, such as SunPower and Unbound. Over 20 years he has installed  about 2,000 MW of solar panels across the US.

The question of solar panel cleaning stirs controversy. Can the rain do the job for me, or do I still have to add panels to my cleaning list? And how often to clean solar panels? Let's clear up the subject.

Quick answer: Most US homeowners should clean solar panels once or twice a year, which means every 6 to 12 months. Steep roofs in rainy regions can go longer. Dusty, pollen-heavy or low-tilt systems often need a wash every 3 to 6 months. Clean sooner if you see dirt build up or your output drops below the same period last year.

Key takeaways

The baseline is once or twice a year. EnergySage suggests about every six months, and Enphase says at least once or twice a year.
Tilt changes the answer. Google's flat carport panels roughly doubled their output after a wash. Its tilted rooftop panels barely changed.
Rain doesn't always finish the job. At NREL-studied plants in North Carolina, pollen cut output by up to 15% despite regular rain.
Paying for a cleaning only makes sense when the output you recover is worth more than the visit. Your electricity rate decides that.

How Often Do I Need to Clean Solar Panels? Check These Factors

In general, it's recommended to clean solar panels every 6 to 12 months. Enphase recommends at least once or twice a year, and more often if you live in a dusty or heavily polluted area.

The United States runs from arid deserts to rainy coasts and everything in between, so the right schedule depends on where you live and how your panels are mounted. Dirt on panels is called soiling: dust, pollen, bird droppings, salt and film that block sunlight from reaching the cells.

By Region

Where you live	Main soiling source	Typical cleaning rhythm	What to watch
Drylands and desert (Southwest, inland California)	Dust and sand, very little rain	Every 3 to 6 months	Check after dust storms. Sand can pile up on low-tilt panels.
Southeast and Mid-Atlantic	Spring pollen, frequent rain	Once after pollen season, again if output drops	Rain doesn't fully remove pollen (NREL).
Wildfire regions (California, Oregon, Washington)	Dry-season dust, ash and soot	Twice a year, plus after fire events if deposits are visible	Smoke in the air can lower output for a while even when the glass is clean.
Midwest and Plains	Field dust, crop residue, bird droppings	Twice a year, spring and fall	More often near dirt roads and farms.
Northeast, Pacific Northwest and other rainy areas	Light dust, rain and snow rinse tilted roofs	Once a year, inspect twice	Steep roofs benefit most from rainfall.
Coastline	Salt deposits, bird droppings	Twice a year, sooner if you see a film	Remove droppings promptly.
Big cities and industrial areas	Traffic and industrial grime	Twice a year	Air pollutants settle on the glass and build up a layer of grime over time.

By Mounting Type

Mounting	Why it matters	Typical cleaning rhythm
Steep rooftop	Rain runs off and rinses dirt away	Once a year, more in dusty or pollen-heavy areas
Flat or low-tilt (carports, flat roofs)	Dirt and water sit on the glass instead of running off	At least twice a year
Ground-mounted	Low and easy to reach	Twice a year, and a safe DIY job

These ranges are general guidance drawn from manufacturer and installer recommendations and NREL soiling research. They are not hard rules, and your own production data is a better guide than any calendar.

Every 6 to 12 months:

how often to clean solar panels in general.

Is It Time? Signs That Your Solar Panels Need Cleaning

It's not hard to figure out whether it's time for cleaning. Two signs matter most:

Visible dirt and dust. A layer of dirt, dust, pollen, leaves, bird droppings or other debris on the glass means the panels need a wash.
Reduced energy output. A decline in electricity generation that you can't explain by weather or season may come from dirt or debris.

To check whether dirt is the cause:

CompareCheck your monitoring app against the same weeks or months last year, not single days
Allow for aging The median panel loses about 0.5% of its output per year (NREL), so a bigger gap points to something else
Rule out causes Look for new shade from tree growth, inverter alerts or a damaged panel
Clean If nothing else explains the drop and the glass looks dirty, give the panels a wash

Cleaning is an essential part of solar panel maintenance. The next question is whether rain already does it for you.

To Clean or Not to Clean? Does Rain Clean Solar Panels?

Sometimes. Rain keeps steeply tilted panels fairly clean in wet climates. It doesn't reliably remove pollen or film, it does little for flat panels, and it can't help much where rain is rare.

Long ago, in 2007, Google assembled a huge solar panel installation at its Mountain View headquarters and faced a hard question: how often should solar panels be cleaned to run effectively? The team conducted an experiment. It left some flat panels on carports and some tilted rooftop ones unwashed for 15 months.

When the carport panels were finally washed, their output roughly doubled overnight. A second cleaning eight months later lifted it another 36%. The rooftop PV modules didn't show a substantial increase in energy yield, so Google concluded that the need for cleaning depends on system design, since rain can take care of tilted panels. It was one site in one dry climate, so treat it as an illustration, not a rule.

Rain has limits, though. NREL researchers studied five utility-scale plants in North Carolina that had run more than seven years without manual cleaning. During peak pollen season, losses reached as much as 15%, and wet-brush cleaning recovered 5% to 11%. Even after the pollen faded, the panels didn't return to clean-level performance. The authors wrote that "rainfall is not sufficient to assume that solar plants are fully cleaned in certain environments," according to Renewable Energy World.

Source	Setting	What it found
Google (2009)	Flat carport and tilted rooftop panels, Mountain View, CA	Carport output doubled after the first wash and rose 36% after the second. Rooftop panels gained little.
NREL (2023)	Five utility-scale plants, North Carolina	Losses up to 15% in peak pollen season. Cleaning recovered 5% to 11%. Rain alone wasn't enough.
SMUD and UC San Diego (reported 2018)	Sites in the western US	Representative annual output losses of about 7% from soiling.

The last row comes from a Green Building Advisor summary of utility field research. Soiling varies a lot with local farming, industry and rainfall, so read 7% as a rough orientation, not a forecast.

Is It Worth Cleaning Solar Panels?

If you do it yourself, usually yes. If you pay for every visit, it depends. Cleaning pays off when the output you recover is worth more than what you spend.

The math is simple:

annual production × share lost to soiling × your electricity rate

Rates vary widely. In July 2026 the US residential average was 18.31 ¢/kWh, with California at 30.71 and North Dakota at 9.09 (EIA). The table shows what a year of soiling is worth for a system that produces 10,000 kWh.

Share of output lost	Energy lost	North Dakota (9.09 ¢)	US average (18.31 ¢)	California (30.71 ¢)
3%	300 kWh	$27	$55	$92
5%	500 kWh	$45	$92	$154
7%	700 kWh	$64	$128	$215
10%	1,000 kWh	$91	$183	$307

These figures are illustrative. Real losses rise and fall between cleanings.

A paid visit has to cost less than the output it recovers. At the US average rate, a 5% yearly loss is worth around $92, so an expensive service may not break even, while a DIY wash easily does. The numbers tip toward cleaning when your rate is high, your losses run to 7% or 10% (pollen-heavy or dusty areas), or you do the work yourself.

Do your solar panels need cleaning?

Fill out form and compare offers from solar professionals

Get quotes

Asking Reddit: What Solar Owners Say

Numerous threads on Reddit with a wide range of views only confirm that the question is hot. Many homeowners don't clean their panels for years and are fine with it:

"Personally I don't consider cleaning worth the effort even when fairly dirty (as in after dusty winds, spring pollen, etc.) I only see a negligible drop in power, and rain usually cleans them off soon enough so the barely noticeable hit in production isn't worth risking my neck." – nocaps00

Some see a bigger drop and still skip it, for a simple reason: getting up on the roof is too difficult.

"I know mine are filthy up there, I can tell our production is less than last year by a good margin. The problem is we have a two story house and the panels are on the side that there is no good way for me to go up there and scrub them." – chepnut

Others find that a quick rinse isn't enough:

"I'll wash off my 27 panels with a hose and call it a day... I've had these panels for about 8 years. I was surprised to find a jump in power of roughly 10%! Just for fun, I got down to one panel and rubbed my finger on the panel. There was a film that a garden hose didn't get off! I bought a window washing thing... It was not all that hard, took about 30 minutes. I picked up another few percentage points in power." – hmspain

These are personal experiences, not measurements. Output also shifts with weather and time of day, so a before-and-after comparison on a single day can overstate the gain. In one Sense community thread, an owner reported a 15% jump after cleaning, and other members questioned whether day-to-day numbers prove it. The pattern is consistent, though: owners skip cleaning when the loss feels small or the roof feels risky, and they clean when they can see a gain.

DIY or Professional? Before You Clean

Panels you can reach from the ground or a low roof are a reasonable DIY job. Steep or high roofs are better left to professionals. Enphase recommends hiring a pro for roof-mounted panels, and the Energy Saving Trust warns against working at height without proper training.

Before you start:

Check your panel and inverter manuals. Follow the manufacturer's maintenance guidelines to protect your warranty (Enphase).
Use a soft, non-abrasive brush or cloth with soapy water. Skip abrasive scrubbers and pressure washers, which can damage seals (Energy Saving Trust).
Don't stand or walk on the panels. They can crack.
Pick a cool time of day, early morning or evening, so water doesn't dry into streaks.

Note: Enphase advises following the manufacturer's maintenance guidelines to keep warranty coverage intact. If you're unsure what yours allow, check the warranty terms before you scrub.

For step-by-step instructions, see our complete cleaning guide. If your panels are on a roof, start with How to clean solar panels on roof.

FAQ

How often should solar panels be cleaned?

Most US homes need cleaning once or twice a year, or every 6 to 12 months. Dusty, pollen-heavy and low-tilt systems may need it every 3 to 6 months, while steep roofs in rainy regions can go longer. Clean sooner if you see dirt or your output drops below the same period last year.

Do solar panels ever need to be cleaned?

Yes, in most places. Rain keeps steeply tilted panels fairly clean in wet climates, but it doesn't reliably remove pollen, film or dust. NREL found that pollen cut output by up to 15% at North Carolina plants despite regular rain.

Does rain clean solar panels?

Partly. Rain rinses loose dust off tilted panels, which is why Google's rooftop panels stayed productive without washing. It does little for flat panels, and it doesn't fully remove pollen or other residue.

Can I clean solar panels myself?

Often, yes, if the panels are ground-mounted or easy to reach from the ground. Use a hose, mild soap and a soft cloth or brush. Steep and high roofs are a job for professionals. Never walk on the panels.

Is it worth washing solar panels?

It depends on how much output you lose and what electricity costs where you live. At the US average rate, a 5% yearly loss on a 10,000 kWh system is worth about $92, so a costly professional visit may not pay for itself. DIY cleaning, a higher electricity rate or heavier soiling changes the math.

Should I turn off my solar panels before cleaning?

Follow your manufacturer's and inverter's instructions for the exact steps. Many guides recommend switching the system off before cleaning, but the procedure differs between systems.

Can I use hose water to clean solar panels?

Yes, for a rinse, especially on ground-mounted systems. Pair it with a soft brush and mild soapy water for stuck-on dirt, and avoid pressure washers, which can damage the seals.

What is the best equipment for cleaning solar panels?

A soft, non-abrasive brush or cloth, mild soapy water and, if you're cleaning from the ground, an extension pole. Avoid abrasive scrubbers, pressure washers and standard brooms.