Wildfire Ash on Solar Panels and Windows: Cleaning Guide

Short answer: do not dry-wipe it, do not blow it, and do not blast it. Wait until the air outside is safe, wear a tight-fitting N95 or P100 respirator, mist the ash with water, then rinse it off the glass with a gentle hose. A panel maker (REC) says dirt itself does not harm panels, and a solar publication (SolarQuotes, Australia) calls ash "not a serious problem" unless it is hot. The bigger risks are to you, from breathing it, and to the glass, from grinding grit into it.

We rinse and clean windows and single-story solar panels from the ground with a water-fed pole and pure water. We book visits after the air clears and the wind settles, not during the fire.

Step zero: your lungs come first

Wildfire ash is a health problem before it is a cleaning problem. Fire ash may be irritating to the skin, nose and throat, and may cause coughing, says the California environmental health agency. Contact with wet ash may cause chemical burns or irritation on skin, per the same fact sheet. Ash from burned structures is generally more hazardous than forest ash, says the California fact sheet.

Per the EPA, people with heart or lung disease, older adults and pregnant women should not participate in ash cleanup efforts. Children should not be near ash or sites contaminated with ash, per the EPA. The CDC and NIOSH say to wear proper protective equipment, such as long sleeve shirts, pants, gloves and safety glasses, when working around ash.

Before you go outside at all, check the smoke map. AirNow points people to its Fire and Smoke map for conditions in their area. If the air is bad, the glass can wait.

Is ash corrosive or abrasive to glass and panels?

We looked for a test of wildfire ash on window glass or solar glass and did not find one. So we cannot tell you a number for how much ash scratches or etches anything. Here is what we can say from sources we opened.

Grit scratches glass. Viracon, a commercial glass maker, says no abrasive particles should be trapped between the glass and cleansing materials. Heavily soiled glass should first be rinsed with clean water, per Viracon. Per another glass maker, spray the glass liberally with water to soften and dissolve hard abrasive particles. Both pages are about construction dirt on building glass, not ash, but the physics of dragging grit across glass is the same.
Alkaline materials can dull glass if left on. Concrete and mortar slurries are highly alkaline and cause the glass to corrode (become dull) if not immediately rinsed off, per the second glass maker. That page is about concrete, not ash. The California fact sheet notes that ash can contain caustic materials, so rinsing soon is sensible, but we have no source that measures ash on glass.
Ash on panels is mostly a dirt problem. REC, a panel maker, says the dirt itself will not harm the panels, but allowing it to build up over time can affect output. SolarQuotes, written for Australian homeowners after bushfires, says ash on panels is not a serious problem; the risk is hot ash or burning embers.

What to do, in order

This order follows the agency advice and the glass makers' advice. Skip any step that does not apply.

1. Wait until the fire is out, the wind has dropped and the air is clear. Ash that is still falling or blowing will land again. Hot ash and embers are a fire risk and a risk to the system.
2. Photograph first. If you may file an insurance claim, take photos of the roof, panels and windows with the ash in view before you touch anything. This is our advice, not a rule from the sources below.
3. Put on the right mask. Per the EPA, surgical masks and one-strap dust masks will not protect your lungs. Per AirNow, cloth masks will not protect you from ash. The EPA recommends a close-fitting, two-strap respirator marked NIOSH with N95 or P100.
4. Do not use a leaf blower, and do not dry-sweep. After a fire, the EPA says never use a leaf blower. After a fire, NIOSH says do not use leaf blowers. Dry sweeping also puts ash into the air.
5. Mist, then sweep or mop gently. Per the regional air district, mist lightly with water and then sweep gently with a broom or wet mop. Per the same sheet, direct ash-filled water to ground areas and away from the storm drains. After a fire, when you wet down ash, the EPA says to use as little water as you can.
6. Use a HEPA vacuum indoors. Shop vacuums and other common vacuum cleaners do not filter out small particles, but rather blow such particles out the exhaust into the air.
7. Rinse the glass before you wipe it. Water first, then a soft cloth or squeegee. Never wipe a dusty window dry.

Solar panels: what the makers say

We could open one panel maker's cleaning guide: REC's quick guide to cleaning (a copy hosted by a reseller, undated). We could not open pages from SunPower or Maxeon, Enphase, Tesla, Q Cells or Canadian Solar, so we do not quote them. Check your own panel's manual.

REC says a standard garden hose at normal household pressure may be used. It says high-pressure hoses, pressure or steam cleaners, knives, blades and metallic sponges are not permitted and will invalidate the warranty. For stubborn marks it allows a soft sponge, microfiber cloth or soft non-abrasive brush. It says to clean in the early morning, with water at about the same temperature as the panel, to avoid thermal shock. It prefers de-ionized water, and says the water should be free of grit. It also warns that you should never stand or walk on panels.

SolarQuotes adds practical points for ash: water should fall like rain, high-pressure streams can damage the seal between glass and frame, and cleaning should be done from the ground. If a fire is nearby, SolarQuotes says to shut down the solar power system as a precaution. It also says not to reactivate a system that may have fire damage until it has been inspected.

Warranty caution: REC says its warranty is only valid if the instructions in its installation manual are followed. Other makers write their own rules. If a pressure washer or hard scrubbing is not allowed in your manual, using one can cost you coverage.

How much power does ash cost you?

Two things reduce output after a fire, and they are different. Smoke in the air blocks sunlight while it is there. Ash on the glass blocks light until it is rinsed off or rained off.

Smoke: a Sandia National Laboratories study (Gilletly and Staid, Applied Energy, October 15, 2023) found Western US solar output fell 8.3 percent on average on high-smoke days compared with similar days without smoke. Cleaning your panels does not fix that, because the smoke is in the air.
Power Factors studied the performance of 150 solar PV arrays in California between 2018 and 2020. It estimated that ash from wildfires can reduce the performance of solar PV projects in nearby areas by 1 to 3 percent a year. The firm calls the 2020 wildfire season an outlier.

Put together: a rooftop system may lose a few percent while ash sits on it. If your monitoring app shows a clear drop on a sunny day after a fire, and the panels are visibly gray, a rinse is reasonable. If the app shows no change, you can wait for rain. See the solar cleaning frequency guide for how to check before and after.

Why not pressure-wash it off?

It is tempting, and it is the one thing the panel maker and the solar publication both told us not to do. REC says high-pressure hoses can exert more pressure than the panel's certified load, damage the frame bonding, laminate or cells, and push water between glass and frame. SolarQuotes warns about the glass-to-frame seal. Neither source is about windows, and we found no window-maker statement on pressure washers, so we simply do not use them. A gentle rinse first, then a pole with a soft brush, is our method.

Inland Empire history: why this matters here

The Santa Ana winds are strong, extremely dry winds that come from inland and affect coastal Southern California. Wikipedia says their low humidities and high wind speeds create critical fire weather conditions that fan destructive wildfires.

Two fires from the same week in October 2003 show the pattern. Wikipedia says Rancho Cucamonga, Alta Loma and Etiwanda were most affected by the October 2003 Grand Prix Fire. The Old Fire was a large complex wildfire that started on October 25, 2003. The Old Fire burned 91,281 acres. The fire forced upwards of 80,000 residents to evacuate their homes. We do not have a source on how much ash fell on any one street, so we do not claim it.

Our Santa Ana wind guide covers the dust side of the same season.

When to book us after ash fall

Wait for three things: the fire is out or no longer near you, the wind has dropped, and the smoke map shows clear air. Then the ash that has landed is the ash you will clean. Cleaning earlier means doing it twice.

If it is only a thin gray film, rain may handle it. If it is thick, if it has been wet and dried into a crust, or if the panels are visibly dimmer on your app, book a visit.

Situation	What to do
Fire still burning nearby, or wind still gusting	Stay inside. Do not wash anything. SolarQuotes says to shut a solar system down if a fire is nearby; ask your installer how for your system.
Ash has stopped falling, air is clear	Mist, then rinse glass with a gentle hose. Wear an N95 or P100. Do not use a leaf blower.
Panels still gray after a rinse	Book a pole cleaning from the ground. Do not climb.
Burned-structure ash, or an older home near the burn	Treat as a hazard. OEHHA says ash from burned buildings can contain asbestos and metals. Ask a professional.

Prices: windows are $9 each outside with a $130 minimum, and single-story solar panels are $6 each with a $110 minimum. Both in one visit is 10 percent off.

We do not clean second-story panels, we do not walk on roofs, and we do not do structural-fire or insurance cleanup. If your home itself was burned, call a restoration company.

Common questions

Does wildfire ash damage solar panels?

A panel maker (REC) says dirt itself does not harm its panels, and SolarQuotes says ash is not a serious problem unless it is hot. The risk comes from how you clean it: pressure washers and hard scrubbing can damage panels and, per REC, void the warranty.

Can I hose ash off my solar panels?

A gentle hose is what REC allows, with water at about panel temperature, when the panels are cool, in the early morning. Never use a pressure washer, and never go on the roof to do it.

Should I wipe ash off windows with a dry cloth?

No. Glass makers say to rinse abrasive grit off first. Dragging a dry cloth across gritty glass can scratch it. Mist, rinse, then wipe or squeegee.

What mask do I need for ash cleanup?

The EPA says a close-fitting, two-strap respirator marked NIOSH with N95 or P100. Surgical masks and one-strap dust masks do not protect your lungs.

Can I use a leaf blower to clear ash?

No. The EPA says never use a leaf blower, and NIOSH says not to use leaf blowers or dry sweeping, because they put the ash back in the air.

How long should I wait before cleaning after a fire?

Until the fire is no longer near you, the wind has dropped and the smoke map shows clear air. Ash that is still moving will land again.

Where this applies

We work in every place within 15 miles of Ontario: Ontario, Upland, Montclair, Chino, Rancho Cucamonga, Claremont, Alta Loma, Eastvale, Pomona, Etiwanda, Chino Hills, Jurupa Valley, La Verne, Norco, Fontana, San Dimas, Diamond Bar, Corona, Walnut, Rialto, Covina, Glendora.

Related services: Window cleaning, Solar panel cleaning, Instant quote.

More guides

Sources

U.S. EPA, "Protect Yourself from Ash" (ash cleanup guidance; last updated July 28, 2026). “Select a respirator that is NIOSH Approved® and has the words 'NIOSH' and either 'N95” or 'P100” printed on it”
California OEHHA, "Protecting Public Health from Home and Building Fire Ash" (fact sheet updated January 14, 2025). “Fire ash may be irritating to the skin, nose, and throat, and may cause coughing”
California OEHHA, "Protecting Public Health from Home and Building Fire Ash" (fact sheet updated January 14, 2025). “Contact with wet ash may cause chemical burns or irritation on skin”
California OEHHA, "Protecting Public Health from Home and Building Fire Ash" (fact sheet updated January 14, 2025). “Ash from burned structures is generally more hazardous than forest ash”
U.S. EPA, "Protect Yourself from Ash" (ash cleanup guidance; last updated July 28, 2026). “People with heart or lung disease, older adults, and pregnant women should not participate in ash cleanup efforts”
U.S. EPA, "Protect Yourself from Ash" (ash cleanup guidance; last updated July 28, 2026). “Children should not be near ash or sites contaminated with ash”
CDC / NIOSH, "Hazards During Wildland Fire Cleanup" (page dated July 16, 2026). “always wear proper personal protective equipment (long sleeve shirts, pants, gloves and safety glasses) when working around ash”
Viracon, "Glass Cleaning and Maintenance Recommendations," August 1, 2025 (rinse first; no trapped abrasive particles). “no abrasive particles are trapped between the glass and cleansing materials”
Viracon, "Glass Cleaning and Maintenance Recommendations," August 1, 2025 (rinse first; no trapped abrasive particles). “the glass surface should first be rinsed with clean water”
Glas Troesch, "Technical leaflet: Useful information on glass cleaning" (no dry cleaning; alkaline slurries; 10/2026 edition). “Spray the glass liberally with water to soften and dissolve hard abrasive particles”
Glas Troesch, "Technical leaflet: Useful information on glass cleaning" (no dry cleaning; alkaline slurries; 10/2026 edition). “are highly alkaline and cause the glass to corrode (become dull) if not immediately rinsed off with plenty of water”
REC, "Quick guide to cleaning" (panel maker; undated; copy hosted by a reseller). “the dirt itself will not harm the panels, but allowing it to build up over time can affect”
U.S. EPA, "Protect Yourself from Ash" (ash cleanup guidance; last updated July 28, 2026). “Surgical masks and one-strap dust masks will not protect your lungs”
AirNow, "After a Fire" (respirators, wet cleanup, Fire and Smoke map). “Cloth masks will not protect you from ash”
U.S. EPA, "Protect Yourself from Ash" (ash cleanup guidance; last updated July 28, 2026). “Never use a leaf blower”
CDC / NIOSH, "Hazards During Wildland Fire Cleanup" (page dated July 16, 2026). “Do not use leaf blowers”
South Coast AQMD, "After a Wildfire: Safe Clean-Up" fact sheet (file dated 2021). “Mist lightly with water and then sweep gently with a broom or wet mop”
South Coast AQMD, "After a Wildfire: Safe Clean-Up" fact sheet (file dated 2021). “Direct ash-filled water to ground areas and away from the storm drains”
U.S. EPA, "Protect Yourself from Ash" (ash cleanup guidance; last updated July 28, 2026). “When you wet down ash, use as little water as you can”
California OEHHA, "Protecting Public Health from Home and Building Fire Ash" (fact sheet updated January 14, 2025). “Shop vacuums and other common vacuum cleaners do not filter out small particles, but rather blow such particles out the exhaust into the air”
SolarQuotes (Australia), "Solar Power And Bushfires: Safety, Shutdowns And Cleaning Off Soot," January 13, 2020. “shut down solar power system as a precaution”
SolarQuotes (Australia), "Solar Power And Bushfires: Safety, Shutdowns And Cleaning Off Soot," January 13, 2020. “do not reactivate solar system until”
Gilletly and Staid (Sandia National Laboratories), "Evaluating the impact of wildfire smoke on solar photovoltaic production," Applied Energy 348, October 15, 2023. “8.3% on average during high smoke days”
Power Factors, "How to Identify Soiling Losses Caused by Wildfires," January 20, 2022 (vendor analysis of 150 California arrays). “we studied the performance of 150 solar PV arrays in California between 2018 and 2020”
Power Factors, "How to Identify Soiling Losses Caused by Wildfires," January 20, 2022 (vendor analysis of 150 California arrays). “ash from wildfires can reduce the performance of solar PV projects in nearby areas”
Power Factors, "How to Identify Soiling Losses Caused by Wildfires," January 20, 2022 (vendor analysis of 150 California arrays). “the 2020 wildfire season was an outlier”
Wikipedia, "Santa Ana winds" (strong, extremely dry winds; fire weather). “are strong, extremely dry katabatic winds that originate inland and affect coastal Southern California”
Wikipedia, "Santa Ana winds" (strong, extremely dry winds; fire weather). “These low humidities, combined with the warm, compressionally heated air mass and high wind speeds, create critical fire weather conditions that fan destructive wildfires”
Wikipedia, "Alta Loma, California" (Grand Prix Fire, October 2003). “Rancho Cucamonga, Alta Loma and Etiwanda were most affected by the October 2003 Grand Prix Fire”
Wikipedia, "Old Fire" (October 25 to November 2, 2003). “The Old Fire was a large complex wildfire that started on October 25, 2003”
Wikipedia, "Old Fire" (October 25 to November 2, 2003). “the Old Fire burned 91,281 acres”
Wikipedia, "Old Fire" (October 25 to November 2, 2003). “forcing upwards of 80,000 residents to evacuate their homes”

Written by Foothill Home Services. Local prices on this page are our own draft rates from the price list the quote tool uses. Where we quote an outside page, the quote is linked in the sources above, and we last checked this page on October 13, 2026. Other outside figures are described as the source reports them.

How to clean wildfire ash off solar panels and windows in the Inland Empire