The best way to clean solar panels is to switch the system off, rinse loose dust with a gentle stream of water, wash the glass with a soft-bristle brush or sponge and deionized (pure) water or a pH-neutral cleaner, then rinse again and let it dry. Clean early in the morning or in the evening when the glass is cool, never use a pressure washer or abrasive tools, and stay off the roof — use an extension pole from the ground or hire a professional.
Key takeaways
- Dirt, pollen and bird droppings can cut output by roughly 2–7% a year in typical U.S. locations and far more in dusty or pollen-heavy areas.
- Most homes need cleaning once or twice a year; desert, farm and coastal homes may need it every 3–4 months.
- Use soft brushes + pure water. Pressure washers, scouring pads, ammonia and hard tap water can scratch the anti-reflective coating or leave mineral spots — and may affect your warranty.
- If panels are on a steep or second-storey roof, a professional clean (about $150–$450 per visit) is safer than DIY.
In this guide
Do solar panels need cleaning?
Yes — but not as often as many cleaning companies suggest. Dust, pollen, leaves, soot and bird droppings form a film called soiling that blocks some of the light reaching the solar cells. Research from the U.S. National Renewable Energy Laboratory (NREL) puts annual energy loss from soiling at up to about 7% in parts of the United States, rising to 50% or more in extreme desert conditions in the Middle East.[1] NREL’s commonly used modeling assumption is a typical soiling loss of around 5%, and dust can accumulate anywhere from 0.01% to 0.5% per day depending on how dusty the site is.[2]
Rain helps, but it is less effective than most people assume. An NREL-led study of solar farms in North Carolina found that rain did not fully clear pollen, and at the peak of pollen season output fell by as much as 15%.[3] Low-tilt panels, panels under trees and panels near roads, farms or the coast collect grime fastest.
When should you clean your solar panels?
Clean when you can see a film or patches of dirt, or when your monitoring app shows output falling below what you would expect for the season and weather. Good triggers include:
- Visible soiling: a grey haze, yellow pollen, sap, leaves or bird droppings on the glass.
- A production dip: compare this month’s sunny-day output with the same month last year. A 5–10% drop on clear days with no other explanation usually means dirt or shading.
- After events: wildfire smoke, dust storms, nearby construction, heavy pollen season or a long dry spell.
- Before peak season: a clean in late spring sets you up for the highest-production months.
Best time of day: early morning or evening. Hot glass makes water evaporate instantly, leaving streaks, and cold water on sun-baked glass causes thermal stress. Many manufacturers also advise against cleaning in freezing weather.
What you need to clean solar panels
| Item | Why it matters | Avoid |
|---|---|---|
| Soft-bristle brush (nylon or microfiber) on a telescopic pole | Lifts grime without scratching the anti-reflective coating; lets you work from the ground | Stiff deck brushes, metal bristles, scrapers |
| Deionized, distilled or RO-filtered water | Dries spot-free; no mineral residue left on the glass | Very hard tap water left to dry in the sun |
| Garden hose with a gentle spray nozzle | Rinses loose dust before brushing | Pressure washers, jet nozzles |
| pH-neutral, biodegradable soap or a panel-specific cleaner (only if allowed by your manufacturer) | Breaks down sticky pollen, sap and droppings | Ammonia, bleach, solvents, abrasive powders |
| Rubber-edged squeegee and microfiber cloths | Removes final water for a streak-free finish | Paper towels, scouring pads |
| Safety gear: sturdy ladder, harness/fall arrest, non-slip shoes, gloves | Roof work is the biggest risk of DIY cleaning | Standing on panels or working alone |
Manufacturers are consistent here: Maxeon (SunPower), for example, recommends clean water — or distilled/deionized water — with soft brushes and squeegees, and warns against scouring powder, steel wool, scrapers and blades.[4] Panasonic’s EverVolt manual likewise specifies deionized water at ambient temperature with a sponge, microfiber cloth or soft brush.[5] A ready-made solar panel cleaning kit (pole + brush + inline water filter) is the easiest way to get everything in one purchase.
How to clean solar panels: step-by-step
- Check your manual and warranty. Download the installation and maintenance manual for your panel model. Note any rules on water pressure, cleaning agents and temperature, and keep a simple log of each clean in case you ever need to make a warranty claim.
- Shut the system down. Follow your installer’s shutdown procedure (usually the AC disconnect, then the inverter or DC isolator). Panels still produce voltage in daylight, so never touch connectors, cables or junction boxes.
- Pick a cool, calm time. Early morning, evening or an overcast day. Avoid wind, which blows dust back onto wet glass.
- Rinse first. Spray low-pressure water from the top edge down to float off loose dust and grit. Brushing dry dust grinds it into the glass like sandpaper.
- Wash gently. Using a soft brush on a pole and deionized water (with a little pH-neutral soap only if your manufacturer allows it), work in light, straight strokes from top to bottom. Let water do the work — no hard scrubbing.
- Spot-treat stubborn marks. Soak bird droppings or sap for a few minutes, then wipe with a soft sponge (see below).
- Rinse thoroughly. Remove all soap from the glass and frame edges so no film is left to attract new dust.
- Dry or let it air-dry. Pure water dries spot-free. With tap water, follow with a rubber squeegee or microfiber cloth.
- Restart and check output. Turn the system back on in the reverse order and compare production over the next sunny days with your pre-clean baseline.
How to clean solar panels on a roof safely
Most residential arrays sit on pitched roofs, and falls — not electrical shock — are the main risk of DIY cleaning. Follow these rules:
- Clean from the ground whenever possible using a water-fed telescopic pole (many reach 20–30 ft / 6–9 m).
- Never walk, kneel or lean on panels. Pressure on the glass can create micro-cracks in the cells that reduce output for years and are not covered by warranty.
- If you must go on the roof, use a properly footed ladder, a harness tied to a rated anchor, and never work alone or on wet or icy surfaces.
- Single-storey roof with low pitch? DIY is usually fine. Two-storey, steep, tile or metal roofs? Hire an insured pro.
Do not use a pressure washer. Residential units run around 1,000–1,750 psi — enough to force water past frame seals, strip coatings and crack cells. Major manufacturers exclude pressure-wash damage from warranty cover.
Removing bird droppings, pollen, snow and hard-water spots
Bird droppings and sap
Droppings are the worst kind of soiling because even a small patch can shade a whole cell and create a hot spot. Wet the spot, let it soak for 5–10 minutes, then lift it with a soft sponge. Repeat rather than scrubbing harder. If pigeons are nesting under your array, droppings will keep coming back — ask a professional about fitting bird-proofing mesh around the array (see the warning signs in our maintenance checklist).
Pollen and fine dust
Pollen is sticky and does not wash off with rain. A pre-rinse followed by a soft-brush wash with pure water normally removes it. In heavy pollen regions (the U.S. Southeast, for example), plan your main clean just after the spring pollen peak.
Hard-water spots and mineral film
White spots usually come from tap water drying on the glass. Re-wash with deionized water. A diluted vinegar solution is sometimes used by cleaners, but only use it if your panel manufacturer permits it, and rinse very thoroughly.
How to clean snow off solar panels
Usually you don’t need to: panels are dark, tilted and warm up quickly, so snow tends to slide off within a day or two of sunshine. If you want to speed it up, use a foam-head roof rake from the ground and leave a thin layer on the glass. Never chip ice, use metal shovels, or pour hot water on cold glass.
7 mistakes that damage solar panels
- Using a pressure washer or jet nozzle.
- Scrubbing with abrasive pads, steel wool or stiff brushes.
- Using harsh chemicals — ammonia glass cleaners, bleach, solvents or strong alkaline detergents.
- Cleaning hot panels at midday, causing streaks and thermal shock.
- Walking on panels or resting ladders against them.
- Brushing dry dust without rinsing first.
- Touching wiring, connectors or junction boxes, or cleaning while the system is energised and wet.
How often should you clean solar panels?
For most homes, once or twice a year is enough. Use this as a starting point and adjust using your monitoring data:
| Your situation | Suggested frequency |
|---|---|
| Rainy, low-pollution area; panels tilted 25°+ | Every 12 months (or only when visibly dirty) |
| Typical suburban home | Every 6–12 months |
| Heavy pollen, trees overhead, or bird activity | Every 4–6 months, after pollen season |
| Desert, farmland, unpaved roads, construction nearby | Every 3–4 months |
| Coastal (salt spray) or near highways/industry | Every 4–6 months |
| Low-tilt or flat-mounted panels | More often — water and dirt pool on the glass |
Climate makes a big difference, so we built state-specific guidance: see solar panel cleaning schedules by state, for example Arizona, California and Florida. Cleaning is only one part of looking after a system; pair it with the checks in our solar panel maintenance checklist.
DIY vs professional solar panel cleaning
| DIY | Professional | |
|---|---|---|
| Typical cost | $30–$250 one-off for a pole, brush and filter kit | About $150–$450 per visit for a typical home; roughly $10–$25 per panel |
| Best for | Ground-mounted or single-storey, low-pitch roofs | Steep, high or fragile roofs; large arrays; warranty-sensitive systems |
| Equipment | Soft brush, hose, optional DI filter | Water-fed poles, purified-water systems, fall protection, insurance |
| Extras | — | Many include a visual inspection and photo report |
For a full price breakdown by panel count, roof type and region, read our solar panel cleaning cost guide — it includes a quick calculator. Large or remote arrays can also use robotic solar panel cleaners or automatic waterless systems, but these are rarely cost-effective for a typical home.
Frequently asked questions
Can I clean solar panels with just water?
Yes. Plain water — ideally deionized or distilled — and a soft brush is the method most manufacturers recommend. Pure water dries without spots, so soap is usually unnecessary.
Can I use Windex or dish soap on solar panels?
Avoid ammonia-based glass cleaners like standard Windex; they can harm the anti-reflective coating and seals. A small amount of mild, pH-neutral dish soap is acceptable for many panels, but check your manufacturer’s manual first and rinse thoroughly.
Is it OK to pressure wash solar panels?
No. High-pressure water can force moisture past the frame seals, damage the coating and crack cells. Use a low-pressure hose or water-fed brush instead.
Does rain clean solar panels?
Rain removes some loose dust, but it does not reliably remove pollen, bird droppings or greasy films, and it can leave mineral spots as it dries. Tilted panels in rainy climates need cleaning less often.
How much more power will I get after cleaning?
It depends on how dirty the panels were. Lightly dusty panels may gain 2–5%; heavily soiled panels in dusty or pollen-heavy areas can recover 10% or more. Check your monitoring app before and after to measure it.
Will cleaning my panels void the warranty?
Cleaning itself does not void a warranty — using a method your manufacturer prohibits might. Follow the manual (soft brush, pure water, no pressure washer, no harsh chemicals) and keep a record of each clean.
What is the best time of day to clean solar panels?
Early morning or evening, when the glass is cool and output is low. Avoid midday heat and freezing temperatures.
Sources
- National Renewable Energy Laboratory (NREL), PV soiling research — U.S. soiling losses up to ~7% per year; 50%+ reported in the Middle East.
- Aurora Solar, PV System Losses: Soiling & Snow, citing NREL performance parameters.
- NREL-led North Carolina pollen soiling study, reported by The Cool Down.
- Maxeon / SunPower panel care guidance.
- Panasonic EverVolt EVPV series user manual, cleaning section.
Our guides are researched from manufacturer manuals, NREL studies and real price data, and reviewed for safety. How we write our guides.