Can You Power Wash Solar Panels?

No. A solar panel is cleaned with a soft brush and a gentle flow of water, never a pressure washing lance, and the reason is not really the glass. It is the edges. EvoEnergy warns that high pressure can crack the glass and force water into the junction box on the back of the panel, which turns a cleaning job into an electrical fault. Sunsave warns about the seals. Ageas warns about scratching the surface. Three separate publishers, three separate failures, and none of them is an argument for turning the pressure down.

That is the short answer, and it comes from a pressure washing business, which is the last place you would expect it. Below is what each source actually says, the pressure limits the panel makers themselves publish, the one point where the published advice does not agree, and whether it is safe to clean solar panels yourself.

What does high-pressure water do to a solar panel?

EvoEnergy's cleaning guide is the most specific of the sources we read. It says a pressure washer set to high pressure "can crack solar panel glass, dislodge mounting brackets, and force water into electrical junction boxes". Those are three separate failures with three separate costs, and only the first one is visible from the ground.

Sunsave, whose solar panel cleaning guide was last updated on 28 July 2026 and is credited to Josh Jackman, puts it flatly: "You definitely shouldn't pressure-wash your solar panels. The high-pressure water can upset the delicate surfaces and seals of the panels, potentially leading to permanent damage." Note the word seals. A panel is a sandwich of glass, cells and backing held in a frame, and water getting in at the join is the failure mode that matters, because it sits behind the glass where nobody can see it drying out. Sunsave stops there: it does not mention junction boxes or cracked glass, and we are not going to put those words in its mouth.

Ageas, the insurer, comes at it from the surface instead. Its cleaning guide for solar panels, dated 4 May 2025, says: "Avoid high-power water jets that can scratch the surface of your panels." That is the whole of what Ageas publishes on the point, and it is enough. A scratch is permanent in a way dirt is not. Dirt washes off next time. A scratched panel stays scratched for the rest of its life on the roof.

Put those three together and the damage from a lance falls into three groups, plus the reason none of them shows up on the day:

• Water ingress: EvoEnergy warns that high pressure can force water into electrical junction boxes, and Sunsave warns about the seals.
• Glass: EvoEnergy lists cracked panel glass, and Ageas warns that high-power jets can scratch the surface.
• Fixings: EvoEnergy also lists dislodged mounting brackets, which is a roof problem rather than a panel problem.

None of the three shows up as a bad clean on the day. They show up later, as an output drop or a fault, long after the person with the lance has gone.

What pressure is safe for cleaning a solar panel?

The module manufacturers do publish numbers, and they are worth seeing because of how far apart they are. ChemiTek's summary of what the ten largest module makers say about cleaning records Canadian Solar allowing a "maximum water pressure of 4 MPa (40 bar)", Risen Energy saying "water pressure on the glass surface should not exceed 700 Kpa (7 bar)", and First Solar requiring "water temperature must be < 20°C from module temperature applied with water pressure < 35 bar (500 psi) at nozzle", which is one condition and not a free-standing pressure ceiling. Two things about that summary before you lean on it: it is dated 31 August 2023, so current manuals may differ, and ChemiTek sells solar cleaning products, so it is a vendor reading the manuals rather than a maker writing them.

Read those numbers again. For the same product, on the same roof, Canadian Solar allows 40 bar and Risen Energy caps the glass at 7 bar. That is why we will not print a safe pressure for your panels, and why anybody who quotes you one confident figure for all panels is guessing. The only number that governs your roof is the one in your own installation manual, and most homeowners have never opened it. The three-year-old summary makes that argument stronger rather than weaker: if the published ceilings were that far apart then, a figure copied off the internet today is worth even less than it looks.

There is a second reason the manuals matter. ChemiTek's summary records Canadian Solar stating that improper dry-cleaning methods leading to module damage will void the warranty, and records 6 of the 10 makers imposing a prohibition on the use of scrapers. Ageas makes the same point about chemicals: "Using chemicals like detergent can also invalidate your warranty." We do not decide warranty claims and neither does any cleaner, so treat all of that as a reason to read the manual rather than as a promise from us.

Is a low-pressure setting ever safe on solar panels?

This is the honest part, because the sources are not unanimous. Sunsave says you definitely should not pressure-wash panels, full stop. Ageas leaves a door open: "You could use a low-pressure power wash if the solar panel manufacturer approves it, but a standard hose will work without the risk of damaging your panels." EvoEnergy leaves the same door open with a measurement attached: "If using a pressure washer, always set it to the lowest available pressure setting and maintain a distance of at least 30cm from the panel surface."

Look at what the two permissive sources are actually permitting. One requires the panel maker's approval first. The other requires the lowest setting on the machine and a hand held at least 30cm back. Neither of them is describing jet washing, and neither says a lance is a good idea. Ageas adds the line that settles it for most houses: a standard hose will do the job without the risk.

Our own view, from doing exterior cleaning for a living, is that the conditional advice is hard to follow in practice. Nobody standing on a roof or at the top of a ladder can verify the pressure leaving the nozzle, and 30cm is a distance that slips the moment you stretch. If the safe version of the technique is a low-pressure, wide, distant flow of water, then a hose or a water-fed pole delivers exactly that with no setting to get wrong. So the practical answer stays no.

Is it safe to clean solar panels yourself?

The detail people underestimate is what a pressure lance does to your balance. It pushes back, it pushes back the whole time the trigger is held, and on a solar array you are usually holding it out and up rather than down at a driveway. On a driveway that reaction just walks you back a step. On a ladder, with both arms extended above your head and a stiff hose dragging behind you, it is the wrong thing to be fighting, and the correction you make against it is what takes you off the rungs. It is also the one force you cannot ease off gradually, because it stops the instant you let go of the trigger and your weight is already committed. The Health and Safety Executive's page on the Work at Height Regulations 2005 addresses employers and people who control work at height rather than a homeowner on their own roof, so the real limit here is your own balance.

Ageas is blunter and aimed squarely at householders: "It's dangerous to clean solar panels from a ladder without health and safety training." It adds a simple rule of thumb, to call in the experts if your solar panels are above the first floor. Between those two lines there is not much room left for a lance at the top of a ladder.

There is an electrical side that a driveway job does not have. EvoEnergy's guide says to turn off the solar panels before cleaning to avoid electrical hazards, and Ageas describes cleaning from ground level only once the system has been turned off. If you find damaged or exposed cabling while you are up there, that is the point to stop and call the company that installed the system, not to keep washing.

What to clean a panel with instead

The published method is consistent across every source we read, and it is dull on purpose:

• Soft only: EvoEnergy recommends telescopic poles with soft brushes or sponges, which it says let you reach the panels without leaving the ground.
• Plain water where possible: EvoEnergy names deionised water for light soiling, and a pH-neutral detergent formulated for photovoltaic glass where more is needed.
• Nothing abrasive and nothing scraped: ChemiTek's summary records 6 of the 10 largest makers prohibiting scrapers, and Ageas warns about scratching the surface.
• Cool, not hot: Sunsave says it is best to clean panels on a cool day, or first thing in the morning or in the evening if it has to be a hot one.
• Ground first: Ageas describes using a soft brush, water and a sponge from ground level where you can reach, and calling in the experts where you cannot.

That is how we do it, with a soft brush head on a water-fed pole from the ground wherever the roof allows. The point of a pole is not that we are being careful with it. It is that a pole can only deliver a low-pressure, wide, distant flow of water, so the technique the sources describe as the safe one is the only technique the equipment is capable of. There is no dial to get wrong, no trigger to hold too long, and nothing standing on the glass. It is slower than a jet wash, and it is the version the published advice supports. Our solar panel cleaning page covers what that involves.

One thing worth settling before any of this: whether the panels need cleaning at all, which is often no, and which we work through properly in our guide to whether solar panels need cleaning. If the answer there is yes and you would rather it was done for you across Surrey, Sussex or Kent, get in touch and we will give you a price for the roof you actually have.