Do solar panels need cleaning, and how often?

Rain handles most of it on a tilted panel; cleaning matters where something stays put — pollen, salt, bird droppings, dust in a dry season, or a film in a flat installation that never drains. The maker’s instructions state what may be used on the glass and the frame.

Panel cleaning is one of the few maintenance tasks on this shelf, and it is worth less than the internet suggests on a tilted roof and more than expected on a flat one.

Why tilt does most of the work

Water runs off a tilted panel carrying dust with it, and self-cleaning is genuinely effective where rain is regular. A panel mounted flat holds water and lets it evaporate in place, which leaves a deposit instead of removing one.

What actually costs output

A uniform film reduces output roughly in proportion to the light it blocks. A single opaque patch does much more damage, because the cells in a string are in series and the shaded one governs. Bird droppings and leaf debris are therefore worth removing promptly and a general dusting is not urgent.

What the maker permits

Cleaning instructions are published per product and they are specific: water temperature, permitted implements, forbidden chemicals, and whether pressure washing voids anything. Anti-reflective coatings are the reason these lists exist.

The part that is not cleaning

Checking the frame fixings, the cable strain relief and the connectors at the same time costs nothing and catches the failures that actually stop a system — a lead chafing on a roof rail does more damage than a season of dust.

Where this page and the manufacturer’s documentation differ, the documentation is the one to follow. Every capacity, output, input window, current limit, cycle count and temperature threshold on this page comes from the maker’s own published figures, with the unit as printed and the source named. None of it is measured here, and no figure is converted into another convention, because a converted number is a different number. And for any panel rating: peak watts are measured under standard test conditions — a defined irradiance, a defined cell temperature and a defined spectrum. Those conditions exist so that two panels can be compared, not so that a yield can be predicted. This page reports the maker’s figure as a test result and derives no daily energy from it.