Does Cleaning Your Solar Panels Actually Improve Efficiency?

New Mexico is one of the best states in the country for solar — Albuquerque alone gets more than 310 days of sunshine a year. But that same high-desert environment that makes solar such a good investment also works against your panels in a specific way: it doesn't rain enough to keep them clean.

In wetter parts of the country, regular rainfall does a lot of the cleaning work automatically, rinsing dust and debris off panels before it has a chance to build up. Albuquerque doesn't get that luxury. Between low annual rainfall and long dry stretches, fine desert dust, pollen, and bird droppings accumulate on panel surfaces and stay there — sometimes for months.

That buildup has a real, measurable cost. In arid climates like ours, dust and soiling on solar panels can reduce energy output by an estimated 10 to 25 percent. For a system that's supposed to be paying for itself through energy savings, that's a meaningful chunk of performance left on the table — quite literally sitting on top of your panels.

The timing of that buildup matters too. Summer monsoon rain can actually make things worse in the short term: it often deposits mineral-laden water on panels that evaporates and leaves behind a calcium film, rather than truly rinsing the surface clean the way a heavier, sustained rain might.

Most homeowners get the most value out of cleaning their panels once or twice a year — once after monsoon season ends in the fall, when mineral deposits are heaviest, and again in spring before peak sunlight season ramps up. Properties near dusty roads, open desert, or agricultural land often need it more often.

If it's been a year or more since your panels were cleaned, a professional cleaning is a reasonable place to start before assuming something else is wrong with your system's output. Sandia Window Cleaning uses soft-brush, deionized-water techniques designed specifically not to scratch panel glass or damage anti-reflective coatings.