Many solar panels stay reasonably clean with rain, but dust, pollen, bird droppings, or persistent soiling can justify cleaning. The method should prioritize safety and manufacturer instructions: there is no need to climb an unsafe roof or use high pressure or abrasives to make the glass shine.
First decide whether the soiling actually warrants cleaning
Inspect from the ground or another safe location and compare output with normal conditions. A light uniform film may have little effect, while bird droppings or localized debris can block more light.
Clean when panels are cool
Work early or in mild conditions according to manufacturer guidance. Applying cold water to very hot glass can create thermal stress, and cleaning in strong sun speeds evaporation and spotting.
Use water and soft compatible tools
Low-pressure water from the ground and a soft telescoping tool may be enough. Avoid abrasive pads, unapproved detergents, and pressure-washer jets that can damage seals, coatings, or connections.
Do not turn cleaning into unsafe roof work
If access requires walking on a steep roof, working near edges, or touching wiring, hire a properly equipped professional. Do not disconnect solar connectors or open electrical boxes as part of household cleaning.
Sources
- U.S. Department of Energy — Energy Saver — Practical information on home heating, cooling, efficiency, and energy maintenance.