You can rinse your solar panels in some cases. For example, periodically rinsing your solar panels can remove light debris if you live in an agricultural or dusty area. Light dust and dirt won’t affect efficiency much, but they can build up and mix with other debris like animal droppings, leaves, and small sticks. 

There are several telltale signs that your roof needs to be professionally cleaned. It's best to hire a professional as soon as you notice any indicators of wear to preserve your roof's longevity. Key signs to look for include:

• Moss, Algae, or Plant Growth: Look for moss growth, black streaks (which are often a type of black algae), or any other plant life on your roof's surface.

• Dirt and Grime Buildup: A general layer of dirt and grime can accumulate over time.

• Leaf Buildup: An accumulation of leaves, especially in the gutters, is a clear sign.

• Buildup Under Shingles: Dirt and debris can get trapped under the edges of your shingles.

• Shifting Roof Shingles: While this can indicate other problems, it can also be a sign that cleaning and maintenance are overdue.

• Comparison to Neighbors: If your roof appears significantly dirtier or different from your neighbors' roofs, that’s another sign it may be time for a cleaning.

If you’re painting your home or monitoring a job as it’s being completed, squash the issue ASAP if you notice paint is getting onto the roof. Keeping it clean is one of the keys to extending your roof’s life.

Removing latex paint before it dries is much easier and lowers the risk of damaging your shingles (more on that below). Simply spray the spot with a hose for one to two minutes to clear away the drying paint. In general, this is a good way to remove ugly stains from your roof without using chemicals.

The best time to clean the outside of your house is during your outdoor spring cleaning. Wait until late spring, after the wave of pollen is done coating your home. You can also wash your house in late fall–before the first freeze–to remove leaves and branches from the gutters.