Output can decline by approximately 20% due to accumulation of dirt and grime on Solar Panels
Because solar panels are similar to the windows on your car, house or office they can get dirty very quickly from rain, dust, pollen, smog, bird droppings, leaves and various other environmental debris. This dirt and debris decreases the efficiency of your solar panels by blocking sunlight from being absorbed into the panel, therefore less energy is collected for use in your home or for sale to your electricity company. In some instances, debris like bird droppings, algae/fungus or leaves can block all light from your solar panel rendering portions of the panel ineffective. In fact, studies have shown that even a small amount of dirt, clouding or soiling on your solar panels can decrease their efficiency by as much as 20%.
Unfortunately, rain or simply spraying your panels with water from a garden hose will not effectively clean your panels. When it rains does your car suddenly become clean and clear of all dirt and bird droppings? The answer is obviously no, it needs more than a simple water spray or rinse, it needs a more substantial cleaning, and solar panels are no different. They are exposed to the elements and the outdoor environment everyday, so regularly cleaning your solar panels is extremely important to maximize their efficiency and useful life. It is also important to regularly clean and maintain your solar panels to prevent the voiding of any manufacturer or installer warranties on the system.