When your solar panels are first installed, they perform at their highest level. However, this performance gradually decreases over time due to various factors. One factor is the accumulation of dirt and dust on your panels, which blocks sunlight and reduces your panels’ efficiency.

To address this issue, you have the option to hire professionals or clean the panels yourself. While cleaning may seem like an obvious solution, most solar panel cleaning is a waste of time and money.

Unless your panels are heavily soiled due to a dust storm or bird droppings, the benefits of cleaning are usually outweighed by the costs.

Negligible Effect of Cleaning on Panel Performance 

Regular dirt accumulation on solar panels typically has minimal impact on performance. This is because in most households, the amount of rainfall received is sufficient to adequately cleanse the panels. While grime may accumulate over time, rainfall eventually washes off most of it.

Supplemental cleaning, in addition to natural rainfall, can slightly enhance the output of the panels. However, the improvement is not significant.

A study conducted in Tucson, Arizona, revealed that cleaning solar panels only led to a 1% increase in their output. For wetter climates, the difference is likely to be even less. (Tucson has a hot desert climate.)

The 1% improvement mentioned above is an average, and individual outcomes may vary depending on location. If you reside in an area with a high level of dirt or bird activity, the benefits of cleaning may be more pronounced. Nevertheless, for most households, cleaning solar panels twice a year is estimated to result in an average output improvement of only 2%.

The Special Case of Flat Panels

Most of the dirt on solar panels can be washed away by rain, but only if the panels are positioned at an angle. When solar panels are horizontal, water can accumulate on them and cause problems. Eventually, the water evaporates and leaves behind dirt and grime.

Additionally, leaves and debris can land on solar panels and negatively impact their performance. While a thin layer of dirt may still allow most light to pass through, a leaf is specifically designed to capture light. After all, leaves are like natural solar panels.

To prevent these issues, it’s highly recommended to tilt panels on flat roofs. When installing solar panels on flat roofs, use frames that tilt the panels at least 10 degrees. East-west tilts are particularly effective when possible.

If your panels are not tilted, cleaning them becomes necessary to maintain their performance.


Installing a slightly larger solar system to offset dirt-related losses is more cost-effective than hiring someone to clean the panels. Adding one extra panel to a 20-panel system can increase its output by approximately 5%, which is more than twice the average loss expected from not cleaning them.

The cost of installing a system with one additional panel is definitely lower than the cost of cleaning. Hiring a cleaner can set you back $450 per year or more. One extra panel can effectively compensate for dirt losses throughout the entire lifespan of the system.

Although it’s often impractical to add panels to an existing solar system, there are still numerous actions that individuals can take that are more sensible than paying for panel cleaning. For instance, they can invest in insulation, LED lighting, or a heat pump hot water system.

Image Source: HM Maintenance, https://shorturl.at/bEV19