Do Solar Panels Need to be Cleaned?

People often ask us, “Do solar panels need to be cleaned?” There are a few ways to answer this, but the primary comparison to be done is how much does it cost to clean vs. how much energy production is returned to the system when they are cleaned? There are some systems that won’t see a net positive return unless they clean their panels every few years. Some panels, however, particularly those affected by algae, dirt or droppings, need to be cleaned regularly, and cleaning them brings a valuable improvement to their total output.

We try to recommend the appropriate intervals where customers will maximize their energy efficiency both in output and value.

Solar Panel Cleaning Data

We were fortunate enough to have a customer with some very challenging panels. They took the time to report the data to us (Below). There are a few things to note in this study:

1. This solar panel array was in the top 5% worst condition panels we have had to clean.
2. The second reading was taken just over a month after the first. Both were taken after the Summer Solstice.
3. The days of the readings had comparable weather (It’s Kihei).
4. There was some tree trimming done between these dates.
5. This grid had 40 panels, the customer cleaned 6 panels on their own.

Findings:

1. We found that the panel in the worst condition, showing an output of 647 Wh initially, improved to 1.54 kWh, a 138.02% increase after cleaning.
2. The total output improvement for the whole grid was an 84.86% increase from the first to the final reading.
3. At the current rate of 31 cents / kWh for Maui residential power service, the savings after this cleaning is approximately $7 – $9 per day ($8.72 in this comparison).

This evidence, even with a significant error term to account for weather and tree trimming, proves that solar panel cleaning, especially of dirty panels, improves the output of the system. Learn more about our Solar Panel Cleaning and let’s get to work. Thanks for asking “Do solar panels need to be cleaned?”