Soiling of solar PV modules will degrade system performance, particularly In California’s agricultural regions where tilling and harvesting operations stir up dust. One of the most common questions we get is, “How frequently should we clean our solar panels?” Let’s take a look at a recent soiling analysis we conducted to help answer that question.

CalCom Energy uses real-time monitoring to track solar production data at sites within our asset management portfolio. We measure actual solar production against weather-adjusted production estimates. If a system is underperforming and equipment malfunction is ruled out, we can quantify the impact of soiling.

The chart below demonstrates the loss of performance on a system that was not being cleaned regularly. Over a four-month period, soiling reduced the performance of this 1MW system by half: