Loss of Electricity
When solar panels are dirty, the do not produce the electricity they are capable of producing; the dirtier the panel, the less the electrical output. One also runs the risk of damaging or killing a solar panel if dirt accumulates in one area of a panel (source SunPower Engineers).
Most clean two to four times a year. This results in clean panels 50 to 100 days over a lifecycle of 9,125 days (excluding leap years).As a panel gets dirty the output reduces. This reduction, which is cumulative, means simply that you are not getting the ROI that you thought. To overcome this, some companies actually have to add additional panels to ensure that they are able to generate the amount of electricity the customer contracted to receive. Often adding our system can eliminate the need for additional panels. This offset can pay for the cost of our system and still generate additional profit. The higher the loss at the specific location of your solar field, the greater the ROI with our system.