Energy and economic losses due to soiling on utility scale PV system to guide timing of cost effective cleaning

The cost benefit analysis of when to wash a solar system and how often is an important consideration for solar PV system operators. This paper discusses two site specific methods for owners to cost effectively determine suitable timings of module washings. One method uses IV curve tracing on test panels while the other uses direct measurement of energy production on control and system panels. Through a specific California based case study it is shown that both methods can provide details that will give the operator greater confidence that the choice to clean is a cost effective decision.