Cleaning cycle optimization and cost evaluation of module dust for photovoltaic power plants in China

The photovoltaic (PV) power plants installed in the northwest and northeast areas of China have a serious dust pollution problem. In this paper, a model for optimizing the cleaning cycle of module dust and evaluating the cost for the PV power plants in China was proposed by the use of dust deposition monitoring with image recognition and two cleaning technologies. Outdoor experimental results showed that the degradation of power conversion efficiency changed linearly with increasing the image gray value and the dust deposition density had an asymptotic relationship with dust deposition time. Based on the proposed model and corresponding dry and wet cleaning technologies, the optimal cleaning cycles for a PV power plant in northeast China were approximately 10.1 and 22.8 days when the power conversion efficiency was reduced by 4.5% and 10.2%, respectively. The annual cost resulting from dust on the PV power modules in China was estimated to be $0.0161–0.0222 million per MW with current fixed cleaning cycle and wet cleaning technology. However, the annual cost could be reduced to 36.5–50.3% by using the optimized cleaning cycle and applying dry cleaning technology.