Simulation Resolution of PV System Partial Shading Studies

Many research groups have studied the operation of partially shaded photovoltaic (PV) systems during the past decades, and the well-known one-diode model of a PV cell has been mainly used to model the electrical behaviour of the PV systems. However, the effects of data sampling resolution have obtained little attention and even some meaningless results appear in the literature caused by unsuitable sampling resolution.
In this paper, the effects of the length of a simulation time step, the resolutions of irradiance and I–U curves and the size of a basic simulation unit on the accuracy of the simulations of PV system operation under partial shading conditions were studied. The operation of PV systems was simulated by using the one-diode model of a PV cell. The study aimed to find out adequate resolution for the simulation parameters to minimise the computing time while retaining sufficient accuracy of the simulations. The study was based on the apparent velocity and other characteristics of 7880 irradiance transitions caused by moving clouds and identified in measured irradiance data. The results show that the accuracy of 1 W/m2 is sufficient for the irradiance and, accordingly, 1000 points for the I–U curves for PV string and array level partial shading studies.