Shadowing effect on the power output of a photovoltaic panel

Shadowing effect occurs when a photovoltaic system does not receive the same amount of incident irradiation level throughout the system due to obstacles. In these conditions, the cells receiving a lower level of irradiance can absorb power instead of producing it. Bypass diodes are used to reduce the impact of shadowing effect and to protect the solar panel. In this paper, the shadowing effect on a panel is analyzed. A single diode solar cell model is built from datasheet values and the parameters are used to obtain the Simulink model of the panel with irradiance for each cell as a variable. Bypass diodes are used across every 10 cells in the panel and shadowing effect on this system is studied. A maximum power point tracking system using the perturb and observe algorithm and a buck converter are also added to the system. The simulation results show that the model derived is accurate. When the irradiance level is changed, the percentage increase in the maximum power point (MPP) is almost equal to the percentage increase in the incident irradiance level on the panel. Additionally, when bypass diodes are added to the system, higher values of MPP can be obtained during a partial shadow. However, they also introduce multiple local MPP into the system and this cause the maximum power point tracking (MPPT) algorithm to get stuck at a local maximum instead of the global maximum in some cases.