Investigation of the Effect of Different Shading Scale on the Operating of Photovoltaic Modules Using Numerical Simulations

The photovoltaic (PV) module is the basic building block of each photovoltaic system. Output power of the PV module and the produced energy strongly depends on the operating conditions. The operating temperature of the device, ambient temperature, solar radiation intensity, humidity, and dustiness can be considered as the most important factors. A significant decrease of delivered power occurs in the case of partial or complete shading of PV module, which comes e.g. from clouds, surrounding buildings, pillars, snow or e.g. from various impurities (bird droppings). This shading brings, in addition to power loss, an associated problem of existence two (or more) power maxima in the P-V curve. Existence of "two knees" on the I-V characteristic can negatively affect the operation of the associated electronics (MPP tracker). No less important problem related to power losses is creation of the hotspots (places of excessive local heating). Shaded part of the module behaves like an electric load and converts electric energy into joule heat. Hotspot affects safety (fire, destruction of equipment) and reliability of electricity supply from PV device. Comprehensively analysis of the negative consequences of the different degree of shading of the PV module parts, as well as the role of bypass diodes following the reliability in power engineering is very useful. Practical experiments on created experimental PV module were confronted with the simulations in MATLAB. Presentation of simulation and results useful for practice are main aim of this paper.