1. IntroductionShading is the most important cause of vulnerability for the power delivered by the photovoltaic module. 5% (for example) of shading on the photovoltaic module leads to a decrease in the module capacity which can reach over 60 or 70% of the module power. This is due to the cells connected in a string, where the cell with the lowest illumination is the main reason for the complete reduction of the current series. On the other hand, it is possible that the cells become shaded and reverse polarized, and power dissipation by the rest of the cells in the string creates "hot spots" that have the thermal potential to destroy the module. This is why it is advisable to avoid any cause of shading on photovoltaic modules. Shading due to buildings, chimneys, trees, towers, or even other parts of the same building.2. Research2. 1. Previous research Shading, which is found on one cell of a group of cells connected in series, leads to reverse polarization in these cells, the reverse polarization and breakdown of the microplasma were explained and physically described by Bishop (1988) . A comprehensive analysis of reverse-polarized solar cells was carried out, and applied to the Bishop model by Kovach (1995), in order to obtain conclusions regarding the formation of hot spots and the reduction of the performance of photovoltaic panels. Alonso and Chenlo (1988) provided measurements for crystalline cells and amorphous cells which led to them becoming commercially available. Kovach (1995) again found that poor placement of photovoltaic panels and under the same shading conditions leads to significant energy losses, and even small shadows can significantly influence energy return. The researchers also observed that all UI characteristics of the solar cells in the reverse polarization show greater variation compared to the polarization... in the center of the paper... in the electrical behavior of the PV panels in the shade. First, Rauschenbach (1968) presented a mathematical description of shaded photovoltaic fields. Subsequently, Abete et al. (1989) studied the behavior of solar cells connected in series and parallel, subjected to partial shade by applying the Bishop model. Today the commercial market thrives with a large number of software tools capable of evaluating the behavior of photovoltaic systems. But not all are suitability tests at the solar cell level under reverse bias conditions (Zehner, 2001). RESEARCH QUESTIONS: - How to estimate the reduction in energy yield of partially shaded photovoltaic systems? - How to make changes in the system design to bring about improvements in energy production efficiency? - What are the latest methodologies that can be adopted to overcome the demerits related to shading? - What are the advantages of using the micro inverter ?