Partial Shading Fault Analysis In A Photovoltaic System

Photovoltaic Solar energy is without a doubt one of the most certain sources of energy that will become a large supplier of consumer energy in the future.Currently,it has become one of the most important renewable energy technologies,reaching a global cumulative installed capacity of about 303 GWDC at the end of 2016,with a forecasted additional capacity of at least 79 GW by the end of 2017,according to GSR 2017 report.This exponential growth was possible due to favorable policies,as well as decreasing cost of PV modules and balance-of-system components.With the said advancements however,the technology is faced with output related losses,posing a great challenge to compete effectively with the fossil energies.One of the major sources of losses in photovoltaic is the mismatch between the amounts of energy generated by some of the modules inside an array.This mismatch can be caused by for instance partial shading of the modules due to array's modules self-shading,cloud effect among other shading agents.Partial Shading greatly affects the performance of solar photovoltaic(PV)array system.It reduces the power output of the system drastically as the modules of the array receive different solar irradiance.Abnormal conditions such as faults and partial shading lead to a reduction in the maximum available power from a photovoltaic(PV)array.Thus,it is necessary to detect partial shading fault in a PV array for improved system output and reliability.This study investigates the effect of partial shading on a PV array of crystalline silicon modules.This was done through the study and analysis of the I-V/P-V characteristic curves under illuminated and shaded conditions under row and column shading patterns.When analyzing the shading impacts,the ?-?/P-V curve has been shown to be most useful,where the main indicator of reduced potential power production is the short-circuit current.Outdoor experiments were conducted to study the output characteristics and later Simulink simulations to validate the experimental results.To create the partial shading effect,a thick sheet of low transmissivity was used to cover the modules under investigation.The ?-? tracer was used in the experiment to display the results of the output parameters along the ?-?/P-V curves.These parameters;Pm,Voc,Vm,Isc and Im were used in analyzing the effect of each shading pattern on the PV array.The results revealed that partial shading losses are not proportional to the shaded area in the module but they are dependent on the shading pattern.In this sense,row shading critically affects power output of a PV module as compared to column shading.