# Investigation of Failures during Commissioning and Operation in Photovoltaic Power Systems
## 5 Conclusions  
Faults in photovoltaic power plants are situations that prevent or reduce power production. While these malfunctions are sometimes easy to fix, sometimes it may take a long time to detect and fix them, and this may lead to financial losses.  
In this study, electrical faults seen in photovoltaic power plants are classified and standardized. The classification process is made according to the places where the faults occur and the reasons why faults occur. With this categorization process, the possible causes and locations of malfunctions are described to make it easier to detect and eliminate malfunctions. A real power plant, which was implemented in the field, was modeled in the MATLAB Simulink program, electrical faults were simulated, and the results of the modeled faults were concretized. In this way, fault detection and finding solutions are no longer a challenge for businesses, and with the help of modeling fault situations, the equipment that may be affected by the fault and the ways in which it is affected are concretized.  
In the study, the data that can be used to interpret the effects of faults are the graphical outputs of the model and the size of the region where the faults are created.  
According to the graphical outputs obtained from the modeled faults, the fault type that has the most impact on the network is the phase-to-phase short-circuit fault that occurs on the AC side. It is seen that the phase-to-phase short-circuit fault occurring on the AC side is the fault that causes the biggest differences in current and voltage values. On the DC side, the highest value change was seen in the line-ground short-circuit fault that occurred on the DC side.  
According to the graphical outputs obtained from the modeled faults, it is seen that the fault types that have the most impact on the system are line-to-line and line-to-ground short-circuit faults on the DC side. In photovoltaic power systems, there are various types of equipment on the DC side such as photovoltaic panels, combiner junction boxes, and DC input parts of inverters. For this reason, DC line-to-line and line-to-ground short-circuit faults are the faults that most affect the equipment in photovoltaic power plants.  
Although causing production stops, it has been determined that the fault that has the least impact on the equipment and the least risk of permanent damage is the AC open-circuit fault.  
Although there are other studies on this subject, the most important feature that distinguishes this study from other studies is that this study is comprehensive and detailed. Since the model here is a real photovoltaic power plant, similar work can be applied to other photovoltaic power plants.  
Even though a real photovoltaic power plant is modeled in this study, the real effects of the faults may not be seen since most photovoltaic power plants do not record faults regularly. Also, it is not easy to detect all the faults in a power plant. In addition to this study, if the faults seen in a photovoltaic power plant are recorded in the future and modeled on MATLAB Simulink, then the model outputs can be compared with the fault records kept during the actual fault to test the accuracy of the model.  
**Author Contributions:** Conceptualization, S.S., B.O. and M.G.; methodology, S.S.; software, M.G.; validation, S.S., B.O. and M.G.; formal analysis, S.S.; investigation, M.G.; resources, M.G.; data curation, S.S. and B.O.; writing--original draft preparation, M.G.; writing--review and editing, M.G.; visualization, M.G.; supervision, B.O.; project administration, S.S. and B.O.; funding acquisition, S.S., B.O. and M.G. All authors have read and agreed to the published version of the manuscript.  
This research received no external funding.  
Not applicable.  
**Data Availability Statement:** Data are contained within the article.  
The authors declare no conflict of interest.