Abstract
Photovoltaic system construction of the module capacity in domestic is specified criteria to less than 105% of the inverter capacity. However, the modules are installed in the outdoor actual output is reduced due to factors such as the irradiation intensity, module surface temperature. Thus, it needs the capacity of the inverter to be designed according to the actual module output. In this paper, the first approach to find the actual module output is to analyze the actual PV system monitoring data. Next, four sites where the loss analysis, system utilization, inverter utilization, and the ratio of the inverter overload are performed using PVSYST software. By changing the ratio of the module capacity, the inverter capacity of the site B is confirmed 20% less than the module capacity. Site A, C, D are identified as the ratio of the inverter capacity is 10% less than the module capacity.