One method for the maintenance and inspection of photovoltaic power generation systems is to confirm the shape change of their I-V characteristics. In this study, we propose a method to represent the shape of the I-V characteristic by FF and determine the shape change based on the numerical value of FF. The determination condition of the shape change is derived based on the relationship between FF, irradiance, and module temperature, and the data outside this condition are eliminated. The determination condition is derived again from the remaining data, and the data outside this condition are eliminated. This is repeated until there are no data outside the determination condition. The eliminated data are considered to exhibit a shape change. By applying this method to mega photovoltaic systems, it is possible to determine the shape change of their I-V characteristics.
