In the long-term stable use of the photovoltaic (PV) power plant, the regular confirmation of output power drop is important. In the large-scale PV power plant, remote monitoring system for power generation state is introduced. However, such a system is not provided in the small and middle scale PV power plant. We developed a portable generation amperometry recording device of solar cell string as a tool watching a generation state. In this paper, we report the brief introduction of the device and the experimental results that were obtained in a PV power plant operated for about 17 years.
