As monthly generations of solar power plants vary according to their environment, especially to solar radiation and temperature on the backside of the PV panels, it is difficult to quantitively grasp a long-term decline trend of generation and to estimate the main hazard only by monitoring a time series of the generation data．This paper reports a development of a hazard estimation method of photovoltaics, especially for small-scale plants, based on long-term trend of generation and solar radiation data.
