The single diode equivalent circuit allows describing photovoltaic panels behavior quite accurately. The values of the five parameters appearing in this model are usually identified in Standard Test Conditions, at which irradiance and temperature values are given. Instead, when this identification has to be performed on field, suitable environmental sensors are required. In this paper, a method is presented for identifying the single diode model parameters as well as the irradiance and temperature conditions at which the panel is actually working. The method has the measured panel current vs voltage curve as the only input and it is suitable for being implemented on an embedded system for field applications. The method is validated through a large database of experimental results.