This paper presents a practical method to detect any accidental partial shadowing on an operating photovoltaic (PV) panel in a smart generation system including a control center. Given a known solar irradiance level and temperature it is possible to make an automatic estimation of the output electrical power and to trigger an alarm in case of an accidental shadowing occurrence. Preliminary field measurements data are taken to evaluate the PV panel parameters once and for all. Simulation of the panel in operation is performed with the mathematical method of Design of Experiments (DoE): the maximum power parameter is considered as critical for the protection and security of the PV panel. Its value is computed and any amount of partial shadowing is then detected from the difference between the measured and the calculated values of this parameter. This method can be easily implemented in any smart PV generation system as an alarm trigger in actual operation to insure complete safety of the generation system.