Fault Diagnostic Device for Photovoltaic Panels

A device for fault diagnosis of photovoltaic (PV) panels is presented. By sampling the terminal voltage and current of the panel when the connected PV system is tracking the maximum power point, the device simultaneously utilizes the sampled information to estimate and observe the drift of the intrinsic parameters of the panel. Compared with prior-art approaches of using static current-voltage characteristics to perform fault diagnosis, the proposed device extracts the dynamic characteristics, allowing fast parameter estimation and offering an in-depth understanding of the failure mode. A prototype device has been built and evaluated on a test bed with four 80W panels, with two of them being healthy and the other two having different degrees of damage. All experiments are conducted under a controlled testing environment. Results reveal that the intrinsic parameters, such as the reverse saturation current, output resistance, and junction capacitance, of the damaged panels can significantly deviated from the nominal values. This gives an indication of the health of the panel. Moreover, the prototype sends the estimated intrinsic parameters to the PV system over the power cable through power line communication. Therefore, the merits of this concept lie in its modularity, scalability, and remote fault diagnosis capability.