Guidelines for Protection against Overcurrent in Photovoltaic Generators

This paper gives the scientific background and basic premises that should guide the design of overcurrent protection in photovoltaic generators (PVGs). Overcurrent protection first requires a thorough knowledge of potential risk scenarios and how to evaluate them. Accordingly, this paper describes electrical faults that may pose a risk to PVG because of overcurrents. It also evaluates these faults with a dynamic PVG model. This simulation model provides a realistic vision of the thermal and electrical behavior of the PVG from which implications of overcurrent protection can be drawn. A field test on a functioning 68-kWp PVG showed the accuracy of the simulation results regarding the risk of overcurrents, and validated the model used in our study. Within this context, this paper discusses how protective measures in the IEC 60364-4-43 can be applied to PVG. Since the measures in this standard were specifically conceived for alternating current low voltage (AC LV) systems, the unique operational characteristics of a PVG now make it necessary to revise and adapt them.